Hydraulic Characteristics of Bedrock Constrictions and an 

Evaluation of One- and Two-Dimensional Models of Flood 

Flow on the Big Lost River at the Idaho National Engineering 

and Environmental Laboratory, Idaho

Scientifi c Investigations Report 2007–5080

Prepared in cooperation with the U.S. Department of Energy

U.S. Department of the Interior

U.S. Geological Survey

DOE/ID-22194
Cover: View looking downstream through the site 2 constriction in the Big Lost River, 

about 2.5 miles downstream of the diversion dam, Idaho National Engineering and 

Environmental Laboratory, Idaho (photograph taken on July 19, 2000).

View looking downstream through the site 2 constriction in the Big Lost River, about 2.5 miles downstream of the diversion dam, Idaho National Engineering and 

Environmental Laboratory, Idaho (photograph taken on May 31, 2006). Measured flow was 10 m3/s on May 31, 2006. Water-surface elevation for this flow was 

measured on July 11, 2006.
Hydraulic Characteristics of Bedrock 

Constrictions and an Evaluation of One- and 

Two-Dimensional Models of Flood Flow on the 

Big Lost River at the Idaho National Engineering 

and Environmental Laboratory, Idaho

By Charles Berenbrock, Joseph P. Rousseau, and Brian V. Twining

Prepared in cooperation with the

U.S. Department of Energy

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2007–5080
U.S. Department of the Interior

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Meyers, Director

U.S. Geological Survey, Reston, Virginia: 2007

For sale by U.S. Geological Survey, Information Services

Box 25286, Denver Federal Center

Denver, CO 80225

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Telephone: 1-888-ASK-USGS

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Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply 

endorsement by the U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Berenbrock, C., Rousseau, J.P., and Twining, B.V., 2005, Hydraulic characteristics of bedrock constrictions and an 

evaluation of one- and two-dimensional models of flood flow on the Big Lost River at the Idaho National Engineering 

and Environmental Laboratory, Idaho: U.S. Geological Survey Scientific Investigations Report 2007-5080, 206 p. 
iii

Contents

Abstract ................................................................................................... 1

Introduction................................................................................................ 2

Purpose and Scope ................................................................................. 4

Description of Study Area ........................................................................ 5

Previous Investigations ........................................................................... 8

Streambed and Channel Characterization ............................................................ 10

Sampling of Armored Surface Layer ............................................................ 10

Trench Excavation and Channel-Fill Sampling ................................................ 10

Coarse-Grained Particle-Size Analysis ................................................... 16

Fine-Grained Particle-Size Analysis......................................................... 17

Description of Trench Excavations ......................................................... 17

Channel Surveys .................................................................................... 21

Horizontal Referencing ..................................................................... 23

Vertical Referencing ........................................................................ 23

TIN-Generated Cross Sections ............................................................ 23

Hydraulics of the Study Reach ........................................................................ 28

Constriction-Controlled Sections.................................................................. 28

Channel-Controlled Sections ..................................................................... 28

Numerical Modeling .................................................................................... 29

HEC-RAS Model Implementation.................................................................. 29

Manning’s n Determination .................................................................. 30

HEC-RAS Simulation Results ............................................................... 31

HEC-RAS Sensitivity Analysis ............................................................... 39

HEC-6 Model Implementation ..................................................................... 46

HEC-6 Simulation Results..................................................................... 47

Comparisons of HEC-6 and HEC-RAS Water-Surface Elevations........................ 51

Comparisons of Channel and Floodplain Geometries Used in HEC-RAS and HEC-6 Models with 

Those Used in TRIM2D Model ..................................................................... 53

Thalwegs............................................................................................. 53

Channel Cross Sections ........................................................................... 54

Comparisons of HEC-RAS, HEC-6, and TRIM2D Simulation Results .............................. 61

Comparisons of HEC-RAS and TRIM2D Water-Surface Elevations ........................... 62

Constrictions ................................................................................. 66

Paleoindicator Sites ........................................................................ 67

Flow Equivalency.............................................................................. 67

Comparisons of HEC-6 and TRIM2D Water-Surface Elevations .............................. 71

Comparisons of HEC-RAS and TRIM2D Flow Depths .......................................... 71

Comparisons of HEC-RAS and TRIM2D Flow Velocities ....................................... 76

Comparisons of HEC-RAS and TRIM2D Stream Power ....................................... 77

Summary and Conclusions .............................................................................. 81
iv

Figures

Figure 1. Map showing location of the Big Lost River Basin and the Idaho National

Engineering and Environmental Laboratory, Idaho .................................... 3

Figure 2. Map showing general location of study area, constrictions, trench sites,

reference points, control points, and streamflow-gaging stations on the Big

Lost River, Idaho National Engineering Environmental Laboratory, Idaho............ 6

Figure 3. Map showing generalized geology in the vicinity of the study area, Idaho

National Engineering and Environmental Laboratory, Idaho ........................... 7

Figure 4. Map showing location of the study area, constrictions, control points,

surface-particle sampling sites, and trenches T-4-A and T-5-A on the Big Lost

River upstream of the Pioneer diversion structures, Idaho National

Engineering and Environmental Laboratory, Idaho .................................... 9

Figure 5. Maps showing location of particle-sampling sites at sites 1, 2, and 3 on the Big 

Lost River, Idaho National Engineering and Environmental Laboratory, Idaho ...... 11

Figure 6. Graph and trilinear diagrams showing median size (d50) and ternary size

distribution of selected samples collected from the armored surface layer on

the Big Lost River upstream of the Pioneer diversion structures, Idaho

National Engineering and Environmental Laboratory, Idaho ........................... 13

Figure 7. Cross sections showing lithology of trenches T-1-B, T-1-D, and T-1-C across

the Big Lost River at site 1, Idaho National Engineering and Environmental

Laboratory, Idaho. ........................................................................... 19

Figure 8. Map showing location of field-surveyed cross sections on the Big Lost River

upstream of the Pioneer diversion structures, Idaho National Engineering and

Environmental Laboratory, Idaho ......................................................... 22

Figure 9. Maps showing location of field-surveyed, TIN-extended, and TIN-generated

cross sections used for flow simulations of 10, 50, and 70 cubic meters per

second and greater on the Big Lost River upstream of the Pioneer diversions

structures, Idaho National Engineering and Environmental Laboratory, Idaho...... 25

Contents—Continued

Acknowledgments ....................................................................................... 83

References Cited.......................................................................................... 83

Glossary ................................................................................................... 87

Appendix 1. Results of Armored-Surface-Layer Sampling at Various Locations on the Big 

Lost River Upstream of the Pioneer Diversion Structures, Idaho National Engineering 

and Environmental Laboratory ..................................................................... 89

Appendix 2. Sieve Analyses of Trench Samples from Sites 1, 2, 3, 4, and 5 on the Big Lost 

River Upstream of the Pioneer Diversion Structures, Idaho National Engineering and 

Environmental Laboratory ...........................................................................121

Appendix 3. Field-Surveyed Map of the Saddle Area at Site 1 on the Big Lost River 

Upstream of the Pioneer Diversion Structures, Idaho National Engineering and

Environmental Laboratory ...........................................................................197

Appendix 4. HEC-RAS, HEC-6, and TRIM2D Model Results for a Peak Flow of 100 Cubic 

Meters per Second on the Big Lost River Upstream of the Pioneer Diversion 

Structures, Idaho National Engineering and Environmental Laboratory .....................201
Figures—Continued

Figure 10. Graph showing daily mean discharge for the Big Lost River below the Idaho

National Engineering and Environmental Laboratory diversion dam

(13132520), Idaho, 1984–2000 ............................................................... 32

Figure 11. Graph showing flood-frequency curve for the Big Lost River near Arco

(13132500), Idaho, 1947–61 and 1965–2000................................................ 33

Figure 12. Longitudinal sections showing high-water marks, measured thalweg

elevation, and HEC-RAS simulated water-surface elevation for a peak flow of

10 cubic meters per second at the sites 1 and 2 constrictions on the Big Lost

River upstream of the Pioneer diversion structures, Idaho National

Engineering and Environmental Laboratory, Idaho .................................... 34

Figure 13. Longitudinal sections showing measured thalweg elevation and HEC-RAS

simulated water-surface elevations for selected flows of 50, 100, 150, and 200

cubic meters per second on the Big Lost River and sites 1 and 2 constrictions

upstream of the Pioneer diversion structures, Idaho National Engineering and

Environmental Laboratory, Idaho ......................................................... 36

Figure 14. Longitudinal section showing effects of changes in Manning’s n (roughness

coefficient) on HEC-RAS simulated water-surface elevations for a peak flow

of 100 cubic meters per second on the Big Lost River and sites 1 and 2

constrictions upstream of the Pioneer diversion structures, Idaho National

Engineering and Environmental Laboratory, Idaho .................................... 41

Figure 15. Longitudinal sections showing effects of lowering streambed elevation on

HEC-RAS simulated water-surface elevations for a peak flow of 100 cubic

meters per second on the Big Lost River and site 2 constriction upstream of

the Pioneer diversion structures, Idaho National Engineering and

Environmental Laboratory, Idaho ......................................................... 44

Figure 16. Longitudinal sections showing HEC-6 simulated water-surface and thalweg

elevations for peak flows of 70, 100, and 150 cubic meters per second on the

Big Lost River and at the site 2 constriction upstream of the Pioneer diversion

structures, Idaho Nation Engineering and Environmental Laboratory, Idaho ...... 48

Figure 17. Longitudinal sections showing linear-regression fits to the HEC-RAS and

HEC-6 thalweg elevations for a peak flow of 100 cubic meters per second for

the upper, middle, and lower reaches of the Big Lost River upstream of the

Pioneer diversion structures, Idaho National Engineering and Environmental

Laboratory, Idaho ........................................................................... 50

Figure 18. Longitudinal section showing HEC-RAS and HEC-6 simulated water-surface

elevations for peak flows of 70, 100, and 150 cubic meters per second on the

Big Lost River upstream of the Pioneer diversion structures, Idaho National

Engineering and Environmental Laboratory, Idaho .................................... 52

Figure 19. Longitudinal section showing thalweg elevations used in the HEC-RAS and

TRIM2D models of the Big Lost River upstream of the Pioneer diversion

structures, Idaho National Engineering and Environmental Laboratory, Idaho...... 55

Figure 20. Longitudinal sections showing linear-regression fits to the HEC-RAS and

TRIM2D thalweg elevations for the upper, middle, and lower reaches of the

Big Lost River upstream of the Pioneer diversion structures, Idaho National

Engineering and Environmental Laboratory, Idaho .................................... 56
vi

Figures—Continued

Figure 21. Cross sections showing selected channel cross sections used in the

HEC-RAS, HEC-6, and TRIM2D models of the Big Lost River upstream of the

Pioneer diversion structures, Idaho National Engineering and Environmental

Laboratory, Idaho ........................................................................... 57

Figure 22. Graphs showing stage- and depth-area curves for selected channel cross

sections used in the HEC-RAS and TRIM2D models of the Big Lost River

upstream of the Pioneer diversion structures, Idaho National Engineering and

Environmental Laboratory, Idaho ......................................................... 59

Figure 23. Longitudinal sections showing HEC-RAS and TRIM2D simulated

water-surface elevations for peak flows of 70, 100, and 150 cubic meters per

second on the Big Lost River and sites 1 and 2 constrictions upstream of the

Pioneer diversion structures, Idaho National Engineering and Environmental

Laboratory, Idaho ........................................................................... 63

Figure 24. Cross sections showing HEC-RAS and TRIM2D simulated water-surface

elevations at selected cross sections for a peak flow of 100 cubic meters per

second on the Big Lost River upstream of the Pioneer diversion structures,

Idaho National Engineering and Environmental Laboratory, Idaho .................. 68

Figure 25. Graphs showing HEC-RAS and TRIM2D simulated water-surface elevations

at selected cross sections for peak flows of 70, 100, and 150 cubic meters per

second on the Big Lost River upstream of the Pioneer diversion structures,

Idaho National Engineering and Envinromental Laboratory, Idaho .................. 70

Figure 26. Longitudinal section showing HEC-6 and TRIM2D simulated water-surface

and thalweg elevations for peak flows of 70, 100, and 150 cubic meters per

second on the Big Lost River upstream of the Pioneer diversion structures,

Idaho National Engineering and Environmental Laboratory, Idaho .................. 72

Figure 27. Graphs showing HEC-RAS, HEC-6, and TRIM2D simulated flow depths and

LOWESS-smoothed flow depths for peak flows of 70, 100, and 150 cubic

meters per second on the Big Lost River upstream of the Pioneer diversion

structures, Idaho National Engineering and Envinronmental Laboratory, Idaho ... 73

Figure 28. Graph showing HEC-RAS and TRIM2D simulated flow velocities in the main

channel for a peak flow of 100 cubic meters per second on the Big Lost River

upstream of the Pioneer diversion structures, Idaho National Engineering and

Environmental Laboratory, Idaho ......................................................... 79

Figure 29. Graph showing HEC-RAS and TRIM2D simulated stream power in the main

channel for a peak flow of 100 cubic meters per second on the Big Lost River

upstream of the Pioneer diversion structures, Idaho National Engineering and

Environmental Laboratory, Idaho ......................................................... 80
vii

Tables

Table 1. Particle-size characteristics of samples collected from the armored surface

layer at selected sites on the Big Lost River upstream of the Pioneer

diversion structures, Idaho National Engineering and Environmental

Laboratory, Idaho ........................................................................... 14

Table 2. Particle-size characteristics from sieve analysis of trench samples used in

the HEC-6 model at sites 1 through 5 on the Big Lost River upstream of the

Pioneer diversion structures, Idaho National Engineering and Environmental

Laboratory, Idaho ........................................................................... 15

Table 3. Location and description of elevation control and reference points used to

establish horizontal and vertical control for the thalweg and cross-section

surveys on the Big Lost River upstream of the Pioneer diversion structures,

Idaho National Engineering and Environmental Laboratory, Idaho .................. 24

Table 4. Sensitivity of simulated water-surface elevations to changes in Manning’s n

(roughness coefficient) for a peak flow of 100 cubic meters per second on the

Big Lost River upstream of the Pioneer diversion structures, Idaho National

Engineering and Environmental Laboratory, Idaho .................................... 40

Table 5. Sensitivity of simulated water-surface elevations to lowering of the

streambed elevation by 1, 2, and 4 feet for a peak flow of 100 cubic meters

per second on the Big Lost River upstream of the Pioneer diversion

structures, Idaho National Engineering and Environmental Laboratory, Idaho...... 40

Table 6. Differences in HEC-RAS and HEC-6 simulated water-surface and thalweg

elevations for peak flows of 70, 100, and 150 cubic meters per second on the

Big Lost River upstream of the Pioneer diversion structures, Idaho National

Engineering and Environmental Laboratory, Idaho .................................... 51

Table 7. Differences in HEC-RAS and TRIM2D thalweg elevations and slopes along

the upper, middle, and lower reaches of the Big Lost River upstream of the

Pioneer diversion structures, Idaho National Engineering and Environmental

Laboratory, Idaho ........................................................................... 54

Table 8. Differences in HEC-RAS, HEC-6, and TRIM2D simulated water-surface

elevations for peak flows of 70, 100, and 150 cubic meters per second on the

Big Lost River upstream of the Pioneer diversion structures, Idaho National

Engineering and Environmental Laboratory, Idaho .................................... 66

Table 9. HEC-RAS peak flows needed to match TRIM2D water-surface elevations for

peak flows of 70, 100, and 150 cubic meters per second on the Big Lost River

upstream of the Pioneer diversion structures, Idaho National Engineering and

Environmental Laboratory, Idaho ......................................................... 67

Table 10. HEC-RAS and TRIM2D simulated flow velocities at selected cross sections

for peak flows of 70, 100, and 150 cubic meters per second on the Big Lost

River upstream of the Pioneer diversion structures, Idaho National

Engineering and Environmental Laboratory, Idaho .................................... 77

Table 11. HEC-RAS and TRIM2D simulated stream power at selected cross sections for

peak flows of 70, 100, and 150 cubic meters per second on the Big Lost River

upstream of the Pioneer diversion structures, Idaho National Engineering and

Environmental Laboratory, Idaho ......................................................... 78
viii

Conversion Factors and Datums

Conversion Factors

Multiply By To obtain

acre-foot (acre-ft) 1,233 cubic meter

cubic foot per second (ft3/s) 0.02832 cubic meter per second

foot (ft) 0.3048 meter

foot (ft) 30.48 centimeter

foot per mile (ft/mi) 0.1894 meters per kilometer

inch (in.) 2.54 centimeter

inch per year (in/yr) 25.4 millimeter per year

mile (mi) 1.609 kilometer 

pound (lb) 0.4536 kilogram

pound per foot-second [lb/)ft-s)] 14.594 Watt per square meter

square foot (ft2) 0.0929 square kilometer

square mile (mi2) 2.590 square kilometer

Watt per square meter (W/m2) 1.0 meter-Newton per second per 

square meter

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

 °C=(°F-32)/1.8

Datums

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD83).

Elevation, as used in this report, refers to distance above the vertical datum.

A note about units used in this report: English units (ft-lb-s) are used for measures of elevation, 

vertical and horizontal distance, volumetric flow rate, flow velocity, flow depth, and stream 

power. SI units (m-kg-s) are used for measures of volumetric flow rate and particle size. Both 

types of units are used to facilitate comparisons with earlier work, to preserve the integrity 

of the original field-surveyed data, and to provide consistency between field survey units and 

topographic map units that were used in this and earlier cited studies.
Abstract 

A 1.9-mile reach of the Big Lost River, between the 

Idaho National Engineering and Environmental Laboratory 

(INEEL) diversion dam and the Pioneer diversion structures, 

was investigated to evaluate the effects of streambed erosion 

and bedrock constrictions on model predictions of watersurface elevations. Two one-dimensional (1-D) models, 

a fixed-bed surface-water flow model (HEC-RAS) and a 

movable-bed surface-water flow and sediment-transport 

model (HEC-6), were used to evaluate these effects. The 

results of these models were compared to the results of a 

two-dimensional (2-D) fixed-bed model [Transient Inundation 

2-Dimensional (TRIM2D)] that had previously been used to 

predict water-surface elevations for peak flows with sufficient 

stage and stream power to erode floodplain terrain features 

(Holocene inset terraces referred to as BLR#6 and BLR#8) 

dated at 300 to 500 years old, and an unmodified Pleistocene 

surface (referred to as the saddle area) dated at 10,000 years 

old; and to extend the period of record at the Big Lost River 

streamflow-gaging station near Arco for flood-frequency 

analyses. The extended record was used to estimate the 

magnitude of the 100-year flood and the magnitude of floods 

with return periods as long as 10,000 years.

In most cases, the fixed-bed TRIM2D model simulated 

higher water-surface elevations, shallower flow depths, 

higher flow velocities, and higher stream powers than the 

fixed-bed HEC-RAS and movable-bed HEC-6 models for 

the same peak flows. The HEC-RAS model required flow 

increases of 83 percent [100 to 183 cubic meters per second 

(m3

/s)], and 45 percent (100 to 145 m3/s) to match TRIM2D 

simulations of water-surface elevations at two paleoindicator 

sites that were used to determine peak flows (100 m3

/s) with 

an estimated return period of 300 to 500 years; and an increase 

of 13 percent (150 to 169 m3/s) to match TRIM2D watersurface elevations at the saddle area that was used to establish 

the peak flow (150 m3/s) of a paleoflood with a return period 

of 10,000 years. A field survey of the saddle area, however, 

indicated that the elevation of the lowest point on the saddle 

area was 1.2 feet higher than indicated on the 2-ft contour map 

that was used in the TRIM2D model. Because of this elevation 

discrepancy, HEC-RAS model simulations indicated that a 

peak flow of at least 210 m3/s would be needed to initiate flow 

across the 10,000-year old Pleistocene surface. 

HEC-6 modeling results indicated that to compensate for 

the effects of streambed scour, additional flow increases would 

be needed to match HEC-RAS and TRIM2D water-surface 

elevations along the upper and middle reaches of the river, 

and to compensate for sediment deposition, a slight decrease 

in flows would be needed to match HEC-RAS water-surface 

elevations along the lower reach of the river. 

Differences in simulated water-surface elevations 

between the TRIM2D and the HEC-RAS and HEC-6 models 

are attributed primarily to differences in topographic relief and 

to differences in the channel and floodplain geometries used 

in these models. Topographic differences were sufficiently 

large that it was not possible to isolate the effects of these 

differences on simulated water-surface elevations from those 

attributable to the effects of supercritical flow, streambed 

scour, and sediment deposition. 

Hydraulic Characteristics of Bedrock Constrictions and 

an Evaluation of One- and Two-Dimensional Models of 

Flood Flow on the Big Lost River at the Idaho National 

Engineering and Environmental Laboratory, Idaho

By Charles Berenbrock, Joseph P. Rousseau, and Brian V. Twining
Introduction

The Big Lost River in southeastern Idaho flows onto the 

Idaho National Engineering and Environmental Laboratory 

(INEEL) and the Eastern Snake River Plain southeast of 

Arco, Idaho (fig. 1) and northward across the INEEL where it 

terminates in a series of playas and sinks. Flow in the river is 

extensively regulated to provide water for irrigation in the Big 

Lost River valley. Mackay Reservoir, a 38,500 acre-ft capacity 

reservoir (Williams and Krupin, 1984, p. 72) northwest of 

Mackay and about 45 mi upstream of the INEEL (fig. 1), and 

many large diversion channels are used to store and deliver 

irrigation water throughout the growing season. Although 

flooding at the INEEL is rare, it is important to accurately 

define these rare flood events so that planners and managers 

can evaluate the effects that flooding may have on facilities at 

the INEEL.

In 1996, the U.S. Geological Survey (USGS) completed 

a study for the U.S. Department of Energy (DOE) to estimate 

the 100-year peak flow for the Big Lost River at the INEEL. 

In that study, flow data from a streamflow-gaging station near 

Arco, upstream of the INEEL, were evaluated to estimate 

flood-flow frequency using a three-parameter log-Pearson 

Type III distribution as outlined in Guidelines for Determining 

Flood Flow Frequency, Bulletin #17B (Interagency Advisory 

Committee on Water Data, 1982). The resulting estimates for 

the 100-year flood for the Big Lost River near Arco produced 

very high levels of uncertainty at the upper and lower 95-

percent confidence limits. The log-Pearson Type III analysis 

resulted in a computed 100-year peak flow of 5,480 ft3

/s with 

upper and lower 95-percent confidence limits of 11,600 and 

3,150 ft3/s, respectively (Kjelstrom and Berenbrock, 1996)1. 

The large uncertainty was attributed primarily to interference 

effects caused by upstream flow regulation on recorded peak 

flows at the streamflow-gaging station near Arco, Idaho.

To circumvent the influence of flow regulation on 

peak-flow measurements at the Big Lost River streamflowgaging station near Arco, Kjelstrom and Berenbrock (1996) 

subsequently estimated the 100-year peak flow near Arco 

by adding flows estimated from flood-frequency curves for 

the Big Lost River at the Howell Ranch streamflow-gaging 

station (85 years of record; upstream of flow-regulation 

interference effects), and from Lower Cedar Creek (16 years 

of record; upstream of flow-regulation interference effects) 

to flows estimated using a regional-regression model applied 

to 22 ungaged subbasins in the Big Lost River drainage 

basin. Combined flows were routed downstream to Arco, 

and Dawdy’s (1979) equation was used to calculate channel 

infiltration losses. Channel infiltration losses between Arco 

and the INEEL boundary were not subtracted from the 

100-year peak flow estimate at Arco because these losses were 

assumed to be offset by runoff from local drainages between 

Arco and the INEEL. The resulting estimate for the 100-year 

peak flow using this approach was 7,260 ft3/s. Upper and 

lower confidence limits for this estimate were not provided. 

In 1999, the Bureau of Reclamation published a study 

of the Big Lost River (Ostenaa and others, 1999) that also 

included estimates of the 100-year peak flow at the INEEL. 

These estimates were derived from a combination of 

paleohydrologic data, streamflow-gaging data, and the results 

of a two-dimensional (2-D) numerical model that was used to 

simulate flood elevations for different assumed peak flows. 

Radiocarbon dating of buried charcoal remnants in terrace 

deposits adjacent to the main channel of the Big Lost River 

was used to establish the minimum age of floodplain terrain 

features that might be susceptible to inundation and erosion 

in the event of a large flood. The 2-D model was used to 

determine the flow needed to overtop and erode these dated 

surfaces. Long-term preservation of these surfaces was used as 

evidence that floods would need to exceed a limiting discharge 

for overtopping and erosion of these surfaces to occur. The age 

of the surface was used to define the minimum return period 

for the overtopping flood. These data were incorporated with 

data from the streamflow-gaging station near Arco to extend 

the period of record available for flood-frequency analysis. 

The resulting estimate of the 100-year peak flow was 

2,910 ft3/s, with upper and lower 97.5 percent confidence 

limits of 3,270 and 2,386 ft3/s, respectively (Ostenaa and 

others, 1999, p. 53). The 1999 Bureau of Reclamation 

estimate for the 100-year peak flow is 40 percent lower than 

the regional-regression model estimate presented in the 1996 

USGS study by Kjelstrom and Berenbrock (1996). 

In 2000, the USGS conducted another study (Hortness 

and Rousseau, 2002) to reevaluate the approach used by 

Kjelstrom and Berenbrock (1996) to estimate the 100-year 

peak flow. In this study, the 100-year peak flow at the Howell 

Ranch streamflow-gaging station, derived from a log-Pearson 

Type III analysis based on 93 years of flow record, was routed 

downstream and the magnitude of this flow was adjusted to 

account for gains and losses in streamflow based on regression 

models of flow attenuation between the Howell Ranch gaging 

station and Mackay Reservoir, between Mackay Reservoir 

and Arco, and between Arco and the INEEL diversion dam. 

The resulting estimate using this approach was 3,750 ft3

/s, 

with upper and lower 95-percent confidence limits of 6,250 

and 1,300 ft3/s, respectively. Uncertainty estimates using this 

approach were determined by pooling the upper and lower 

95-percent confidence limits for each of the three regression 

models with the uncertainty limits for the log-Pearson Type III 

analysis at the Howell Ranch gaging station. 

1

These values were revised in 2000 to correct an error in the earlier 

computations and to include additional data obtained since the 1996 study 

(n=47). Revised values are 4,990 ft3/s for the 100-year peak flow, 9,590 ft3/s 

for the upper 95-percent confidence limit, and 3,030 ft3/s for the lower 95-

percent confidence limit for the period 1947 through 1961, and 1965 through 

2000 (n=51).

 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
ID9HZ12_fig01

Study

area

Test 

Support

Facility

Central

Facilities

Area

Idaho Nuclear 

Technology and 

Engineering Center 

Firing

Range

area

Test 

Reactor

Area

Naval

Reactor

Facility

13132500

13120500

13128900

Butte

City

Arco

Leslie

Mackay

Moore

BirchCreekPlaya

BigLostRiverSinks

Playa 1

Playa 2

Creek

Playa 3

Birch

Creek

Antelope

Creek Wildhorse

Spreadingareas

Warm Springs

Creek

Thousand Springs Creek

ade C er ow L r r C

saP keer C s

Chilly

Buttes

Darlington

Sinks

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Canyon

I.N.E.E.L.

Diversion

Dam

ChillySinks

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Ranch

Borah

Peak

Mackay 

Big

Reservoir

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River

North

Fork 

East

Fork 

BUTTE

CLARK

BLAINE

CUSTER

JEFFERSON

BINGHAM

LOST

RIVER

RANGE

PIONEER

MOUNTAINS 

44°43°30’

113°30' 114° 112°30' 113°

IDAHO Figure location

Boise

Eastern Snake 

River Plain 

Snake 

River

Idaho

Falls 

EXPLANATION 

BIG LOST RIVER BASIN BOUNDARY

13132500

IDAHO NATIONAL ENGINEERING AND ENVIRONMENTAL LABORATORYSTREAMFLOW-GAGING STATION AND NO.

Base from U.S. Geological Survey 1:100,000 quadrangles 

0

0 5

5

10

10

15

15

20 30 25 35 40 45 KILOMETERS 

20 25 30 MILES 

Figure 1. Location of the Big Lost River Basin and the Idaho National Engineering and Environmental Laboratory, Idaho.

Introduction 
In the 2-D model simulations conducted by Bureau of 

Reclamation, overtopping of dated surfaces was used as the 

basis for assigning a magnitude and minimum return period 

for paleofloods with sufficient stream power to erode the 

dated surfaces. These modeling efforts and their associated 

geomorphologic studies were a pioneering contribution 

to understanding the hydraulics of flood flow on the Big 

Lost River and to bridging data limitations to estimate the 

magnitude of floods with return periods that are much longer 

than the existing historic record will support. 

In this study, the effect of bedrock constrictions and 

streambed scour on simulated water-surface elevations 

are evaluated. Bedrock constricts flow in the river at three 

locations in the study area. A field reconnaissance in 1999 

indicated that the depth of the alluvial fill in the channel 

bed in some of these constrictions is as much as 4 ft. If this 

fill is erodible, as was suggested by the ease with which 

steel rods were driven into the channel bed to determine 

depth of fill, then the through-flow or discharge capacity 

of the constrictions for a given stage quite likely increases 

as flow increases, thus lowering the water surface below 

those simulated under conditions that assume a fixed-bed 

configuration. Visual evidence of bed scour inside the 

constrictions is readily apparent (cover photograph) indicating 

that flow velocities and shear stresses are sufficient to erode 

the channel at flows that historically have been less (70 m3

/s) 

than current estimates [205 m3/s (Kjelstrom and Berenbrock, 

1996); 82 m3/s (Ostenaa and others, 1999); and 106 m3/s 

(Hortness and Rousseau, 2002)] of the 100-year peak flow.

Purpose and Scope

Earlier computer models used to analyze flooding on the 

Big Lost River did not account for scouring of the channel 

bed during flood events. Both the USGS one-dimensional 

(1-D) implementation (Kjelstrom and Berenbrock, 1996) of 

the Water-Surface PROfile (WSPRO) model and the Bureau 

of Reclamation’s two-dimensional (2-D) implementation 

(Ostenaa and others, 1999) of the Transient Inundation 2-

Dimensional (TRIM2D) model (Walters and Casulli, 1998) 

assumed that the channel bed remained stable during all flows. 

In natural streams high flows are likely to scour the channel 

bed, particularly in areas where water is forced to flow through 

narrow constrictions at high velocities. Backwater effects that 

produce higher hydraulic gradients across the constrictions, 

and thus higher flow velocities with greater potential to 

scour the streambed locally, accompany higher flows in the 

constrictions. Scouring, particularly within the constrictions, 

increases the cross-section area available for flow, reducing or 

limiting the accumulation of backwater that would result from 

a given flow. Because streambed scour was not accounted 

for in the earlier TRIM2D model simulations, predictions of 

water-surface elevations may have underestimated the amount 

of flow needed to overtop and erode floodplain surfaces that 

were used to date paleofloods with return periods of 300 to 

500 years and 10,000 years. These simulated flows along 

with their associated return periods were used to compute the 

magnitude of floods with return periods greater than 100 years 

and as long as 10,000 years (Ostenaa and others, 1999).

The purposes of the current study, the results of which 

are reported here, were (1) to evaluate the effects of channel 

constrictions and streambed scour and sediment deposition on 

simulated water-surface elevations in a reach of the Big Lost 

River downstream of the INEEL diversion dam, and (2) to 

compare these simulated water-surface elevations to those of 

the TRIM2D model that were used to determine the magnitude 

of peak flows needed to overtop and erode inset channel 

terraces dated at a minimum of 300 to 500 years old, and an 

unmodified Pleistocene surface dated at 10,000 years old.

Specific objectives of this study included: 

1. Determining the effects of channel constrictions on 

flow velocities and backwater;

2. Determining water-surface elevations resulting from 

the separate and combined effects of changes in flow 

regime and streambed scour and sediment deposition 

during periods of high flow, and comparing these 

elevations to those estimated by Ostenaa and others 

(1999) for paleofloods with return periods of 300 to 

500 years and 10,000 years; and

3. Determining flow velocities and stream powers 

associated with peak flows capable of overtopping 

and eroding floodplain terrain features that were 

used to establish paleoflood return periods of 300 to 

500 years and 10,000 years in the study by Ostenaa 

and others (1999).

The scope of this study included:

1. Excavation of the river channel upstream, 

downstream, and within the confines of three key 

bedrock constrictions to determine depth to bedrock 

and composition of the alluvial fill;

2. Characterization of the armored surface layer 

in selected reaches of the river to determine the 

susceptibility of the streambed to scour;

3. High resolution definition of the channel and 

floodplain geometry to support 1-D modeling of 

flow through a reach of the river that includes all 

three bedrock constrictions of interest;

4. A field topographic survey of the land-surface 

elevations near the “saddle area” to determine the 

lowest elevation of the unmodified 10,000-year old 

Pleistocene surface;

5. Development of two 1-D flow models to simulate 

water-surface elevations and backwater effects at 

peak flows of 50, 100, 150, 187, and 200 m3/s using 

the: 

 (a) Current streambed elevation of the channel

 bed (HEC-RAS); and 

 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
 (b) Streambed elevation under conditions of 

 maximum possible scour (HEC-6); 

6. Comparison of the results of the 1-D models 

(HEC-RAS and HEC-6) to those of the 2-D 

model (TRIM2D) that were used by the Bureau 

of Reclamation to establish the magnitude of 

paleofloods with minimum return periods of 300 

to 500 years and 10,000 years (Ostenaa and others, 

1999).

Description of Study Area

The Big Lost River is on the northwestern side of the 

Eastern Snake River Plain (fig. 1). The upper portion of the 

Big Lost River drainage basin trends northwest to southeast 

and is bordered by mountains along its northern, western, 

and southern boundaries. Southeast of Arco, Idaho, the Big 

Lost River flows onto the broad, undulating Eastern Snake 

River Plain, a northeast-trending structural basin about 200 mi 

long and 50 to 70 mi wide. Most of the INEEL overlies 

extensively fractured and highly permeable Holocene and 

Pleistocene basalt lava flows that are covered by a thin veneer 

of eolian and sedimentary deposits. As a result, all flow from 

the Big Lost River onto the Eastern Snake River Plain either 

evaporates or infiltrates into the ground. The Big Lost River 

terminates in a series of interconnected playas and the Big 

Lost River sinks near the northern end of the INEEL. 

The Big Lost River drains about 1,410-mi2 upstream of 

the USGS gaging station near Arco. The upper basin is mostly 

mountainous with a relatively flat, elongated valley varying 

in width between 2 and 10 mi. Elevations range from about 

5,300 ft on the valley floor near Arco to more than 12,600 ft 

in the Lost River Range (fig. 1). The mean basin elevation 

is about 7,700 ft and the mean basinwide precipitation is 

about 20 in/yr. The mean elevation of the valley floor is about 

6,000 ft and the mean precipitation over the valley floor is 

about 10 in/yr. Precipitation on the mountains, in the form of 

snow, supplies most water in the valley. 

Mackay Reservoir, 30 mi upstream of Arco and 45 mi 

upstream of the boundary of the INEEL, stores water from the 

Big Lost River for irrigation. Before reaching the plain, most 

water stored in the reservoir and most tributary inflow between 

the reservoir and Arco are diverted for irrigation or lost by 

infiltration through the streambed. During many years, little 

or no flow is recorded at streamflow-gaging station 13132500, 

Big Lost River near Arco. When the water supply is adequate, 

the Big Lost River flows onto the INEEL and terminates in 

a series of playas in the northern part of the INEEL (fig. 1). 

A diversion dam (fig. 1) on the INEEL is used to route water 

away from the main channel of the Big Lost River to a series 

of interconnected spreading areas to prevent flooding of 

several downstream facilities—the Idaho Nuclear Technology 

and Engineering Center (INTEC), the Test Reactor Area 

(TRA), and the Naval Reactor Facility (NRF). 

The study area covers a 1.9 mi reach that extends 

upstream of the Pioneer weir and canal diversion structures to 

a point about 2.3 mi downstream of the INEEL diversion dam 

(fig. 2). In the study area, the Big Lost River is an ephemeral 

stream with broad, sweeping meanders that typically are 

incised less than 20 ft into the surficial sediments and 

subcropping basalts (fig. 3).

The river channel is constricted at three points within the 

study area (fig. 2). At these constrictions, the river narrows 

considerably (45 to 27 ft at site 1; 57 to 17 ft at site 2; and 53 

to 46 ft at site 3) and is confined by nearly vertical walls cut 

into basalt. At the site 2 constriction (cover photograph), the 

narrowest point of the river in the study area, the Big Lost 

River is less than 20 ft wide and more than 20 ft deep. At sites 

1 and 3 constrictions, basalt subcrops also confine the river, 

but the constrictions at these sites are 10 to 30 ft wider than 

the constriction at site 2. 

Streambed material in the study area consists of sand, 

pebbles, cobbles, and boulders, with lesser amounts of silt and 

clay-size material. The streambed is armored with lightlycemented pebbles and cobbles except inside and near the 

constrictions. Bed material at the constriction sites consists 

of silts and very-fine to coarse sands containing pebbles 

dispersed in lenticular sand lenses. Large boulders, some 

up to several feet in diameter, are present in the streambed 

immediately upstream and downstream of the constrictions 

and probably originated from basalt breaking off the nearly 

vertical sides of the constrictions. Boulders and large 

cobble-size materials are conspicuously absent inside the 

constrictions. Trench excavations, (see section “Description 

of Trench Excavations”) uncovered no evidence of buried 

boulder accumulations inside the constrictions, and no 

evidence of cementation of the channel fill underlying the 

armored surface layer in the study area. Alluvial deposits 

are considerably thicker near the modern-day Big Lost River 

floodplain. These deposits were derived from streams and 

deposited as channel, overbank, eolian, and lacustrine 

deposits (fig. 3) (Kuntz and others, 1994; Geslin and 

others, 1999).

Vegetation in the study area primarily is sagebrush and 

grass. Vegetation density increases near the river. Sparse 

stands of cottonwood and juniper grow along the river banks. 

Most of these trees are now dead because of infrequent 

streamflow and a range fire that occurred in May 2000.

Several man-made features are within or adjacent to the 

study area. The INEEL diversion dam is about 2 mi upstream 

of the study area (fig. 2). The diversion dam is a low to 

moderate height (about 25 ft high across the Big Lost River 

channel) earthen berm that was constructed in 1958 

and enlarged in 1984 to divert water from the main channel 

of the Big Lost River to a series of off-channel depressions 

known locally as the spreading areas. The purpose of the 

diversion dam is to reduce the risk of flooding on downstream 

facilities along the Big Lost River. The combined storage 

capacity of the spreading areas is about 50,000 acre-ft. 

Introduction 
ID9HZ12_fig02

Union Pacific Railroad (Discontinued)

INEEL

Diversion channel

diversion dam

Dirt road

Dirt road

Firing

Range

area

Van Buren

Boulevard 26

Constriction

Site 1

(Figure 5A)

Site 2-3

(Figure 5B)

Constriction

Site 3

Pioneer weir and

canal diversion

structures

5’ 113°06’

43°33’

4’

3’ 113°00’ 112°59’ 2’ 1’

32’

43°31’

R. 28 E.

R. 29 E.

T.

3

E.

T.

2

E.

Base from U.S. Geological SurveyArco Hills SE, 1972;Circular Butte 3 SW, 1973; 1:24,000Albers Equal-Area Conic projectionStandard parallels 43 27' 30" and 43 47' 30",central meridian -112 53' 45", no falsenorthing, false easting (meters) 24,384.8River, roads, canals, railroads, and facilities are based on 2-foot contours from AerialMapping Inc. (Wayne Eskridge, Aerial Mapping Inc., written commun., 1996)

31 32 33 34

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Canal

Canal

Canal

Big

Lost

River

Big

Lost

River

LOST

INEEL

BIG

RIVER

BASIN

Figure location

0 2 1 3 MILES

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EXPLANATION

STUDY AREATRENCH SITE AND NO.CONTROL POINT AND IDENTIFIER—See table 3REFERENCE POINT AND IDENTIFIER—See table 3STREAMFLOW-GAGING STATION AND NO.

13132520

N892

13132520

13132513

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N892

GAGE

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WELL WEL3

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PKR1

OS12

Constriction

Figure 2. General location of study area, constrictions, trench sites, reference points, control points, and streamflow-gaging stations on the Big Lost River, Idaho National Engineering Environmental Laboratory, Idaho.

 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
ID9HZ12_fig03

31 32 33 34

4 5 6 1 2 3

10 11 12 7

Firing

Range

area

Big

Lost

River

Van Buren Boulevard 26

Big

Lost

River

Geology from Kuntz and others, 1994

EXPLANATION

TERRACE-FORMED ALLUVIUM (HOLOCENE TO UPPER PLEISTOCENE)ALLUVIUM (UPPER PLEISTOCENE)PLAYA DEPOSITS (HOLOCENE TO UPPER PLEISTOCENE)BASALTIC LAVA FLOWS FROM THE NORTHERN PART OF THE IDAHO NATIONAL ENGINEERING AND ENVIRONMENTAL LABORATORY (UPPER TO MIDDLE PLEISTOCENE)BASALTIC LAVA FLOWS FROM THE SOUTHERN PART OF THE IDAHO NATIONAL ENGINEERING AND ENVIRONMENTAL LABORATORY (MIDDLE TO LOWER PLEISTOCENE)

BOUNDARY OF STUDY AREA

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Qmt

Qmt

5’ 113°06’

43°33’

4’

3’ 113°00’ 112°59’ 2’ 1’

32’

43°31’

R. 28 E.

R. 29 E.

T.

3

E.

T.

2

E.

0 2 1 3 MILES

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Figure 3. Generalized geology in the vicinity of the study area, Idaho National Engineering and Environmental Laboratory, Idaho.

Introduction 
Two culverts, with manually operated control valves, are 

used to regulate flow through the diversion dam. The culverts 

are corrugated circular steel, 6 ft in diameter and about 

150 ft long. With the gated control valves completely open, 

the combined open-culvert through-flow capacity is about 

1,200 ft3/s (Berenbrock and Doyle, 2003, p. 17-18). All 

flows in excess of 1,200 ft3/s are automatically routed into a 

diversion channel that conveys the water away from the main 

river channel into the spreading areas. Additional regulation of 

downstream flow is accomplished by closing the gated control 

valves which forces more water to flow from the main channel 

into the diversion channel. Another pair of circular corrugated 

culverts is immediately downstream of the diversion dam 

under an abandoned railroad crossing. These culverts are about 

6 ft in diameter and about 75 ft long, with no control devices.

During the early 1940s, farmers constructed a wooden 

bridge (Brenda Pace, Bechtel BWXT Idaho, oral commun., 

2004) with cement wingwalls across the basalt constriction 

at site 2, about 3.6 mi downstream of the INEEL diversion 

dam. The wingwalls were placed on basalt above the erodible 

banks leading into the constriction and are the only remaining 

remnants of the bridge (cover photograph). 

A concrete weir with twin control structures was 

constructed at the downstream end of the study area to divert 

water to canals on both sides of the river. The weir, control 

structures, and canals were constructed for irrigation before 

the inception of the INEEL in 1949, and have since been 

abandoned. The weir has deteriorated and mostly fallen apart. 

The control structures also have deteriorated but probably 

could channel water to the adjoining canals; however, the 

canals have been filled in at their heads and have been 

breached in many other places to prevent water from flowing 

in them. The canal north of the river is about 20 mi long, 

intersects the TRA, goes around the NRF, and ends at playa 1. 

The canal south of the river is about 5 mi long, intersects the 

Firing Range area, and ends at the river upstream of INTEC. 

These canals generally parallel the river downstream (figs. 1

and 2). 

Previous Investigations

Many studies of the water resources of the Big Lost 

River have been conducted over the past 100 years. Earlier 

investigators primarily were concerned with base flows, mean 

annual runoff, and basin yield. Wright (1903) reported on the 

effects of irrigation on gains and losses in the Big Lost River. 

Stearns and others (1938) estimated surface- and ground-water 

outflows from the Big Lost River Basin as part of a study of 

the geology and ground-water resources of the Eastern Snake 

River Plain. Crosthwaite and others (1970) estimated surfacewater outflows from 44 subbasins in the Big Lost River Basin.

Several other reports describe flooding or the probability 

of flooding in the Big Lost River Basin. The U.S. Army Corps 

of Engineers (1967) reported on the extent of flooding along 

the Big Lost River in 1967 and on antecedent conditions 

in the basin leading up to the flood event. The U.S. Army 

Corps of Engineers (1991) also presented information on 

flood mitigation options available for the Big Lost River 

Basin. Carrigan (1972), Druffel and others (1979), Nobel 

(1980), and Koslow and Van Haaften (1986) examined 

the probable hydrologic effects of flooding arising from 

a hypothetical failure of Mackay Dam. Estimates of the 

attenuated peak flow resulting from a failure of Mackay 

Dam ranged from 45,000 ft3/s (Koslow and Van Haaften, 

1986) to about 54,000 ft3/s (Druffel and others, 1979) 45 mi 

downstream at the western boundary of the INEEL. Rathburn 

(1989) presented evidence for a late Pleistocene glacial-lakeoutburst paleoflood with an estimated flow of between 2 and 

4 million ft3/s in the Box Canyon area between Arco and the 

INEEL.

Lamke (1969) developed stage-discharge relations for 

the spreading-area diversion channel and the lower reaches 

of the Big Lost River on the INEEL. Bennett (1986) used the 

step-backwater computations model WSPRO to determine 

stage-discharge relations in the diversion channel and flow 

to the spreading areas. Berenbrock and Kjelstrom (1998) 

developed the first floodplain map of the Big Lost River at 

the INEEL using results from WSPRO. In the report for that 

study, Berenbrock and Kjelstrom indicated that their analysis 

should be considered preliminary and that additional data and 

a 2-D model would be needed to accurately estimate the extent 

of flooding. In refining the WSPRO model, Downs and others 

(1999) doubled the number of cross sections, and added three 

additional cross sections in the reach of the river between 

the INEEL diversion dam and Highway 26. Data for these 

additional cross sections were obtained from 2-ft topographic 

contour maps. Model simulation results from Downs and 

others (1999) were not compared to those of Berenbrock and 

Kjelstrom (1998) because different flows were used to define 

the extent of flooding.

Ostenaa and others (1999) developed a 2-D surfacewater flow model (TRIM2D) for the study area to determine 

flow conditions needed to produce overtopping and erosion 

of Holocene floodplain terrain features (inset terraces) that 

were presumed to be at least 300 to 500 years old and an 

unmodified Pleistocene surface estimated to be 10,000 years 

old. The grid for this model consisted of 2,800 columns and 

1,519 rows or about 4.2 million cells; only about 2.5 million 

cells were active and the remaining cells were dry (inactive). 

The size of each computational cell was 2 m (6.56 ft) long by 

2 m wide (2×2m). 

The study by Ostenaa and others (1999) determined that 

a flood flow only slightly larger than 110 m3

/s (3,884 ft3/s) 

would initiate flow across an unmodified Pleistocene surface 

referred to as the “saddle area” north of the site 1 constriction 

(fig. 4); and that a flow of 150 m3

/s (5,297 ft3/s) would 

severely erode this feature. Ostenaa and others (1999, p. 31) 

considered a flood of this magnitude to be the maximum flood 

flow since the late Pleistocene. Their study also indicated that 

 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Figure 4. Location of the study area, constrictions, control points, surface-particle sampling sites, and trenches T-4-A and T-5-A on the Big Lost River upstream 

of the Pioneer diversion structures, Idaho National Engineering and Environmental Laboratory, Idaho.

ID9HZ12_fig04

R. 28 E. R. 29 E.

6

T.

2

N.

1

113°02'30" 113°03'30"

43°32'43°31'30"

113°03'

0 2000 3000 FEET 1000

0 300 600 900 METERS

Base from Dean Ostenaa (Bureau of Reclamationaerial photographs, written commun., 2001).

Figure 5B

Figure 5A

Site 3

Trench T-4-A

Trench T-5-A

constriction

constriction

constriction

Site 2

Site 1

Saddle

area

Gravel road

Dirt road Dirt road

Dirt road

Big

Lost

River

TRENCH SITE AND NO.THALWEG—A line connecting the lowest points along the length of a streambedAPPROXIMATE BOUNDARY OF TOP OF BANKCONTROL POINT AND IDENTIFIER—See table 3ARMORED-SURFACE PARTICLE-SAMPLING SITE AND IDENTIFIER—Particle analyses are  shown in table 1 and appendix 1 V

Pioneer weir and

canal diversion

structures

PT05

PT04

HUB4

WELL

WEL3

PT01

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OS12

AB

AC

A

B

DE

C

F

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I J

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L

M

N O

P

Q R

U

V

T

W

S

X

AD

Introduction 
a flow of 100 m3

/s (3,531 ft3/s) was not sufficient to overtop 

the saddle area, but was sufficient to overtop and erode inset 

terraces, upstream and downstream of the saddle area, dated 

at 300 to 500 years old. The study by Ostenaa and others also 

included a simulated flood flow of 70 m3/s (2,472 ft3/s), which 

is approximately equivalent to the largest recorded peak flow 

[70.8 m3/s (2,500 ft3/s)] (Kjelstrom and Berenbrock, 1996; 

O’Dell and others, 2002, p. 194) on the Big Lost River near 

the Arco gaging station (13132500). Model simulation of this 

flow by Ostenaa and others (1999) using TRIM2D indicated 

that values of stream power were great enough to cause 

substantial erosion and modification of the river channel. 

At sites 1 and 2 constrictions, the resultant stream power 

was about 100 W/m2 for a peak flow of 70 m3/s (2,471 ft3/s) 

(Ostenaa and others, 1999, appendix D, figs. D-25 and D-26). 

Stream powers of this magnitude can easily scour the sand-silt 

streambed at the sites 1 and 2 constrictions as demonstrated 

in the HEC-6 sediment-transport model simulations presented 

in the section “HEC-6 Simulation Results” of the current 

report. At the site 3 constriction, the stream power was about 

25 W/m2

 and probably is great enough to scour the fine-grain 

channel fill at this location.

Streambed and Channel 

Characterization

In 2000, field data were collected to characterize the 

susceptibility of the armored surface layer and underlying 

streambed sediments to scour, and to define the cross-section 

geometry of the channel and floodplain for use in a 1-D 

surface-water flow model (HEC-RAS) and a 1-D surfacewater flow and sediment-transport model (HEC-6). In 2001, 

two additional streambed sites, sites 4 and 5, were trenched 

and sampled.

Sampling of Armored Surface Layer

The armored surface layer was sampled at 30 locations 

between the INEEL diversion dam and the Pioneer diversion 

structures (labeled A through AD in figs. 4, 5A, and 5B). 

Armoring is not present everywhere in the study reach and is 

conspicuously absent immediately upstream, downstream, and 

within the three bedrock constrictions evaluated in this study. 

Sites selected for sampling included locations within channelcontrolled and constriction-controlled sections of the river. 

Channel-controlled sections are defined as sections of the 

river that are dominated by friction and are not substantially 

affected by backwater. Constriction-controlled sections are 

defined as sections of the river that are strongly affected by 

backwater and minimally affected by friction. The hydraulic 

characteristics that distinguish channel-controlled from 

constricted-controlled sections, as defined in this study, are 

described in the section “Hydraulics of the Study Reach.”

The armored surface layer was sampled using a method 

described by Wolman (1954) to determine the size distribution 

of sediments along the surface of the streambed. Lag deposits 

on gravel-bed streambeds commonly are larger in size 

than the underlying channel fill. These lag deposits tend to 

armor or protect the streambed from erosion under low- to 

moderate-flow conditions. Sampling consisted of measuring 

the intermediate axis of 100 individual rocks picked randomly 

from the channel bed at nominal 1-ft spacings on the basis of a 

grid system. Grid dimensions used in this study were 10×10 ft. 

After measuring, a particle-size distribution was developed to 

examine the range in particle size. The counting method gives 

a size distribution based on the number of rocks sampled. 

Particle-count size distributions are presented in appendix 1

(at back of report) and summarized in table 1. The median size 

(d50) of particles from the streambed ranged from 6.21 to 48.7 

mm, and generally d50 decreased downstream. 

A plot of the d50 distribution of particle sizes from the 

upstream end to the downstream end of the study area is 

presented in figure 6. Ternary diagrams of the particle-size 

distribution of materials composing the armored surface 

layer are also shown in figure 6. The armored surface layer is 

composed predominately of granule- to cobble-size material 

(2 to 64 mm) with a large proportion of this material in the 

pebble- to cobble-size range (16 to 64 mm). This particlesize distribution for the armored surface layer (Folk, 1980) 

indicates that the river would be classified as a gravel-bed 

river. 

Trench Excavation and Channel-Fill Sampling 

Five sites along the Big Lost River were selected for 

trenching and sampling of the channel fill to determine the 

grain-size distribution of sediments beneath the armored 

surface layer (figs. 4, 5A, and 5B). Sediment samples were 

collected from trenches oriented perpendicular and parallel 

to the channel, or on terraces immediately adjacent to the 

channel. Twenty-two trenches were excavated at sites 1, 2, 

and 3. Excavations were made at these sites in both channelcontrolled and constriction-controlled sections of the river. 

Sites 4 and 5 are in channel-controlled sections of the river. 

Site 4 provides information on the upstream boundary of the 

sediment-transport model, and site 5 provides channel-fill 

information in the reach between sites 1 and 2. Two trenches 

were excavated at sites 4 and 5. 

A backhoe was used to excavate sediments to be sampled 

and to expose streambed depositional features. The trenches 

at each site were excavated to the top of basalt or to the 

capacity of the backhoe tractor, about 8 to 12 ft depending on 

the backhoe used. The backhoe was used to retrieve sediment 

samples from depths greater than about 4 ft. The objective of 

trenching was to provide a composite representation of the 

grain-size distribution of the channel fill below the armored 

surface layer, determine the degree of sediment consolidation, 

and determine the depth to bedrock where possible. 

10 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
ID9HZ12_fig05A

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113°03'40" 35" 30" 113°03'25"

45"

43°

31'

40"

Base and contours from Dean Ostenaa

(Bureau of Reclamation; aerial photographs

written commun., 2001).

To match North American Vertical

Datum of 1988, add 1.955 feet to the

contour elevation. Contour interval

1 foot

43°

31'

50"

0

0 50 100 150 METERS

100 200 300 400 500 FEET

WELL

WEL3

PT05

PT04

X

W

V

S

R

Saddle

area

Site 1

constriction

MT-1-C

MT-1-B T-1-F

ML-1-A

MT-1-A

T-1-D

T-1-C

T-1-B

L-1-F

L-1-D

L-1-C L-1-E

L-1-A L-1-B

T-1-A

T-1-E

Big

Lost

River

EXPLANATION

ARMORED SURFACE PARTICLE-SAMPLING SITE AND IDENTIFIER—

 Partical analyses are shown in table 1 and appendix 1

TRENCH PARTICLE-SAMPLING SITE AND IDENTIFIER—

 T, transverse; L, longitudinal; M, meander. Particle analyses

 are shown in table 2 and appendix 1

THALWEG—A line connecting the lowest points along the

 length of a streambed

APPROXIMATE BOUNDARY OF TOP OF BANK

CONTROL POINT AND IDENTIFIER—See table 3

T-1-D

V

PT05

A. Site 1

Figure 5. Location of particle-sampling sites at sites 1, 2, and 3 on the Big Lost River, Idaho National Engineering and 

Environmental Laboratory, Idaho.

Streambed and Channel Characterization 11
ID9HZ12_fig05B

5020

5021

5022

5024

5023

5019

5018

5017

5016

5023

5022

5022

5023 5021

5023

5023

5022

5021

5021

5022 5021

5022

5021

5020

5019

5018

5017 5016

5014

5015

5010

5010

5006

5008

5007

5020

5019

5019

5017

5018

5016

5015

5019

5014

5013

5012

5011

5006

5009

5008

5007

5008

5018

5019

5020

5017

5021

5022

5023

5024

5025

5026

5009

5011

5013

5014

5012

5009 5008

5010

5015

5016

5024

5024

5027

5027

5024

5028

5023

5024

5025

5025

5023

5022

5021

5021

5018

5019

5020

5021

5017

5015

5012

5010

5008

5009

5007

5019

5018

5017

5009

5020

5021

5022

5023

5024

5025

5024

5008

5012

5007

5023

5022

5021

5020

5019

5013 5014

5015

5016 5017

5018

50085009

5020

5020

5019

5024

5025

5023

5022

5021

5024

5024

5023

5024

5024

5023

5024

5024

5023

5023

5023 5025

5022

5022

5022

5021

5025

5018

5022

B

A

C

D

E

F

T-2-B

L-2-A

T-2-A L-2-C

T-3-A

L-3-A

PT06

PT07

HUB2 HUB2

Site 2

constriction

Site 3

constriction

113°02'40" 45" 113°02'50"

43°32'43°31'55"

0

0 50 100 METERS

200 100 300 FEET

EXPLANATION

ARMORED-SURFACE

 PARTICLE-SAMPLING SITE AND IDENTIFER— Particle analyses are shown in table 1 and  appendix 1TRENCH PARTICLE- SAMPLING SITE AND IDENTIFIER—T, transverse; L, longi- tudinal. Particle analyses are shown in table 1 and  appendix 1THALWEG—A line con- necting the lowest points along the length of a streambedAPPROXIMATE BOUNDARY OF TOP OF BANKCONTROL POINT AND IDENTIFIER—See table 3

B

Base and contours from Dean Ostenaa (Bureau of Reclamationaerial photographs, written commun., 2001).To match North American Vertical Datum of 1988, add 1.955 feetto the contour elevation. Contour interval 1 foot

Big

Lost

River

T-2-A

B. Sites 2 and 3

Figure 5.—Continued.

12  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
ID9HZ12_fig06

0

60

80

40

20

100

0

60

80

40

20

100

100

80

60

40

20

0

0

60

80

40

20

100

0

60

80

40

20

100

100

80

60

40

20

0

PERCENTAGE OF MEDIAN BED-MATERIAL SIZE (d50)

0.0625–2 mm

64–256 mm

2–64 mm

8–16 mm

16–64 mm

2–8 mm

50

45

40

35

30

25

20

15

10

5

0

10,000 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 0

DISTANCE, IN FEET UPSTREAM OF THE PIONEER DIVERSION STRUCTURES

MEDIAN BED-MATERIAL SIZE (d50), IN MILLIMETERS

AB

AC

C B

D

E

F

G

H

I

J

K

LM

N

O

P

Q

R

S

V

W

X

AD

Sample and identifier — 

 See table 1

AB

Figure 6. Median size (d50) and ternary size distribution of selected samples collected from the armored surface layer on the 

Big Lost River upstream of the Pioneer diversion structures, Idaho National Engineering and Environmental Laboratory, Idaho.

Streambed and Channel Characterization 13
The elevations of the streambed and the top of bedrock, where 

encountered, were surveyed at each trench site. Samples 

collected from the trenches were stored in buckets and 

bags and were labeled and recorded in a field book for later 

analysis. Each trench was given an identifier that corresponded 

to the site number and the trench designation within the site 

preceded by the letter T or L, corresponding to transverse 

or longitudinal, to describe the trench orientation in relation 

to the alignment of the stream channel; or the designation 

ML (meander longitudinal) or MT (meander transverse) 

to describe trenches excavated on a meander-scarred 

terrace adjacent to the active channel upstream of the site 1 

constriction. At many of the trench sites stratified sedimentary 

layers were encountered and were individually sampled. 

The labeling scheme for these sites included a numerical 

designation to distinguish between individual layers and their 

sampling depths (table 2).

Table 1. Particle-size characteristics of samples collected from the armored surface layer at selected sites on the Big Lost River 

upstream of the Pioneer diversion structures, Idaho National Engineering and Environmental Laboratory, Idaho.

[Location of sampling sites is shown in figures 4 and 5; and fig. 1-1 of appendix 1. Particle-size data are shown in appendix 1. Particle-size diameter: The letter 

d with numerical subscript denotes the particle diameter of the sample for which the percentage by count is finer than the designated diameter size. For example, 

d65 = 21.9 is the diameter of particles for which 65 percent of the sample is finer than 21.9 mm. ft, ft; mm, millimeter]

Sampling site 

identification 

No.

Distance upstream 

of Pioneer diversion 

structures (ft)

Particle-size diameter (mm)

Geometric 

standard 

deviation 

(mm)

(σg

) d15.9 d35 d50 d65 d84.1 d90

A1 2,220 8.42 12.5 16.7 20.3 27.3 30.0 1.80

B 2,210 7.24 10.5 14.2 17.3 21.4 23.3 1.72

C 2,770 7.52 10.4 13.9 17.7 24.5 29.0 1.80

D 2,940 8.24 12.9 20.1 25.3 33.2 40.5 2.01

E 3,070 12.7 17.8 21.9 27.5 40.2 45.4 1.78

F 3,400 11.4 19.8 25.4 30.1 38.5 44.1 1.84

G 3,630 11.9 23.7 32.5 40.7 52.4 56.1 2.10

H 3,800 16.9 38.8 47.2 61.3 80.3 91.1 2.18

I 4,110 8.38 14.8 19.5 27.4 48.2 53.1 2.40

J 4,920 3.87 5.11 6.21 7.34 9.20 11.0 1.54

K 5,160 4.65 7.61 9.71 11.7 24.2 32.5 2.28

L 5,410 20.5 26.8 30.7 35.3 44.3 47.3 1.47

M 5,640 18.4 26.2 30.7 36.1 45.6 53.6 1.57

N 5,850 9.95 15.4 25.5 41.7 55.5 68.0 2.36

O 6,060 8.53 15.9 19.7 27.2 54.1 59.2 2.52

P 6,360 5.96 11.3 18.0 29.5 47.1 63.0 2.81

Q 6,760 11.6 20.6 29.6 37.7 55.3 64.1 2.18

R 6,930 12.4 20.9 25.9 34.4 48.1 51.3 1.97

S 7,280 8.61 13.2 18.2 22.1 38.8 48.1 2.12

T2 7,380 14.8 22.5 29.2 38.2 50.3 55.1 1.84

U1 7,580 16.9 35.6 44.7 53.1 66.1 74.1 1.98

V 8,200 11.2 18.4 24.5 30.7 39.2 43.1 1.87

W 8,550 9.78 22.1 39.5 46.7 62.8 67.1 2.53

X 8,850 17.2 26.5 36.5 46.2 62.1 67.2 1.90

Y 19,300 6.41 7.78 8.88 9.69 11.9 12.7 1.36

Z 19,500 14.7 29.6 43.2 50.2 65.1 77.1 2.10

AA 20,100 16.7 34.3 48.7 58.7 77.5 82.1 2.15

AB 1,040 10.1 14.7 17.6 21.9 26.3 31.1 1.61

AC 1,950 10.9 16.2 20.2 24.6 34.3 38.1 1.77

AD 10,200 5.67 15.6 22.2 26.8 50.3 59.5 2.98

1

Sampled gravel bar.

2

Sampled narrow chute of channel between bedrock in middle of channel.

14  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Table 2. Particle-size characteristics from sieve analysis of trench samples used in the HEC-6 model at sites 1 through 5 on the Big 

Lost River upstream of the Pioneer diversion structures, Idaho National Engineering and Environmental Laboratory, Idaho.

[Sampling site identification No.: Location of sampling sites is shown in figures 4 and 5. Letters ‘L’ or ‘T’ correspond to longitudinal or transverse to describe 

the trench orientation in relation to the alignment of the stream channel. Particle-size data are shown in appendix 2. Particle-size diameter: The letter d with 

numerical subscript denotes the particle-size diameter of the sample for which the percentage by count is finer than the designated diameter size. For example, 

d65 = 42.9 indicates that 65 percent of the sediment by weight is finer than 42.9. ft, ft; mm, millimeter; –, no data]

Sampling site 

identification No.

Distance 

upstream 

of Pioneer 

diversion 

structures (ft)

Sample

depth 

(ft)

Particle-size diameter (mm) Geometric 

standard 

deviation (mm)

(σg

)

d15.9 d35 d50 d65 d84.1 d90

SITE 1

L-1-A1 7,140 1.0-5.5 1.28 9.87 22.3 42.9 108 149 9.19

L-1-B1 7,010 0.0-3.0 .76 2.58 8.52 16.5 34.6 43.4 6.75

L-1-C1 7,200 0.0-3.0 1.04 8.80 18.7 32.4 47.0 52.7 6.72

L-1-D1 7,270 0-1.0 .47 2.59 7.85 15.8 29.4 37.9 7.87

L-1-D2 7,270 1.0-1.5 .23 .29 .33 .37 .44 .46 1.37

L-1-D3 7,270 1.5-5.5 1.15 4.31 14.8 35.7 91.3 134 8.93

L-1-DC1 7,270 1.0-1.5 .08 .14 .20 .38 1.22 1.90 3.92

L-1-DC2 7,270 5.5 .07 .17 .52 1.13 2.48 3.23 6.03

L-1-DC3 7,270 3.5-4.0 .22 .48 .91 1.66 4.22 5.35 4.35

L-1-E1 7,120 0-4 .17 .44 1.27 4.14 27.3 68.0 12.7

T-1-A1 7,090 0-0.75 .21 .29 .33 .37 .44 .47 1.45

T-1-A2 7,090 0.75-4.0 .49 3.62 13.8 25.6 43.7 50.3 9.44

T-1-B1 8,080 1

0.0-1.5 2.36 15.9 34.2 50.1 107 148 6.74

T-1-B2 8,080 11.5-2.5 .28 .48 .60 .73 .95 1.15 1.84

T-1-B3 8,080 1

2.5-4.0 .92 4.71 14.8 22.8 38.7 46.7 6.49

T-1-C1 7,960 20.0-2.5 .08 .16 .31 .64 1.61 2.22 4.57

T-1-C2 7,960 22.5-5.0 .26 .30 .34 .38 .45 .47 1.32

T-1-C3 7,960 25.0-5.5 .07 .12 .15 .18 .24 .35 1.84

T-1-C4 7,960 2

5.5-7.5 .88 17.0 26.2 36.4 49.6 54.5 7.51

T-1-C5 7,960 2

7.5-10.0 3.17 21.5 35.5 44.1 58.1 63.2 4.28

T-1-C6 7,960 1

1.0-3.0 .77 8.69 15.1 28.4 45.5 51.6 7.69

T-1-C7 7,960 13.0-3.75 .12 .17 .21 .28 0.41 .46 1.85

T-1-C8 7,960 13.75-5.5 .88 8.80 26.9 39.5 53.6 58.9 7.80

T-1-D1 8,050 2

2.5-3.5 1.25 5.21 12.1 24.5 44.0 50.6 5.93

T-1-D2 8,050 2

8.0 .30 .42 .54 .66 .84 .90 1.67

T-1-D3 8,050 23.5-4.5 1.03 3.96 5.88 8.59 13.1 14.9 3.57

T-1-D4 8,050 29.0-11.0 .70 5.30 12.5 21.0 37.6 45.8 7.33

T-1-D5 8,050 28.0 .26 .31 .37 .43 .60 .76 1.52

T-1-DCLAY2 8,050 3

6.0 .09 .27 .53 .98 2.06 3.10 4.84

T-1-E1 9,100 4.0-5.0 .64 5.05 10.8 19.0 35.9 44.5 7.49

SITE 2

L-2-A1 3,190 0-0.7 0.18 0.28 0.34 0.42 0.75 1.19 2.04

L-2-A2 3,190 0.7-2.0 .39 1.14 1.93 2.69 4.09 5.46 3.22

L-2-A3 3,190 2.0-3.5 .51 .63 .74 .88 1.31 1.63 1.61

L-2-A4 3,190 3.5-4.5 .28 .56 1.10 2.69 8.08 11.9 5.39

L-2-B1 3,280 0-0.5 .16 .26 .32 .39 .51 .83 1.78

L-2-B2 3,280 0.5-2.5 .30 .41 .51 .64 .85 .93 1.69

L-2-B3 3,280 2.5-4.5 .53 1.74 4.26 14.8 28.2 35.6 7.26

L-2-C1 3,070 0-0.5 .73 3.65 6.66 9.92 14.9 19.1 4.51

L-2-C2 3,070 0.5-1.0 .36 .57 .70 .87 1.68 2.63 2.17

L-2-C4 3,070 2.0-2.5 .35 .99 1.64 2.73 6.61 9.33 4.35

T-2-A1 3,140 0.0-0.5 .23 .29 .34 .39 .46 .49 1.41

T-2-A2 3,140 0.5-2.0 .28 .33 .38 .44 .71 .98 1.60

T-2-A3 3,140 2.0-3.5 .51 .90 1.77 5.22 18.6 25.7 6.02

T-2-A4 3,140 3.5-4.5 .59 1.43 4.67 10.7 33.9 43.0 7.60

T-2-A5 3,140 4.5-7.7 .15 .27 .34 .43 .78 1.08 2.25

T-2-A6 3,140 6 .07 .13 .17 .22 .39 .48 2.32

Streambed and Channel Characterization 15
Coarse-Grained Particle-Size Analysis

Grain-size analyses were conducted at the USGS Core 

Library in the Central Facilities Area (CFA) at the INEEL. 

The methods and procedures used for the grain-size analyses 

are outlined in the American Society of Testing Material’s 

(ASTM) Manual on Test Sieving Methods (1985), the USGS 

Vancouver Sediment Laboratory’s Quality Control and Quality 

Assurance Plan (Daniel J. Gooding, U.S. Geological Survey, 

written commun., 2000), and the American Society of Civil 

Engineers (ASCE) Manual on Sedimentation (1975).

Seventy-five sediment samples were collected from 

24 trenches in the study area. Sixty-four of these samples 

(table 2) were used to classify sediment sizes that were used 

in the HEC-6 model. Samples from the meander-scarred 

terrace were not used for this purpose. Most samples were 

placed into bags, but some were collected in buckets to ensure 

representative sampling of the larger-size materials. Particles 

greater than (>) the opening of a 0.0625 mm sieve and less 

than (<) the opening of a 4 mm sieve are considered largegrained and are composed of very fine sands to very coarse 

sands (>0.0625 – <4 mm), pebbles (>4 – <64 mm), cobbles 

(>64 – <256 mm), and boulders (>256 mm). Particles less than 

0.0625 mm are classified as fine-grained silts and clays. The 

samples were analyzed using the dry-sieve method described 

in the aforementioned references to determine the percentfiner-than and the cumulative percent-finer-than fractions, and 

the characteristic particle sizes.

Sampling site 

identification No.

Distance 

upstream 

of Pioneer 

diversion 

structures (ft)

Sample

depth 

(ft)

Particle-size diameter (mm) Geometric 

standard 

deviation (mm)

(σg

)

d15.9 d35 d50 d65 d84.1 d90

SITE 3

L-3-A1 2,220 0-1.5 0.66 4.63 9.32 15.4 26.0 30.5 6.26

L-3-A2 2,220 0-1.5 .75 3.90 8.40 15.1 26.2 30.9 5.91

L-3-A3 2,220 1.5-1.6 .86 4.75 8.07 11.5 19.2 23.8 4.73

L-3-A4 2,220 1.5-1.6 .21 .71 1.72 3.75 10.3 13.8 7.03

L-3-A5 2,220 1.6-1.8 .15 .28 .39 .55 1.16 1.90 2.78

L-3-A6 2,220 1.6-1.8 .07 .11 .20 .75 2.92 4.02 6.66

L-3-A7 2,220 1.8-2.9 .13 .30 .49 1.58 3.85 5.16 5.41

L-3-A8 2,220 1.8-2.9 .58 1.00 1.66 3.18 9.24 12.6 4.00

L-3-A9 2,220 2.9-4.0 .73 2.02 4.38 8.39 15.2 20.9 4.55

L-3-A11 2,220 4.0 .11 .16 .20 .24 .42 0.53 1.98

L-3-A12 2,220 4.0 1.37 2.99 4.79 7.34 12.2 14.2 2.98

T-3-A1 2,270 1.5-1.75 .54 .70 .86 1.09 1.68 1.92 1.77

T-3-A2 2,270 1.75-2.25 .26 .31 .36 .42 .54 .73 1.45

T-3-A3 2,270 2.25-4.0 .58 1.50 2.60 4.87 12.5 16.7 4.65

T-3-A4 2,270 0-1.5 .38 1.95 4.25 7.60 14.2 19.7 6.12

SITE 4

T-4-A1 9,840 1.0-5.0 1.20 6.16 13.9 27.8 87.3 130.0 8.53

SITE 5

T-5-A1 4,960 0.0-5.0 0.93 5.43 12.3 23.1 42.4 49.4 6.75

T-5-A2 4,960 5.0 .10 .19 .31 .49 1.1 1.58 3.34

1

Depth is measured from top of left bank where sample was taken.

2

Depth is measured from top of right bank where sample was taken.

3

Depth is measured from the streambed in the center of the channel where sample was taken.

Table 2. Particle-size characteristics from sieve analysis of trench samples from sites 1 through 5 on the Big Lost River upstream of 

the Pioneer diversion structures, Idaho National Engineering and Environmental Laboratory, Idaho.—Continued

[Sampling site identification No.: Location of sampling sites is shown in figures 4 and 5. Letters ‘L’ or ‘T’ correspond to longitudinal or transverse to describe 

the trench orientation in relation to the alignment of the stream channel. Particle-size data are shown in appendix 2. Particle-size diameter: The letter d with 

numerical subscript denotes the particle-size diameter of the sample for which the percentage by count is finer than the designated diameter size. For example, 

d65 = 42.9 indicates that 65 percent of the sediment by weight is finer than 42.9. ft, ft; mm, millimeter; –, no data]

16  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
The first step in the analysis was to dry the samples 

thoroughly and obtain a gross weight. All samples were 

open-air dried in trays for a minimum of 24 hours. Samples 

that contained semi-consolidated, or aggregated, fine-grained 

particles were oven dried to assist with moisture removal.

Large-volume bucket samples were split using a 

mechanical sample splitter to reduce the sample size to an 

appropriate volume for sieving. Particles greater than 64 

mm were too large for the splitter and were hand split and 

placed into separate bins. Hand-split samples were weighed 

separately from the finer fraction and the weights added back 

to the cumulative weight of the sample to calculate weight 

percentages for each size fraction. Bagged sample volumes 

were small enough that they did not need to be split and the 

entire sample was run through the sieves. Aggregated finegrained particles were broken apart using a mortar and pestle 

prior to sieving. 

After drying and splitting, the samples were poured over 

the largest sieve (256 mm openings) and set in a mechanical 

shaker, which was then operated for 10 minutes (American 

Society of Civil Engineers, 1975, p. 412). Sieve sizes ranged 

from 256 to 0.0625 mm and were partitioned into 10 size 

classifications, ranging from silt and clay (<0.0625 mm) to 

boulder (>256 mm).

After shaking, each sieve containing sediments was 

weighed and the tare weights of the sieves subtracted from the 

combined weight of the retained sample and sieve. Results 

were entered into a spreadsheet programmed to (1) calculate 

the percent-finer-than fraction, cumulative percent-finer-than 

fraction, and the characteristic particle sizes, and (2) graph the 

cumulative percent-finer-than fraction and the distribution of 

sediment sizes. Particles ranged in size from about 100 to less 

than 0.0625 mm. Particles less than 0.0625 mm were collected 

in a closed sieve pan at the bottom of the sieve stack and were 

weighed. 

If any residual aggregated particles were found after 

sieving, this was noted in the remarks column of the 

spreadsheet. If a sieve retained a small number of particles 

(less than or equal to 100), an approximate count of the 

particle number was noted in the remarks column of the 

spreadsheet. This procedure was implemented to ensure 

that the total volume of the sample was large enough to be 

representative of all particle sizes. For example, one or two 

large particles that together make up more than one-fourth of 

the sample weight indicate a sample with insufficient volume 

to accurately represent the particle-size distribution of the 

channel fill. During collection, if a sample contained large 

pebbles and cobbles, about 20 pounds of material were taken 

from the site to ensure that the sample was large enough to 

be representative of the site. Sieve analyses are presented in 

appendix 2 (at back of report).

The channel-fill material is composed primarily of 

particles ranging in size from medium sand to coarse pebble 

(appendix 2). The d50 of these samples ranges from 0.15 to 

35.5 mm. The dominant material size is characteristic of a 

gravel-bed river.

Fine-Grained Particle-Size Analysis

A laser diffraction particle-size analyzer (Coulter 

Counter) was used to measure the silt and clay size 

fraction (<0.0625 mm) of one sample, a very fine-grained 

layer encountered at the base of trench T-5. Particle-size 

characteristics using the Coulter Counter were a mean grain 

size of 0.033 mm, a d50 of 0.0013 mm, a d10 of 0.0001 mm, and 

a d90 of 0.108 mm. The grain-size distribution indicates that 

this sample is classified as clay. Clay, identified on the basis 

of visual examination, also was encountered in several other 

trenches (L-1-D, L-1-E, T-1-B, T-1-D, L-2-C, and T-5-A; see 

“Description of Trench Excavations”) near the contact of the 

channel-fill with the underlying bedrock. Visual examination 

of the samples and the underlying bedrock indicated that the 

clay was of allothogenic origin (transported) and was not a 

basalt-weathering product (authigenic). 

Description of Trench Excavations

Site 1 Trenches 

Site 1 is about 2.2 mi downstream of the INEEL 

diversion dam and includes a section of the river that is about 

2,200 ft long. This S-curved section of the river is controlled 

by a bedrock constriction (site 1 constriction in figs. 2 and 5A) 

which generates considerable backwater for flows greater than 

about 100 m3/s. Twelve trenches inside the main channel and 

four trenches on an alluvial terrace, formed by an abandoned 

river meander north of the main channel, were excavated and 

thirty-eight samples were collected. For descriptive purposes, 

trenches have been organized into four groups at site 1.

Working from the upstream side (left to right, fig. 5A), 

the two groups for the trenches inside the channel (T-1-E and 

T-1-F) and along the meander scar (MT-1-C, ML-1-A, MT1-B, and MT-1-A) are designated groups 1 and 2, respectively. 

Group 3 (T-1-D, T-1-B, and T-1-C) and group 4 (L-1-F, 

L-1-D, L-1-C, L-1-A, L-1-E, T-1-A, and L-1-B) another 

500 ft downstream, is near the site 1 basalt constriction. Sieve 

analyses for each trench are presented in appendix 2. 

Streambed and Channel Characterization 17
Group 1 (Trenches T-1-E and T-1-F)

Trenches T-1-E and T-1-F were excavated into the left 

alluvial bank and part way into the main channel. Materials 

excavated from these two trenches consisted of poorly 

sorted sands and pebbles, interspersed with silts that gave 

the material a very dirty appearance. Stratification in T-1-

F consisted of discontinuous lenses of fine sand and silt 

interspersed in a matrix of poorly sorted sands and pebbles 

(note: no samples were collected from T-1-F). T-1-F is near 

a basalt exposure and bedrock was encountered at a depth 

of 12 ft in the main channel. T-1-E also was excavated to a 

depth of 12 ft, but bedrock was not encountered. Stratification 

at T-1-E was similar to that at T-1-F and consisted of poorly 

sorted sands and pebbles overlain by moderately sorted 

pebbles and granules in a coarse sand matrix. Very finegrained, well-sorted silt (loess?) and sand deposits overlie the 

channel fill deposits along the banks of the channel at both 

trench sites. 

Group 2 (Trenches MT-1-C, ML-1-A, MT-1-B, and MT-1-A)

Four trenches were excavated on a meander-scarred 

terrace north of the main channel. Several feet of very finegrained, well-sorted silt (loess?) and sand overlie the alluvial 

fill at this location. Trenches MT-1-C and MT-1-B exposed a 

2- to 5-ft thick cover of silt and fine sand underlain by poorly 

stratified, and poorly sorted sands, pebbles, and cobbles. 

Trench ML-1-A, in an inset channel, consisted of a 4-ft thick 

stratified sequence of poorly sorted sands and pebbles near the 

base of the trench, fining upward into alternating sequences 

of medium- to well-sorted coarse sands to well-sorted fine 

sand and silt. Trench MT-1-B, near the center of the meanderscarred terrace was unique. Material from this trench consisted 

of many well-stratified layers composed of well-sorted sand 

and pebble layers near the bottom, grading upward into layers 

of fine sand and silt interspersed with layers of well-sorted 

sand and pebbles, overlain by a 2.5-ft thick layer of silt 

(loess?) and fine sand. The material from this trench appeared 

exceptionally “clean” compared to that in the other trenches 

that were excavated on this meander scar. Trenches within this 

group were excavated to depths of 10 to 12 ft and bedrock was 

not encountered.

Group 3 (Trenches T-1-B, T-1-D, and T-1-C)

Trenches T-1-B and T-1-D were constructed separately 

(offset by 10 ft) and later joined to construct a composite 

lithologic cross section of the streambed fill (fig. 7A; note: 

lithologic descriptions based on field observations). Trench 

T-1-C, 100 ft downstream of T-1-B and T-1-D, consists 

of two overlapping trenches that span the entire active 

channel (fig. 7B; note: lithologic descriptions based on field 

observations). Clay, likely of allothogenic origin, was found 

along the top of the basalt bedrock in T-1-B and T-1-D 

(not shown in fig. 7A). Depths to bedrock in these trenches 

ranged from 3.5 (T-1-C) to 8 ft (T-1-B) below the streambed. 

Trench cross sections indicated a poorly stratified basal 

section composed of poorly sorted sands, pebbles, cobbles, 

and small boulders. Both the size and quantity of the cobbleand boulder-size material increased with depth, with the 

highest concentrations occurring near the bedrock contact. 

Discontinuous, well-sorted, fine- to medium-grained sand 

lenses were found just above the basal fill in both sets of 

trenches. These were overlain by poorly stratified sequences 

of moderately-sorted sands, pebbles and cobbles below the 

channel surface. 

Thick deposits of loess (?), underlain by well-sorted 

sands and silty sands, form the banks above the active channel. 

A well-preserved animal bone and a large wood fragment 

(2-ft long and 1 to 2 in. in diameter; mountain mahogany?) 

were found in trench T-1-D at a depth of about 2.5 ft below 

the active channel (fig. 7A). Many more poorly preserved 

wood fragments were found interspersed in allothogenic clay 

deposits near the bedrock contact. 

Group 4 (L-1-F, L-1-D, L-1-C, L-1-A, L-1-E, T-1-A, and L-1-B)

Seven trenches were excavated immediately upstream, 

downstream, and within the site 1 constriction (fig. 5A). 

Trench L-1-F was excavated in a gravel (pebble and cobble) 

bar upstream of a basalt subcrop that spans the entire width 

of the channel. The material from this trench consisted of 

well-sorted pebbles, cobbles, and small boulders overlain by 

a thin cover of sands, pebbles, and cobbles. The trench was 

excavated to a depth of 6 ft and bedrock was not encountered 

(note: no samples were collected from trench L-1-F). 

Trench L-1-D, 75 ft upstream of the site 1 constriction, was 

excavated to bedrock at a depth of 4 ft. Material from this 

trench consisted of a poorly sorted mixture of coarse sands, 

pebbles, cobbles, and small boulders overlain by well-sorted, 

stratified layers of fine sands and coarse sands mixed with 

pebbles. Clay, in contact with bedrock, was present at the 

base of the trench. Trench L-1-C, about 35 ft upstream of 

the site 1 constriction, was excavated to bedrock at a depth 

18  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Figure 7. Lithology of trenches T-1-B, T-1-D, and T-1-C across the Big Lost River at site 1, Idaho National Engineering and 

Environmental Laboratory, Idaho. 

ID9HZ12_fig07A

T-1–D1

T-1-D2

T-1-D3

T-1-D4

Bone

Wood

Wood

T-1-B2

T-1-B3

T-1-B1

T-1-DC2

T-1-D5

5,028 LEFT BANK

5,026

5,024

5,022

5,020

5,018

5,016

5,014

5,012

0 10 20 30 40 50 60 70 80 90 100 120

5,028

5,026

5,024

5,022

5,020

5,018

5,016

5,014

5,012

DISTANCE FROM REFERENCE POINT, IN FEET

ELEVATION, IN FEET ABOVE NORTH AMERICAN 

VERTICAL DATUM OF 1988

Vertical exaggeration 

 approximately × 5

LOESS

SAND

SAND AND PEBBLE

PEBBLE

SAND, PEBBLE, AND COBBLES

T-1-D5

SAND, PEBBLE, COBBLES, AND BOULDERS

BEDROCK

CONTACT—Approximately located. Dashed where

 uncertain

SITE WHERE SAMPLE WAS COLLECTED FOR

 ANALYSES—Location of site 1 is shown in figure 2.

 Locations of trenches are shown in figure 5A. Particle 

 analyses are shown in table 2 and appendix 2 

EXPLANATION

A. Trenches T-1-B and T-1-D

of 3 ft. Material in this trench exhibited no stratification, and 

consisted of poorly sorted sands and pebbles. Trench L-1-A, 

within the site 1 constriction, was excavated to bedrock at a 

depth of 5.5 ft. No stratification was observed and material 

from this trench consisted of poorly sorted sands, pebbles, 

cobbles, and small boulders. 

Three trenches, L-1-E, T-1-A, and T-1-B, 25, 80 and 

100 ft downstream of the site 1 constriction, respectively, 

were excavated to bedrock ranging in depth from 3 to 4.5 ft. 

Bedding structure was absent in these trenches, and material 

from these trenches consisted of poorly sorted coarse sands, 

pebbles, and cobbles overlain by a 1-ft thick layer of wellsorted fine to coarse sand.

Streambed and Channel Characterization 19
ID9HZ12_fig07B

T-1-C1

T-1-C2

T-1-C3

T-1-C4

T-1-C5

T-1-C6 T-1-C7

T-1-C8

5,030 LEFT BANK

5,028

5,026

5,024

5,022

5,020

5,018

5,016

5,030

5,028

5,026

5,024

5,022

5,020

5,018

5,016

0 10 20 30 40 50 60 70 80 90 100

DISTANCE FROM REFERENCE POINT, IN FEET

ELEVATION, IN FEET ABOVE NORTH AMERICAN 

VERTICAL DATUM OF 1988

Vertical exaggeration 

approximately × 5

LOESS

SAND

SILTY SAND

SAND, PEBBLE, AND COBBLES

SAND, PEBBLE, COBBLES, AND BOULDERS

T-1-C5

BEDROCK

CONTACT—Approximately located.

 Dashed where uncertain

SITE WHERE SAMPLE WAS COLLECTED 

 FOR ANALYSES—Location of site 1 is shown 

 in figure 2. Location of trench is shown in 

 figure 5A. Particle analyses are shown in 

 table 2 and appendix 2 

EXPLANATION

B. Trench T-1-C

Figure 7.—Continued.

Site 2 Trenches

The site 2 constriction is about 200 ft long and is at 

an old bridge site about 3.6 mi downstream of the INEEL 

diversion dam (figs. 2 and 5B). At this location, 4 trenches 

were excavated, 1 upstream and 3 downstream of the 

abandoned bridge site. Sixteen sediment samples were 

collected from multiple stratified layers in these trenches. 

The three downstream trenches all exhibited similar sediment 

stratification that differed appreciably from stratification that 

was observed in the upstream trench. 

Working from the upstream side (left to right), the 

trench excavation site upstream of the basalt constriction 

is designated group 1. The three downstream trenches are 

designated group 2. Sieve analyses for each trench are shown 

in appendix 2.

Group 1 (T-2-B)

Trench T-2-B is 15 ft upstream of the old bridge 

abutments within the site 2 constriction. This trench was 

excavated to bedrock at a depth of 4.5 ft. Excavated material 

consisted of well-sorted fine to coarse sand with welldeveloped horizontal and cross-bedding stratification to a 

depth of 2.5 ft. A poorly sorted mixture of coarse sands and 

pebbles with no obvious bedding structure underlies these 

sands.

Group 2 (L-2-A, T-2-A, and L-2-C)

Three trenches, excavated downstream of the bridge 

constriction, range in depth from 2.5 to 7.7 ft. Trench L-2-A 

was excavated to bedrock at a depth of 5 ft. Material from 

20 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
this trench consisted of alternating layers of well-sorted fine 

to medium sand interspersed with layers of coarse sand and 

granules, in turn overlying a basal layer of fine to coarse sand 

with pebble lenses near the bedrock contact. Trench T-2-A 

was excavated to bedrock at a depth of 7.5 ft. Material in 

this trench consisted of alternating fining-upward layers of 

poorly sorted sands, granules, and pebbles down to a depth 

of 4.5 ft, underlain by medium to coarse sands containing 

lenses of very-fine sand and silt. Trench L-2-C was excavated 

to bedrock at a depth of 2.5 ft. Material from this trench 

consisted of well-sorted medium sands and pebbles to a depth 

of 1 ft, overlying a 1-ft thick section of poorly sorted sands, 

pebbles, and small boulders, in turn overlying a well-sorted 

layer of clayey silt and sand. A fragment of a dummy artilleryshell casing was found at a depth of 1 ft in the L-2-C trench. 

Site 3 Trenches

This trench site is at a basalt constriction about 3.4 mi 

downstream of the INEEL diversion dam (figs. 2 and 5B). At 

this site two trenches were excavated to depths of about 4 ft, 

and 16 alluvial horizons were sampled and analyzed. Trench 

T-3-A was excavated perpendicular to the channel and trench 

L-3-A was excavated parallel to the channel. Alluvial horizons 

indicated similar sedimentary features in both trenches. Just 

above bedrock, the basal deposits consisted of a poorly sorted 

mixture of sands and pebbles. A well-sorted, fine- to mediumgrained sand layer was interbedded between poorly sorted 

sands and pebbles. This well-sorted, fine- to medium-grained 

sand lens increased in thickness toward the channel terrace and 

almost pinched out toward the channel thawleg. The channel 

surface deposits consisted of poorly sorted sands and pebbles 

with some cobbles present. 

Site 4 Trenches

Trench T-4-A, about 2.0 mi downstream of the INEEL 

diversion dam, is in a channel-controlled reach of the river 

(fig. 4). This trench was excavated to a depth of 7.9 ft; bedrock 

was not encountered. The channel at this site is 43 ft wide 

and exhibits a well-developed, armored surface layer. One 

large-volume bulk sample was collected. Material in this 

trench consisted of a poorly sorted mixture of sands, pebbles, 

cobbles, and small boulders with no discernible stratification. 

Site 4 was selected to provide information needed to formulate 

the upstream sediment-boundary condition for the HEC-6 

sediment-transport model.

Site 5 Trenches

Trench T-5-A, about 2.8 mi downstream of the INEEL 

diversion dam is in a channel-controlled section of the river 

(fig. 4). This trench was excavated to bedrock at a depth 

of 6.5 ft. Two representative samples were collected. From 

the channel surface to a depth of 5 ft, the alluvial deposits 

consisted of a poorly sorted mixture of sands, pebbles, 

cobbles, and small boulders. No armored surface layer was 

present in the channel at this location. Streambed material 

at the surface consisted of sand and small pebbles. Material 

in contact with bedrock consisted of a 1.5-ft thick layer of 

dense allothogenic clay. This trench site was selected to obtain 

streambed sediment information in a channel-controlled 

section of the river between sites 1 and 2. 

Channel Surveys

The HEC-RAS and HEC-6 computer models, which 

were used to simulate water-surface and streambed elevations, 

require accurate representation of the channel and floodplain 

cross-section geometry. Channel and floodplain geometries 

were defined by a series of cross sections measured at 

variably spaced distances along lines oriented perpendicular 

to the direction of flow. Cross sections were surveyed in 

a local coordinate system using conventional surveying 

techniques and transformed from the local coordinate system 

to a common, geographically referenced coordinate system 

using global positioning system (GPS) data and a geographic 

information system (GIS) interface. 

In September 2000, USGS personnel surveyed the 

Big Lost River from the Pioneer weir and canal diversion 

structures (fig. 2) to a point about 2 mi upstream. Seventysix cross sections were surveyed (fig. 8). At each cross 

section, a tag line was stretched across the channel and held 

in place by wooden stakes to insure that the orientation of 

the measured section remained perpendicular to the direction 

of flow. Cross-section locations were placed closer together 

in areas near constrictions and large river bends. Sections 

within constrictions were spaced less than 50 ft apart, and 

sections in straight reaches were spaced several hundred feet 

apart. Each section also was located to best represent the 

hydraulic characteristics of that part of the river. The most 

downstream cross section, at the Pioneer weir and canal 

diversion structures, was assigned cross-section number 1 

and numbering increased in an upstream direction for each 

section (note: figure 8 does not include cross sections 30 

through 39 because of errors that were discovered in the field 

surveys for these cross sections. These missing cross sections 

were replaced with TIN-generated cross sections using a 1-ft 

contour map of the study area described in the section “TINGenerated Cross Sections”).

Streambed and Channel Characterization  21
ID9HZ12_fig08

R. 28 E. R. 29 E.

6

T.

2

N.

1

Gravel road

Dirt road

Dirt road

Dirt road

Big

Lost

River

113°02'30" 113°03'30"

43°32'43°31'30"

113°03'

0 2000 3000 FEET 1000

0 300 600 900 METERS

THALWEG—A line connecting the lowest points along the length of a streambedCROSS SECTION AND IDENTIFICATION NO.APPROXIMATE BOUNDARY OF TOP OF BANKBUREAU OF RECLAMATION PALEOINDICATOR SITE (Dean Ostenaa, written commun., 2001)

65

Site 1

constriction

Site 2

constriction

Site 3

constriction

Base from Dean Ostenaa (Bureau of Reclamation aerial photographs, written commun., 2001).

Pioneer weir and

canal diversion

structures

Saddle

area

BLR#6

BLR#8 1

4 41

44

64

68

76 80

48 52

12

16

20 28 29

40

60

84

86

8

24

56

72

Figure 8. Location of field-surveyed cross sections on the Big Lost River upstream of the Pioneer diversion structures, Idaho National Engineering and Environmental Laboratory, Idaho.

22  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Horizontal Referencing

All cross-section data were referenced to a common 

datum. Horizontal control was based on the North American 

Datum of 1983 (NAD 83), State Plane Coordinates, Idaho East 

Zone, in feet. Horizontal referencing of the cross sections and 

control points was accomplished using a differential GPS and 

a GIS interface. A GPS receiver (base station) was positioned 

at N892 (fig. 2), a well-documented survey-reference marker 

on the INEEL. A second roving GPS receiver was used to 

obtain coordinates at 20 additional control points between the 

INEEL diversion dam and the Pioneer diversion structures 

(fig. 2). For differential GPS, the GPS coordinates for the base 

station (N892) were compared with the known coordinates 

for the base station, and the differences inserted into the 

calculations for the roving GPS receiver. Both receivers must 

use the same satellites, and a minimum of four satellites. 

The differential GPS procedure assumes that error sources 

are the same for all GPS receivers in the survey area that are 

using the same GPS satellites at any given instant. These 

errors are measured at the base station and inserted into 

calculations for the roving receiver. Three other reference 

points (fig. 2 and table 3) near the study area were included in 

the differential GPS survey to verify accuracy. The horizontal 

accuracy for this survey was determined to be better than ±0.1 

ft. A number of the control points used in this survey were 

established by the Bureau of Reclamation (D.A. Ostenaa, 

Bureau of Reclamation, written commun., 2000) for use in 

the development of a 1-ft contour digital-terrain map (DTM) 

of the study area. The location and identification number of 

each reference mark and control point used during the survey 

are shown in figures 2 and 4. The latitude and longitude 

(horizontal position) and a description of each of the control 

and reference points used in this study are presented in table 3.

Vertical Referencing

Vertical control was based on the North American 

Vertical Datum of 1988 (NAVD 88), in feet. Vertical 

referencing of cross-section data and control points was 

accomplished using the differential GPS and GIS interface 

previously described. The vertical accuracy for this survey 

was determined to be better than ±0.05 ft on the basis of a 

comparison of the differential GPS survey results to known 

elevations at the three reference points (fig. 2 and table 3) that 

were used to verify survey accuracy.

TIN-Generated Cross Sections

To simulate floods in the study area, field-surveyed 

cross sections were extended out into the floodplain using a 

procedure approved by the Federal Emergency Management 

Agency (1998). Cross sections were extended using the 

Triangulated Irregular Network (TIN) interpolating procedure 

and data obtained from the 1-ft contour DTM of the study 

area that was prepared by the Bureau of Reclamation 

(D.A. Ostenaa, Bureau of Reclamation, written commun., 

2000). TIN-generated cross sections are constructed from 

interpolation of a network of triangulated DTM derived points 

(nodes) that define latitude, longitude, and elevation. Thus any 

point (x, y, and z) can be interpolated within the boundaries 

defined by the TIN control points.

To properly simulate flow through the site 1 constriction, 

additional cross sections were needed upstream of cross 

section 86 so that boundary conditions in the models would 

not affect flow computations at the site 1 constriction. An 

additional 22 cross sections, numbered 87 through 108, were 

generated using the TIN procedure (figs. 9A, 9B, 9C).

Seven cross sections, numbered 30 through 36, were 

generated using the TIN procedure because of problems with 

the data that prevented transformation of the field-surveyed 

cross sections at these locations to NAD 83 (horizontal) and 

NAVD 88 (vertical) coordinates. 

Three in-fill cross sections (60.5, 70.5, and 76.5) were 

generated using the TIN procedure. These cross sections 

were needed in the model simulations to minimize excessive 

conveyance changes between surveyed cross sections and to 

maintain computational stability. 

Five TIN-generated cross sections, numbered S1 through 

S5 (fig. 9B), were constructed for a small channel to represent 

water flowing around a small knob north of the channel near 

the site 1 constriction. These cross sections were used for flow 

simulations of 50 m3

/s.

A comparison of data from the field surveys and those 

generated from the TIN procedure indicated that the TINgenerated cross sections were within an accuracy of ±0.5 ft 

as recommended by the Federal Emergency Management 

Agency (1998). The average difference at most sections 

was less than 0.5 ft, except in areas where terrain relief was 

extreme. Because of extreme terrain relief, TIN-generated 

cross sections in and around the constrictions at sites 1 and 2 

differed significantly from the field-surveyed cross sections. 

Consequently, TIN-generated cross sections were not used in 

these areas; instead, seven linearly interpolated cross sections, 

between sections 49 and 54 (49.5, 50.5, 51.25, 51.5, 51.75, 

52.5, and 53.5) were used to model flows greater than 70 m3

/s 

through the site 2 constriction. Two adjacent field-surveyed 

cross sections were used to produce each interpolated cross 

section. These linearly interpolated sections were needed to 

maintain gradually-varied flow through the site 2 constriction 

for flows that transitioned from subcritical to supercritical.

The type of material composing the streambed, banks 

and floodplain was noted at each surveyed point. If there was 

more than one type of material at a point, all were noted with 

the dominant material listed first and the other materials listed 

in decreasing order. The occurrence of bedrock was especially 

important to note because model simulations assumed that 

scour depths would be limited by the presence of bedrock.

Streambed and Channel Characterization  23
Table 3. Location and description of elevation control and reference points used to establish horizontal and vertical control for the 

thalweg and cross-section surveys on the Big Lost River upstream of the Pioneer diversion structures, Idaho National Engineering and 

Environmental Laboratory, Idaho.

[Locations of reference points and control points are shown in figures 2 and 4. Latitude and longitude are based on the North American Datum of 1983 and are 

shown in degrees (°), minutes (’), and seconds (’’). Reference mark elevations are based on the North American Vertical Datum of 1988. Abbreviations: ft, ft; 

COE, U.S. Army Corps of Engineers; USGS, U.S. Geological Survey; Reclamation, Bureau of Reclamation]

Reference 

or control 

point and 

identification

Latitude Longitude Elevation

(ft) Description

Reference Points

BIGLOST1, 2 43°32’50.89476’’ 113°01’14.78261’’ 5,021.950 COE, Bronze disk

N8922 43°30’56.03889’’ 113°04’52.79188’’ 5,058.018 Brass disk near well NA-89-2

Control Points

0S12 43°32’02.25472’’ 113°02’13.87089’’ 5,021.562 Aluminum cap on rebar on Pioneer diversion structure

GAGE2 43°30’56.86456’’ 113°04’55.03646’’ 5,053.861 Brass disk near gaging station 13132520

HUB2 43°31’56.02522’’ 113°02’46.54081’’ 5,026.880 USGS, wooden stake

HUB3 43°31’41.96139’’ 113°03’15.27893’’ 5,030.466 USGS, wooden stake

HUB4 43°31’38.85863’’ 113°03’43.37538’’ 5,031.512 USGS, rebar

HUB5 43°31’29.32913’’ 113°03’57.21326’’ 5,037.493 USGS, rebar

HUB6 43°31’34.93367’’ 113°04’13.17101’’ 5,041.906 USGS, rebar

HUB7 43°31’32.47292’’ 113°04’28.92617’’ 5,043.596 USGS, rebar

HUB8 43°31’12.50069’’ 113°04’49.56396’’ 5,047.861 USGS, rebar

HUB9 43°30’50.83204’’ 113°05’03.43743’’ 5,070.190 USGS, rebar on INEEL diversion dam

PKR1 43°31’57.49975’’ 113°02’32.57683’’ 5,025.561 PK nail in basalt rocks

PT01 43°31’49.64287’’ 113°03’01.12794’’ 5,027.379 Reclamation, rebar

PT02 43°31’22.06486’’ 113°04’43.87643’’ 5,049.590 Reclamation, rebar

PT03 43°31’20.13931’’ 113°04’44.34819’’ 5,047.031 Reclamation, rebar

PT04 43°31’33.15356’’ 113°03’34.20555’’ 5,031.870 Reclamation, rebar

PT05 43°31’34.23366’’ 113°03’29.47427’’ 5,030.000 Reclamation, rebar

PT06 43°31’57.28505’’ 113°02’41.77107’’ 5,022.274 Reclamation, rebar

PT07 43°32’00.40034’’ 113°02’42.22723’’ 5,018.763 Reclamation, rebar

WEL3 43°31’42.89729’’ 113°03’33.95965’’ 5,028.665 USGS, rebar

WELL2 43°31’42.85368’’ 113°03’34.08158’’ 5,029.938 Top of well casing at well

1

Elevation reference point not shown in figures 2 and 4.

2

Used for survey verification.

24  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
ID9HZ12_fig09A

0 2000 3000 FEET 1000

0 300 600 900 METERS

Base from Dean Ostenaa (Bureau of Reclamation,aerial photographs, written commun., 2001).

R. 28 E. R. 29 E.

T.

2

N.

6 1

Gravel road

Dirt road

Dirt road

Dirt road

Big

Lost

River

113°02'30" 113°03'30"

43°32'43°31'30"

113°03'

Site 1

constriction

Site 2

constriction

Site 3

constriction

THALWEG—A line connecting the lowest points along the length of a streambedCROSS SECTION AND IDENTIFICATION NO.APPROXIMATE BOUNDARY OF TOP OF BANKBUREAU OF RECLAMATION PALEOINDICATOR SITE (Dean Ostenaa, written commun., 2001)

65

Pioneer weir and

canal diversion

structures

Saddle

area

BLR#6

BLR#8

1 3

8

13 20 23 26 28

29 30

40

31

41 42 43

44

45

4748

57

58

59 60

61

60.5

62

63

71

70.5

65

64

66

68 67

69

70

72

73

74 75

76

76.5

77

78 79

80 81

90

495051

46

35

36

56

55

33 34

32

108

107

106

105

104

103

102

101

100

99 98

97

96

95

93

4.6

6.3

9.6 11.3

16.5

92

91

88

89

94

A. Cross sections used for flow simulations of 10 cubic meters per second

Figure 9. Location of field-surveyed, TIN-extended, and TIN-generated cross sections used for flow simulations of 10, 50, and 70 cubic meters per second and greater on the Big Lost River upstream of the Pioneer diversions structures, Idaho National Engineering and Environmental Laboratory, Idaho

Streambed and Channel Characterization  25
0 2000 3000 FEET 1000

0 300 600 900 METERS

ID9HZ12_fig09B

6

1

R. 28 E. R. 29 E.

T.

2

N.

Gravel road

Dirt road

Dirt road

Dirt road

Big

Lost

River

113°02'30" 113°03'30"

43°32'43°31'30"

113°03'

B. Cross sections used for flow simulations of 50 cubic meters per second

Site 1

constriction

Site 3

constriction

Site 2

constriction

THALWEG—A line connecting the lowest points along the length of a streambedCROSS SECTION AND IDENTIFICATION NO.APPROXIMATE BOUNDARY OF TOP OF BANKBUREAU OF RECLAMATION PALEOINDICATOR SITE (Dean Ostenaa, written commun., 2001)

65

Pioneer weir and

canal diversion

structures

Saddle

area

BLR#6

BLR#8 1 3

8

13 20 23 26 28

29 30

40

31

41 42 43

44

45

4748

57

58

59 60

61

60.5

62

63

71

70.5

65

64

66

68 67

69

70

72

73

74 75

76

76.5

77

78 79

80 81

90

495051

46

35

36

56

55

33 34

32

108

107

106

105

104

103

102

101

100

99 98

97

96

95

93

4.6

6.3

9.6 11.3

16.5

92

91

88

89

94

Side channel

S1 through S5

Base from Dean Ostenaa (Bureau of Reclamation,aerial photographs, written commun., 2001).

Figure 9.—Continued.

26  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
ID9HZ12_fig09C

6 1

R. 28 E. R. 29 E.

T.

2

N.

Gravel road

Dirt road

Dirt road

Dirt road

Big

Lost

River

113°02'30" 113°03'30"

43°32'43°31'30"

113°03'

0 2000 3000 FEET 1000

0 300 600 900 METERS

Site 1

constriction

Site 3

constriction

Site 2

constriction

THALWEG—A line connecting the lowest points along the length of a streambedCROSS SECTION AND IDENTIFICATION NO.APPROXIMATE BOUNDARY OF TOP OF BANKBUREAU OF RECLAMATION PALEOINDICATOR SITE (Dean Ostenaa, written commun., 2001)

65

Base from Dean Ostenaa (Bureau of Reclamation,aerial photographs, written commun., 2001).

C. Cross sections used for flow simulations of 70 cubic meters per second and greater

Pioneer weir and

canal diversion

structures

Saddle

area

BLR#6

BLR#8 1 3

8

13 20 23 26 28

29 30

40

31

41 42 43

44

45

4748

57

58

59 60

61

60.5

62

63

71

70.5

65

64

66

68 67

69

70

72

73

74 75

76

76.5

77

78 79

80 81

90

495051

46

35

36

56

55

33 34

32

108

107

106

105

104

103

102

101

100

99 98

97

96

95

93

Figure 9.—Continued.

Streambed and Channel Characterization  27
Hydraulics of the Study Reach

In the study reach, the Big Lost River is incised into 

Holocene and upper Pleistocene alluvium and middle to 

upper Pleistocene basalt lava flows (fig. 3) (Kuntz and others, 

1994). Shallow subcropping basalt beneath the alluvial fill 

strongly influences the present-day course of the river and 

channel slope. At three locations in the study area bedrock 

forms constrictions in the channel that locally control the 

course of the river and the slope of the channel. Bedrock 

also is exposed in the streambed at cross sections 1, 6, 7, 41, 

59, 62, and 65-67 (fig. 8). These bedrock controls locally 

restrict the depth of scour and thus control streambed slope. 

The distinction between a constriction-controlled section and 

channel-controlled section is based on HEC-RAS simulations 

of backwater and the effect that backwater accumulation has 

on frictional resistance to flow and hence on scour. 

In the study reach, the general slope of the streambed 

is about 0.0023 between cross sections 1 and 108. The slope 

of the streambed between the sites 1 and 2 constrictions is 

0.0019. The slope of the streambed in this section of the 

river is lower than elsewhere in the study area and reflects 

the effects of backwater accumulation upstream of the site 2 

constriction. Locally, the streambed slope varies considerably, 

especially in the immediate vicinity of the constrictions at sites 

1, 2, and 3 and in sections of the river where basalt is exposed 

in the streambed.

Constriction-Controlled Sections

Constriction-controlled sections, for the purposes of 

this study, occur within the boundaries that define sites 1, 2, 

and 3 (fig. 4). These boundaries are defined by the extent of 

backwater accumulation upstream of bedrock constrictions. 

Convergence of streamflow inside constrictions and upstream 

velocity reduction cause upstream water-surface elevations to 

be higher and channel slopes to be lower than would be the 

case in the absence of flow convergence. 

At three locations in the study area, bedrock walls narrow 

and confine the river. The hydraulic effect of constrictions, or 

a local reduction in channel width, depends on flow magnitude 

and channel size. For natural rivers and streams, resistance or 

friction from the channel sides and bottom controls the flow. 

Constrictions cause flows to converge. If the approaching flow 

to the constrictions is subcritical, the constriction causes a 

backwater effect that may extend for a long distance upstream. 

Model simulations, described in the section “Numerical 

Modeling,” indicate that flow approaching all the constrictions 

is subcritical. Constriction-controlled reaches are susceptible 

to backwater, resulting in water-surface elevations that are 

higher than those that would occur in the absence of the 

constriction.

 The constriction at site 2 is quite narrow, about 17 ft 

wide, with nearly vertical bedrock walls greater than 20 ft 

high. The constrictions at sites 1 and 3 are much wider. At site 

1 the constriction is about 27 ft wide, and at site 3 it is about 

46 ft wide. Another constriction occurs just downstream of the 

gaging station below the INEEL diversion dam (13132520) 

(fig. 2). This constriction is upstream of the study area and was 

not included in the surface-water flow and sediment-transport 

simulations described in this report. It is, however, included in 

the TRIM2D simulations described in the report by Ostenaa 

and others (1999).

The channel bed within the confines of the constrictions 

consists of a 4- to 6-ft thick accumulation of easily erodible 

alluvium. At the site 2 constriction, the bed material is 

composed of loose, unconsolidated sands and silts. Depth 

to bedrock inside this constriction ranges from 4.5 to 5.5 ft. 

During a flood, all bed materials at this site probably are 

removed and the underlying bedrock is exposed. As the flood 

recedes and velocities decrease, residual bed load and finer 

suspended sediments are deposited inside the constriction. 

Water often pools inside this constriction when flows in the 

river recede. Pooling of water is indicated by the accumulation 

of very-fine sand and silt materials inside this constriction. 

The channel fill material in the constrictions at sites 1 and 

3 consists of fine- to medium-grained sand near the surface 

that becomes coarser with depth. Because these constrictions 

are wider than the constriction at site 2, flow velocities 

through these constrictions are less than those through the 

constriction at site 2. The greater width of these constrictions 

limits flow velocities and, as demonstrated in the HEC-6 

model, decreases the depth of scour. Only very large floods 

have the potential to scour the channel down to bedrock at 

these constrictions. Trenching inside the three constrictions 

indicated that depths to bedrock are as much as 6, 5.5, and 

almost 4 ft at the site 1, 2, and 3 constrictions, respectively. 

Channel-Controlled Sections

Unlike the constriction-controlled sections, channelcontrolled sections are not strongly influenced by backwater 

effects. In channel-controlled sections, frictional resistance 

forces dominate, the streambed slope is steeper, and flow 

velocities are higher. Flow in these sections is more uniform 

than in the constriction-controlled sections. Cross-section 

geometry and the armored surface layer within the channelcontrolled sections also tend to be more uniform than in the 

constriction-controlled reaches. Most armored surface-layer 

sampling sites in the channel-controlled sections of the river 

are near the center of the active channel. These locations 

generally are representative of conditions across the entire bed 

because armoring appears to be uniform from bank to bank in 

the channel-controlled sections of the river.

28  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
For discussion purposes, it is convenient to divide the 

study area into upper, middle, and lower reaches (fig. 9). 

The upper reach extends from cross section 108, at the 

upstream end of the model reach, to the site 1 constriction; 

the middle reach extends from the site 1 constriction to the 

site 2 constriction; and the lower reach extends from the site 

2 constriction to cross section 1, at the downstream end of 

the model reach. Each of these subdivisions includes both 

channel- and constriction-controlled sections of the river as 

previously described.

Numerical Modeling

The primary objective of numerical modeling was to 

simulate the effects of the constrictions at sites 1, 2, and 3 on 

flood elevations. Numerical models can be used to estimate 

water-surface elevations, flow depths, flow velocities, stream 

power, scour, deposition, and sediment transport for flows of 

varying magnitude. In the two previous modeling studies, one 

conducted by the USGS (Kjelstrom and Berenbrock, 1996) 

using WSPRO, and the other conducted by the Bureau of 

Reclamation (Ostenaa and others, 1999) using TRIM2D, the 

channel bed was assumed to remain stable during all flows, 

and sediment transport processes were not simulated. For the 

present study, HEC-RAS (U.S. Army Corps of Engineers, 

1997a, 1997b, and 1997c) version 3.0.1 was used to construct 

a surface-water flow model, and HEC-6 (U.S. Army Corps 

of Engineers, 1993) version 4.1.0 was used to construct 

a surface-water flow and sediment-transport model. The 

modeled reach of the river in this study extends from a point 

about 2.3 mi downstream of the INEEL diversion dam to the 

Pioneer diversion structures, a distance of 9,850 ft. The reach 

that was modeled in the Bureau of Reclamation study using 

TRIM2D (Ostenaa and others, 1999) extends from the INEEL 

diversion dam to the Pioneer diversion structures, a distance of 

22,050 ft.

HEC-RAS Model Implementation

HEC-RAS is a computer program that simulates 1-D, 

gradually varied, steady flow in open channels with fixed 

boundaries. In areas where flow velocity is changing rapidly, 

the gradually varied flow assumption requires the use of 

closely spaced cross sections. The HEC-RAS model uses 

the standard step method (Chow, 1959, p. 265) to determine 

changes in water-surface elevations from one cross section to 

the next by balancing total energy head at the sections. This 

1-D model assumes that energy is uniform in a cross section. 

This assumption is not valid at locations where flow is not 

parallel to the main channel or where vertical velocities are 

significant. The model also assumes that flow is unobstructed 

with the channel and floodplain free of debris.

The field-surveyed and TIN-generated cross sections and 

the roughness coefficients (n values) derived from the earlier 

WSPRO model (Kjelstrom and Berenbrock, 1996) were used 

to define channel and floodplain hydraulic characteristics for 

the initial HEC-RAS simulations. Roughness coefficients in 

the WSPRO model were determined by calibrating the model 

against field-measured flows and stages at three cross sections 

downstream of the INEEL diversion dam gaging station 

(13132520) (fig. 2). These stage-discharge measurements were 

made in the spring and summer of 1995 (L.C. Kjelstrom, U.S. 

Geological Survey, oral commun., 2003).

Three separate HEC-RAS models were developed to 

accommodate the different hydraulic conditions that occur 

upstream of the site 1 constriction for the peak flows that 

were simulated. In the first model a flow of 10 m3

/s (353 

ft3/s), representing a 2-year (or 50-percent probability) flood, 

was simulated, and in the second model a flow of 50 m3/s 

(1,765 ft3/s) was simulated. The 10 m3/s model included the 

field-surveyed and TIN-generated cross sections shown in 

figure 9A. Five side-channel cross sections, numbered S1 

through S5, were added to the second HEC-RAS model 

to represent water that flows around a small knob north of 

the channel at cross section 90 (fig. 9B). The third model 

simulated flows equal to and greater than 70 m3/s. The third 

model differs from the first by the exclusion of cross sections 

87, 88, 89, 91, 92, and 94 and the elongation of cross sections 

86, 90, and 93 (fig. 9C); and differs from the second by the 

exclusion of cross sections numbered S1 through S5. The 

removal of cross sections and the elongation of cross sections 

were necessary because the meander bend upstream of the site 

1 constriction was completely flooded for flows greater than 

about 70 m3/s. Figures 9A, 9B, and 9C show the cross sections 

that were used for flow simulations of 10, 50, and 70 m3/s and 

greater, respectively.

Critical depth occurs at free outfalls. A free outfall 

occurs at cross section 1, where the streambed drops nearly 

15 ft vertically (Berenbrock and Kjelstrom, 1998; and 1-ft 

contours from the Bureau of Reclamation’s aerial-photography 

mapping, D.A. Ostenaa, Bureau of Reclamation, written 

commun., 2001) below the Pioneer diversion structures. 

For critical flow, the Froude (Fr) number is set equal to 1. 

To determine the starting elevation, equations 1 and 2 are 

expressed in terms of velocity and set equal to each other. The 

resulting equation is solved iteratively by adjusting average 

flow depth (D) and width of the water surface (W) to compute 

the average depth of flow for each simulated flow discharge 

(Q) with Fr = 1. For rectangular cross sections, W is held 

constant and D is equal to the depth of flow (Chow, 1959, p. 

81).

Numerical Modeling  29
Starting water-surface elevations for the HEC-RAS 

and HEC-6 models at cross section 1 were determined by 

computing critical depth from the Froude number:

Fr V gD = /( ) /1 2

, (1)

and the flow equation:

Q VA VDW = = , (2)

where:

Fr is Froude number [L0],

V is mean velocity [L/T],

g is acceleration of gravity [L/T2

], (9.81 m/s2 in SI units, 

32.16 ft/s2 in English units),

D is average flow depth [L]

Q is flow discharge [L3

/T]

A is cross section area [L2

], and 

W is width of the water surface [L].

The units for these terms are length [L], time [T], and 

dimensionless [L0].

At the upstream end of the model reach, cross section 

108, the starting water-surface elevation was determined from 

the flow equation (2) and a slope-conveyance computation 

of normal depth using Manning’s equation for open-channel 

flow:

V n R S = ( / ) / / 1 2 3 1 2

, (3)

where:

V is velocity [L/T],

n is Manning’s roughness coefficient [L0], (note: in 

equation (3) use 1/n for SI units, and 1.486/n for 

English units),

R is hydraulic radius [L],

S is slope of the energy grade line [L0],

A is cross-section area [L2

], and 

Q is flow discharge [L3

/T].

The units for these terms are length [L], time [T], and 

dimensionless [L0].

In channel-controlled sections, where the stage-discharge 

relation is determined primarily by the channel shape and 

local channel-bed friction, the channel slope can be used to 

approximate the energy grade line (S). Equation (3) is solved 

for each simulated Q using this assumption. 

The upper boundary condition is required only if flow 

in the modeled reach is supercritical. If flow in the entire 

reach is subcritical, then the upper boundary condition is not 

required and was not used during the simulation. It was noted 

during simulations that flow through the site 2 constriction 

transitioned from subcritical to supercritical when modeled 

flow was equal to and greater than 100 m3/s. For the modeled 

reach, flows equal to and greater than 100 m3/s at the site 2 

constriction were supercritical, and flows equal to and less 

than 70 m3/s were subcritical. It was not the purpose of this 

study to determine the minimum flow necessary to initiate 

supercritical flow. Transitioning from one flow regime to the 

other was done automatically by HEC-RAS with the inclusion 

of the specified upstream boundary condition for supercritical 

flow. As noted previously, to maintain computational stability, 

seven interpolated cross sections were used to model flows 

greater than 70 m3/s through the site 2 constriction. 

Manning’s n Determination

Manning’s n, also known as the roughness coefficient, 

represents the flow resistance in a channel. Factors that affect 

flow resistance include: (1) size, gradation, and angularity of 

materials composing the streambed; (2) channel shape; (3) 

type of bed forms (for example dunes, antidunes, and ripples); 

(4) presence of bars; (5) riparian vegetation; (6) man-made 

and natural structures (for example bridges, causeways, and 

constricted openings); (7) presence of suspended sediment 

and movement of bed load; and (8) degree of meandering. 

In channel-controlled sections, resistance decreases as flow 

increases; resistance also decreases as the size of the bed 

material decreases. In the straight channel-controlled sections 

of the model reach, the size, gradation, and angularity 

of the materials composing the streambed probably are 

more important than the other factors for determining flow 

resistance. In constriction-controlled sections, the size of the 

constriction is the major control on flow resistance. Flowresistance equations and the roughness coefficients established 

from the previous 1-D WSPRO model (Berenbrock and 

Kjelstrom, 1998) were used to determine n values at selected 

cross sections where resistance forces are dominated by the 

character of the streambed materials. The WSPRO-derived 

n values were modified on the basis of flow-resistance 

equations for gravel-bed channels because no stage-discharge 

or n-verification measurements have been made in the study 

area. Cross sections 20, 70.5, and 76 (fig. 9) were selected as 

representative sections for initial estimates of Manning’s n

because these sections are in virtually straight reaches of the 

river, and the materials composing the channel bed in these 

reaches of the river are the primary source of flow resistance.

The flow-resistance equations developed by Limerinos 

(1970), Bray (1979), Hey (1979), and Mussetter (1989) have 

been used extensively for gravel-bed rivers. The Mussetter 

(1989) equations were not used in this study, however, because 

preliminary scoping calculations estimated Froude numbers in 

the supercritical range (Fr > 1), which is not realistic for the 

flows being considered in these channel-controlled sections. 

The calculated n values, derived by using the aforementioned 

flow-resistance equations, ranged from 0.019 to 0.037, with 

an average of 0.025 for the relatively straight channel reaches 

represented by cross sections 20, 70.5, and 76. To account for 

30 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
the irregular land surface, vegetation, and other obstructions 

an n value of 0.040 was assigned to the floodplain portion of 

these sections. 

For channel reaches with modest curvature or changes in 

cross-section shape from one section to another, the n values 

were increased from the straight-channel-section values by 

about 30 percent (Chow, 1959); and for channel sections 

where there is substantial variation in cross-section shape 

or severe curvature, the values were increased by 50 percent 

(Chow, 1959) of the straight-section values. With these 

adjustments, n values for modest curvature of the channel were 

0.033 and 0.052 for the channel and floodplain, respectively; 

and n values for severe curvature of the channel were 0.038 

and 0.060 for the channel and floodplain, respectively. 

Elevations of high-water marks at cross sections in 

and adjacent to the constrictions at sites 1 and 2 also were 

surveyed at the time of the cross-section field surveys. These 

marks consisted of white, sub-horizontal water stains on basalt 

outcrops that form the banks of these constrictions (cover 

photograph shows the character of the high-water marks for 

the site 2 constriction) and were interpreted to represent the 

high water marks for floods with short return periods, in this 

case assumed to be the 2-year flood2

. The quality of the highwater marks at the site 3 constriction, the widest of the three 

constrictions, were poor and were not used to represent the 

elevation of the 2-year flood. Simulations of the 2-year flood 

and elevations of the high-water marks (assumed to represent 

the 2-year flood) were used to evaluate the initial estimates of 

the n value chosen to represent frictional resistance in the main 

channel of the river.

Daily mean discharges for the Big Lost River below the 

INEEL diversion dam (13132520) gaging station, about 1.5 mi 

upstream of site 1 (fig. 2), are shown in figure 10. This gaging 

station has been in operation since 1984. Peak flows measured 

at this gaging station are all less than 13.2 m3/s (466 ft3/s) 

and only two events exceeded 13 m3/s (459 ft3/s) (fig. 10). A 

zero flow was recorded 77 percent of the time at this station. 

The diversion dam just upstream of this gaging station affects 

flows and peak flows at this gaging station and in the study 

area. Flow downstream of the diversion dam can be entirely 

shut off and rerouted into a diversion channel that discharges 

into a series of off-channel depressions or spreading areas 

southwest of the study area. Because flow is regulated at 

the diversion dam, peak-flow data for the gaging station Big 

Lost River near Arco (13132500) were used to estimate the 

2-year flood in the study area. A three-parameter log-Pearson 

Type III flood-frequency analysis of these data, as outlined in 

“Guidelines for Determining Flood Flow Frequency” (Bulletin 

#17B by the Interagency Advisory Committee on Water Data, 

1982), showed that the 2-year flood is about 10 m3/s (353 ft3/s) 

(fig. 11) with lower and upper 95-percent confidence limits of 

7.1 and 13.9 m3/s, respectively. The period of record used for 

this computation was 1947 through 1961, and 1965 through 

2000 (n=51; six of these peak values were zero for the period 

of record).

Water-surface elevations simulated by the HEC-RAS 

model, with cross sections configured to simulate a flow of 

10 m3/s (fig. 9A), were compared to elevations of the surveyed 

high-water marks. If differences occurred, then n values 

pertaining only to the channel portion of the cross section 

were modified because the mean annual flood (10 m3/s) can 

be contained wholly within the active channel. For calibration 

purposes, the n value is the only parameter that can be 

adjusted in the HEC-RAS model. 

Simulated water-surface elevations for the 2-year flood 

plot between the measured high-water marks (figs. 12A and 

12B). The average difference between the high-water marks 

and model simulation results was 0.38 ft at site 1 (5 measured 

marks) and 0.12 ft at site 2 (7 measured marks), and the 

maximum differences were 1.2 ft at the site 1 constriction and 

0.8 ft at the site 2 constriction. The closely spaced distribution 

of high-water marks, both above and below the simulated 

water-surface elevation line, suggests that the initial estimates 

of the n values for low flows in the main channel of the river 

were appropriate3

.

HEC-RAS Simulation Results

Water-surface elevations for peak flows of 50, 70, 100, 

150, 187, and 200 m3/s were simulated with HEC-RAS. Flows 

of 70, 100, 150, and 187 m3/s also were simulated in the 

TRIM2D model (Ostenaa and others, 1999). For presentation 

clarity, only the results for simulations of 50, 100, 150, and 

200 m3

/s (fig. 13A) are presented in this section. Results for 

the intermediate flows of 70, 100, and 150 m3/s are presented 

in the section “Comparisons of HEC-RAS, HEC-6, and 

TRIM2D Simulation Results.” 

At the sites 1 and 2 constrictions, where the channel slope 

abruptly steepens, large changes in water-surface elevation 

occur for all simulated flows greater than 50 m3

/s (fig. 13A). 

As peak flow increases, differences between water-surface 

elevations upstream and downstream of the constrictions 

also increase. For a flow of 200 m3/s, these differences are 

about 2.0 ft through the site 1 constriction (between cross 

sections 85 and 83) and 5.0 ft through the site 2 constriction 

(between cross sections 53.5 and 51.25). For a flow of 50 m3/s, 

these differences are about 1.0 ft for both the site 1 and 2 

constrictions. Because the channel is much wider and the slope 

much gentler, changes in water-surface elevation through the 

site 3 constriction were minimal for all simulated flows. 

2

The 2-year flood is approximately equal to the mean annual flood which 

is defined as a flood with a return period of 2.33 years (Chow, 1964, p. 8-25). 

The computed mean annual flood is 12.8 m3/s (n=51), with lower and upper 

95-percent confidence limits of 9.1 m3/s and 18.0 m3/s, respectively.

3

The HEC-RAS simulated water-surface elevation for a flow of 10 m3/s was 

confirmed at the site 2 constriction in July 2006. The water-surface line for a 

measured flow of about 10 m3/s (9.97 m3/s) at cross section 53.5 was marked 

on May 31, 2006; and the elevation of this mark was measured on July 11, 

2006. The surveyed elevation was 5,014.02 ft—in very close agreement with 

the HEC-RAS simulated elevation of 5,014.03 ft (fig. 12B and photograph on 

inside of report cover).

Numerical Modeling  31
ID9HZ12_fig10

BIG LOST RIVER BELOW INEEL DIVERSION DAM, IDAHO (13132520)

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

1984 1986 1988 1990 1992 1994 1996 1998 2000

DAILY MEAN DISCHARGE, IN CUBIC METERS PER SECOND 

YEARS

2-year flood at Arco

gaging station (13132500)

Periods of no flow

Figure 10. Daily mean discharge for the Big Lost River below the Idaho National Engineering and Environmental 

Laboratory diversion dam (13132520), Idaho, 1984–2000.

32  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
ID9HZ12_fig11

BIG LOST RIVER NEAR ARCO, IDAHO (13132500)

Period of record: 1947-61; 1965-2000 (n=51; 6 of these values had zero peak flow)

Source: Interagency Advisory Committee on Water Data, 1982, Bulletin No. 17B

5

1

10

989999.5 9095 7080 50 2030 12510 0.20.5

1.021.011.005 1.05 1.11 1.481.25 2 53 2010 10050 500200

7

3

0.5

0.1

0.7

0.3

50

100

70

30

500

1,000

700

300

ANNUAL PEAK FLOW, IN CUBIC METERS PER SECOND 

ANNUAL EXCEEDANCE PROBABILITY, IN PERCENT 

RECURRENCE INTERVAL, IN YEARS 

Annual peak flow

Bulletin #17B curve

2-year flood

1958

Figure 11. Flood-frequency curve for the Big Lost River near Arco (13132500), Idaho, 1947–61 and 1965–2000.

Numerical Modeling  33
ID9HZ12_fig12A

WEST DIRECTION OF FLOW EAST

5,023

5,022

5,021

5,020

5,019

5,018

5,017

5,016

5,015

5,014

5,013

7,100 7,050 7,000 6,950 6,900 6,850 6,800

85

84

83

82

81

80

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

DISTANCE , IN FEET UPSTREAM OF PIONEER DIVERSION STRUCTURES 

CROSS SECTIONS 

HEC-RAS simulated water-surface 

elevation for a peak flow of

10 cubic meters per second

High-water

mark

Site 1

constriction

Measured

thalweg

elevation

A. Site 1 constriction

Figure 12. High-water marks, measured thalweg elevation, and HEC-RAS simulated water-surface elevation for 

a peak flow of 10 cubic meters per second at the sites 1 and 2 constrictions on the Big Lost River upstream of the 

Pioneer diversion structures, Idaho National Engineering and Environmental Laboratory, Idaho.

34  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
ID9HZ12_fig12B

WEST

DIRECTION OF FLOW

EAST

3,300 3,250 3,200 3,150 3,100

55

54

53.5

53

52.5

52

51.75

51.5

51.25

51

50.5

50

49.5

49

48

5,016

5,015

5,014

5,012

5,011

5,010

5,009

5,008

5,007

5,006

5,005

5,013

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

DISTANCE , IN FEET UPSTREAM OF PIONEER DIVERSION STRUCTURES 

CROSS SECTIONS 

HEC-RAS simulated water-surface 

elevation for a peak flow of

10 cubic meters per second

B. Site 2 constriction

Measured

thalweg

elevation

High-water

mark

Measured water-level

elevation on May 31, 2006,

for a discharge of 10 cubic

meters per second.

Site 2

constriction

Figure 12.—Continued.

Numerical Modeling  35
ID9HZ12_fig13A

WEST DIRECTION OF FLOW EAST

Site 1

constriction

Site 2

constriction

Site 3

constriction

42

(BLR #8)

66

68

72

(BLR #6)

98

(Saddle area)

Cross section

8

5,040

5,035

5,030

5,025

5,020

5,015

5,010

5,005

5,000

4,995

10,000 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 0

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

DISTANCE, IN FEET UPSTREAM OF PIONEER DIVERSION STRUCTURES 

SIMULATED WATER-SURFACE ELEVATION 

WHEN FLOW, IN CUBIC METERS PER SECOND, IS:

 HEC-RAS MODEL 

 50

 100 

 150

 200

MEASURED THALWEG ELEVATION

Middle

Reach

Lower

Reach

Upper

Reach

A. Big Lost River

Figure 13. Measured thalweg elevation and HEC-RAS simulated water-surface elevations for selected flows of 50, 100, 

150, and 200 cubic meters per second on the Big Lost River and sites 1 and 2 constrictions upstream of the Pioneer diversion 

structures, Idaho National Engineering and Environmental Laboratory, Idaho.

36  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
ID9HZ12_fig13B

WEST DIRECTION OF FLOW EAST

Site 1

constriction

5,035

5,033

5,031

5,029

5,027

5,025

5,023

5,021

5,019

5,017

5,015

5,013

5,011

7,100 7,050 7,000 6,950 6,900 6,850 6,800

85

84

83

82

81

80

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

CROSS SECTIONS 

DISTANCE , IN FEET UPSTREAM OF PIONEER DIVERSION STRUCTURES 

B. Site 1 contriction on Big Lost River

HEC-RAS SIMULATED WATER-SURFACE ELEVATION 

WHEN FLOW, IN CUBIC METERS PER SECOND, IS:

 50

 100 

 150

 200

MEASURED THALWEG ELEVATION

Figure 13.—Continued.

Numerical Modeling  37
ID9HZ12_fig13C

WEST

DIRECTION OF FLOW

EAST

Site 2

constriction

3,300 3,250 3,200 3,150 3,100

55

54

53.5

53

52.5

52

51.75

51.5

51.25

51

50.5

50

49.5

49

48

5,030

5,025

5,020

5,015

5,010

5,005

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

CROSS SECTIONS 

DISTANCE , IN FEET UPSTREAM OF PIONEER DIVERSION STRUCTURES 

C. Site 2 constriction on Big Lost River

HEC-RAS SIMULATED WATER-SURFACE ELEVATION 

WHEN FLOW, IN CUBIC METERS PER SECOND, IS:

 50

 100 

 150

 200

MEASURED THALWEG ELEVATION

Figure 13.—Continued.

38  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
The development of extensive backwater upstream of 

the constrictions at sites 1 and 2 also is shown in figure 13A. 

Backwater effects are indicated in areas where the watersurface slope becomes significantly less than the channel 

slope. Simulation results indicate that backwater extends more 

than 2,000 ft upstream of the site 1 constriction for a peak 

flow of 200 m3/s, and that backwater decreases as discharge 

decreases (fig. 13A). For a peak flow of 100 m3/s, backwater at 

the site 1 constriction affects about 500 ft of the river upstream 

of the constriction. Backwater affects about 1,000 ft of the 

river upstream of the site 2 constriction for a peak flow of 

100 m3/s, but does not extend upstream of cross section 68 

for the higher flow simulations. This is due to a local control 

at cross sections 69 and 70 (figs. 9C and 13A), where the 

cross-section flow area is much less than the adjacent sections 

(cross sections 68 and 71), and to supercritical flow through 

the site 2 constriction for flows equal to and greater than 

100 m3

/s thereby limiting the upstream extent of backwater 

accumulation at higher flows.

Backwater also occurs upstream of cross section 8 

(figs. 9C and 13A) and extends about 1,000 ft to almost cross 

section 23 for flows greater than 100 m3/s. Backwater at this 

location occurs upstream of a minor constriction that was not 

emphasized in this study. The constriction at cross section 8 

is a considerable distance downstream of BLR#6 and BLR#8, 

two locations in the Bureau of Reclamation’s study where 

TRIM2D model simulations of water-surface elevations 

(Ostenaa and others, 1999) were used to establish the 

magnitude of peak flows with a 300-to 500-year return period.

The water-surface elevations upstream of several local 

controls within the modeled reach are affected by these 

controls at low flow. As discharge increases, however, many of 

these smaller controls become submerged and their influence 

on backwater accumulation gradually is reduced or drowned 

out, leaving a small depression on the water surface. For 

example, the control at cross section 66 probably becomes 

drowned out at flows equal to and greater than 50 m3/s, thus 

limiting the accumulation of additional backwater at higher 

flows.

HEC-RAS model simulations indicate that the 

constrictions at sites 1 and 2 are the two major controls that 

have a significant effect on the accumulation of backwater 

in the study reach. These controls begin to have major effect 

when flows exceed 50 m3

/s at the site 2 constriction, and when 

flows exceed 100 m3/s at the site 1 constriction.

The water-surface profile through the constrictions also 

is influenced by flow magnitude and channel size. As flow 

passes through these constrictions, flow depths decrease 

and velocities increase until there is no more decrease in 

flow depth. The observed effect depends on whether flow 

depth is greater than or less than critical depth. If flow depth 

is greater than critical depth, then flow depth or the water 

surface gradually will decrease as flow accelerates through 

the constriction. This occurs at the site 1 constriction for all 

modeled flows (fig. 13B). Flow through the site 1 constriction 

remains subcritical and the constriction does not act as a choke 

(see glossary at end of report). The streambed elevation also 

increases slightly downstream of the constriction (between 

cross sections 80 and 81). The elevated streambed downstream 

of the constriction likely is due to deceleration after flow exits 

the constriction and to the deposition of suspended sediment 

and bed load during flood recession. 

If flow depth in the constriction is less than the critical 

depth, then flow is supercritical and a hydraulic jump forms 

downstream to bring the flow back to subcritical. This occurs 

at the site 2 constriction for peak flows of 100 m3/s and 

greater (fig. 13C) and, in the case of supercritical flow, the 

constriction is considered to have choked flow. The maximum 

difference in flow depth through the constriction is greater for 

a peak flow of 100 m3/s than at 200 m3/s because the increased 

flow drowns out the effect of the constriction. Flows less 

than 70 m3/s are subcritical and the water-surface elevation 

remains relatively steady through the constriction. At the site 

2 constriction, the elevation of the streambed is significantly 

higher downstream of the constriction than upstream. This 

elevation difference likely is the result of the deposition of 

sediment and bed load caused by a hydraulic jump that is 

accompanied by a sudden reduction in flow velocity.

HEC-RAS Sensitivity Analysis 

The sensitivity of the HEC-RAS model to variations in 

Manning’s n and to variations in streambed elevation was 

evaluated. The procedure involves holding all input parameters 

constant except the one being analyzed and then varying that 

value. Changes in model-simulated water-surface elevations 

were used to determine the sensitivity of the model to changes 

in Manning’s n and to changes in streambed elevation. For 

all sensitivity simulations, the boundary conditions at the 

upstream and downstream cross sections were not changed. 

All sensitivity analyses were conducted for a peak flow of 100 

m3/s—the flow that is of primary interest to this study. Watersurface elevation changes, however, at these high peak flows 

probably are more dependent on the magnitude of the flow 

than on the channel roughness indicated by Manning’s n.

Manning’s n

To determine the sensitivity of the model to variations in 

Manning’s n, a series of simulations for a peak flow of 

100 m3/s were made in which the n value was varied by a 

factor of 0.5 and by a factor of 1.5 times the initial calibrated 

values.

Variations in the results of the simulations in response to 

changes in n values (figs. 14A, 14B, and 14C) indicate that the 

model is sensitive to the n values chosen to represent frictional 

resistance. Varying n values by 0.5 times (decreasing) and 

by 1.5 times (increasing) the calibrated values resulted in 

water-surface elevation changes from near 0 to about 2.0 ft 

(fig. 14A). Larger changes, from 4 to 5 ft, occur through the 

sites 1 and 2 constrictions (figs. 14B and 14C); however, 

these changes probably are more a reflection of flow regime 

Numerical Modeling  39
changes than changes in frictional resistance. The average 

difference was -0.8 and +1.0 ft for the 0.5 and 1.5 times 

simulations, respectively. The average difference in simulated 

water-surface elevations for all cross sections (1 through 108) 

and the cross sections at the paleoindicator sites [cross section 

42 (BLR#8), cross section 72 (BLR#6), and cross section 98 

(near the saddle area)] are shown in table 4. The differences 

are large and indicate that the model is sensitive to changes in 

n values for flows as large as 100 m3/s. Stage is most sensitive 

to changes in Manning’s n in channel-controlled sections of 

the river, and least sensitive in backwatered reaches where 

the dominant effect is the hydraulic control of the bedrock 

constrictions (for example immediately upstream of the site 2 

constriction sections).

Ostenaa and others (1999, p. 31 and 32) indicated that 

water-surface elevations changed by 0.23 ft [7 centimeters 

(cm)] at cross section 42, and by 0.33 ft (10 cm) at cross 

section 98 when the n values (n=0.038) were adjusted by 

factors of 0.8 (n=0.03) and 1.6 (n=0.06) for a flow of 

100 m3

/s. These results are presented in terms of the total 

change in water-surface elevation over a range of n values 

from n=0.03 to 0.06. For comparison purposes the HEC-RAS 

sensitivity changes range from 1.0 ft (30 cm at cross section 

98) to 2.7 ft (82 cm at cross section 42) over a range of n

values from n=0.012 to 0.038. 1-D models generally exhibit 

much greater sensitivity to variations in Manning’s roughness 

coefficient than do 2-D models because roughness coefficients 

in 1-D models are used to account for both channel bed 

roughness and larger-scale resistance features such as channel 

curvature, bars, and bank irregularities. In 2-D models, 

roughness parameters generally are used to represent frictional 

resistance effects that result primarily from channel bottom 

roughness. 

Cross-Section Geometry

Sensitivity simulations also were conducted to evaluate 

the effects of streambed scour on water-surface elevations 

during flooding. In these simulations, the streambed elevation 

between the toes of the confining banks was artificially 

lowered by 1, 2, and 4 ft except in areas where bedrock is 

exposed or was encountered at depths that were shallower than 

those selected for simulating the effects of streambed scour. 

All cross sections were lowered to the specified depths except 

as noted. For example, cross sections 1, 41, 59, 62, 65, 66, and 

67 were not lowered because bedrock is present at the surface. 

Cross section 58 was lowered 1.4 ft to bedrock.

As anticipated, artificial lowering of the streambed in 

these model simulations resulted in water-surface elevations 

that were equal to or lower than those in the fixed-streambed 

simulations (fig. 15A). The presence of shallow bedrock 

at cross section 50 (fig. 15B) indicates that the streambed 

cannot be lowered more than 1.1 ft, and thus may act as a 

local control at lower flows. For the 100 m3

/s simulation, 

deeper flow depth drowns out the effect of this local control 

on water-surface elevations that would occur for smaller flow 

simulations. The average differences between the original 

simulation and the simulations in which the bed was lowered 

by 1, 2, and 4 ft were -0.4, -0.8, and -1.1 ft, respectively 

(table 5). The largest changes occur upstream of the site 1 

constriction. Water-surface elevation differences increased as 

the streambed was lowered and varied from -1.0, -1.5, and -1.2 

ft for the 4 ft lowering, and from -0.4, -0.5, and -0.2 ft for the 

1 ft lowering at cross sections 42 (BLR#8), 72 (BLR#6), and 

98 (near the saddle area), respectively.

Table 4. Sensitivity of simulated water-surface elevations to 

changes in Manning’s n (roughness coefficient) for a peak flow 

of 100 cubic meters per second on the Big Lost River upstream of 

the Pioneer diversion structures, Idaho National Engineering and 

Environmental Laboratory, Idaho.

[Location of cross sections is shown in figure 9C. Positive value indicates an 

increase in the water-surface elevation as compared with the calibrated model; 

negative value indicates a decrease in the water-surface elevation as compared 

with the calibrated model. –, no data]

Cross section

Difference in water-surface 

elevation, in feet, when 

Manning’s n is changed by

HEC-RAS TRIM2D

1.5

times

0.5

times

1.6 to

0.8 times

42 (BLR#8) 1.4 –1.3 10.2

72 (BLR#6) 1.1 –.9 –

98 (near Saddle area) .6 –.4 .3

Average difference (cross 

sections 1 through 108; n=89)

1.0 –.8 –

1

Value represents total difference between water-surface elevations for 

n=0.06 and n=0.03.

Table 5. Sensitivity of simulated water-surface elevations 

to lowering of the streambed elevation by 1, 2, and 4 feet for a 

peak flow of 100 cubic meters per second on the Big Lost River 

upstream of the Pioneer diversion structures, Idaho National 

Engineering and Environmental Laboratory, Idaho.

[Location of cross sections is shown in figure 9C. Positive value indicates an 

increase in the water-surface elevation as compared with the calibrated model; 

negative value indicates a decrease in the water-surface elevation as compared 

with the calibrated model]

Cross section

Difference in water-surface 

elevation, in feet, when the 

streambed is lowered by

1 ft 2 feet 4 feet

42 (BLR#8) -0.4 -0.6 -1.0

72 (BLR#6) -.5 -1.0 -1.5

98 (near saddle area) -.2 -.4 -1.2

Average difference (cross 

sections 1 through 108; n=89)

-.4 -.8 -1.1

40 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
ID9HZ12_fig14A

WEST DIRECTION OF FLOW EAST

Site 1

constriction

Site 2

constriction

42

(BLR #8)

72

(BLR #6)

98

(Saddle area)

Cross section

Site 3

constriction

5,040

5,035

5,030

5,025

5,020

5,015

5,010

5,005

5,000

4,995

10,000 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 0

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

DISTANCE, IN FEET UPSTREAM OF PIONEER DIVERSION STRUCTURES 

HEC-RAS SIMULATED WATER-SURFACE ELEVATION 

 WHEN FLOW IS 100 CUBIC METERS PER SECOND

HEC-RAS SIMULATED WATER-SURFACE ELEVATION 

 WHEN FLOW IS 100 CUBIC METERS PER SECOND, AND

 MANNING'S n (ROUGHNESS COEFFICIENT) IS: 

 Increased by a factor of 1.5

 Decreased by a factor of 0.5

MEASURED THALWEG ELEVATION

Middle

Reach

Lower

Reach

Upper

Reach

A. Big Lost River

Figure 14. Effects of changes in Manning’s n (roughness coefficient) on HEC-RAS simulated water-surface 

elevations for a peak flow of 100 cubic meters per second on the Big Lost River and sites 1 and 2 constrictions 

upstream of the Pioneer diversion structures, Idaho National Engineering and Environmental Laboratory, Idaho.

Numerical Modeling  41
ID9HZ12_fig14B

WEST DIRECTION OF FLOW EAST

Site 1

constriction

5,035

5,033

5,031

5,029

5,027

5,025

5,023

5,021

5,019

5,017

5,015

5,013

7,100 7,050 7,000 6,950 6,900 6,850 6,800

85

84

83

82

81

80

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

CROSS SECTIONS 

DISTANCE , IN FEET UPSTREAM OF PIONEER DIVERSION STRUCTURES 

HEC-RAS SIMULATED WATER-SURFACE ELEVATION 

 WHEN FLOW IS 100 CUBIC METERS PER SECOND

HEC-RAS SIMULATED WATER-SURFACE ELEVATION 

 WHEN FLOW IS 100 CUBIC METERS PER SECOND, AND

 MANNING'S n (ROUGHNESS COEFFICIENT) IS: 

 Increased by a factor of 1.5

 Decreased by a factor of 0.5

MEASURED THALWEG ELEVATION

B. Site 1 constriction on the Big Lost River

Figure 14.—Continued.

42  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
ID9HZ12_fig14C

WEST DIRECTION OF FLOW EAST

Site 2

constriction

5,030

5,027

5,024

5,021

5,018

5,015

5,012

5,009

5,006

5,003

3,300 3,250 3,200 3,150 3,100

55

54

53.5

53

52.5

52

51.75

51.5

51.25

51

50.5

50

49.5

49

48

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

CROSS SECTIONS 

DISTANCE , IN FEET UPSTREAM OF PIONEER DIVERSION STRUCTURES 

HEC-RAS SIMULATED WATER-SURFACE ELEVATION 

 WHEN FLOW IS 100 CUBIC METERS PER SECOND

HEC-RAS SIMULATED WATER-SURFACE ELEVATION 

 WHEN FLOW IS 100 CUBIC METERS PER SECOND, AND

 MANNING'S n (ROUGHNESS COEFFICIENT) IS: 

 Increased by a factor of 1.5

 Decreased by a factor of 0.5

MEASURED THALWEG ELEVATION

C. Site 2 constriction on Big Lost River

Figure 14.—Continued.

Numerical Modeling  43
ID9HZ12_fig15A

Site 1

constriction

WEST DIRECTION OF FLOW EAST

Site 2

constriction

Site 3

constriction

42

(BLR #8)

66

67

72

(BLR #6)

98

(Saddle area)

Cross section

65

62

50 41 58

59

5,040

5,035

5,030

5,025

5,020

5,015

5,010

5,005

5,000

4,995

10,000 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 0

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

DISTANCE, IN FEET UPSTREAM OF PIONEER DIVERSION STRUCTURES 

HEC-RAS SIMULATED WATER-SURFACE ELEVATION 

 WHEN FLOW IS 100 CUBIC METERS PER SECOND

HEC-RAS SIMULATED WATER-SURFACE ELEVATION 

 WHEN FLOW IS 100 CUBIC METERS PER SECOND, AND 

 ALLUVIAL MATERIAL IN STREAMBED IS 

 LOWERED BY THE FOLLOWING DEPTH 

 OR BEDROCK IS ENCOUNTERED:

1 foot

 2 feet

 4 feet

MEASURED THALWEG ELEVATION

Middle

Reach

Lower

Reach

Upper

Reach

A. Big Lost River

Figure 15. Effects of lowering streambed elevation on HEC-RAS simulated water-surface elevations for a peak 

flow of 100 cubic meters per second on the Big Lost River and site 2 constriction upstream of the Pioneer diversion 

structures, Idaho National Engineering and Environmental Laboratory, Idaho.

44  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
ID9HZ12_fig15B

Site 2

constriction

3,300 3,250 3,200 3,150 3,100

55

54

53.5

53

52.5

52

51.75

51.5

51.25

51

50.5

50

49.5

49

48

5,028

5,026

5,024

5,022

5,020

5,018

5,016

5,014

5,012

5,010

5,008

5,006

5,004

5,002

5,000

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

CROSS SECTIONS 

DISTANCE, IN FEET UPSTREAM OF PIONEER DIVERSION STRUCTURES 

MEASURED THALWEG ELEVATION

STREAMBED ELEVATION WHEN THE STREAM-

 BED IS LOWERED BY THE FOLLOWING DEPTH

 OR BEDROCK IS ENCOUNTERED:

 1 foot

 2 feet

 4 feet

B. Site 2 constriction on the Big Lost River

HEC-RAS SIMULATED WATER-SURFACE 

 ELEVATION WHEN FLOW IS 100 CUBIC 

 METERS PER SECOND

HEC-RAS SIMULATED WATER-SURFACE 

 ELEVATION WHEN FLOW IS 100 CUBIC 

 METERS PER SECOND, AND ALLUVIAL 

 MATERIAL IN STREAMBED IS LOWERED BY 

 THE FOLLOWING DEPTH OR BEDROCK IS 

 ENCOUNTERED:

 1 foot

 2 feet

 4 feet

WEST DIRECTION OF FLOW EAST

Figure 15.—Continued.

Numerical Modeling  45
HEC-6 Model Implementation

HEC-6 is a computer program that analyzes 1-D, 

gradually varied, steady flow in open channels with movable 

boundaries due to scour and deposition. HEC-6 allows for 

simultaneous erosion and deposition to occur depending on 

the competency of the stream to transport suspended sediment 

and bed load. HEC-6 does not, however, enable the simulation 

of bank erosion or lateral migration of the channel. This 

model can simulate the transport of sediment from upstream 

sources, transport of bed and suspended loads, and the 

effects of an armored surface layer on flow. The model can 

simulate transport of sediment sizes up to 2,048 mm and has 

11 pre-defined sediment transport equations. The model first 

calculates the water-surface elevation at each cross section 

using the standard step method (Chow, 1959, p. 265). Potential 

sediment transport rates are computed at each section and are 

combined with the flow to determine the volume of suspended 

sediment within each reach. If this volume exceeds the 

transport capacity of the reach, deposition occurs in the reach. 

If the volume is less than the transport capacity of the reach, 

scouring occurs. After each time step, the model updates the 

channel geometry in each section of the reach to account for 

the effects of scour and deposition. Finally, the flow value 

from the next time step is read and a new water-surface 

elevation is calculated using the updated channel geometries. 

This procedure is repeated until all time steps specified by the 

user have been completed. The number of time steps is based 

on trial-and-error simulations to determine when changes in 

streambed elevation are minimal between one time step and 

the next. Sediment calculations are performed by grain-size 

class, which allows the model to simulate hydraulic sorting 

and to control the rate of erosion and redeposition of sediment 

during the simulation period.

 Channel geometry characteristics (cross-section data, 

n values, reach lengths) used for the 70 m3

/s and greater 

HEC-RAS model (fig. 9C) were used to develop a HEC6 model of the study reach. In addition, the HEC-6 model 

required information for each cross section on the elevation 

of bedrock beneath the streambed, movable bed limits, 

particle-size distribution for the armored surface layer 

and underlying channel fill, bed and sediment loads of the 

incoming flows, and the selection of an appropriate transport 

equation. HEC-6 specifies that no scour will occur below 

the specified model bottom and outside the lateral limits 

of the movable bed. For this study, bedrock was defined as 

the model bottom. The model bottom was determined from 

measurements of bedrock elevation during trenching and 

from field-surveyed cross sections where bedrock occurs at 

or near the surface of the channel. At cross sections where 

no trenches were constructed or where no bedrock was 

present at the surface, the elevation was estimated by linearly 

interpolating between cross sections or trenches with known 

bedrock elevations. Movable bed limits were defined as the 

toes of the channel banks. For most cross sections this was 

easy to determine because of the flatness of the streambed 

profile and the well-defined boundaries of the channel banks. 

For bed material distributions, particle-size analyses obtained 

from trench samples and sampling of the armored surface 

layer (appendixes 1 and 2) were input into the model at the 

appropriate sections. For sections without particle-size data, 

the model linearly interpolated the bed material distribution 

from adjacent sections where these data were available.

 Because no measurements were available on sediment 

inflow to the model at the upstream end of the model reach 

(cross section 108), several transport-capacity equations were 

used to estimate the incoming sediment load at this section. 

Many transport equations have been used for gravel-bed 

rivers. The Meyer-Peter and Müller equation (1948) and 

the mountain-river modification of the Schoklitsch (1962) 

equation were used in this study because river conditions 

in the study area, defined by thalweg slope, channel width, 

flow depths, and flow velocities were well suited to these 

equations. Results from the solution of these equations were 

averaged for each particle-size fraction and used in the model 

to represent the incoming sediment load at cross section 108. 

The incoming sediment load was calculated for each peak flow 

that was simulated.

The HEC-6 model requires that the user select a 

sediment-discharge equation. Eleven transport functions 

are available in the HEC-6 model. These equations were 

developed under different flow, hydraulic, and sediment 

conditions. Some of these equations are used for sand-bed 

streams, gravel-bed streams, or both; small streams, large 

streams, or both; and some are used to simulate bed load, 

suspended load, or both (total load). Stream-discharge 

equations based on the stream-power concept are more 

accurate than those based on other concepts (Gomez and 

Church, 1989; Nakato, 1990; Yang and Huang, 2001) such 

as the regression-equation approach of Rottner (1959), the 

probabilistic approach of Einstein (1950), and the shear-stress 

approach of Kalinske (1947) and Meyer-Peter and Müller 

(1948). For the Big Lost River study reach, an equation was 

needed that can compute total load for particles ranging in 

size from very-fine sands to cobbles. Although the Ackers 

and White (1973) equation was developed from particles 

ranging in size from 0.04 to 4 mm, White and Day (1982) and 

Yang and Huang (2001) successfully applied the Ackers and 

White (1973) equation to particles as large as 11 and 32 mm, 

respectively. Muskatirovic (2005) also demonstrated that 

the Ackers and White (1973) equation performed the best to 

measured data. Her analysis included several dozen rivers and 

creeks in the Salmon River basin, Idaho with d50’s ranging 

from 10 mm to greater than 100 mm and with channel slopes 

ranging from mild to very steep. In a paper about accuracies 

of transport equations, Yang and Huang (2001) indicated that 

the Ackers and White (1973) equation was quite accurate for a 

wide range of stream power. Therefore, the Ackers and White 

(1973) equation was selected as the transport equation for the 

HEC-6 simulations.

46  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
At the site 2 constriction, HEC-RAS model simulations 

indicated that flows of 100 and 150 m3/s are supercritical. 

These simulations also showed that subcritical flow was 

reestablished after one or two cross sections, about 10 to 20 

ft downstream of the location where flow became critical 

(fig. 13C). The HEC-6 model does not have the capability 

to transition from subcritical to supercritical flow and 

back again. If supercritical conditions had persisted for an 

appreciable distance, then separate models would be needed 

to simulate each flow condition. Because subcritical flow was 

reestablished within a relatively short distance downstream 

of the site 2 constriction, only one model was developed to 

represent scour at this location.

All flows were held constant during each simulation, 

and each simulation was run until water-surface elevations 

and streambed elevations remained nearly constant from one 

time step to the next. A time step of 0.001 day (86.4 seconds) 

was used to simulate peak flows equal to and greater than 70 

m3

/s. It took about 2,000 time-step iterations or about 2 days 

of model simulation time, equivalent to 5 to 10 minutes of 

computer runtime, for the computations to stabilize using a 

time step of 0.001 day.

HEC-6 Simulation Results

Water-surface elevations and changes in streambed 

elevations for peak flows of 70, 100, 150, 187, and 200 m3/s 

were simulated with the HEC-6 model. For presentation 

clarity, only results for simulations of 70, 100, and 150 m3/s 

are shown in figure 16A. These results also are used later in 

this report for comparisons with HEC-RAS and TRIM2D 

simulation results.

The constrictions at sites 1 and 2 produce noticeable 

backwater effects at upstream distances comparable to 

those of the HEC-RAS simulations for a peak flow of 

150 m3/s. At lower peak flows HEC-6 backwater effects are 

less pronounced than those for the HEC-RAS simulations 

(compare figs. 13A and 16A). For a peak flow of 150 m3/s, 

backwater effects also can be seen in the simulated water 

surface upstream of the site 3 constriction (fig. 16A). Within 

the site 2 constriction water-surface elevations decline sharply, 

from 2 to 4 ft between cross sections 49 to 55 for peak flows 

of 100 and 150 m3

/s, respectively (fig. 16B), and about 1 ft for 

a peak flow of 70 m3/s.

Profiles for the movable streambed in HEC-6 also are 

shown in figure 16A for peak flows of 70, 100, and 150 m3/s. 

The measured streambed profile is markedly different from the 

streambed profile that develops during the passage of a flood 

(fig. 16A). Both streambed erosion and sediment deposition 

occur within each of the three reaches. Immediately upstream 

of the sites 2 and 3 constrictions and near the center section 

of the middle reach several feet of sediment accumulation is 

simulated by the HEC-6 model for all three peak flows. 

The average differences in streambed elevations between 

the measured thalweg and the HEC-6 thalweg for all three 

peak flows are given in table 6. Average differences for the 

entire model reach range from 0.5 to 0.7 ft for the 70, 100, and 

150 m3/s flow simulations and indicate that streambed erosion 

dominates in the upper and middle reaches of the river and that 

substantial sediment deposition occurs in the lower reach for 

all simulated flows shown in figure 16A.

At the site 2 constriction, the streambed was eroded to 

bedrock (fig. 16B) for flows greater than and equal to 70 m3/s. 

At the sites 1 and 3 constrictions, flows did not scour the 

streambed completely to bedrock. For a peak flow of 150 m3/s, 

the residual thickness of the channel fill inside the sites 1 and 

3 constrictions averaged about 1.0 and 1.5 ft, respectively.

At the BLR#8 (cross section 42) paleoindicator site, the 

HEC-6 simulated streambed elevation was 0.4 ft higher than 

the measured streambed elevation for peak flows of 70 and 

100 m3

/s, and 1.1 ft lower for a peak flow of 150 m3/s. At 

BLR#6 (cross section 72) the HEC-6 simulated streambed 

was 1.0, 2.6, and 0.2 ft lower than the measured streambed for 

peak flows of 70, 100, and 150 m3/s, respectively (table 6 and 

fig. 16A). Near the saddle area (cross section 98), the HEC-6 

simulated streambed elevation was slightly higher, from 0.1 

to 0.2 ft, than the measured streambed for the three simulated 

peak flows.

Quantitative comparisons of the HEC-RAS and HEC-6 

thalweg profiles, for a peak flow of 100 m3/s, are represented 

by the slope of a linear-regression fit to the thalwegs along 

the upper, middle, and lower reaches of the river as shown 

in figure 17. Linear-regression fits to the resulting HEC6 thalweg profiles indicate a slightly steeper slope along 

the upper reach, a flatter slope along the middle reach, and 

almost no change in slope along the lower reach of the river. 

Streambed elevation changes occur in all three reaches. The 

most notable of these changes is the nearly 3 ft decrease in 

elevation at the upstream end of the middle reach, and the 1 ft 

increase in elevation along the entire length of the lower reach. 

Figures 16 and 17 indicate considerable disturbance to 

the measured thalweg profile resulting from a combination 

of sediment deposition and streambed erosion. The resulting 

HEC-6 thalweg profiles represent equilibrium profiles for 

sustained, steady flow at the simulated peak discharge. During 

the receding limb of a flood and during long periods of low 

to moderate flow between major flood events, much of the 

temporary disturbance to the channel bed resulting from a 

large flood is destroyed. The last major flood event (event 

with the highest peak flow) in the study area occurred in 1958 

prior to construction of the INEEL diversion dam. The peak 

flow for the 1958 event was 33.7 m3

/s (1,190 ft3/s) (fig. 11), 

considerably less than the simulated peak flows shown in 

figure 16A. Since enlargement of the diversion dam in 1984, 

peak flows in the study area have been limited to a maximum 

of about 13.2 m3

/s (466 ft3/s) (fig. 10).

Numerical Modeling  47
ID9HZ12_fig16A

WEST DIRECTION OF FLOW EAST

Site 1

constriction

Site 3

constriction

Site 2

constriction

42

(BLR #8)

72

(BLR #6)

98

(Saddle area)

Cross section

5,040

5,035

5,030

5,025

5,020

5,015

5,010

5,005

5,000

4,995

10,000 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 0

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

DISTANCE, IN FEET UPSTREAM OF PIONEER DIVERSION STRUCTURES 

HEC-6 SIMULATED WATER-SURFACE ELEVATION 

 WHEN FLOW, IN CUBIC METERS PER SECOND, IS:

 70

 100

 150

HEC-6 SIMULATED THALWEG 

 ELEVATION WHEN FLOW, IN 

 CUBIC METERS PER SECOND, IS:

 70

 100

 150

Middle

Reach

Lower

Reach

Upper

Reach

MEASURED THALWEG 

 ELEVATION

BEDROCK ELEVATION USED 

 IN HEC-6 SIMULATIONS

A. Big Lost River

Figure 16. HEC-6 simulated water-surface and thalweg elevations for peak flows of 70, 100, and 150 cubic meters 

per second on the Big Lost River and at the site 2 constriction upstream of the Pioneer diversion structures, Idaho 

National Engineering and Environmental Laboratory, Idaho.

48  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
ID9HZ12_fig16B

WEST DIRECTION OF FLOW EAST

Site 2

constriction

5,025

5,020

5,015

5,010

5,005

5,000

3,300 3,250 3,200 3,150 3,100

55

54

53.5

53

52.5

52

51.75

51.5

51.25

51

50.5

50

49.5

49

48

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

CROSS SECTIONS 

DISTANCE, IN FEET UPSTREAM OF PIONEER DIVERSION STRUCTURES 

B. Site 2 constriction on the Big Lost River

HEC-6 SIMULATED THALWEG 

 ELEVATION WHEN FLOW, IN 

 CUBIC METERS PER SECOND, IS:

 70

 100

 150

BEDROCK ELEVATION USED 

 IN HEC-6 SIMULATIONS

HEC-6 SIMULATED WATER-SURFACE ELEVATION 

 WHEN FLOW, IN CUBIC METERS PER SECOND, IS:

 70

 100

 150

Figure 16.—Continued.

Numerical Modeling  49
ID9HZ12_fig17

UPPER REACH

MIDDLE REACH 

LOWER REACH 

5,030

5,028

5,026

5,024

5,022

5,020

5,018

5,016

5,500 5,000 4,500 4,000 3,500 3,000

5,020

5,018

5,016

5,014

5,012

5,010

5,008

5,006

3,000 2,500 2,000 1,500 1,000 500 0

5,014

5,012

5,010

5,008

5,006

5,004

5,001

5,000

6,000

10,000 9,500 9,000 8,500 8,000 7,500 7,000

7,000 6,500

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

FEET

Slope=0.00252

Slope=0.00193

Slope=0.00232

Slope=0.00298

Slope=0.00089

Slope=0.00245

THALWEG ELEVATION 

 HEC-RAS model 

 HEC-6 model

THALWEG REGRESSION LINE

 HEC-RAS model

 HEC-6 model

Figure 17. Linear-regression fits to the HEC-RAS and HEC-6 thalweg elevations for a peak flow of 100 cubic 

meters per second for the upper, middle, and lower reaches of the Big Lost River upstream of the Pioneer 

diversion structures, Idaho National Engineering and Environmental Laboratory, Idaho.

50 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Table 6. Differences in HEC-RAS and HEC-6 simulated water-surface and thalweg elevations for peak flows of 70, 100, and 150 cubic 

meters per second on the Big Lost River upstream of the Pioneer diversion structures, Idaho National Engineering and Environmental 

Laboratory, Idaho.

[Location of cross sections is shown in figure 9C. m3/s, cubic meter per second]

Cross section

Differences in water-surface elevations,

HEC-RASelev minus HEC-6elev

in feet, for a peak flow of

Differences in thalweg elevations,

HEC-RASelev minus HEC-6elev

in feet, for a peak flow of

70 m3/s 100 m3/s 150 m3/s 70 m3/s 100 m3/s 150 m3/s

20 -2.2 -2.4 -2.4 0.5 1.2 -0.3

42 (BLR#8) -1.6 -1.4 -1.6 .4 .4 -1.1

56 .6 1.5 .5 .3 .4 .3

72 (BLR#6) .5 1.0 .6 1.0 2.6 .2

76 -.0 .5 .2 2.3 3.4 2.3

98 (near saddle area) -.2 .2 .5 -.1 -.2 -.1

Average difference Average difference

Entire reach (all, n = 89) -0.4 -0.1 -0.4 0.5 0.7 0.5

Upper reach (85 to 108) -.4 .0 .3 .1 .1 .1

Middle reach (58 to 81) .4 1.0 .4 .4 .7 -.4

Lower reach (3 to 45) -1.5 -1.5 -1.8 -1.0 -.9 -.9

Comparisons of HEC-6 and HEC-RAS 

Water-Surface Elevations

Simulated HEC-6 and HEC-RAS water-surface 

elevations for peak flows of 70, 100, and 150 m3/s are 

shown in figure 18. The average difference in water-surface 

elevations simulated by the two models along the entire model 

reach is less than 0.5 ft for the three flows (table 6). The most 

notable difference in the water-surface elevation profiles 

simulated by these two models occurs between the combined 

upper and middle reaches of the river and the lower reach 

of the river. Along the upper and middle reaches of the river 

HEC-6 water-surface elevations generally are lower than those 

of HEC-RAS, and along the lower reach of the river HEC-6 

water-surface elevations everywhere are higher than those of 

HEC-RAS. Higher HEC-6 water-surface elevations reflect 

the effects of sediment deposition in the lower reach of the 

river, and lower HEC-6 water-surface elevations reflect the 

effects of erosion in the upper and middle reaches of the river. 

These differences are consistent with changes in streambed 

elevation as reflected in the HEC-6 thalweg profiles shown in 

figure 16A. 

Differences in water-surface elevations at the 

paleoindicator sites also are shown in table 6. Differences in 

water-surface elevations at the paleoindicator sites indicate 

that flows lower than those simulated by the HEC-RAS 

model will overtop the BLR#8 (cross section 42) site because 

of sediment deposition, and that flows higher than those 

simulated by the HEC-RAS model will overtop the saddle area 

(near cross section 98) and BLR#6 (cross section 72) because 

of streambed erosion.

Numerical Modeling  51
ID9HZ12_fig18

WEST DIRECTION OF FLOW EAST

Site 1

constriction

Site 2

constriction

Site 3

constriction

42

(BLR #8)

20

56

72

(BLR #6)

98

(Saddle area)

Cross section

76

5,040

5,035

5,030

5,025

5,020

5,015

5,010

5,005

10,000 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 0

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

DISTANCE, IN FEET UPSTREAM FROM PIONEER DIVERSION STRUCTURES 

HEC-6 model

 70

 100

 150

SIMULATED WATER-SURFACE ELEVATION WHEN

 FLOW, IN CUBIC METERS PER SECOND, IS:

Middle

Reach

Lower

Reach

Upper

Reach

HEC-RAS model

 70

 100

 150

Figure 18. HEC-RAS and HEC-6 simulated water-surface elevations for peak flows of 70, 100, and 150 

cubic meters per second on the Big Lost River upstream of the Pioneer diversion structures, Idaho National 

Engineering and Environmental Laboratory, Idaho.

52  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Comparisons of Channel and 

Floodplain Geometries Used in 

HEC-RAS and HEC-6 Models with 

Those Used in TRIM2D Model

Channel and floodplain geometries are defined by 

thalweg slope, cross-section flow area, and changes that 

occur in these features along the course of the river. The field 

survey that was conducted to define channel and floodplain 

geometries for the HEC-RAS and HEC-6 models revealed 

topographic errors and inconsistencies in the 2-ft contour base 

map that was used in the TRIM2D model. These included a 

datum shift of 3.484 ft between the NGVD 29 datum and the 

NAVD 88 datum (the established INEEL datum standard), and 

elevation errors amounting to about 5.0 ft of relief between the 

upstream and downstream ends of the study area. Although 

the TRIM2D model did not simulate the effects of streambed 

erosion on water-surface elevations, differences between the 

channel and floodplain geometries used in the TRIM2D model 

and those used in the HEC-RAS/HEC-6 models probably 

are the primary reasons for the large differences in simulated 

water-surface elevations, flow depths, flow velocities, and 

stream power between the TRIM2D and HEC-RAS/HEC-6 

models that are described in the section “Comparisons of 

HEC-RAS, HEC-6, and TRIM2D Simulation Results.”

 Channel and floodplain geometries used in the TRIM2D 

model were constructed from a 2-ft contour map of the study 

area prepared by Aerial Mapping, Inc. (Wayne Eskridge, 

Aerial Mapping, Inc., written commun., 1996). The 2-ft 

contour interval implies a topographic resolution of ±1 ft. 

Inside the main channel, spacing between contours on the 2-ft 

contour map averaged 932 ft. The maximum distance between 

adjacent contours was 2,184 ft, and the minimum distance was 

50 ft. Twelve contour lines were used to map the 24 ft of relief 

between the upstream and downstream ends of the model 

reach shown on the 2-ft contour map. Channel and floodplain 

geometries used in the TRIM2D model were represented 

by elevations assigned to a rectangular array of grid nodes 

located at 1-m spacings that were subsequently subsampled to 

generate a computational grid consisting of 2×2 m cells. The 

TRIM2D computational grid consisted of about 4.2 million 

cells; of these, about 2.5 million were active (Ostenaa and 

others, 1999, p. 31). Because of the sparse contour spacing, 

interpolation over long distances was required to construct the 

elevation control grid used in the TRIM2D model. 

 The channel and floodplain geometries used in the HECRAS and HEC-6 models were constructed from (1) a field 

survey of the channel thalweg that incorporated more than 

430 leveling stations spaced at distances averaging 23 ft; (2) 

76 field-surveyed cross sections oriented perpendicular to the 

direction of flow and spaced at intervals ranging from 50 to 

several hundred feet depending on complexity and uniformity 

of the channel section; and (3) TIN-generated, TIN-extended, 

and linearly interpolated cross sections. The accuracy of the 

field-surveyed data was better than ±0.1 ft. Field-surveyed 

cross sections were extended and 31 additional cross 

sections were added using the TIN interpolating procedure, 

described in the section “TIN-Generated Cross Sections,” and 

elevation data from a 1-ft contour map of the study area that 

was prepared in 2000 by the Bureau of Reclamation (D.A. 

Ostenaa, Bureau of Reclamation, written commun., 2001). 

The elevation datum for this map (figs. 5A and 5B) is 1.955 ft 

lower than the NAVD 88 datum, and an elevation correction 

of +1.955 ft is needed to convert elevations on this map so that 

these conform to the NAVD 88 datum. The elevation accuracy 

of the channel cross sections that were constructed using the 

TIN interpolating procedure was ±0.5 ft.

Thalwegs

Profiles of the field-surveyed and TIN-generated thalweg 

used in the HEC-RAS model (and for initial conditions in the 

HEC-6 model), and the 2×2 m grid-generated thalweg used in 

the TRIM2D model are shown in figure 19. Elevations of the 

TRIM2D thalweg have been adjusted by +3.484 ft to account 

for the elevation difference between the NGVD 29 datum and 

NAVD 88 datum. The profiles indicate major differences in 

the elevation, slope, and topographic character of the thalwegs 

used in the HEC-RAS and TRIM2D models.

The elevation of the TRIM2D thalweg is higher 

than the HEC-RAS thalweg throughout the model reach. 

Elevation differences increase in a downstream direction. 

At the downstream end of the model reach, cross section 1, 

the elevation of the TRIM2D thalweg is about 7 ft higher 

than the HEC-RAS thalweg (fig. 19). The average elevation 

difference, based on a one-to-one comparison of the fieldsurveyed and TIN-generated data with those extracted from 

the computational grid used in the TRIM2D model, was 2.5 ft 

(table 7). At the paleoindicator sites, BLR#8 (cross section 

42), BLR#6 (cross section 72), and the saddle area (near cross 

section 98), the TRIM2D streambed was 2.2, 2.8, and 0.6 ft 

higher, respectively, than the HEC-RAS streambed. Elevation 

differences between the upstream (cross section 108) and 

downstream (cross section 1) ends of the model reach indicate 

that the overall slope of the TRIM2D thalweg (0.0019) is 

15 percent less than the slope of the HEC-RAS thalweg 

(0.0023). The higher TRIM2D streambed elevations (adjusted 

for the +3.484 ft elevation difference between the NGVD 29 

and NAVD 88 datums) and flatter thalweg slope imply that 

TRIM2D-simulated water-surface elevations should be higher 

than those of the HEC-RAS and HEC-6 models.

The topographic character of the TRIM2D and HECRAS thalwegs also differ noticeably (fig. 19). The TRIM2D 

thalweg is characterized by numerous high- and low-amplitude 

undulations, resulting in a pattern of positive- and negativerelief features that obscures the more uniform character of the 

profile. In contrast, the field-surveyed thalweg is punctuated 

by narrow, widely-spaced, and deeply-incised negativerelief features that, for the most part, have only a very local 

influence on the thalweg slope.

Comparisons of Channel and Floodplain Geometries Used in sHEC-RAS and HEC-6 Models with Those Used in TRIM2D Model  53
A quantitative comparison of elevation and topographic 

differences between the TRIM2D and HEC-RAS thalwegs 

is represented by the slope of a linear-regression fit to the 

thalwegs along the upper, middle, and lower reaches of the 

river. The upper-reach regression extends from the upstream 

model boundary (cross section 108) to a point immediately 

upstream (cross section 85) of the site 1 constriction, the 

middle-reach regression from a point immediately downstream 

(cross section 81) of the site 1 constriction to a point about 

500 ft upstream (cross section 58) of the site 2 constriction, 

and the lower-reach regression from a point immediately 

downstream (cross section 45) of the site 2 constriction 

to a point about 250 ft (cross section 3) upstream of the 

downstream boundary (fig. 19). The regression fits do not 

include (1) the scoured depressions within the site 1 and site 

2 constrictions, and (2) the free outfall section of the lower 

reach near the downstream boundary. These were excluded 

from the slope computations to avoid biasing that would 

result from inclusion of these topographically prominent, but 

locally-isolated negative-relief features that appear in the fieldsurveyed thalweg profile. 

 The regression fits along the upper, middle, and lower 

reaches of the river are shown in figure 20. The slope of 

the TRIM2D thalweg is 13 percent less than the HEC-RAS 

thalweg along the upper reach, 23 percent less along the 

middle reach, and 44 percent less along the lower reach.

The undulating pattern of positive- and negative-relief 

features along the TRIM2D thalweg is conspicuous near cross 

section 72 (BLR#6), cross section 42 (BLR#8), and cross 

section 20 (fig. 19). The undulating pattern of the thalweg 

slope in these areas tends to obscure the overall 

smoothness of the thalweg because the 2-ft contour 

map (Eskridge, Aerial Mapping Inc., 1996) did not 

have sufficient resolution to support construction 

of a computational grid for the 2-D model. This 

may, to some extent, account for (1) the very large 

difference in water-surface elevations between the 

HEC-RAS and TRIM2D simulations for a flow 

of 70 m3/s, (2) an anomalous bulge in the water 

surface near cross section 72 (BLR#6), and (3) 

higher water-surface elevations than simulated 

by HEC-RAS and HEC-6 as described in the 

section “Comparisons of HEC-RAS, HEC-6, and 

TRIM2D Simulation Results.” 

Channel Cross Sections

Comparisons of selected cross sections 

used in the HEC-RAS model (and for the initial 

conditions in the HEC-6 model) with those used 

in the TRIM2D model are shown in figure 21. The 

locations of these six cross sections are shown in 

figure 9. Elevations of the TRIM2D floodplain 

and main channel are higher than those of HECTable 7. Differences in HEC-RAS and TRIM2D thalweg elevations and 

slopes along the upper, middle, and lower reaches of the Big Lost River 

upstream of the Pioneer diversion structures, Idaho National Engineering 

and Environmental Laboratory, Idaho.

[Location of sampling sites is shown in figure 9C. Abbreviations: ft, ft; ft/ft, ft per ft]

Cross section

Difference in 

thalweg elevation

(TRIM2Delev minus 

HEC-RASelev)

(ft)

42 (BLR#8) 2.2

72 (BLR#6) 2.8

98 (near saddle area) .6

Thalweg slope (ft/ft)

Average

difference (ft) HEC-RAS TRIM2D

Entire reach (all, n = 89) 2.5 0.0023 0.0019

Upper reach (85 to 108) 1.3 .0025 .0022

Middle reach (58 to 81) 2.0 .0019 .0015

Lower reach (3 to 45) 3.1 .0023 .0013

RAS at cross sections 20, 42, and 56 (fig. 21). Elevations of 

the TRIM2D floodplain are lower and the elevations of the 

main channel are higher than HEC-RAS at cross sections 72 

and 76 (fig. 21). Floodplain and channel elevation differences 

are small near the upstream boundary (cross section 108) and 

are large near the downstream boundary of the model reach 

(cross section 1). The transition between predominantly higher 

floodplain elevations and lower floodplain elevations between 

the TRIM2D and HEC-RAS models appears to occur in the 

middle reach of the river between cross sections 56 and 72.

Graphical comparisons of the cross sections used in the 

HEC-RAS (and for initial conditions in the HEC-6 model) 

with those used in the TRIM2D model are represented by 

the stage-area and depth-area curves shown in figure 22. The 

depth-area curves indicate larger cross-section areas per unit of 

depth for the TRIM2D cross sections than for the HEC-RAS 

cross sections. At low stages, the TRIM2D and HEC-RAS 

stage-area curves, corrected for elevation datum differences, 

are similar; at high stages, however, these curves deviate 

considerably. The stage-area curves, corrected for elevation 

datum differences, indicate similar TRIM2D and HEC-RAS 

stage-area relations at cross sections 42, 72, 76, and 98 for 

flows that remain within the confines of the main channel and 

are less than about 10 ft deep, and higher stage-area relations 

for flow that occurs outside the main channel. Lower TRIM2D 

stage-area relations are indicated for flow that occurs both 

within and outside the confines of the main channel at cross 

sections 20 and 56.

54  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
ID9HZ12_fig19

WEST DIRECTION OF FLOW EAST

Site 1

constriction

Site 2

constriction

Site 3

constriction

42

(BLR #8)

56

76

72

(BLR #6)

98

(Saddle area)

108

20

85

CROSS SECTION AND NO. 

85

81

58

45

3

5,030

5,025

5,020

5,015

5,010

5,005

5,000

4,995

10,000 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 0

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

DISTANCE, IN FEET UPSTREAM OF PIONEER DIVERSION STRUCTURES 

 HEC-RAS model

 TRIM2D model (Dean Ostenaa,

 U.S. Bureau of Reclamation, 

 written commun., 2001)

Middle

Reach

Lower

Reach

Upper

Reach

 THALWEG ELEVATION

Figure 19. Thalweg elevations used in the HEC-RAS and TRIM2D models of the Big Lost River upstream of the 

Pioneer diversion structures, Idaho National Engineering and Environmental Laboratory, Idaho.

Comparisons of Channel and Floodplain Geometries Used in sHEC-RAS and HEC-6 Models with Those Used in TRIM2D Model  55
ID9HZ12_fig20

UPPER REACH 

MIDDLE REACH 

LOWER REACH

5,030

5,028

5,026

5,024

5,022

5,020

5,018

5,016

5,500 5,000 4,500 4,000 3,500 3,000

5,020

5,018

5,016

5,014

5,012

5,010

5,008

5,006

3,000 2,500 2,000 1,500 1,000 500 0

5,014

5,012

5,010

5,008

5,006

5,004

5,002

5,000

6,000

10,000 9,500 9,000 8,500 8,000 7,500 7,000

7,000 6,500

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

FEET

Slope=0.00218

Slope=0.00252

Slope=0.00148

Slope=0.00193

Slope=0.00130

Slope=0.00232

THALWEG ELEVATION 

 HEC-RAS model 

 TRIM2D model (Dean Ostenaa, U.S. Bureau

 of Reclamation (written commun., 2001)

THALWEG ELEVATION REGRESSION LINE

 HEC-RAS model

 TRIM2D model

Figure 20. Linear-regression fits to the HEC-RAS and TRIM2D thalweg elevations for the upper, middle, and 

lower reaches of the Big Lost River upstream of the Pioneer diversion structures, Idaho National Engineering and 

Environmental Laboratory, Idaho.

56  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Figure 21. Selected channel cross sections used in the HEC-RAS, HEC-6, and TRIM2D models of the Big Lost 

River upstream of the Pioneer diversion structures, Idaho National Engineering and Environmental Laboratory, 

Idaho.

Locations of cross sections shown in figure 9.

ID9HZ12_fig22p1

CROSS SECTION 20

CROSS SECTION 42 (BLR#8)

CROSS SECTION 56 

LEFT BANK

LEFT BANK

LEFT BANK

5,033

5,029

5,024

5,020

5,016

5,012

5,008

5,004

-500 -400 -300 -200 -100 0

5,026

5,023

5,020

5,017

5,014

5,011

5,008

100 200 300 400 500 600 700

5,034

5,030

5,026

5,022

5,018

5,014

5,010

5,006

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

DISTANCE FROM REFERENCE POINT, IN FEET 

HEC-RAS AND HEC-6 MODELS

TRIM2D MODEL (Dean Ostenaa, Bureau

 of Reclamation, written commun., 2001)

Comparisons of Channel and Floodplain Geometries Used in sHEC-RAS and HEC-6 Models with Those Used in TRIM2D Model  57
Figure 21.—Continued.

ID9HZ12_fig22p2

CROSS SECTION 72 (BLR#6)

CROSS SECTION 76 

CROSS SECTION 98

(near saddle area)

LEFT BANK

LEFT BANK

LEFT BANK

5,032

5,028

5,024

5,020

5,016

5,012

-100 0 200100 300 400

5,035

5,032

5,029

5,026

5,023

5,020

5,017

5,014

5,038

5,034

5,030

5,026

5,022

500 700600 900800 1,000 1,100

-500 -400 -300 -200 -100 0 100 200 300 400 500 600 700

1,200 1,400 1,300 1,500 1,600 1,700

DISTANCE FROM REFERENCE POINT, IN FEET 

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

HEC-RAS AND HEC-6 MODELS

TRIM2D MODEL (Dean Ostenaa, Bureau of

 Reclamation, written commun., 2001)

???

58  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
ID9HZ12_fig22p1

CROSS SECTION 42 (BLR#8)

CROSS SECTION 56 

CROSS SECTION 20 

14,000

12,000

10,000

8,000

6,000

4,000

2,000

0

12,000

10,000

8,000

6,000

4,000

2,000

0

8,000

7,000

6,000

5,000

4,000

3,000

2,000

1,000

0

5,005 5,010 5,015 5,020 5,025 5,030 5,035 5,040 0 5 1510 2520 30 35

AREA, IN SQUARED FEET

STAGE–AREA DEPTH–AREA

STAGE–AREA DEPTH–AREA

STAGE–AREA DEPTH–AREA

STAGE, IN FEET ABOVE NORTH AMERICAN

VERTICAL DATUM OF 1988 

DEPTH, IN FEET

HEC-RAS MODEL

TRIM2D MODEL (Dean Ostenaa,

 U.S. Bureau of Reclamation,

 written commun., 2001)

Figure 22. Stage- and depth-area curves for selected channel cross sections used in the HEC-RAS and TRIM2D 

models of the Big Lost River upstream of the Pioneer diversion structures, Idaho National Engineering and 

Environmental Laboratory, Idaho. (Locations of cross sections shown in figure 9.)

Comparisons of Channel and Floodplain Geometries Used in sHEC-RAS and HEC-6 Models with Those Used in TRIM2D Model  59
ID9HZ12_fig22p2

CROSS SECTION 72 (BLR#6)

CROSS SECTION 76

CROSS SECTION 98 (near saddle area)

10,000

9,000

8,000

7,000

6,000

5,000

4,000

3,000

2,000

1,000

0

5,010 5,015 5,020 5,025 5,030

4,500

4,000

3,500

3,000

2,500

2,000

1,500

1,000

500

0

0 5 10 15 20 25 30 35

5,000

4,500

4,000

3,500

3,000

2,500

2,000

1,500

1,000

500

0

5,035 5,040

AREA, IN SQUARED FEET

STAGE–AREA DEPTH–AREA

STAGE–AREA DEPTH–AREA

STAGE–AREA DEPTH–AREA

STAGE, IN FEET ABOVE NORTH AMERICAN

VERTICAL DATUM OF 1988 

DEPTH, IN FEET

HEC-RAS MODEL

TRIM2D MODEL (Dean Ostenaa, 

 U.S. Bureau of Reclamation,

 written commun., 2001)

Figure 22.—Continued.

60 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
The depth-area curves indicate that flow depths should be 

shallower in the TRIM2D simulations than in the HEC-RAS 

simulations. The stage-area curves indicate that water-surface 

elevations should be higher in the TRIM2D simulations than 

in the HEC-RAS simulations for the same flow. However, as 

noted previously, lower thalweg slopes imply that TRIM2D 

flow depths, in the absence of extensive overbank flow, should 

be deeper than HEC-RAS flow depths to compensate for the 

effects of lower velocity that should result from the lower 

thalweg slopes in the upper, middle, and lower reaches of 

the river (fig. 20). Comparisons of simulated water-surface 

elevations, flow depths, and flow velocities presented in the 

section “Comparisons of HEC-RAS, HEC-6, and TRIM2D 

Simulation Results” indicate that in simulations made with 

TRIM2D (1) water-surface elevations are higher, (2) flow 

depths are shallower, and (3) flow velocities generally are 

higher in the upper and middle reaches of the river, and lower 

in the lower reach of the river than those simulated with HECRAS. Under steady-flow conditions these results do not appear 

to be internally consistent with the thalweg-slope, stage-area, 

and depth-area relations presented in figures 19, 20, and 22.

Comparisons of HEC-RAS, HEC-6, and 

TRIM2D Simulation Results

Comparisons of model simulation results in the previous 

sections were restricted to 1-D simulations involving a fixedbed model (HEC-RAS) and a movable-bed model (HEC-6), 

and to comparisons of HEC-RAS sensitivity simulations 

involving the effects of changes in Manning’s n (roughness 

coefficient), and changes in streambed elevation. Comparisons 

were presented to emphasize the effects of roughness 

coefficients, bedrock constrictions, and streambed erosion and 

sediment deposition on water-surface elevations. 

HEC-RAS model simulation results indicated that flows 

greater than or equal to 100 m3/s will accelerate through 

the site 2 constriction and will transition from subcritical to 

supercritical. HEC-6 model simulation results indicated that 

supercritical flow velocities are sufficient to scour the 4.5- to 

5.5-ft thick section of fine-grained channel fill inside this 

constriction. A combination of flow acceleration and scouring 

tends to limit the extent of backwater accumulation upstream 

of the site 2 constriction that would result if flow through the 

constriction remained subcritical. 

HEC-6 model simulation results indicated that streambed 

erosion will reduce water-surface elevations an average of 

0.4, 1.0, and 0.4 ft in the middle reach of the river for peak 

flows of 70, 100, and 150 m3/s, respectively; and that sediment 

deposition will increase water-surface elevations an average 

of 1.5, 1.5, and 1.8 ft in the lower reach of the river for 

peak flows of 70, 100, and 150 m3/s, respectively (fig. 16A, 

table 6). In the upper reach, sediment deposition will increase 

water-surface elevations an average of 0.4 ft for a peak flow 

of 70 m3/s, and streambed erosion will reduce water-surface 

elevations an average of 0.3 ft for a peak flow of 150 m3/s 

(fig. 16A, table 6). On average, no changes in the elevation of 

the streambed will result for a peak flow of 100 m3/s.

Differences in elevation datums, floodplain and channel 

geometries, and topographic relief complicate comparisons 

of HEC-RAS and HEC-6 model simulations to those of 

TRIM2D. For comparison purposes, elevation datum shifts 

are generally straightforward to apply; however, corrections 

for differences in channel and floodplain geometries and 

topographic relief are virtually impossible to apply. As noted 

previously:

 1. The NVGD 29 elevation datum used in the TRIM2D 

model is 3.484 ft lower than the NAVD 88 elevation 

datum used in the HEC-RAS and HEC-6 models; 

2. The slope of the TRIM2D thalweg along the entire 

model reach is 15 percent lower than the thalweg 

slope used in the HEC-RAS model resulting in a 

5-ft difference in the topographic relief of these two 

models between the upstream and downstream ends 

of the model reach (fig. 19);

3. Thalweg slopes used in the TRIM2D model are 

13, 23, and 44 percent lower than those used in the 

HEC-RAS model along the upper, middle, and lower 

reaches, respectively (fig. 20); 

4. Topographic variability of the TRIM2D thalweg is 

greater than the HEC-RAS thalweg along the upper, 

middle, and lower reaches (figs. 19 and 20); 

5. Cross-section areas at many locations in the 

TRIM2D model are larger than those in the HECRAS model for the same flow depth—the slope of 

the depth-area curves are steeper (fig. 22); and 

6. Cross-section areas in the TRIM2D model generally 

are smaller than those in the HEC-RAS model for 

the same stage or water-surface elevation over the 

upper one-half of the model reach (stage-area curves 

are steeper) and larger over the lower one-half of the 

model reach (stage-area curves are flatter) (fig. 22).

Other topographic differences occur throughout the 

model reach, particularly in the overbank areas; however, these 

are difficult to characterize on the basis of trend or offset. 

The most significant difference of interest to this study is the 

elevation of the lowest point in the saddle area upstream of 

the site 1 constriction. The most recent aerial-photography 

mapping (fig. 5) indicates that the elevation of the lowest 

Comparisons of HEC-RAS, HEC-6, and TRIM2D Simulation Results  61
point on this topographic feature is between 5,034.0 and 

5,035.0 ft (1-ft contour survey, Bureau of Reclamation, 1999; 

D.A. Ostenaa, Bureau of Reclamation, written commun., 

2001)4. The elevation of the lowest point in the saddle area 

derived from the 1-ft contour map indicates that the saddlearea elevation is between 5,031.5 and 5,033.5 ft (5,028.0 to 

5,030.0 ft using the 2-ft contour survey by Eskridge, Aerial 

Mapping Inc, 1996; NVGD 29)5. Field-surveyed data indicate 

that the lowest point of the saddle area is at an elevation of 

5,033.7 ft (NAVD 88; appendix 3, at back of report). The 

field-surveyed elevation (5,033.7; NAVD 88 datum) is 0.8 

ft lower than the interpolated elevation (5,034.5 ft) based on 

the 1-ft contour map, and 1.2 ft higher than the interpolated 

elevation (5,032.5 ft) based on the 2-ft contour map. The 1.2 

ft elevation difference indicates that peak flows higher than 

those predicted by the TRIM2D model are needed to produce 

overtopping and erosion of the saddle area. 

Comparisons of HEC-RAS and HEC-6 water-surface 

elevations to those of TRIM2D, corrected for the 3.484 ft 

datum shift, are presented in this section. These comparisons 

provide a means of evaluating the overall reliability of 

TRIM2D simulations of peak flows needed to overtop 

and erode surfaces that were used to establish minimum 

return periods for hypothetical flood events with return 

periods of 300 to 500 years, and 10,000 years. Because 

simulated TRIM2D water-surface elevations formed the 

basis for assigning flood magnitudes to these return periods, 

comparisons of water-surface elevations take into account 

the simulation results for both the fixed-bed (HEC-RAS) and 

movable-bed (HEC-6) models, even though TRIM2D is a 

fixed-bed model.

 Comparisons of simulated flow depths, flow velocities, 

and stream power offer an alternative way to assess model 

results and to evaluate the effects that differences in floodplain 

and channel geometries and topographic relief have on these 

results. To some extent these comparisons are less dependent 

on elevation, and are therefore useful for determining if flow 

simulations are internally consistent. These comparisons are 

limited to the fixed-bed HEC-RAS and TRIM2D simulations 

and assume that:

1. Flow into and out of the model reach and at each 

cross section within the model reach is steady—

inflow equals outflow everywhere within the model 

reach (appendix 4, at back of report)6; 

2. Deeper flow depths and/or larger cross-section flow 

areas are needed to maintain steady flow at lower 

velocities;

3. Flow velocities in channels with flatter thalweg 

slopes should be lower than flow velocities in 

channels with steeper thalweg slopes; 

4. Stream power is a linear function of and is directly 

proportional to flow depth and velocity; and 

5. The highest flow velocities and stream power will 

occur within the main channel along, or in close 

proximity to the alignment of the thalweg. This will 

normally be the case if flow is contained within the 

main channel and overbank and side-channel flow 

are limited. High stream powers, offset from the 

thalweg alignment, also are possible in areas where 

flow is forced to accelerate around a bend. 

Comparisons of HEC-RAS and TRIM2D 

Water-Surface Elevations

Simulated HEC-RAS and TRIM2D water-surface 

elevations for peak flows of 70, 100, and 150 m3/s are shown 

in figure 23A. The TRIM2D water-surface elevations have 

been adjusted by +3.484 ft to account for elevation differences 

between the TRIM2D datum (NGVD 29) and the HECRAS datum (NAVD 88). Simulated TRIM2D water-surface 

elevations generally are higher than corresponding HECRAS water-surface elevations throughout the model reach 

(fig. 23A). To some extent, the higher TRIM2D water-surface 

elevations can be attributed to:

1. Topographic relief between the upstream (cross 

section 108) and downstream (cross section 1) ends 

of the model reach that is 5 ft less in the TRIM2D 

model than in the HEC-RAS model;

2. Elevation of the TRIM2D thalweg (corrected for the 

+3.484 ft datum shift) that is on average 2.5 ft higher 

than the HEC-RAS thalweg (table 7); and

3. Thalweg slopes that are 13, 23, and 44 percent less 

in the TRIM2D model than in the HEC-RAS model 

along the upper, middle, and lower reaches of the 

river, respectively.

4

To conform to the NAVD 88 datum, a +1.955 ft elevation correction has 

been applied to the contours shown in figure 5. 

5

To conform to the NAVD 88 datum, a +3.484 ft elevation correction has 

been applied to the 2-ft contour map prepared by Eskridge, Aerial Mapping 

Inc. (1996). 

6

TRIM2D model simulations were initialized for a flow of 10 m3/s and 

increased incrementally to 50, 70, 100, 150, 187, 263, and 400 m3/s using 

results from the previous and smaller flow simulation as the initial conditions 

for the specified simulation (Ostenaa and others, 1999, p. 31). Appendix 4

includes an evaluation of the steady-flow assumption at three cross sections 

for the TRIM2D 100 m3

/s simulation.

62  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
ID9HZ12__fig23A

WEST DIRECTION OF FLOW EAST

Site 1

constriction

Site 2

constriction

Site 3

constriction

42

(BLR #8)

76 72

(BLR #6)

98

(Saddle area)

Cross section

20

56

5,040

5,035

5,030

5,025

5,020

5,015

5,010

5,005

10,000 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 0

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

DISTANCE, IN FEET UPSTREAM FROM PIONEER DIVERSION STRUCTURES 

Middle

Reach

Lower

Reach

Upper

Reach

TRIM2D model (Ostenaa and others, 1999)

 70

 100

 150

SIMULATED WATER-SURFACE ELEVATION WHEN

 FLOW, IN CUBIC METERS PER SECOND, IS:

HEC-RAS model

 70

 100

 150

A. Big Lost River

Figure 23. HEC-RAS and TRIM2D simulated water-surface elevations for peak flows of 70, 100, and 150 cubic 

meters per second on the Big Lost River and sites 1 and 2 constrictions upstream of the Pioneer diversion 

structures, Idaho National Engineering and Environmental Laboratory, Idaho.

Comparisons of HEC-RAS, HEC-6, and TRIM2D Simulation Results  63
ID9HZ12_fig23B

Site 1

constriction

5,033

5,032

5,031

5,030

5,029

5,028

5,027

5,026

5,025

5,024

7,100 7,000 6,900 6,800

85

84

83

82

81

80

7,050 6,950 6,850

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

CROSS SECTIONS 

DISTANCE, IN FEET UPSTREAM OF PIONEER DIVERSION STRUCTURES 

TRIM2D model (Ostenaa and others, 1999)

 70

 100

 150

WEST DIRECTION OF FLOW EAST

SIMULATED WATER-SURFACE ELEVATION WHEN

 FLOW, IN CUBIC METERS PER SECOND, IS:

HEC-RAS model

 70

 100

 150

B. Site 1 constriction

Figure 23.—Continued.

64  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
ID9HZ12_fig23C

WEST DIRECTION OF FLOW EAST Site 2

constriction

5,026

5,025

5,024

5,023

5,022

5,021

5,020

5,019

5,018

5,017

5,016

5,015

5,014

3,300 3,250 3,200 3,150 3,100

55

54

53.5

53

52.5

52

51.75

51.5

51.25

51

50.5

50

49.5

49

48

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

DISTANCE, IN FEET UPSTREAM OF PIONEER DIVERSION STRUCTURES 

CROSS SECTIONS 

TRIM2D model (Ostenaa and others, 1999)

 70

 100

 150

SIMULATED WATER-SURFACE ELEVATION WHEN

 FLOW, IN CUBIC METERS PER SECOND, IS:

HEC-RAS model

 70

 100

 150

C. Site 2 constriction

Figure 23.—Continued.

Comparisons of HEC-RAS, HEC-6, and TRIM2D Simulation Results  65
A few minor exceptions in which HEC-RAS watersurface elevations are higher than those of TRIM2D occur 

immediately upstream and downstream of cross section 98 

(near the saddle area) for peak flows of 70 and 100 m3/s, 

downstream of the site 1 constriction for a peak flow of 

150 m3/s, and immediately upstream of the site 2 constriction 

for a peak flow of 150 m3/s. The average elevation of the 

TRIM2D water surface for the entire model reach, computed 

on the basis of a one-to-one comparison of HEC-RAS 

water-surface elevations to those of TRIM2D at all cross 

sections, was 1.2, 1.1, and 0.9 ft higher than HEC-RAS watersurface elevations for peak flows of 70, 100, and 150 m3

/s, 

respectively (table 8). The largest average difference in 

water-surface elevations between the two models (1.2 ft) is 

associated with the lowest peak flow, 70 m3/s, and probably 

reflects the combined effects of differences in the thalweg 

slopes and channel-bottom topographies (figs. 19 and 20) used 

in the HEC-RAS and TRIM2D models. 

Constrictions 

Maximum energy dissipation, represented by large 

changes in water-surface elevations over short distances, 

should occur within and immediately downstream of the 

sites 1 and 2 constrictions where flow is forced to converge 

and accelerate and where energy is lost to the formation 

of hydraulic jumps. At the downstream end of the site 1 

constriction (cross section 81, fig. 23B), TRIM2D water 

surfaces are 0.5 to 1.0 ft higher than HEC-RAS water 

surfaces; and the TRIM2D water-surface depressions through 

this constriction are not as well defined as the HEC-RAS 

water-surface depressions (cross sections 81 to 85, fig. 23B). 

However, changes in water-surface elevation through the 

site 1 constriction are comparable for both models. Changes 

in HEC-RAS water-surface elevations of 1.2, 1.3, and 1.7 

ft (cross sections 81 to 85) compare closely to changes in 

TRIM2D water-surface elevations of 1.0, 1.1, and 1.8 ft (cross 

sections 81 to 85) for peak flows of 70, 100, and 150 m3/s, 

respectively.

At the site 2 constriction, the character of the TRIM2D 

and HEC-RAS water-surface profiles are very different. At 

the downstream end of the site 2 constriction (cross section 

49, fig. 23C) TRIM2D water surfaces are 1.5 to 2.0 ft higher 

than HEC-RAS water surfaces; and elevation changes 

through the constriction are much smaller than HEC-RAS 

elevation changes (cross sections 49 to 55, fig. 23C). TRIM2D 

elevation changes of 1.4, 1.4, and 1.7 ft do not compare 

closely to HEC-RAS elevation changes of 3.4, 3.3, and 2.4 ft 

for flows of 70, 100, and 150 m3

/s, respectively. The smaller 

changes in TRIM2D water-surface elevations through the 

site 2 constriction contribute significantly to the much higher 

TRIM2D water-surface elevations downstream of the site 

2 constriction, even though the water-surface elevations 

immediately upstream of this constriction are nearly identical 

Table 8. Differences in HEC-RAS, HEC-6, and TRIM2D simulated water-surface elevations for peak flows of 70, 100, and 150 cubic 

meters per second on the Big Lost River upstream of the Pioneer diversion structures, Idaho National Engineering and Environmental 

Laboratory, Idaho.

[Location of cross sections is shown in figure 9C. ft, ft; m3/s, cubic meter per second]

Cross section

Differences in water-surface elevations (ft)

Between HEC-RAS and TRIM2D models

(HEC-RASelev minus TRIM2Delev)

for a peak flow of

Between HEC-6 and TRIM2D models

(HEC-6elev minus TRIM2Delev)

for a peak flow of

70 m3/s 100 m3/s 150 m3/s 70 m3/s 100 m3/s 150 m3/s

20 -2.6 -2.4 -2.2 -0.4 -0.2 0.2

42 (BLR#8) -2.9 -2.9 -2.7 -1.3 -1.5 -1.1

56 -1.4 -.1 .1 -1.9 -1.6 -.4

72 (BLR#6) -1.6 -1.4 -.8 -2.1 -2.4 -1.4

76 -1.4 -1.2 -.5 -1.4 -1.7 -.7

98 (near saddle area) .5 .3 -.4 .7 .1 -1.0

Average difference Average difference

Entire reach (n = 89) -1.2 -1.1 -0.9 -0.8 -1.0 -0.5

Upper reach (85 to 108) .2 .1 -.4 .6 .0 -.7

Middle reach (58 to 81) -1.2 -.6 -.3 -1.6 -1.6 -.7

Lower reach (3 to 45) -2.5 -2.5 -2.2 -1.0 -1.0 -.4

66  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
to those of HEC-RAS for the 100 and 150 m3

/s simulations 

(figs. 23A and 23C). The much larger changes in HEC-RAS 

water-surface elevations through the site 2 constriction reflect 

the effects of subcritical to supercritical flow acceleration 

[from 6.0 ft/s immediately upstream of the constriction (cross 

section 54) to a maximum of 22.3 ft/s inside the constriction 

(cross section 51.75) for a peak flow of 100 m3/s]. This flow 

regime change was not simulated in the TRIM2D model.

Paleoindicator Sites 

TRIM2D model simulations indicate that a flow of 

about 100 m3/s will overtop and erode the 300- to 500-year 

old paleoindicator sites at BLR#6 and BLR#8. TRIM2D 

simulations also indicated that “...discharges only slightly 

larger than about 110 m3/s will initiate extensive flow across 

the unmodified Pleistocene alluvial surfaces” (Ostenaa and 

others, 1999; referring to the saddle area) and that overtopping 

and severe erosion of the saddle area would occur at a flow of 

150 m3

/s, thus establishing the basis for “... a paleohydrologic 

bound at a discharge of 150 m3/s for the past 10 k.y.” (10 

thousand years). 

TRIM2D water-surface elevations for peak flows of 70, 

100, and 150 m3/s were 2.9, 2.9, and 2.7 ft higher at BLR#8 

(cross section 42) and 1.6, 1.4, and 0.8 ft higher at BLR#6 

(cross section 72) than HEC-RAS water-surface elevations 

(table 8). The TRIM2D model simulation results predict 

that a flow of 100 m3/s will overtop the inset terraces at 

BLR#6 (water-surface elevation = 5,027.5 ft) and BLR#8 

(water-surface elevation = 5,021.5 ft) (fig. 24). This flow is 

significantly smaller than flows simulated by the HEC-RAS 

model that are discussed in the section on “Flow Equivalency.” 

At cross section 98 (near the saddle area), the TRIM2D 

water-surface elevation was 0.5 and 0.3 ft lower than HECRAS for peak flows of 70 and 100 m3

/s, respectively, and 

0.4 ft higher for a peak flow of 150 m3/s (table 8). However, 

a field survey of the saddle area (appendix 3) indicates that 

the saddle-area elevation (5,033.7 ft, NAVD 88) is about 1.2 

ft higher than indicated on the 2-ft contour map (Eskridge, 

Aerial Mapping Inc., 1996), corrected for the 3.484 ft datum 

shift that was used in the TRIM2D model, and 0.8 ft lower 

than the 1-ft contour map (fig. 5; D.A. Ostenaa, Bureau of 

Reclamation, written commun., 2001), corrected for the 1.955 

datum shift that was used in the HEC-RAS model. These 

elevation differences indicate that flows higher than simulated 

by the TRIM2D model are needed to overtop and erode the 

10,000-year old Pleistocene saddle-area surface.

Flow Equivalency

 Estimates of HEC-RAS peak flows needed to match 

TRIM2D water-surface elevations at six selected cross 

sections are presented in table 9. Equivalent flow estimates 

assume that simulated changes in water-surface elevation are 

linear from one flow simulation to the next (fig. 25). Thus, at 

cross section 42 (BLR#8), increases in HEC-RAS peak flows 

of 72 m3/s (103 percent), 83 m3/s (83 percent), and 79 m3/s 

(53 percent); and at cross section 72 (BLR#6), increases 

in HEC-RAS peak flows of 24 m3/s (34 percent), 45 m3/s 

(45 percent), and 37 m3/s (25 percent) are needed to match 

water-surface elevations in the TRIM2D model for peak flows 

of 70, 100, and 150 m3/s, respectively. 

Table 9. HEC-RAS peak flows needed to match TRIM2D water-surface elevations for peak flows of 70, 100, and 150 cubic meters per 

second on the Big Lost River upstream of the Pioneer diversion structures, Idaho National Engineering and Environmental Laboratory, 

Idaho.

[Location of cross sections is shown in figure 9C. m3/s, cubic meter per second]

Cross section

TRIM2D peak flow of

70 m3/s 100 m3/s 150 m3/s

Equivalent 

HEC-RAS 

peak flow

Difference Equivalent 

HEC-RAS 

peak flow

Difference Equivalent 

HEC-RAS 

peak flow

Difference

Flow Percent Flow Percent Flow Percent

20 137 67 9 176 76 76 221 71 47

42 (BLR#8) 142 72 103 183 83 83 229 79 53

56 86 16 23 103 3 3 148 -2 -1

72 (BLR#6) 94 24 34 145 45 45 187 37 25

76 93 23 32 140 40 40 176 26 17

98 (near saddle area) 62 -8 -11 87 -13 -13 169 19 13

Comparisons of HEC-RAS, HEC-6, and TRIM2D Simulation Results  67
ID9HZ12_fig24p1

CROSS SECTION 20

CROSS SECTION 42 (BLR#8)

CROSS SECTION 56 

LEFT BANK

LEFT BANK

LEFT BANK

5,032

5,028

5,024

5,020

5,016

5,012

5,008

5,004

-500 -400 -300 -200 -100 0

5,026

5,023

5,020

5,017

5,014

5,011

5,008

100 200 300 400 500 600 700

5,034

5,030

5,026

5,022

5,018

5,014

5,010

5,006

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

DISTANCE FROM REFERENCE POINT, IN FEET 

HEC-RAS

TRIM2D (Dean Ostenaa, Bureau of 

 Reclamation, written commun., 2001)

HEC-RAS simulated water-surface

 elevation when flow is 100 cubic 

 meters per second

TRIM2D simulated water-surface

 elevation when flow is 100 cubic 

 meters per second

Figure 24. HEC-RAS and TRIM2D simulated water-surface elevations at selected cross sections for a peak flow 

of 100 cubic meters per second on the Big Lost River upstream of the Pioneer diversion structures, Idaho National 

Engineering and Environmental Laboratory, Idaho. 

(Location of cross sections shown in figure 9C.)

68  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
ID9HZ12_fig24p2

CROSS SECTION 72 (BLR#6)

CROSS SECTION 76 

CROSS SECTION 98 (near saddle area)

LEFT BANK

LEFT BANK

LEFT BANK

5,032

5,028

5,024

5,020

5,016

5,012

-100 0 200100 300 400

5,035

5,032

5,029

5,026

5,023

5,020

5,017

5,014

5,038

5,034

5,030

5,026

5,022

500 700600 900800 1,000 1,100

-500 -400 -300 -200 -100 0 100 200 300 400 500 600 700

1,200 1,400 1,300 1,500 1,600 1,700

DISTANCE FROM REFERENCE POINT, IN FEET 

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

???

HEC-RAS

TRIM2D (Dean Ostenaa, Bureau of 

 Reclamation, written commun., 2001)

HEC-RAS simulated water-surface

 elevation when flow is 100 cubic 

 meters per second

TRIM2D simulated water-surface

 elevation when flow is 100 cubic 

 meters per second

Figure 24.—Continued.

Comparisons of HEC-RAS, HEC-6, and TRIM2D Simulation Results  69
ID9HZ12_fig25

CROSS SECTION 20 

CROSS SECTION 56 

CROSS SECTION 76 

CROSS SECTION 42 (BLR#8)

CROSS SECTION 72 (BLR#6)

CROSS SECTION 98 (near saddle area)

5,033

5,030

5,027

5,024

5,021

5,018

5,015

5,012

40 60 80 100 120 140

5,033

5,030

5,027

5,024

5,021

5,018

5,015

5,012

5,036

5,033

5,030

5,027

5,024

5,021

5,018

5,015

50 70 90 110 130 150 170160 180 190 40 60 50 70 80 100 120 90 110 130 140 150 170160 180 190

SIMULATED WATER-SURFACE ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

PEAK FLOW, IN CUBIC METERS PER SECOND 

Peak flow at which HEC-RAS

water-surface elevation is equivalent

to TRIM2D water-surface elevation

Saddle area elevation

Water-surface elevation

300 to 500 year paleoflood

HEC-RAS

TRIM2D (Dean Ostenaa, U.S Bureau of

 Reclamation, written commun., 2001)

Water-surface elevation

300 to 500 year paleoflood

Figure 25. HEC-RAS and TRIM2D simulated water-surface elevations at selected cross sections for peak flows of 

70, 100, and 150 cubic meters per second on the Big Lost River upstream of the Pioneer diversion structures, Idaho 

National Engineering and Environmental Laboratory, Idaho. 

Locations of cross sections shown in figure 9.

70 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
At cross section 98 (near the saddle area), decreases 

in HEC-RAS peak flows of 8 m3/s (11 percent) and 13 m3/s 

(13 percent) are needed to match water-surface elevations 

in the TRIM2D model for peak flows of 70 and 100 m3/s, 

respectively; and an increase in HEC-RAS peak flow of 

19 m3/s (13 percent) is needed to match TRIM2D watersurface elevations for a peak flow of 150 m3

/s. 

Results of the HEC-RAS model simulations indicate that 

the TRIM2D model simulations underestimate the magnitude 

of peak flows representing return periods of 300 to 500 years 

and 10,000 years. The TRIM2D model probably predicted 

higher water-surface elevations than the HEC-RAS model 

because of higher thalweg elevations, lower thalweg slopes, 

greater topographic variability of the thalweg, limited energy 

dissipation through the site 2 constriction, and steeper deptharea curves and flatter stage-area curves used to represent the 

channel and floodplain geometries in the TRIM2D model. 

Although the stage-area curves for HEC-RAS and TRIM2D 

are similar near cross section 98, HEC-RAS results indicate 

that a flow greater than 190 m3

/s (about 210 m3/s based on 

linear extrapolation of the HEC-RAS stage-area curve for 

cross section 98 shown in fig. 25) is needed to initiate flow 

across the saddle area because the elevation of the lowest point 

on the saddle area is 1.2 ft higher than indicated on the 2-ft 

contour map (corrected for the 3.484 ft datum) that was used 

in the TRIM2D model.

Comparisons of HEC-6 and TRIM2D 

Water-Surface Elevations

Along the upper and middle reaches of the river, average 

differences in water-surface elevation between HEC-6 and 

TRIM2D generally are larger than those between HEC-RAS 

and TRIM2D for all simulated flows (fig. 26 and table 8). 

Along the lower reach, differences in HEC-6 and TRIM2D 

water-surface elevations (HEC-6elev minus TRIM2Delev) are less 

than those of HEC-RAS and TRIM2D (HEC-RASelev minus 

TRIM2Delev), which reflects the effects of sediment deposition 

in this reach of the river. Average differences in water-surface 

elevation between HEC-6 and TRIM2D were 0.6, 0.0, and -0.7 

ft in the upper reach, -1.6, -1.6, and -0.7 ft in the middle reach, 

and -1.0, -1.0, and -0.4 ft in the lower reach for peak flows of 

70, 100, and 150 m3

/s, respectively (table 8). Differences in 

water-surface elevations between HEC-6 and TRIM2D at the 

paleoindicator sites ranged from -1.4 ft (peak flow of 150 m3/

s) to -2.4 ft (peak flow of 100 m3/s) at BLR#6 (cross section 

72); from -1.1 ft (peak flow of 150 m3/s) to -1.5 ft (100 m3/s) 

at BLR#8 (cross section 42); and from -1.0 ft (peak flow of 

150 m3

/s) to 0.7 ft (peak flow of 70 m3/s) near the saddle area 

(cross section 98). 

When the effects of streambed erosion and sediment 

deposition are included, HEC-6 model results indicate that 

flows greater than those simulated by HEC-RAS are needed 

to match TRIM2D water-surface elevations in the upper and 

middle reaches of the river, where streambed scour dominates, 

and that flows less than those simulated by HEC-RAS are 

needed to match TRIM2D water-surface elevations in the 

lower reach of the river, where sediment deposition dominates. 

HEC-6 model results indicate that the TRIM2D model 

underestimates the magnitude of peak flows needed to overtop 

and erode paleoindicator surfaces that were used to establish 

the return periods of hypothetical flood events with minimum 

return periods of 300 to 500 years and 10,000 years. These 

paleoindicator surfaces are in the upper and middle reaches of 

the river.

Comparisons of HEC-RAS and TRIM2D Flow 

Depths

Flow depths for the HEC-RAS and TRIM2D models for 

peak flows of 70, 100, and 150 m3/s are shown in figures 27A, 

27B, and 27C. Flow depths at each cross section were 

computed by subtracting water-surface elevation from the 

thalweg elevation used in the respective model simulations. In 

the case of HEC-RAS, this difference represents the maximum 

depth of flow at each cross section shown in figure 9C. In the 

case of TRIM2D, this difference represents an approximate 

maximum depth within 2×2 m grid cells aligned along the 

thalweg of the model reach. The size of the grid cell in the 

TRIM2D model is sufficiently small that the flow depth 

represented by the grid cell should reasonably approximate 

the maximum flow depth. To facilitate comparisons of 

flow depths, a locally-weighted least-squares regression 

routine (LOWESS7

) was used to produce a smooth profile of 

simulated flow depths through the irregularly spaced cross 

sections shown in figure 9C.

The LOWESS-smoothed depth profiles shown in 

figures 27A, 27B, and 27C indicate that the TRIM2D flowdepth profiles bear little resemblance to the HEC-RAS flowdepth profiles. TRIM2D flow depths are shallower than HECRAS flow depths along the entire length of the model reach for 

all simulated flows. The LOWESS-smoothing routine clearly 

masks a few isolated exceptions to this observation as can be 

seen in the point-to-point graphs of flow depth that accompany 

the LOWESS-smoothed depth profiles in figures 27A, 27B, 

and 27C. At the upstream end of the model reach (near cross 

section 108), TRIM2D flow depths are 24, 21, and 11 percent 

shallower, and at the downstream end (near cross section 1), 

31, 34, and 38 percent shallower than HEC-RAS flow depths 

for peak flows of 70, 100, and 150 m3/s, respectively. To 

some extent shallower TRIM2D flow depths in the upper and 

middle reaches of the river can be explained by the depth-area 

geometry of the channel cross sections that were used in the 

TRIM2D model. This explanation, however, is difficult to 

apply in the lower reach of the river.

7

The LOWESS smoothing routine was implemented using the S-Plus Curve 

Fitting Toolbox utility (Insightful Corporation, copyright 1998, 2002) with 

an automatic span setting of 0.5 to compute the flow-depth profiles shown in 

figure 27.

Comparisons of HEC-RAS, HEC-6, and TRIM2D Simulation Results  71
ID9HZ12_fig26

WEST DIRECTION OF FLOW EAST

42

(BLR #8) 56

76

72

(BLR #6)

98

(Saddle area)

Site 1

constriction

Site 2

constriction

Site 3

constriction

Cross section

90

96

103

5,035

5,030

5,025

5,020

5,015

5,010

5,005

5,000

10,000 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 0

ELEVATION, IN FEET ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988 

DISTANCE, IN FEET UPSTREAM OF PIONEER DIVERSION STRUCTURES 

TRIM2D model (Ostenaa and others,

 1999) thalweg elevation

HEC-6 model thalweg elevation when

 flow, in cubic meters per second, is:

 70

 100

 150

Middle

Reach

Lower

Reach

Upper

Reach

TRIM2D model

 70

 100

 150

SIMULATED WATER-SURFACE ELEVATION WHEN

 FLOW, IN CUBIC METERS PER SECOND, IS:

HEC-6 model

 70

 100

 150

Figure 26. HEC-6 and TRIM2D simulated water-surface and thalweg elevations for peak flows of 70, 100, and 

150 cubic meters per second on the Big Lost River upstream of the Pioneer diversion structures, Idaho National 

Engineering and Environmental Laboratory, Idaho.

72  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
ID9HZ12_fig27A

Site 1

constriction

Site 2

constriction

Site 3

constriction

A. Peak Flow of 70 cubic meters per second

Site 1

constriction

Site 2

constriction

Site 3

constriction

SIMULATED FLOW DEPTHS

LOWESS CURVES OF SIMULATED FLOW DEPTHS

0

2

4

6

8

10

12

14

16

18

20

10,000 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 0

0

2

4

6

8

10

12

14

16

FLOW DEPTH, IN FEET 

DISTANCE, IN FEET UPSTREAM OF PIONEER DIVERSION STRUCTURES 

FLOW DEPTH, IN FEET 

HEC-RAS

HEC-6

TRIM2D (Dean Ostenaa, U.S. Bureau of 

 Reclamation, written commun., 2001)

Middle

Reach

Lower

Reach

Upper

Reach

Figure 27. HEC-RAS, HEC-6, and TRIM2D simulated flow depths and LOWESS-smoothed flow depths for peak flows 

of 70, 100, and 150 cubic meters per second on the Big Lost River upstream of the Pioneer diversion structures, Idaho 

National Engineering and Environmental Laboratory, Idaho.

Comparisons of HEC-RAS, HEC-6, and TRIM2D Simulation Results  73
ID9HZ12_fig27B

Site 1

constriction

Site 2

constriction

Site 3

constriction

Site 1

constriction

Site 2

constriction

Site 3

constriction

0

2

4

6

8

10

12

14

16

18

20

10,000 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 0

0

2

4

6

8

10

12

14

16

FLOW DEPTH, IN FEET 

DISTANCE, IN FEET UPSTREAM OF PIONEER DIVERSION STRUCTURES 

FLOW DEPTH, IN FEET 

HEC-RAS

HEC-6

TRIM2D (Dean Ostenaa, U.S. Bureau of 

 Reclamation, written commun., 2001)

SIMULATED FLOW DEPTHS

LOWESS CURVES OF SIMULATED FLOW DEPTHS

B. Peak flow of 100 cubic meters per second

Middle

Reach

Lower

Reach

Upper

Reach

Figure 27.—Continued.

74  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
ID9HZ12_fig27C

HEC-RAS

HEC-6

TRIM2D (Dean Ostenaa, U.S. Bureau of 

 Reclamation, written commun., 2001)

Site 1

constriction

Site 2

constriction

Site 3

constriction

Site 1

constriction

Site 2

constriction

Site 3

constriction

C. Peak flow of 150 cubic meters per second

LOWESS CURVES OF SIMULATED FLOW DEPTHS

4

6

8

10

12

14

16

18

20

22

24

10,000 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 0

0

2

4

6

8

10

12

14

16

FLOW DEPTH, IN FEET 

DISTANCE, IN FEET UPSTREAM OF PIONEER DIVERSION STRUCTURES 

FLOW DEPTH, IN FEET 

Middle

Reach

Lower

Reach

Upper

Reach

SIMULATED FLOW DEPTHS

Figure 27.—Continued.

Comparisons of HEC-RAS, HEC-6, and TRIM2D Simulation Results  75
The most conspicuous difference in the shape of the 

LOWESS-smoothed flow-depth profiles occurs downstream 

of the site 3 constriction where flow depths for the HEC-RAS 

model trend in an opposite direction to those of the TRIM2D 

model. To maintain steady flow, TRIM2D flow-depth profiles 

imply that cross-section flow areas per unit of flow depth 

and(or) flow velocities must be greater than those for the 

HEC-RAS model and that either or both of these must increase 

systematically in a downstream direction to compensate for 

the apparent systematic reduction in TRIM2D flow depths that 

occur downstream of the site 3 constriction (figs. 27A, 27B, 

and 27C). The depth-area curves for the field-surveyed and 

TIN-extended cross sections (for example cross sections 20 

and 42, fig. 22) do not indicate an appreciable or systematic 

increase in cross-section flow area as a function of depth that 

would be sufficient to compensate for the TRIM2D flow-depth 

trend shown in figures 27A, 27B, and 27C.

In the lower reach of the river, TRIM2D model results 

for a peak flow of 100 m3

/s (appendix 4) indicate extensive 

overbank flow between cross section 1 and cross section 

43 (fig. 9C). Overbank flow was not simulated in the HECRAS model in the lower reach of the river. Comparisons of 

HEC-RAS and TRIM2D thalweg elevations in this reach of 

the river indicate a substantial difference in relief between 

cross section 1 and cross section 42 (fig. 19). In the TRIM2D 

model, relief between these two locations was 5.6 ft, compared 

to 10.6 ft in the HEC-RAS model, suggesting that higher 

TRIM2D flow velocities are not likely to occur in this reach of 

the river to compensate for shallower flow depths. Extensive 

overbank flow in the TRIM2D model along this reach of the 

river, however, may be sufficient to compensate for shallower 

flow depths to satisfy the steady-flow assumption. 

The effect of the site 2 constriction on flow depths 

is evident in the HEC-RAS, HEC-6, and TRIM2D flowdepth profiles (figs. 27A, 27B, and 27C). Comparisons of 

the flow-depth profiles for peak flows of 70, 100, 150 m3

/s 

indicate that this constriction does not appear to have as 

much influence on the overall shape of the TRIM2D depth 

profile as it does on the HEC-RAS and HEC-6 profiles from 

one flow simulation to another. Furthermore, TRIM2D flow 

depths (smoothed) increase as flow approaches and moves 

through the site 2 constriction, whereas HEC-RAS and HEC-6 

flow depths decrease as flow approaches and moves through 

the site 2 constriction. Reduced HEC-RAS and HEC-6 flow 

depths, immediately upstream of the site 2 constriction, is 

consistent with flow acceleration and the transitioning of flow 

from subcritical to supercritical flow inside this constriction. 

Increasing flow depths, immediately upstream of the site 2 

constriction in the TRIM2D model, suggest that flow is not 

accelerating sufficiently through the site 2 constriction to 

produce supercritical flow. 

 To maintain steady flow into and out of a model reach, 

shallower flow depths imply that average TRIM2D flow 

velocities must be higher than those for HEC-RAS, or that 

cross-section flow areas per unit of depth must be greater (or 

both). Depth-area curves (fig. 22) indicate that cross-section 

flow areas are greater in the TRIM2D model for the same 

flow depth over much of the upper and middle reaches of the 

river. The flatter thalweg slopes used in the TRIM2D model, 

however, imply that flow velocities should be lower than 

those of HEC-RAS. Higher average velocities (discussed in 

the section “Comparisons of HEC-RAS and TRIM2D Flow 

Velocities”) are not consistent with this observation, and 

indicate that cross-section flow areas must be sufficiently 

different to compensate for lower flow velocities for the 

steady-flow assumption to be valid.

Comparisons of HEC-RAS and TRIM2D Flow 

Velocities

Flow-velocity profiles for the 100 m3/s HEC-RAS 

and TRIM2D simulations are shown in figure 28 and flow 

velocities at selected cross sections for peak flows of 70, 100, 

and 150 m3/s are presented in table 10. HEC-RAS velocities 

represent average velocities within a rectangular slice of each 

channel cross section shown in figure 9C. The width of the 

cross-section slice is defined by the left and right banks of 

the main channel. TRIM2D velocities represent maximum 

velocities within the main channel at each of the cross sections 

shown in figure 9C. In the upper reach of the river, overbank 

flow was simulated in both the TRIM2D and HEC-RAS 

models, and because of the wide and complex character of 

the cross sections in this reach of the river, comparisons of 

average velocities are difficult to make. In the lower reach of 

the river, velocity comparisons are less meaningful because 

extensive overbank flow was simulated in the TRIM2D model 

but was not simulated in the HEC-RAS model (appendix 4). 

In the middle reach of the river, velocity comparisons 

between models are more meaningful because all of the flow 

in the HEC-RAS model and most of the flow in the TRIM2D 

model occurs inside the main channel. Flow-depth profiles 

presented previously indicate that flow depths are deepest for 

both the HEC-RAS and the TRIM2D model along the middle 

reach of the river (figs. 27A, 27B, and 27C). For a deep, 

narrow channel, vertically averaged velocity will vary more 

strongly across the channel because of increased frictional 

resistance along the banks of the channel. And because of 

this, maximum TRIM2D flow velocities should be higher than 

average HEC-RAS velocities along the middle reach of the 

river.

76  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Along the upstream section of the middle reach average 

HEC-RAS flow velocities are comparable to maximum 

TRIM2D flow velocities at and immediately downstream of 

the site 1 constriction for a peak flow of 100 m3/s. At the site 

1 constriction (cross section 84), for a peak flow of 100 m3/s, 

TRIM2D and HEC-RAS flow velocities are 9.0 and 10.8 ft/s, 

respectively, and between cross sections 84 and 70.5, TRIM2D 

velocities are, on average, 11 percent higher than HEC-RAS 

velocities. Along the downstream section of the middle reach, 

TRIM2D flow velocities are much higher and do not compare 

closely to HEC-RAS velocities between cross sections 53 

through 70. Along this section of the river, TRIM2D velocities 

are, on average, 70 percent higher than HEC-RAS velocities. 

Immediately upstream of the site 2 constriction, HEC-RAS 

and TRIM2D simulation results are comparable. Within the 

site 2 constriction, however, the maximum TRIM2D velocity 

(12.7 ft/s) is much lower than the maximum HEC-RAS 

velocity (22.3 ft/s). The lower TRIM2D velocity is below 

the threshold velocity required for critical flow, 18.6 ft/s, 

and consequently LOWESS-smoothed TRIM2D flow depths 

increase as flow moves through this constriction; this is in 

contrast to the HEC-RAS flow depths that decrease as flow 

moves through this constriction (figs. 27A, 27B, and 27C). 

 Under the assumption of steady flow, TRIM2D flow 

velocities that are higher than those of HEC-RAS along 

the downstream section of the middle reach of the river 

are consistent with the shallower TRIM2D flow depths in 

this reach of the river (figs. 27A, 27B, and 27C); however, 

velocities higher than HEC-RAS are not consistent with the 

lower thalweg slope that was used in the TRIM2D model 

(23 percent less than the HEC-RAS thalweg slope). 

Downstream of the site 2 constriction, TRIM2D 

velocities are much higher than those of HEC-RAS. As noted 

previously, extensive overbank flow was simulated in the 

TRIM2D model along this reach of the river, and because of 

this velocity comparisons between TRIM2D and HEC-RAS 

are not meaningful. Under the assumption of steady flow, 

higher TRIM2D velocities accompanied by overbank flow 

may be sufficient to compensate for the systematic flow-depth 

reductions that were described previously. However, TRIM2D 

velocities higher than those of HEC-RAS in the lower reach of 

the river are not consistent with the much lower thalweg slope 

that was used in the TRIM2D model (44 percent less than the 

HEC-RAS thalweg slope). 

Comparisons of HEC-RAS and TRIM2D Stream 

Power

Stream power is used as an indicator of the erosional 

forces acting on a channel and floodplain. Stream power was 

used by Ostenaa and others (1999) to identify areas where 

simulated erosional forces would be sufficient to remove 

evidence of older alluvial deposits and floodplain terrain 

features that were used to define non-exceedance bounds for 

paleofloods with return periods of 300 to 500 years and 10,000 

years. In general, stream power is maximum where both flow 

depth and velocity are maximum, and, in most cases, both of 

these conditions will occur along or near the thalweg of the 

channel, assuming off-channel and overbank flow are limited 

and flow is not forced to accelerate around bends in the river. 

Stream power is defined as (Yang, 1996, p. 66):

Table 10. HEC-RAS and TRIM2D simulated flow velocities at selected cross sections for peak flows of 70, 100, and 150 cubic meters 

per second on the Big Lost River upstream of the Pioneer diversion structures, Idaho National Engineering and Environmental 

Laboratory, Idaho.

[Location of cross sections is shown in figure 9C. ft/s, ft per second; m3/s, cubic meter per second]

Cross section

Simulated velocity (ft/s) for selected peak flows in the 

HEC-RAS model TRIM2D model

70 m3/s 100 m3/s 150 m3/s 70 m3/s 100 m3/s 150 m3/s

20 6.0 7.2 7.9 1.8 1

(7.2) 2.5 (8.0) 6.7 (9.1)

42 (BLR#8) 6.7 7.4 7.6 3.1 (7.6) 2.5 (8.3) 1.6 (8.9)

56 5.2 5.0 6.1 6.0 6.8 7.9

72 (BLR#6) 4.4 4.6 5.5 3.8 4.3 5.9

76 6.8 7.1 8.4 5.5 6.7 8.3

98 (near saddle area) 2.5 2.6 2.7 2.4 (4.9) 2.1 (4.1) 0.3 (4.2)

84 (site 1 constriction) 10.1 10.8 12.3 8.3 9.0 10.8

52 (site 2 constriction) 12.0 17.5 12.7 9.2 10.0 (15.5) 11.1 (11.3)

33 (site 3 constriction) 5.9 6.7 7.5 4.5 (8.6) 5.4 (9.2) 3.6 (8.5)

1

(7.2) Value in parenthesis represents the maximum velocity in overbank areas.

Comparisons of HEC-RAS, HEC-6, and TRIM2D Simulation Results  77
Stream Power = =t g V DS V ( ) , (4)

where:

τ is shear stress acting over the wetted perimeter 

[M/LT],

g is specific weight of water [M/L3

],

D is average depth of flow in the cross section [L],

S is energy slope [L0], and

V is average stream flow velocity [L/T].

The units for these terms are mass [M], length [L], time [T], 

and dimensionless [L0].

Stream power is included in the computational output 

of both the HEC-RAS and TRIM2D models. Stream-power 

profiles for the 100 m3/s TRIM2D and HEC-RAS flow 

simulations are shown in figure 29. HEC-RAS stream power 

was computed on the basis of maximum flow depth (fig. 27B) 

and average flow velocity (fig. 28) at each cross section 

shown in figure 9C. TRIM2D stream power represents the 

highest stream power in the main channel at these cross 

sections; however, in many cases this occurs in areas where 

extensive overbank flow was simulated (appendix 4). Stream 

power should not be expected to compare closely in areas 

where simulated flow depths (fig. 27B) and flow velocities 

(fig. 28) differ significantly (primarily in the upper and lower 

reaches of the river). However, there are very few locations 

where TRIM2D and HEC-RAS stream power are comparable 

(fig. 29). 

In general, stream power was much greater in the 

TRIM2D model than in the HEC-RAS model (table 11). 

The average TRIM2D stream power for all cross sections 

shown in figure 9C (fig. 29) is 1.5 times greater than HECRAS, this in spite of the fact that TRIM2D flow depths are 

shallower than HEC-RAS flow depths throughout the model 

reach (figs. 27A, 27B, and 27C) and the average maximum 

TRIM2D flow velocities are only 1.1 times higher than the 

average HEC-RAS flow velocities (fig. 28). For the HEC-RAS 

simulations, stream power ranged by almost three orders of 

magnitude, from a low of 3.6 W/m2 to a high of 3,009 W/m2. 

For the TRIM2D simulations, stream power ranged by almost 

two orders of magnitude, from a low of 8.1 W/m2 to a high of 

559 W/m2 in the main channel (overbank flow excluded).

With the exception of the peak stream power inside the 

site 2 constriction, TRIM2D and HEC-RAS stream powers 

are comparable only in the immediate vicinity of the sites 1, 2, 

and 3 constrictions. The much lower TRIM2D stream power 

at the site 2 constriction results from the much lower velocity 

that was simulated at this location (supercritical flow was not 

simulated). The very high HEC-RAS stream power at the site 

2 constriction reflects the high flow velocities through this 

constriction during supercritical flow. 

A stream power value of 100 W/m2

 or more is capable of 

eroding and transporting pebble- and cobble-size particles as 

demonstrated in the HEC-6 simulations. HEC-6 simulations 

indicated that the lowest stream power would occur at or near 

the saddle area (section 98), and the highest value would occur 

inside the site 2 constriction. Because stream power inside the 

site 2 constriction was much greater than 100 W/m2, HEC-6 

results showed that sediment fill inside this constriction would 

be eroded to bedrock (figs. 16A and 16B). Stream powers for 

the HEC-RAS simulations at the site 3 constriction were much 

less than at the site 1 and 2 constrictions. HEC-6 simulations 

indicated that for a peak flow 100 m3/s stream power would 

not be sufficient to erode the channel fill inside these 

constrictions down to bedrock.

Table 11. HEC-RAS and TRIM2D simulated stream power at selected cross sections for peak flows of 70, 100, and 150 cubic meters per 

second on the Big Lost River upstream of the Pioneer diversion structures, Idaho National Engineering and Environmental Laboratory, 

Idaho.

[Location of cross sections is shown in figure 9C. W, watts; m2, squared meter; W/m2, watts per squared meter; m3/s, cubic meter per second]

Cross section

Simulated stream power (W/m2

) for selected peak flows in the 

HEC-RAS model TRIM2D model

70 m3/s 100 m3/s 150 m3/s 70 m3/s 100 m3/s 150 m3/s

20 29 44 59 25 1

(114) 139 (145) 205 (204)

42 (BLR#8) 106 133 130 139 (149) 147 (227) 165 (269)

56 31 27 46 75 92 199 (237)

72 (BLR#6) 12 13 21 18 22 58

76 47 51 79 52 82 230

98 (near saddle area) 4 5 5 19 (41) 10 (27) 0.4 (24)

84 (site 1 constriction) 161 193 279 160 259 323

52 (site 2 constriction) 440 1,384 482 348 327 (1,841) 382 (2,537)

33 (site 3 constriction) 61 82 109 67 (271) 102 (289) 37 (210)

1

(114) Value in parenthesis represents the maximum stream power in overbank areas.

78  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
ID9HZ12_fig28

Site 1

constriction

Site 2

constriction

Site 3

constriction

10,000 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 0

24

22

20

18

16

14

12

10

8

6

4

2

0

DISTANCE, IN FEET UPSTREAM OF PIONEER DIVERSION STRUCTURES 

VELOCITY, IN FEET PER SECOND 

HEC-RAS

TRIM2D (Dean Ostenaa, U.S. Bureau of 

 Reclamation, written commun., 2001)

Middle

Reach

Lower

Reach

Upper

Reach

Figure 28. HEC-RAS and TRIM2D simulated flow velocities in the main channel for a peak flow of 100 cubic meters 

per second on the Big Lost River upstream of the Pioneer diversion structures, Idaho National Engineering and 

Environmental Laboratory.

Comparisons of HEC-RAS, HEC-6, and TRIM2D Simulation Results  79
ID9HZ12_fig29

Site 1

constriction

Site 2

constriction

Site 3

constriction

10,000 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 0

10,000

1,000

10

1

100

7,000

700

7

70

3,000

300

3

30

DISTANCE, IN FEET UPSTREAM OF PIONEER DIVERSION STRUCTURES 

STREAM POWER, IN WATTS PER SQUARE METER 

Middle

Reach

Lower

Reach

Upper

Reach

HEC-RAS

TRIM2D (Dean Ostenaa, U.S. Bureau of 

 Reclamation, written commun., 2001)

Figure 29. HEC-RAS and TRIM2D simulated stream power in the main channel for a peak flow of 100 cubic meters 

per second on the Big Lost River upstream of the Pioneer diversion structures, Idaho National Engineering and 

Environmental Laboratory, Idaho.

80 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Summary and Conclusions

A 1.9-mile reach of the Big Lost River, between the 

Idaho National Engineering and Environmental Laboratory 

(INEEL) diversion dam and the Pioneer diversion structures, 

was investigated to evaluate the effects of streambed erosion 

and bedrock constrictions on model predictions of watersurface elevations. Two one-dimensional (1-D) models, 

a fixed-bed surface-water flow model (HEC-RAS) and a 

movable-bed surface-water flow and sediment-transport 

model (HEC-6), were used to evaluate these effects. The 

results of these models were compared to the results of a 

two-dimensional (2-D) fixed-bed model [Transient Inundation 

2-Dimensional (TRIM2D)] that had previously been used to 

predict water-surface elevations for peak flows with sufficient 

stage and stream power to erode floodplain terrain features 

(Holocene inset terraces referred to as BLR#6 and BLR#8) 

dated at 300 to 500 years old, and an unmodified Pleistocene 

surface (referred to as the saddle area) dated at 10,000 years 

old.

 Previously developed models of flooding in the Big Lost 

River, the U.S. Geological Survey (USGS) Water-Surface 

PROfile (WSPRO) model and the Bureau of Reclamation 

TRIM2D model, did not account for scouring of the streambed 

and did not simulate the effects of supercritical flow during 

flooding. Because of these limitations, TRIM2D predictions 

of flood stage may have underestimated the magnitude of 

flows required to overtop and erode floodplain terrain features 

that were used to estimate the minimum return period of 

floods with sufficient stage and stream power to erode the 

dated surfaces. TRIM2D model simulation results were 

used to extend the period of record at the streamflow-gaging 

station near Arco for flood-frequency analysis to estimate the 

magnitude of the 100-year flood, and the magnitude of floods 

with return periods as long as 10,000 years. The results of the 

study described in this report were also used to evaluate the 

results of the TRIM2D model simulations that were used to 

predict flood elevations at different assumed peak flows.

On the INEEL, the Big Lost River is an ephemeral stream 

that typically is incised less than 20 ft into Holocene and upper 

Pleistocene alluvium and middle to upper Pleistocene basalt 

lava flows. Alluvial fill overlies basalt bedrock over most of 

the streambed, but in several places bedrock is exposed. At 

three locations in the study reach (designated sites 1, 2, and 

3) the river is constricted by basalt bedrock and the channel 

narrows considerably. At the site 2 constriction, the narrowest 

point along the river, the channel narrows from a width of 

53 to 17 ft and is more than 20 ft deep. The site 1 and site 

3 constrictions are less dramatic. The channel at these two 

constrictions narrows from a width of 45 to 27 ft at site 1, and 

from 53 to 46 ft at site 3.

 Twenty-four trenches were excavated to determine the 

grain-size distribution of sediments composing the channel 

fill. The dominant material in the streambed is coarse sand, 

pebbles, and cobbles. The median diameter (d50) of the 

channel-fill samples ranges from 0.17 to 35.5 mm. Except 

near the constrictions, the streambed is armored with a thin 

veneer of lightly-cemented pebbles and cobbles that protects 

the streambed from scour at low to moderate flows. The 

median diameter of particles composing the armored surface 

layer ranges from 6 to 47 mm, significantly larger than the 

underlying channel fill. The results of streambed and channelfill sampling indicate that the river would be classified as a 

gravel-bed river. 

Inside the three constrictions the channel fill consists 

predominantly of sands and silts with widely dispersed 

pebbles. Stratification of the sands and silts is common inside 

the constrictions and armoring is absent. The fill material 

inside the constrictions is very susceptible to erosion. Bedrock 

was encountered in these constrictions at depths of 4 to 6 

ft. Grain-size distributions for the armored surface layer 

and underlying channel fill were used in the HEC-6 model 

to simulate flow and sediment transport and to evaluate the 

effects of streambed erosion and sediment deposition on 

water-surface elevations. 

Channel and floodplain geometries used in this study 

were defined by 76 field-surveyed cross sections. Fieldsurveyed cross sections inside the constrictions were spaced 

less than 50 ft apart, and sections in straight reaches of 

the channel were spaced several hundred feet apart. Fieldsurveyed cross sections were extended out into the floodplain 

and additional cross sections were constructed using a 1-ft 

contour digital terrain map acquired from a 1999 aerial 

photography survey of the area by the Bureau of Reclamation. 

Several different cross-section assemblages, using a 

combination of field-surveyed, TIN (Triangulated Irregular 

Network) -generated, TIN-extended, and linearly-interpolated 

cross sections were used to simulate peak flows ranging from 

10 to 200 cubic meters per second (m3

/s). 

 Water-surface elevations for peak flows of 10, 50, 70, 

100, 150, 187, and 200 m3/s were simulated with the HECRAS and HEC-6 models. The roughness coefficient, or n

value used in the HEC-RAS model was calibrated against 

the 2-year flood (10 m3/s) to evaluate the n values that were 

selected to characterize frictional resistance in the active 

channel. Representative n values were calculated using 

several flow-resistance equations developed for gravel-bed 

rivers. Comparisons of simulated to field-surveyed high-water 

marks, assumed to represent the water-surface elevation of 

a 2-year flood, indicated that the hydraulic characteristics of 

the channel bed were adequately represented by the initial 

choices for the n values—0.025 for straight reaches, 0.033 

for moderately curved reaches, and 0.038 for severely curved 

reaches. 

The HEC-RAS model results also indicated that 

simulated water-surface elevations for flows less than 100 m3

/s 

were most sensitive to the n values chosen to represent bed 

roughness in the channel-controlled sections of the river and 

least sensitive in constriction-controlled sections of the river, 

the effects of which were simulated by adjusting the n value 

Summary and Conclusions  81
by factors of 0.5 and 1.5. The HEC-RAS model also was used 

to evaluate the sensitivity of channel erosion on water-surface 

elevations by artificially reducing streambed elevation by 1, 

2, and 4 ft, except in areas where bedrock is exposed or was 

encountered at shallower depths. As anticipated lowering of 

the streambed in these model simulations resulted in watersurface elevations that were equal to or less than water-surface 

elevations using the measured streambed.

 HEC-RAS model simulations indicated that the 

constrictions at sites 1 and 2 have the most influence on 

backwater accumulations in the study reach. These controls 

begin to have major impact when flows exceed 50 m3/s at 

the site 2 constriction and 100 m3/s at the site 1 constriction. 

Backwater affects about 500 ft of the river upstream of the 

site 1 constriction and 1,000 ft of the river upstream of the 

site 2 constriction for a peak flow of 100 m3/s. The HECRAS simulations also indicated that flow through the site 2 

constriction becomes supercritical at flows greater than and 

equal to 100 m3

/s. For peak flows less than and equal to 

70 m3/s, flow remained subcritical throughout the model reach.

Because HEC-RAS is a fixed-bed model, the HEC-6 

model was used to study the effects of streambed erosion 

and sediment deposition on water-surface elevations. HEC-6 

model simulations indicated that the streambed was scoured 

down to bedrock at the site 2 constriction for peak flows 

greater than and equal to 70 m3/s. The resulting HEC-6 

streambed elevation averaged about 0.5 to 0.7 ft lower than the 

HEC-RAS fixed-streambed elevation throughout the model 

reach for peak flows ranging from 70 to 150 m3/s. HEC-6 

water-surface elevation differences at the paleoindicator sites 

indicated that sediment deposition will produce overtopping 

of the BLR#6 site at flows smaller than those predicted by the 

HEC-RAS model simulations; and that streambed erosion will 

produce overtopping of BLR#8 and the saddle area at flows 

that are larger than those predicted by the HEC-RAS model 

simulations.

 Simulation results from the 1-D HEC-RAS and HEC-6 

models were compared to the results of the 2-D TRIM2D 

model that was used by the Bureau of Reclamation to evaluate 

flood flows in the study reach. In most cases the TRIM2D 

model simulated higher water-surface elevations, shallower 

flow depths, higher flow velocities, and higher stream powers 

than the HEC-RAS and HEC-6 models for the same peak 

flows. The HEC-RAS model required flow increases of 

83 percent (from 100 to 183 m3/s) and 45 percent (from 100 

to 145 m3/s) to match TRIM2D simulations of water-surface 

elevation at the BLR#6 and BLR#8 paleoindicator sites; and 

an increase of 13 percent (from 150 to 169 m3/s) to match 

TRIM2D simulations of water-surface elevation at the saddle 

area. However, a field survey of the saddle area indicated that 

the elevation of the lowest point on the saddle area was 1.2 ft 

higher than indicated on the 2-ft contour map that was used 

in the development of the TRIM2D model. Because of this 

elevation discrepancy, HEC-RAS model simulations indicated 

that a peak flow of at least 210 m3

/s would be needed to 

initiate flow across the 10,000 year-old Pleistocene surface, 

and flows greater than 210 m3/s (not modeled in this study) 

would be needed to erode this surface.

The increases in flow that needed to be simulated in 

the HEC-RAS and HEC-6 models to match TRIM2D watersurface elevations were attributed in part to the effects of 

supercritical flow through one constriction in the reach and 

to differences in the channel geometry input data that were 

used in the TRIM2D and HEC-RAS models and for initial 

conditions in the HEC-6 model. Field-surveys of the model 

reach indicated that:

1. The average TRIM2D thalweg elevation (corrected 

for a 3.484 ft datum shift between the NVGD 29 

elevation datum used in the TRIM2D model and the 

NAVD 88 elevation datum used in the HEC-RAS 

and HEC-6 models) is 2.5 ft higher than the fieldsurveyed thalweg elevation; 

2. The slope of the TRIM2D thalweg along the entire 

model reach is 15 percent lower than the thalweg 

slope used in the HEC-RAS model resulting in a 5 

ft difference in the topographic relief of these two 

models between the upstream and downstream ends 

of the model reach;

3. The thalweg slopes used in the TRIM2D model are 

13, 23, and 44 percent flatter than those used in the 

HEC-RAS model along the upper, middle, and lower 

reaches, respectively; 

4. The topographic variability of the TRIM2D thalweg 

is greater than the HEC-RAS thalweg along the 

upper, middle, and lower reaches; 

5. The cross-section flow areas at many locations in the 

TRIM2D model are larger than those in the HECRAS model for the same flow depth (the slope of the 

depth-area curves are steeper); and 

6. The cross-section flow areas in the TRIM2D model 

generally are smaller than those in the HEC-RAS 

model for the same stage or water-surface elevation 

over the upper half of the model reach (stage-area 

curves are steeper) and larger over the lower half of 

the model reach (stage-area curves are flatter). 

Differences in simulated water-surface elevations 

between the TRIM2D model and the HEC-RAS and HEC-6 

model are attributed primarily to differences in topographic 

relief and to differences in the channel and floodplain 

geometries used in these models. Topographic differences 

were sufficiently large that it was not possible to isolate 

the effects of these from those attributable to the effects of 

supercritical flow, streambed scour, and sediment deposition. 

82  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Acknowledgments

The authors express their appreciation to Kenneth Beard, 

with Bechtel BWXT Idaho (BBWI), for providing the fieldsurveyed horizontal- and vertical-control data that were 

used in this study. Appreciation is extended to Jay T. Brown, 

with BBWI, and Sabrina A. Conti and Douglas C. Werner, 

with the USGS, for their assistance with surveying the cross 

sections that were used to model flow and sediment transport; 

to Larry Matson and Matthew J. Gilbert, with the USGS, for 

their untiring efforts with the extensive trench excavations 

that were undertaken under severe field conditions following 

a range fire in 2000; to Amy J. Wehnke, with the USGS, for 

her assistance with the particle-size analyses; to Brennon R. 

Orr, formerly with the USGS, for his assistance in obtaining 

the environmental permits to excavate trenches in the river 

channel and for coordinating the field logistics for this study; 

to Dr. James H. Milligan, Professor of Civil Engineering at the 

University of Idaho, for his assistance with formulating the 

flow resistance (Manning’s n) and sediment loading equations 

used in the HEC-RAS and HEC-6 models; to Jon Hortness 

and Stephen Wiele, with the USGS, Dean A. Ostenaa, with the 

Bureau of Reclamation, and Robert J. Creed, with the DOE, 

for their reviews of this manuscript; and finally to Peter J. 

Dirkmaat, formerly with the DOE, for arranging the funding to 

conduct this study.

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86  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho

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Armor layer: A coarser surficial layer of sediments on the 

streambed. This layer ranges from one particle thickness to 

several. This layer can be quite resistant to scour—usually 

only high flows mobilize this layer and it may reform as flows 

decrease.

Backwater: Water backed up or retarded in its course as 

compared with its normal or natural condition of flow. 

Backwater is an increase in upstream flow depth. A sudden 

constriction in a channel can cause this effect.

Bank, left and right: Reference terms used to specify the 

banks on the left and right when facing downstream.

Bedform: Alluvial-channel bottom feature that depends on 

bed-material size, flow depth, and flow velocity. Bedforms 

include ripples, dunes, antidunes, and plane bed.

Conveyance: A measure of the carrying capacity of a channel 

section and is directly proportional to channel discharge. 

Conveyance is that part of Manning’s equation that excludes 

the square root of the energy gradient or friction slope.

Choked flows: The constriction width is reduced to a point 

where critical flow conditions are reached or exceeded.

Critical flow: If the flow is critical, the Froude number is 

equal to one, and the inertial forces balance the gravitational 

forces. This balance takes place at the depth at which flow is 

at its minimum energy.

Ephemeral: A stream or reach of a stream that flows briefly 

in direct response to precipitation, and whose channel is at all 

times above the water table.

Floodplain: Land adjoining (or near) the channel of 

a watercourse which has been, or may be, covered by 

floodwaters. A flood plain functions as a temporary channel or 

reservoir for overbank flows. The lowland that borders a river, 

usually dry but subject to flooding.

Flow regime: A range of flows producing similar bed forms, 

resistance to flow, and mode of sediment transport.

Froude number: A dimensionless number used as an index 

to characterize the type of flow (subcritical, critical, and 

supercritical) in an open channel. The Froude number is the 

ratio of the inertial forces to the gravitational forces, and 

is computed as Fr V gD = /( ) /1 2, where Fr is the Froude 

number; V is mean velocity of flow, in feet per second; g is 

acceleration of gravity, in feet per second squared; and D is 

hydraulic depth, in feet.

Grain size, coarse and fine: Coarse-grained bed material 

generally refers to those particles (pebble, cobble, and 

boulder) whose size can be individually measured with a 

graduated ruler or caliper; fine grained material (sand, silt, 

and clay) is measured by passage through a sieve, by rate 

of sedimentation, or by the Beckman Coulter Particle-Size 

Counter for very fine materials (< 0.0625 mm). See also 

particle size.

High-water marks: Evidence of the stage reached by flow. 

High-water marks generally consist of debris, scour marks, or 

staining of rocks found along the channel boundaries.

Hydraulic radius: Cross-section flow area divided by wetted 

perimeter.

Manning’s roughness coefficient (n values): A measure 

of the frictional resistance exerted by a channel on the flow. 

The n value also can reflect other energy losses such as those 

resulting from the transport of material and debris, unsteady 

flow, extreme turbulence, that are difficult or impossible to 

isolate and quantify.

Particle-size: The size of material on the bed of a stream, 

referenced to a specific diameter (either maximum, 

intermediate, or minimum) of the measured particle.

Peak flow: The largest value of the runoff flow, which occurs 

during a flood, as observed at a particular point in the drainage 

basin.

Scour: Erosion due to flowing water, usually considered as 

being localized as opposed to general bed degradation.

Slope, water-surface: The slope of the water surface, 

computed as the change in elevation per unit change in the 

channel’s length.

Glossary

Glossary  87
Stream power: A measure of energy transfer of the flow. 

Stream power is computed as (γDS)V, where γ is the specific 

weight of water, D, water depth, in feet; S is the energy slope, 

dimensionless; and V is the mean velocity, in feet per second. 

Stream power also is defined as the energy dissipated per unit 

area of the streambed per unit time.

Subcritical flow: If the flow is subcritical, the Froude 

number is less than one and the inertial forces are less than 

the gravitational forces. The flow depth in subcritical flow is 

greater than the flow depth in critical flow.

Supercritical flow: If the flow is supercritical, the Froude 

number is greater than one and the inertial forces are greater 

than the gravitational forces. The flow depth in supercritical 

flow is less than the flow depth in critical flow.

Thalweg: A line connecting the lowest points along the length 

of a streambed. It can be quite sinuous and wander within the 

channel.

Transport capacity: The ability of a stream to transport a 

given volume or weight of sediment material of a specific size 

per time for a given flow condition. The units of transport 

capacity are usually given in tons per day of sediment 

transported past a given cross section for a given flow. 

Transport capacity for each sediment grain size is the transport 

potential for that size material multiplied by the actual fraction 

of each size class present in the bed and bank material.

Transport potential: Transport potential is the rate at which 

a stream could transport sediment of a given grain size for 

given hydraulic condition if the bed and banks were composed 

entirely of material of that size.

Water-surface profile: Longitudinal plots of the watersurface elevation as a function of distance downstream through 

a channel reach.

Wetted perimeter: Length of the line along which the water 

is in contact with the channel bottom in the cross-sectional 

area of the flow.

88  Hydraulic Characteristics of Bedrock Constrictions and Evaluation of Flood Flow Models, Big Lost River, INEEL, Idaho
Appendix 1  89

Appendix 1 

Results of Armored-Surface-Layer Sampling at Various Locations on the 

Big Lost River Upstream of the Pioneer Diversion Structures, Idaho National 

Engineering and Environmental Laboratory
R. 28 E. R. 29 E.

6 1

T.

2

N.

Site 1

constriction

Site 2

constriction

Site 3

constriction

Dirt road

Big

Lost

River

113° 02' 30"

43°

32'

113° 03' 113° 03' 30"

43°

31'30"

0 2000 FEET 1000

0 500 METERS 250

THALWEG—A line connecting the lowest points along the length of a streambedAPPROXIMATE BOUNDARY OF TOP OF BANKARMORED SURFACE PARTICLE-SAMPLING  SITE AND IDENTIFICATION—Particle analyses is shown in table 1 and appendix 1

B

Base from Bureau of Reclamationaerial photographs, written commun., 2001.

Pioneer weir and

canal diversion

structures

AB

AC

B

A

D

E

C

F

G

H I J

K

L

M

N

O

P

Q

R

U

V

T

W

S

X

AD

Figure 1–1. Location of armored-surface layer particle-sampling sites and constrictions on the Big Lost River upstream from Pioneer diversion structures, Idaho National Engineering and 

Environmental Laboratory, Idaho.

90 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 1  91

Site:

Date:

Measurement by:

Remarks:

20 21 4 12 23 d 90 = 30.0 mm

10 14 18 18 10 d 84.1 = 27.3 mm

37 31 23 17 7 d 65 = 20.3 mm

16 28 5 9 14 d 50 = 16.7 mm

20 14 21 4 8 d 35 = 12.5 mm

30 26 10 11 17 d 15.9 = 8.42 mm

28 16 30 26 24 dg = 15.2 mm

26 29 34 27 8 Vg = 1.80 mm

25 19 27 12 15 G = 0.95

22 6 14 11 14

24 37 6 19 10

11 17 20 30 5

18 22 7 7 10

24 12 8 4 10

10 14 27 17 20

5 32 35 6 8

15 27 21 11 19

25 18 13 18 43

12 11 3 13 4

32 11 13 12 18

10' x 10' plot

Sampled gravel bar--near the left bank

August 22, 2000

Brennon Orr

DATA: Particle size (mm) Particle Characteristics

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

A

0

20

40

60

80

100

1 10 100

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean
Site:

Date:

Measurement by:

Remarks:

14 2 13 10 7 d 90 = 23.3 mm

20 22 15 7 21 d 84.1 = 21.4 mm

13 19 20 15 21 d 65 = 17.3 mm

14 23 14 7 4 d 50 = 14.2 mm

23 13 20 22 12 d 35 = 10.5 mm

4 8 12 19 14 d 15.9 = 7.24 mm

23 7 3 16 11 dg = 12.4 mm

17 19 5 23 22 Vg = 1.72 mm

25 14 21 17 13 G = 0.93

7 19 5 24 4

7 8 18 17 10

30 16 3 18 11

5 6 3 24 20

16 25 7 6 9

5 10 30 9 8

7 17 31 13 7

18 12 15 19 20

16 20 14 12 9

9 9 13 7 8

26 14 20 15 7

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

B

August 22, 2000

Jay T. Brown

DATA: Particle size (mm) Particle Characteristics

10' x 10' plot in center of channel

Near Trench Site #3

0

20

40

60

80

100

1 10 100

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean

92  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 1  93

Site:

Date:

Measurement by:

Remarks:

23 14 17 13 4 d 90 = 29.0 mm

14 14 10 8 8 d 84.1 = 24.5 mm

15 17 15 43 21 d 65 = 17.7 mm

21 6 11 33 9 d 50 = 13.9 mm

17 9 22 22 29 d 35 = 10.4 mm

13 7 27 19 14 d 15.9 = 7.52 mm

37 5 13 16 8 dg = 13.6 mm

25 21 10 30 88 Vg = 1.80 mm

5 14 10 17 36 G = 0.95

7 15 7 25 10

39 5 7 18 22

10 9 28 3 23

7 19 3 8 3

22 10 26 13 20

8 9 10 17 22

10 18 21 12 14

10 11 11 59 5

9 15 23 4 22

12 8 8 7 13

7 5 29 3 44

10' x 10' plot in center of channel

Poorly to moderately cemented particles

50% limestone and 50% basalt/tuff

August 22, 2000

Brian Twining

DATA: Particle size (mm) Particle Characteristics

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

C

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean

0

20

40

60

80

100

1 10 100

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph
Site:

Date:

Measurement by:

Remarks:

20 10 27 26 28 d 90 = 40.5 mm

9 3 23 13 37 d 84.1 = 33.2 mm

22 26 12 51 29 d 65 = 25.3 mm

19 5 23 26 28 d 50 = 20.1 mm

14 20 25 11 11 d 35 = 12.9 mm

4 19 12 43 3 d 15.9 = 8.24 mm

6 44 34 20 8 dg = 16.5 mm

11 38 8 7 12 Vg = 2.01 mm

24 3 19 11 31 G = 1.00

8 16 38 22 48

20 2 44 48 14

21 4 32 31 28

7 31 29 8 24

30 14 10 19 9

20 8 18 26 23

5 13 9 38 19

9 7 24 19 44

32 18 28 11 38

35 24 8 6 29

6 44 30 8 43

10' x 10' plot in center of channel

Mostly sub- to well-rounded rocks in a cemented matrix

August 22, 2000

Brian Twining

DATA: Particle size (mm) Particle Characteristics

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

D

0

20

40

60

80

100

1 10 100

Particle size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean

94  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 1  95

Site:

Date:

Measurement by:

Remarks:

46 43 17 27 40 d 90 = 45.4 mm

13 31 8 15 15 d 84.1 = 40.2 mm

13 27 24 8 22 d 65 = 27.5 mm

17 13 10 19 17 d 50 = 21.9 mm

27 27 8 8 8 d 35 = 17.8 mm

18 23 20 28 14 d 15.9 = 12.7 mm

17 29 52 21 36 dg = 22.6 mm

27 25 24 16 52 Vg = 1.78 mm

38 7 15 34 53 G = 0.90

11 19 17 18 7

40 21 11 29 17

5 21 13 45 8

33 30 26 20 23

18 12 38 105 30

21 40 22 57 34

45 52 13 10 18

16 57 22 8 32

16 9 13 38 30

35 47 19 45 18

42 25 24 26 16

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

E

August 22, 2000

Brennon Orr

DATA: Particle size (mm) Particle Characteristics

10' x 10' plot in center of channel

50% limestone, 47% basalt, 2% granite, 1% quartz

0

20

40

60

80

100

1 10 100 1000

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean
Site:

Date:

Measurement by:

Remarks:

8 3 34 28 21 d 90 = 44.1 mm

17 10 18 28 28 d 84.1 = 38.5 mm

10 15 21 12 14 d 65 = 30.1 mm

25 4 9 8 24 d 50 = 25.4 mm

7 14 12 52 75 d 35 = 19.8 mm

20 30 37 32 46 d 15.9 = 11.4 mm

51 30 29 30 28 dg = 20.9 mm

20 48 38 18 7 Vg = 1.84 mm

25 42 36 17 46 G = 1.00

21 23 22 27 37

24 27 32 25 42

18 14 42 30 24

32 57 32 26 29

50 44 42 15 10

13 11 11 45 18

30 37 28 40 25

8 48 7 17 29

22 30 10 17 34

23 7 32 14 27

4 20 36 14 30

10' x 10' plot in center of channel

40% Limestone, 40% ??, 20% basalt

August 22, 2000

Brennon Orr

DATA: Particle size (mm) Particle Characteristics

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

F

0

20

40

60

80

100

1 10 100

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean

96  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 1  97

Site:

Date:

Measurement by:

Remarks:

40 27 30 31 21 d 90 = 56.1 mm

29 9 22 55 9 d 84.1 = 52.4 mm

11 64 32 52 6 d 65 = 40.7 mm

54 61 56 48 46 d 50 = 32.5 mm

38 48 33 42 27 d 35 = 23.7 mm

16 16 48 3 34 d 15.9 = 11.9 mm

9 47 33 31 61 dg = 25.0 mm

18 30 8 22 58 Vg = 2.10 mm

31 48 13 37 11 G = 1.00

23 42 42 69 33

24 8 32 16 58

12 11 16 21 33

40 34 59 32 43

52 39 38 14 53

14 41 52 23 12

59 11 31 51 45

17 28 23 47 8

6 86 57 42 53

33 48 12 33 27

7 23 8 46 6

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

G

August 22, 2000

Brian Twining

DATA: Particle size (mm) Particle Characteristics

10' x 10' plot in center of channel

Well cemented, large cobbles, well and sub-rounded sediment

0

20

40

60

80

100

1 10 100

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean
Site:

Date:

Measurement by:

Remarks:

22 42 37 39 16 d 90 = 91.1 mm

195 45 71 47 84 d 84.1 = 80.3 mm

96 40 46 102 37 d 65 = 61.3 mm

44 16 17 41 143 d 50 = 47.2 mm

17 53 58 59 38 d 35 = 38.8 mm

70 26 63 157 31 d 15.9 = 16.9 mm

90 67 11 48 38 dg = 36.8 mm

18 53 49 29 72 Vg = 2.18 mm

65 7 52 110 39 G = 1.10

64 67 67 69 92

59 12 81 79 16

67 12 57 42 75

9 14 81 11 20

77 91 42 28 79

40 14 37 76 34

65 16 3 99 7

70 149 47 20 52

34 19 42 47 81

18 57 8 56 61

99 42 61 42 15

10' x 10' plot in center of channel

Particles are somewhat cemented

August 22, 2000

Jay T. Brown

DATA: Particle size (mm) Particle Characteristics

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

H

0

20

40

60

80

100

1 10 100 1000

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean

98  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 1  99

Site:

Date:

Measurement by:

Remarks:

30 32 33 20 14 d 90 = 53.1 mm

43 19 16 12 16 d 84.1 = 48.2 mm

3 14 15 3 18 d 65 = 27.4 mm

14 27 55 119 17 d 50 = 19.5 mm

37 5 18 12 8 d 35 = 14.8 mm

27 8 11 14 52 d 15.9 = 8.38 mm

40 42 15 71 29 dg = 20.1 mm

8 46 62 24 5 Vg = 2.40 mm

35 50 29 48 12 G = 1.10

6 6 17 6 48

7 109 20 8 9

45 28 27 22 59

35 26 12 6 54

3 8 7 21 17

15 5 26 29 16

20 67 20 68 51

16 22 13 14 24

8 48 14 8 5

53 12 17 69 9

21 22 11 33 33

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

I

August 22, 2000

Jay T. Brown

DATA: Particle size (mm) Particle Characteristics

10' x 10' plot in center of channel

0

20

40

60

80

100

1 10 100 1000

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean
Site:

Date:

Measurement by:

Remarks:

16 7 4 8 7 d 90 = 11.0 mm

2 7 6 11 4 d 84.1 = 9.20 mm

3 3 6 5 4 d 65 = 7.34 mm

5 5 8 6 9 d 50 = 6.21 mm

3 2 4 9 13 d 35 = 5.11 mm

7 4 5 5 7 d 15.9 = 3.87 mm

8 7 8 10 7 dg = 5.97 mm

42 4 7 5 6 Vg = 1.54 mm

7 4 4 8 7 G = 0.88

6 3 3 4 7

3 3 3 7 8

6 3 4 7 4

5 7 2 5 5

6 14 4 11 5

2 6 6 15 6

1 7 7 6 5

3 4 23 11 4

5 5 12 9 11

7 9 4 9 9

4 2 3 7 5

10' x 10' plot in center of channel

August 22, 2000

Brennon Orr

DATA: Particle size (mm) Particle Characteristics

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

J

0

20

40

60

80

100

1 10 100

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean

100 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 1 101

Site:

Date:

Measurement by:

Remarks:

47 9 7 8 32 d 90 = 32.5 mm

13 1 7 4 4 d 84.1 = 24.2 mm

3 9 23 7 10 d 65 = 11.7 mm

6 7 19 9 14 d 50 = 9.71 mm

79 7 17 9 7 d 35 = 7.61 mm

4 40 23 4 17 d 15.9 = 4.65 mm

9 5 4 5 10 dg = 10.6 mm

30 3 2 12 6 Vg = 2.28 mm

4 1 11 6 8 G = 1.07

12 8 2 5 11

10 22 8 6 3

4 10 10 15 27

2 12 26 12 6

11 32 4 23 22

10 14 9 6 50

33 4 11 11 11

7 9 46 10 3

10 8 42 7 58

7 9 6 9 17

13 4 16 50 73

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

K

August 22, 2000

Jay T. Brown

DATA: Particle size (mm) Particle Characteristics

10' x 10' plot in center of channel

0

20

40

60

80

100

1 10 100

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

35

     

Logarithm of Particle Size

Number of Particles

Mean
Site:

Date:

Measurement by:

Remarks:

20 42 35 35 80 d 90 = 47.3 mm

20 65 40 56 17 d 84.1 = 44.3 mm

32 9 36 34 44 d 65 = 35.3 mm

22 35 25 37 25 d 50 = 30.7 mm

27 25 50 34 7 d 35 = 26.8 mm

26 20 42 26 30 d 15.9 = 20.5 mm

22 9 24 31 22 dg = 30.1 mm

30 40 14 45 22 Vg = 1.47 mm

35 44 29 29 44 G = 0.90

24 12 25 19 64

55 15 40 47 62

45 40 62 32 19

29 33 36 45 5

22 36 30 55 7

16 24 38 28 42

39 27 32 34 16

33 24 23 25 30

35 34 27 52 12

30 14 32 39 30

28 30 44 30 29

10' x 10' plot in center of channel

Moderately cemented

August 22, 2000

Brennon Orr

DATA: Particle size (mm) Particle Characteristics

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

L

0

20

40

60

80

100

1 10 100

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean

102  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 1 103

Site:

Date:

Measurement by:

Remarks:

46 58 18 15 22 d 90 = 53.6 mm

11 25 12 41 27 d 84.1 = 45.6 mm

36 36 13 37 45 d 65 = 36.1 mm

33 19 63 44 35 d 50 = 30.7 mm

13 31 27 32 36 d 35 = 26.2 mm

38 12 65 50 36 d 15.9 = 18.4 mm

95 44 14 52 24 dg = 29.0 mm

60 56 25 30 28 Vg = 1.57 mm

16 32 30 21 18 G = 0.90

8 27 34 40 40

16 38 26 32 30

52 42 40 29 20

75 42 28 22 30

72 68 32 21 22

14 50 40 28 42

55 32 32 26 38

16 17 26 32 28

32 45 30 18 26

35 25 20 25 20

18 16 24 46 22

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

M

August 22, 2000

Brennon Orr

DATA: Particle size (mm) Particle Characteristics

10' x 10' plot in center of channel

0

20

40

60

80

100

1 10 100

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean
Site:

Date:

Measurement by:

Remarks:

12 47 6 24 22 d 90 = 68.0 mm

44 43 9 39 23 d 84.1 = 55.5 mm

16 57 14 11 68 d 65 = 41.7 mm

8 10 6 74 16 d 50 = 25.5 mm

240 17 14 40 8 d 35 = 15.4 mm

9 52 30 18 11 d 15.9 = 9.95 mm

27 35 31 55 67 dg = 23.5 mm

15 44 11 10 47 Vg = 2.36 mm

90 13 12 46 9 G = 1.10

52 24 74 31 14

32 4 15 45 11

9 66 68 48 83

5 51 66 36 9

7 69 17 10 12

5 5 57 53 17

31 47 19 43 30

16 40 7 116 46

9 51 30 12 41

43 15 140 25 43

13 25 15 79 14

10' x 10' plot in center of channel

August 22, 2000

Jay T. Brown

DATA: Particle size (mm) Particle Characteristics

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

N

0

20

40

60

80

100

1 10 100 1000

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean

104  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 1 105

Site:

Date:

Measurement by:

Remarks:

59 30 12 29 31 d 90 = 59.2 mm

54 10 17 4 27 d 84.1 = 54.1 mm

28 29 19 37 6 d 65 = 27.2 mm

35 24 24 67 83 d 50 = 19.7 mm

27 17 73 19 18 d 35 = 15.9 mm

17 5 22 9 5 d 15.9 = 8.53 mm

48 16 55 5 58 dg = 21.5 mm

52 19 43 19 12 Vg = 2.52 mm

10 28 9 21 56 G = 1.10

18 4 74 63 47

8 25 15 14 76

17 3 8 69 5

16 19 9 8 3

5 24 13 17 16

57 61 20 15 50

7 8 21 21 23

49 12 7 19 10

34 21 26 22 9

12 86 15 48 75

2 42 54 11 8

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

O

August 22, 2000

Jay T. Brown

DATA: Particle size (mm) Particle Characteristics

10' x 10' plot in center of channel

0

20

40

60

80

100

1 10 100

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean
Site:

Date:

Measurement by:

Remarks:

63 5 90 38 47 d 90 = 63.0 mm

12 64 38 15 19 d 84.1 = 47.1 mm

5 6 12 7 23 d 65 = 29.5 mm

20 4 4 9 11 d 50 = 18.0 mm

17 7 5 79 46 d 35 = 11.3 mm

7 6 5 25 15 d 15.9 = 5.96 mm

10 43 67 11 5 dg = 16.8 mm

14 63 4 56 7 Vg = 2.81 mm

11 8 32 17 9 G = 1.20

75 29 20 19 14

5 6 70 41 7

44 8 29 39 22

50 12 42 47 4

5 11 64 64 23

48 36 3 34 2

15 4 41 67 4

46 6 26 43 25

23 40 12 9 19

4 16 11 61 17

34 8 40 8 23

10' x 10' plot in center of channel

August 23, 2000

Jay T. Brown

DATA: Particle size (mm) Particle Characteristics

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

P

0

20

40

60

80

100

1 10 100

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean

106  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 1 107

Site:

Date:

Measurement by:

Remarks:

21 29 37 63 25 d 90 = 64.1 mm

32 39 32 50 67 d 84.1 = 55.3 mm

29 15 55 26 11 d 65 = 37.7 mm

10 55 38 53 10 d 50 = 29.6 mm

31 40 25 21 40 d 35 = 20.6 mm

8 75 40 4 12 d 15.9 = 11.6 mm

51 12 35 35 7 dg = 25.3 mm

44 15 70 16 35 Vg = 2.18 mm

40 22 15 20 19 G = 1.10

4 41 65 17 27

29 37 15 38 123

29 55 70 26 6

63 6 12 21 34

13 50 45 5 8

34 26 34 18 15

75 12 7 69 40

7 31 73 50 17

48 22 11 11 60

13 10 77 10 36

30 40 22 58 14

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

Q

August 23, 2000

Charles Berenbrock

DATA: Particle size (mm) Particle Characteristics

10' x 10' plot in center of channel

0

20

40

60

80

100

1 10 100 1000

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean
Site:

Date:

Measurement by:

Remarks:

49 32 9 21 34 d 90 = 51.3 mm

10 23 15 11 19 d 84.1 = 48.1 mm

20 25 34 79 25 d 65 = 34.4 mm

8 31 20 54 40 d 50 = 25.9 mm

35 40 46 27 50 d 35 = 20.9 mm

34 9 26 40 67 d 15.9 = 12.4 mm

65 18 15 47 79 dg = 24.4 mm

15 11 28 8 62 Vg = 1.97 mm

40 47 60 5 23 G = 1.00

8 18 35 29 19

25 11 16 20 30

4 4 47 23 39

30 30 23 27 16

25 44 47 21 23

12 9 62 40 36

21 14 8 16 23

50 45 50 37 17

22 4 28 33 32

13 21 59 17 44

17 51 37 58 12

10' x 10' plot in center of channel

August 23, 2000

Charles Berenbrock

DATA: Particle size (mm) Particle Characteristics

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

R

0

20

40

60

80

100

1 10 100

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean

108  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 1 109

Site:

Date:

Measurement by:

Remarks:

8 20 4 8 7 d 90 = 48.1 mm

13 50 38 36 43 d 84.1 = 38.8 mm

4 5 13 21 18 d 65 = 22.1 mm

17 26 11 11 48 d 50 = 18.2 mm

8 7 10 21 12 d 35 = 13.2 mm

56 3 13 56 18 d 15.9 = 8.61 mm

21 61 8 24 23 dg = 18.3 mm

21 14 12 20 16 Vg = 2.12 mm

51 48 11 14 18 G = 1.00

6 47 9 38 22

3 21 10 13 26

11 6 21 11 20

22 13 8 9 24

32 22 59 15 21

18 31 39 24 30

41 14 34 22 2

38 5 13 20 14

6 8 11 12 50

48 51 33 10 11

13 36 17 13 46

10' x 10' plot in center of channel

Big Lost River below the INEEL Diversion Dam

DATA: Particle size (mm) Particle Characteristics

PARTICLE COUNTS

Well cemented pebbles and cobbles. Consist mostly of limestone (60%-70%)

with 8%-15% basalt, 10%-15% breccia, 10% quartz, and 10% other

S

August 23, 2000

Brian Twining

0

20

40

60

80

100

1 10 100

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean
Site:

Date:

Measurement by:

Remarks:

26 41 12 43 13 d 90 = 55.1 mm

29 6 51 51 54 d 84.1 = 50.3 mm

30 31 14 9 23 d 65 = 38.2 mm

14 7 48 41 14 d 50 = 29.2 mm

18 8 23 38 21 d 35 = 22.5 mm

56 23 21 53 32 d 15.9 = 14.8 mm

18 19 4 72 53 dg = 27.3 mm

12 17 12 22 40 Vg = 1.84 mm

57 16 54 20 36 G = 1.00

36 61 16 41 8

31 22 40 40 74

6 50 23 11 41

9 37 26 46 39

18 22 64 32 23

29 14 33 33 56

41 43 19 27 43

28 22 9 49 81

31 23 47 38 18

26 20 29 22 21

28 31 58 40 72

narrow chute of gravel between bedrock. Not representative of channel.

Losely consolidated pebbles and cobbles. Mostly limestone (50%-65%),

quartzite (10%-20%), basalt (10%-15%), breccia (10%), and other (10%)

August 23, 2000

Brian Twining

DATA: Particle size (mm) Particle Characteristics

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam; 10'x10' plot. Sampled a

T

0

20

40

60

80

100

1 10 100

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean

110 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 1 111

Site:

Date:

Measurement by:

Remarks:

31 81 8 77 21 d 90 = 74.1 mm

42 51 96 44 16 d 84.1 = 66.1 mm

47 9 4 33 34 d 65 = 53.1 mm

47 81 51 43 42 d 50 = 44.7 mm

42 64 67 62 98 d 35 = 35.6 mm

16 49 61 35 51 d 15.9 = 16.9 mm

54 53 17 53 61 dg = 33.4 mm

53 114 35 21 10 Vg = 1.98 mm

27 37 64 29 34 G = 1.00

58 50 89 85 41

39 52 43 25 21

55 13 52 46 65

60 22 26 32 53

11 55 66 37 9

77 53 69 10 66

52 44 30 45 52

14 18 74 34 61

63 38 8 4 38

51 7 28 16 12

75 57 66 39 68

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

U

August 23, 2000

Jay T. Brown

DATA: Particle size (mm) Particle Characteristics

10' x 10' plot

Sampled gravel bar

0

20

40

60

80

100

1 10 100 1000

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

35

     

Logarithm of Particle Size

Number of Particles

Mean
Site:

Date:

Measurement by:

Remarks:

77 22 22 44 16 d 90 = 43.1 mm

32 13 9 46 5 d 84.1 = 39.2 mm

8 9 46 26 32 d 65 = 30.7 mm

19 26 42 60 36 d 50 = 24.5 mm

27 29 9 11 6 d 35 = 18.4 mm

35 17 31 14 30 d 15.9 = 11.2 mm

12 36 36 40 7 dg = 21.0 mm

9 15 57 40 25 Vg = 1.87 mm

37 13 33 42 37 G = 1.00

25 30 19 8 26

20 11 24 17 47

24 24 27 5 10

57 37 17 29 34

36 14 38 15 22

17 2 15 32 27

11 35 16 25 25

40 4 19 7 9

23 38 40 54 21

22 57 16 34 22

16 17 13 33 20

10' x 10' plot in center of channel

August 24, 2000

Jay T. Brown

DATA: Particle size (mm) Particle Characteristics

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

V

0

20

40

60

80

100

1 10 100

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean

112  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 1 113

Site:

Date:

Measurement by:

Remarks:

65 48 38 65 17 d 90 = 67.1 mm

62 40 26 37 6 d 84.1 = 62.8 mm

65 42 12 9 43 d 65 = 46.7 mm

21 10 12 55 33 d 50 = 39.5 mm

7 27 44 17 43 d 35 = 22.1 mm

44 35 9 77 68 d 15.9 = 9.78 mm

48 50 16 7 18 dg = 24.8 mm

20 55 45 3 49 Vg = 2.53 mm

70 55 27 4 4 G = 1.20

80 34 18 69 40

18 16 56 50 3

5 86 49 21 51

38 47 60 45 29

50 7 40 12 95

42 53 45 55 56

33 17 23 9 55

45 36 21 67 43

9 18 25 80 2

65 9 45 20 73

20 73 8 9 66

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

W

August 24, 2000

Charles Berenbrock

DATA: Particle size (mm) Particle Characteristics

10' x 10' plot in center of channel

0

20

40

60

80

100

1 10 100

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean
Site:

Date:

Measurement by:

Remarks:

14 37 88 56 46 d 90 = 67.2 mm

13 35 50 61 32 d 84.1 = 62.1 mm

108 24 15 20 12 d 65 = 46.2 mm

56 74 19 57 54 d 50 = 36.5 mm

11 17 14 42 19 d 35 = 26.5 mm

55 39 12 47 53 d 15.9 = 17.2 mm

43 25 11 34 23 dg = 32.7 mm

72 17 22 70 37 Vg = 1.90 mm

64 76 52 71 79 G = 1.00

44 37 16 15 33

62 34 5 52 47

27 46 26 20 39

63 60 27 30 34

80 48 62 37 9

18 53 4 64 26

24 19 36 29 44

57 38 47 23 14

30 62 13 17 27

25 26 75 62 43

27 21 42 41 24

10' x 10' plot in center of channel

August 24, 2000

Jay T. Brown

DATA: Particle size (mm) Particle Characteristics

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

X

0

20

40

60

80

100

1 10 100 1000

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean

114  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 1 115

Site:

Date:

Measurement by:

Remarks:

5 7 6 5 7 d 90 = 12.7 mm

7 9 10 7 11 d 84.1 = 11.9 mm

5 2 11 8 8 d 65 = 9.69 mm

8 7 13 12 8 d 50 = 8.88 mm

6 17 8 9 7 d 35 = 7.78 mm

9 9 7 10 4 d 15.9 = 6.41 mm

9 5 17 11 9 dg = 8.73 mm

3 7 9 6 6 Vg = 1.36 mm

7 9 12 12 8 G = 0.83

10 14 11 8 6

11 8 9 10 7

7 9 13 9 10

4 16 8 7 11

7 8 9 8 8

11 6 7 7 12

6 14 7 9 16

6 6 10 5 9

12 19 12 9 10

8 9 4 9 12

6 4 6 9 9

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

Y

September 21, 2000

Jay T. Brown

DATA: Particle size (mm) Particle Characteristics

10' x 10' plot in center of channel

0

20

40

60

80

100

1 10 100

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean
Site:

Date:

Measurement by:

Remarks:

44 47 42 24 62 d 90 = 77.1 mm

27 14 19 15 14 d 84.1 = 65.1 mm

30 58 9 82 60 d 65 = 50.2 mm

41 10 90 78 55 d 50 = 43.2 mm

45 58 86 43 47 d 35 = 29.6 mm

77 37 74 19 15 d 15.9 = 14.7 mm

67 35 62 27 54 dg = 30.9 mm

38 19 60 14 67 Vg = 2.10 mm

36 12 7 19 36 G = 1.10

49 36 59 55 35

44 14 52 9 50

82 54 16 10 48

12 9 17 48 87

57 23 12 14 43

92 83 20 67 45

40 52 31 6 75

51 11 47 53 37

29 56 58 45 94

50 37 26 44 6

48 17 28 16 110

10' x 10' plot in center of channel

September 21, 2000

Jay T. Brown

DATA: Particle size (mm) Particle Characteristics

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

Z

0

20

40

60

80

100

1 10 100 1000

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean

116  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 1 117

Site:

Date:

Measurement by:

Remarks:

42 27 29 16 11 d 90 = 82.1 mm

50 53 56 53 83 d 84.1 = 77.5 mm

26 58 87 67 19 d 65 = 58.7 mm

87 65 51 60 10 d 50 = 48.7 mm

68 55 25 27 15 d 35 = 34.3 mm

41 70 62 77 83 d 15.9 = 16.7 mm

74 82 46 72 122 dg = 36.0 mm

57 35 55 80 105 Vg = 2.15 mm

48 81 76 34 79 G = 1.10

57 79 66 37 87

85 13 60 25 35

40 29 9 13 15

45 24 47 73 52

34 32 14 14 108

48 27 48 12 27

42 27 32 172 50

14 60 47 26 30

15 80 60 8 76

17 62 67 47 12

22 64 51 8 48

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

AA

September 21, 2000

Jay T. Brown

DATA: Particle size (mm) Particle Characteristics

10' x 10' plot in center of channel

0

20

40

60

80

100

1 10 100 1000

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean
118  Report Title

Site:

Date:

Measurement by:

Remarks:

12 17 17 10 22 d 90 = 31.1 mm

14 16 20 16 11 d 84.1 = 26.3 mm

17 11 7 29 19 d 65 = 21.9 mm

25 8 17 9 14 d 50 = 17.6 mm

3 37 22 16 21 d 35 = 14.7 mm

34 22 25 16 25 d 15.9 = 10.1 mm

35 34 12 10 15 dg = 16.3 mm

22 17 22 19 30 Vg = 1.61 mm

2 19 10 24 16 G = 0.90

23 10 9 21 27

8 9 10 17 8

10 31 8 9 36

16 15 32 25 20

14 29 35 23 7

25 19 3 18 22

29 24 26 14 14

13 8 21 13 42

21 9 13 21 23

13 23 15 17 11

10 18 22 34 34

10' x 10' plot in center of channel

September 22, 2000

Jay T. Brown

DATA: Particle size (mm) Particle Characteristics

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

AB

0

20

40

60

80

100

1 10 100

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean
Appendix 1 119

Site:

Date:

Measurement by:

Remarks:

13 30 11 25 11 d 90 = 38.1 mm

35 38 10 6 25 d 84.1 = 34.3 mm

85 37 13 24 16 d 65 = 24.6 mm

24 5 17 10 4 d 50 = 20.2 mm

34 6 12 17 16 d 35 = 16.2 mm

14 50 20 21 31 d 15.9 = 10.9 mm

45 27 29 29 16 dg = 19.3 mm

37 29 13 12 18 Vg = 1.77 mm

22 42 25 26 20 G = 0.94

16 9 29 19 10

14 16 12 15 8

10 16 23 22 32

31 18 27 10 5

23 12 9 24 11

14 32 21 41 47

42 16 23 14 24

23 42 14 23 16

38 22 12 25 37

7 41 21 29 8

17 36 16 8 19

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

AC

September 22, 2000

Jay T. Brown

DATA: Particle size (mm) Particle Characteristics

10' x 10' plot in center of channel

0

20

40

60

80

100

1 10 100

Particle Size (mm)

Percent Finer

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean
Site:

Date:

Measurement by:

Remarks:

22 4 20 60 12 d 90 = 59.5 mm

44 68 40 59 72 d 84.1 = 50.3 mm

7 48 34 4 21 d 65 = 26.8 mm

22 5 18 24 32 d 50 = 22.2 mm

7 20 51 9 28 d 35 = 15.6 mm

3 7 11 56 17 d 15.9 = 5.67 mm

24 27 24 1 26 dg = 16.9 mm

60 10 23 26 10 Vg = 2.98 mm

3 40 3 5 23 G = 1.2

20 24 26 75 18

46 56 17 9 68

36 5 35 18 61

24 6 50 78 28

22 20 15 4 8

7 21 39 23 46

59 3 12 18 20

3 27 64 4 41

1 39 26 16 52

6 5 2 8 3

24 12 35 65 14

4' x 25' plot -- across entire channel

June 21, 2001

Charles Berenbrock

DATA: Particle size (mm) Particle Characteristics

PARTICLE COUNTS

Big Lost River below the INEEL Diversion Dam

AD

0

20

40

60

80

100

1 10 100

Cumulative Semilogarithmic Size-Frequency Graph

Histogram

0

5

10

15

20

25

30

     

Logarithm of Particle Size

Number of Particles

Mean

120 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 2  121

Appendix 2 

Sieve Analyses of Trench Samples from Sites 1, 2, 3, 4, and 5 on the Big 

Lost River Upstream of the Pioneer Diversion Structures, Idaho National 

Engineering and Environmental Laboratory
Figure 2–1. Lithology of selected trenches at site 1, Big Lost River, Idaho National Engineering and Environmental Laboratory, Idaho.

113° 03 113° 03' 25" ' 30"

43°

31'

40"

43°

31'

35"

113° 03' 35"

0 100 200 FEET

0 25 50 METERS EXPLANATION

TRENCH LITHOLOGY

 Very fine to very coarse sand

 Silty sand

 Sand, granule, and cobbles

 Sand, granule, cobbles, and boulders

 Basalt bedrock

T-1-D

TRENCH PARTICLE-SAMPLING SITE

 AND IDENTIFICATION—T, transverse; L,

 lateral; M, meander. Particle analyses

 are shown in table 1 and appendix 1

APPROXIMATE BOUNDARY OF TOP

 OF BANK

0

1

2

3

4

5

6

7

8

9

10

11

12

DEPTH

IN FEET

L-1-B

MT-1-C

T-1-E

ML-1-A

MT-1-B

MT-1-A

T-1-F

T-1-D

T-1-C

L-1-F

T-1-A L-1-D

L-1-C

L-1-E

L-1-A

T-1-B

Site 1 

constriction

Base from Bureau of Reclamation

aerial photographs, written commun., 2001.

122  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 2  

123

Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 30362.1 g 512Tare weight: 1359.5 g 256 0.0 0.00 100.00

Net weight: 29002.6 g 64 1990.7 25.63 74.37

32 1262.1 16.25 58.12

Gravel weight: 5794.1 g 16 1216.8 15.67 42.45

Sand weight: 1941.4 g 8 831.6 10.71 31.75

4 492.9 6.35 25.40

Portion analyzed: 7773.9 g 2 464.7 5.98 19.42

1 425.6 5.48 13.94

Remarks: 0.5 391.2 5.04 8.90

0.25 423.1 5.45 3.46

0.125 182.1 2.34 1.11

0.0625 54.7 0.70 0.41

<0.0625 31.6 0.41 0.00

TOTAL 7767.1

d 90 = 149 mm

d 84.1 = 108 mmd 65 = 42.9 mmd 50 = 22.3 mmd 35 = 9.87 mmd 15.9 = 1.28 mmd g = 11.8 mm

V g = 9.19 mm

G = 2.36

Particle Characteristics

Remarks

Poorly sorted sand to cobble-size sediment.

45% consolidated sediment75% consolidated sediment

BVT, AJWDecember 19, 2000Sediments collected during trenching ofthe Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

SIEVE ANALYSIS

L-1-A1Big Lost River (INEEL)August 25, 2000~1/4 of sample analyzed, used splitter.

Cobble

Pebble

Very fine sand

Silt & clays

4968

Size

Class

Boulders

No of Particles0>100

30% consolidated sediment

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100 1000

Sediment size (mm)

Percent Finer
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 28118.4 g 512Tare weight: 808.4 g 256

Net weight: 27310.0 g 64 0.0 0.00 100.00

32 1107.9 17.88 82.12

Gravel weight: 3751.9 g 16 1111.1 17.93 64.18

Sand weight: 2436.2 g 8 965.9 15.59 48.59

4 567.0 9.15 39.44

Portion analyzed: 6200.2 g 2 436.0 7.04 32.41

1 716.0 11.56 20.85

Remarks: 0.5 793.3 12.80 8.05

0.25 356.8 5.76 2.29

0.125 113.1 1.83 0.46

0.0625 21.0 0.34 0.12

<0.0625 7.6 0.12 0.00

TOTAL 6195.7

d 90 = 43.4 mm

d 84.1 = 34.6 mmd 65 = 16.5 mmd 50 = 8.52 mmd 35 = 2.58 mmd 15.9 = 0.76 mmd g = 5.13 mm

V g = 6.75 mm

G = 1.95

Particle Characteristics

Remarks

~1/4 of sample analyzed, used splitter.Poorly sorted sand to pebble-size sediment.

SIEVE ANALYSIS

L-1-B1Big Lost River (INEEL)August 25, 2000BVT, AJWDecember 19, 2000Sediments collected during trenching ofthe Big Lost River.

Cobble

Pebble

Very fine sand

Silt & clays

Medium sand

Fine sand

Very coarse sand

Size

Class

Boulders

Granule

Coarse sand

No. of Particles0965>100

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

124  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 2  

125

Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 28409.9 g 512Tare weight: 808.4 g 256

Net weight: 27601.5 g 64 0.0 0.00 100.00

32 2345.7 35.65 64.35

Gravel weight: 4880.5 g 16 1224.8 18.61 45.74

Sand weight: 1697.5 g 8 819.7 12.46 33.28

4 490.3 7.45 25.83

Portion analyzed: 6586.1 g 2 364.5 5.54 20.29

1 305.2 4.64 15.66

Remarks: 0.5 410.6 6.24 9.42

0.25 416.2 6.32 3.09

0.125 168.7 2.56 0.53

0.0625 32.3 0.49 0.04

<0.0625 2.5 0.04 0.00

TOTAL 6580.5

d 90 = 52.7 mm

d 84.1 = 47.0 mmd 65 = 32.4 mmd 50 = 18.7 mmd 35 = 8.80 mmd 15.9 = 1.04 mmd g = 6.99 mm

V g = 6.72 mm

G = 2.26

Particle Characteristics

Remarks

~1/4 of sample analyzed, used splitter.Poorly sorted sand to pebble-size sediment.

SIEVE ANALYSIS

L-1-C1Big Lost River (INEEL)August 25, 2000

Cobble

Pebble

Very fine sand

Silt & clays

Medium sand

Fine sand

Very coarse sand

Size

Class

Boulders

Granule

Coarse sand

BVT, AJWDecember 14, 2000Sediments collected during trenching ofthe Big Lost River.

No of Particles01887>100

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 5785.5 g 512Tare weight: 164.2 g 256

Net weight: 5621.3 g 64 0.0 0.00 100.00

32 743.0 13.22 86.78

Gravel weight: 3380.1 g 16 1212.0 21.56 65.22Sand weight: 2183.9 g 8 839.0 14.93 50.29

4 586.1 10.43 39.87

Portion analyzed: 5621.3 g 2 435.3 7.74 32.12

1 382.3 6.80 25.32

Remarks: 0.5 489.4 8.71 16.61

0.25 513.9 9.14 7.47

0.125 273.1 4.86 2.61

0.0625 89.9 1.60 1.01

<0.0625 57.0 1.01 0.00

TOTAL 5621.0

d 90 = 37.9 mm

d 84.1 = 29.4 mmd 65 = 15.8 mmd 50 = 7.85 mmd 35 = 2.59 mmd 15.9 = 0.47 mmd g = 3.73 mm

V g = 7.87 mm

G = 2.25

Particle Characteristics

Remarks

BVT, AJWDecember 4, 2000Sediments collected during trenching ofPoorly sorted sand to pebble-size sediment.

SIEVE ANALYSIS

L-1-D1BLR sedimentsAugust 25, 2000the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

Cobble

Pebble

Very fine sand

Silt & clays

0795

Size

Class

Boulders

No. of particles>100

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

126  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 2  

127

Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 1543.7 g 512Tare weight: 110.7 g 256

Net weight: 1433.0 g 64

32

Gravel weight: 2.0 g 16Sand weight: 1427.8 g 8 0.0 0.00 100.00

4 2.0 0.14 99.86

Portion analyzed: 1433.0 g 2 1.6 0.11 99.75

1 1.3 0.09 99.66

Remarks: 0.5 10.8 0.75 98.90

0.25 1169.3 81.60 17.30

0.125 213.7 14.91 2.39

0.0625 31.1 2.17 0.22

<0.0625 3.1 0.22 0.00

TOTAL 1432.9

d 90 = 0.46 mm

d 84.1 = 0.44 mmd 65 = 0.37 mmd 50 = 0.33 mmd 35 = 0.29 mmd 15.9 = 0.23 mmd g = 0.32 mm

V g = 1.37 mm

G = 0.83

No. of particles011

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWDecember 4, 2000Sediments collected during trenching of

SIEVE ANALYSIS

L-1-D2BLR sedimentsAugust 25, 2000Well-sorted coarse sand.

54>100

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10

Sediment size (mm)

Percent Finer
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 11256.9 g 512Tare weight: 275.1 g 256 0.0 0.00 100.00

Net weight: 10981.8 g 64 2348.0 21.38 78.62

32 1776.6 16.18 62.44

Gravel weight: 7232.9 g 16 1260.4 11.48 50.96

Sand weight: 3735.5 g 8 963.5 8.78 42.18

4 884.4 8.05 34.13

Portion analyzed: 10981.8 g 2 1025.7 9.34 24.79

1 1214.6 11.06 13.72

Remarks: 0.5 900.2 8.20 5.52

0.25 436.6 3.98 1.55

0.125 128.3 1.17 0.38

0.0625 30.1 0.27 0.11

<0.0625 11.6 0.11 0.00

TOTAL 10980.0

d 90 = 134 mm

d 84.1 = 91.3 mmd 65 = 35.7 mmd 50 = 14.8 mmd 35 = 4.31 mmd 15.9 = 1.15 mmd g = 10.2 mm

V g = 8.93 mm

G = 2.19

Particle Characteristics

Remarks

BVT, AJWDecember 4, 2000Sediments collected during trenching ofPoorly sorted sand to cobble-size sediment.

SIEVE ANALYSIS

L-1-D3BLR sedimentsAugust 25, 2000the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

Cobble

Pebble

Very fine sand

Silt & clays

41574

Size

Class

Boulders

No. of particles0>100

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100 1000

Sediment size (mm)

Percent Finer

128  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 2  

129

Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 221.9 g 512

Tare weight: 122.8 g 256Net weight: 99.1 g 64

32

Gravel weight: 1.1 g 16Sand weight: 88.8 g 8 0.0 0.00 100.00

4 1.1 1.11 98.89

Portion analyzed: 99.1 g 2 8.1 8.19 90.70

1 9.2 9.30 81.40

Remarks: 0.5 11.9 12.03 69.36

0.25 10.6 10.72 58.65

0.125 29.6 29.93 28.72

0.0625 19.4 19.62 9.10

<0.0625 9.0 9.10 0.00

TOTAL 98.9

d 90 = 1.90 mm

d 84.1 = 1.22 mmd 65 = 0.38 mmd 50 = 0.20 mmd 35 = 0.14 mmd 15.9 = 0.08 mmd g = 0.31 mm

V g = 3.92 mm

G = 1.46

No. of particles012

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWDecember 4, 2000Sediments collected during trenching of

SIEVE ANALYSIS

L-1-DC1BLR sedimentsAugust 25, 2000Fine sand to pebble-size sediment.

>100; 90% consol. clay85% consol. clay90% consol. clay

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10

Sediment size (mm)

Percent Finer
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 410.7 g 512

Tare weight: 122.8 g 256Net weight: 287.9 g 64

32

Gravel weight: 15.1 g 16

Sand weight: 232.4 g 8 0.0 0.00 100.00

4 15.1 5.26 94.74

Portion analyzed: 287.0 g 2 44.3 15.44 79.30

1 50.2 17.49 61.81

Remarks: 0.5 36.2 12.61 49.20

0.25 26.3 9.16 40.03

0.125 26.8 9.34 30.70

0.0625 48.6 16.93 13.76

<0.0625 39.5 13.76 0.00

TOTAL 287.0

d 90 = 3.23 mm

d 84.1 = 2.48 mmd 65 = 1.13 mmd 50 = 0.52 mmd 35 = 0.17 mmd 15.9 = 0.07 mmd g = 0.41 mm

V g = 6.03 mm

G = 1.76

Particle Characteristics

Remarks>100; 20% consol. clay90% consol. clay, silt85% consol. clay, silt

BVT, AJWDecember 4, 2000Sediments collected during trenching ofFine sand to pebble-size sediment.

SIEVE ANALYSIS

L-1-DC2BLR sedimentsAugust 25, 2000the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

Cobble

Pebble

Very fine sand

Silt & clays

No. of particles

Size

Class

Boulders

089; 25% consol. clay

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10

Sediment size (mm)

Percent Finer

130 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 2  

131

Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 169.9 g 512

Tare weight: 116.2 g 256Net weight: 53.7 g 64

32

Gravel weight: 9.2 g 16Sand weight: 42.6 g 8 0.0 0.00 100.00

4 9.2 17.23 82.77

Portion analyzed: 53.7 g 2 7.0 13.11 69.66

1 9.3 17.42 52.25

Remarks: 0.5 8.7 16.29 35.96

0.25 9.8 18.35 17.60

0.125 5.5 10.30 7.30

0.0625 2.3 4.31 3.00

<0.0625 1.6 3.00 0.00

TOTAL 53.4

d 90 = 5.35 mm

d 84.1 = 4.22 mmd 65 = 1.66 mmd 50 = 0.91 mmd 35 = 0.48 mmd 15.9 = 0.22 mmd g = 0.97 mm

V g = 4.35 mm

G = 1.48

No. of particles024

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWDecember 4, 2000Sediments collected during trenching of

SIEVE ANALYSIS

L-1-DC3BLR sedimentsAugust 25, 2000Poorly sorted fine sand to pebble-sizesediment.

>10060% consol. clay90% consol. clay

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10

Sediment size (mm)

Percent Finer
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 4336.7 g 512Tare weight: 113.8 g 256 0.0 0.00 100.00

Net weight: 4222.9 g 64 441.6 10.46 89.54

32 177.7 4.21 85.33

Gravel weight: 1489.2 g 16 228.5 5.41 79.92Sand weight: 2605.1 g 8 409.8 9.71 70.21

4 231.6 5.49 64.72

Portion analyzed: 4222.9 g 2 358.8 8.50 56.22

1 397.7 9.42 46.80

Remarks: 0.5 389.5 9.23 37.58

0.25 614.8 14.56 23.01

0.125 557.8 13.21 9.80

0.0625 286.5 6.79 3.01

<0.0625 127.2 3.01 0.00

TOTAL 4221.5

d 90 = 68 mm

d 84.1 = 27.3 mmd 65 = 4.14 mmd 50 = 1.27 mmd 35 = 0.44 mmd 15.9 = 0.17 mmd g = 2.15 mm

V g = 12.7 mm

G = 2.69

No of Particles011>100; 20% consol. sed60% consol. sediment20% consol. sediment60% consol. sediment

Size

Class

Boulders

Granule

Coarse sand

Cobble

Pebble

Very fine sand

Silt & clays

Medium sand

Fine sand

Very coarse sand

SIEVE ANALYSIS

L-1-E1Big Lost River (INEEL)August 25, 2000BVT, AJWDecember 14, 2000Sediments collected during trenching ofthe Big Lost River.

80% consol. sediment80% consol. sediment

Poorly sorted fine sand to cobble-sizesediment.

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100 1000

Sediment size (mm)

Percent Finer

132  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 2  

133

Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 1917.0 g 512Tare weight: 116.5 g 256

Net weight: 1800.5 g 64

32 0.0 0.00 100.00

Gravel weight: 38.0 g 16 12.8 1.47 98.53

Sand weight: 739.8 g 8 5.2 0.60 97.93

4 20.0 2.30 95.64

Portion analyzed: 871.9 g 2 107.3 12.32 83.32

1 170.0 19.51 63.81

Remarks: 0.5 149.7 17.18 46.63

0.25 110.1 12.64 33.99

0.125 76.7 8.80 25.18

0.0625 126.0 14.46 10.72

<0.0625 93.4 10.72 0.00

TOTAL 871.2

d 90 = 2.91 mm

d 84.1 = 2.09 mmd 65 = 1.04 mmd 50 = 0.57 mmd 35 = 0.26 mmd 15.9 = 0.08 mmd g = 0.41 mm

V g = 5.11 mm

G = 1.64

Particle Characteristics

Remarks

sediment.

95% consol. clay95% consol. clay & organics

BVT, AJWDecember 5, 2000Sediments collected during trenching ofthe Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

SIEVE ANALYSIS

MT-1-A1BLR sedimentsAugurst 26, 2000

Cobble

Pebble

Very fine sand

Silt & clays

Poorly sorted fine sand to pebble-size

No. of Particles01

Size

Class

Boulders

2162>100; 95% consol. clay

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 26458.0 g 512Tare weight: 340.5 g 256

Net weight: 26117.5 g 64

32 0.0 0.00 100.00

Gravel weight: 1759.2 g 16 347.9 5.15 94.85

Sand weight: 4966.0 g 8 707.0 10.47 84.38

4 704.3 10.43 73.95

Portion analyzed: 6758.3 g 2 653.7 9.68 64.27

1 557.6 8.26 56.01

Remarks: 0.5 685.1 10.14 45.87

0.25 2187.9 32.40 13.47

0.125 648.6 9.60 3.87

0.0625 233.1 3.45 0.42

<0.0625 28.2 0.42 0.00

TOTAL 6753.4

d 90 = 11.6 mm

d 84.1 = 7.85 mmd 65 = 2.11 mmd 50 = 0.66 mmd 35 = 0.4 mmd 15.9 = 0.26 mmd g = 1.43 mm

V g = 5.49 mm

G = 1.90

No of Particles035

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

~1/4 of sample analyzed, used splitter.sediment.

SIEVE ANALYSIS

MT-1-B1Big Lost River (INEEL)August 29, 2000

Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWDecember 12, 2000Sediments collected during trenching ofthe Big Lost River.Poorly sorted fine sand to pebble-size

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

134  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 2  

135

Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 1775.4 g 512Tare weight: 116.3 g 256

Net weight: 1659.1 g 64

32

Gravel weight: 27.7 g 16

Sand weight: 1569.1 g 8 0.0 0.00 100.00

4 27.7 1.68 98.32

Portion analyzed: 1659.1 g 2 60.8 3.68 94.64

1 62.3 3.77 90.87

Remarks: 0.5 72.5 4.39 86.48

0.25 478.9 28.99 57.50

0.125 629.1 38.08 19.42

0.0625 265.5 16.07 3.35

<0.0625 55.3 3.35 0.00

TOTAL 1652.1

d 90 = 0.87 mm

d 84.1 = 0.47 mmd 65 = 0.3 mmd 50 = 0.22 mmd 35 = 0.17 mmd 15.9 = 0.11 mmd g = 0.23 mm

V g = 2.07 mm

G = 1.02

Particle Characteristics

Remarks95% consol. clay & silt90% consol. clay & silt

Size

Class

Boulders

some pebbles present.

SIEVE ANALYSIS

MT-1-B2Big Lost River (INEEL)BVT, AJWSediments collected during trenching ofthe Big Lost River.Moderately sorted medium sand with 

Cobble

Pebble

Very fine sand

Silt & clays

Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

No. of Particles0>100; 95% consol clay & silt95% consol. clay & silt

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10

Sediment size (mm)

Percent Finer
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 27735.2 g 512Tare weight: 876.7 g 256

Net weight: 26858.5 g 64 0.0 0.00 100.00

32 2508.1 35.12 64.88

Gravel weight: 4244.1 g 16 1084.5 15.19 49.69

Sand weight: 2893.2 g 8 395.4 5.54 44.16

4 256.1 3.59 40.57

Portion analyzed: 7147.0 g 2 279.8 3.92 36.65

1 307.8 4.31 32.34

Remarks: 0.5 909.8 12.74 19.60

0.25 1098.0 15.38 4.23

0.125 230.6 3.23 1.00

0.0625 67.2 0.94 0.06

<0.0625 4.1 0.06 0.00

TOTAL 7141.4

sediment.

d 90 = 52.5 mm

d 84.1 = 46.8 mmd 65 = 32.1 mmd 50 = 16.2 mmd 35 = 1.53 mmd 15.9 = 0.42 mmd g = 4.43 mm

V g = 10.6 mm

G = 3.22

No of Particles01871; 40% consol. sediment>100; 40% consol. sediment40% consol. sediment40% consol. sediment

Size

Class

Boulders

~1/4 of sample analyzed, used splitter.

Cobble

Pebble

Very fine sand

Silt & clays

SIEVE ANALYSIS

MT-1-B3Big Lost River (INEEL)

Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWSediments collected during trenching ofthe Big Lost River.

45% consol. sediment

Poorly sorted sand to pebble-size

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

136  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 2  

137

Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 2540.1 g 512Tare weight: 113.2 g 256

Net weight: 2426.9 g 64

32

Gravel weight: 3.2 g 16Sand weight: 2403.1 g 8 0.0 0.00 100.00

4 3.2 0.13 99.87

Portion analyzed: 2462.9 g 2 4.8 0.20 99.67

1 13.3 0.55 99.12

Remarks: 0.5 36.9 1.52 97.60

0.25 1879.9 77.68 19.92

0.125 402.3 16.62 3.29

0.0625 65.9 2.72 0.57

<0.0625 13.8 0.57 0.00

TOTAL 2420.1

d 90 = 0.47 mm

d 84.1 = 0.44 mmd 65 = 0.37 mmd 50 = 0.33 mmd 35 = 0.29 mmd 15.9 = 0.21 mmd g = 0.30 mm

V g = 1.45 mm

G = 0.85

Particle Characteristics

Remarks20% consol. sediments40% consol. sediments

Well-sorted coarse sand. 

SIEVE ANALYSIS

T-1-A1Big Lost River (INEEL)August 25, 2000BVT, AJWDecember 14, 2000Sediments collected during trenching ofthe Big Lost River.

Cobble

Pebble

Very fine sand

Silt & clays

Medium sand

Fine sand

Very coarse sand

Size

Class

Boulders

Granule

Coarse sand

No. of Particles016>100

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10

Sediment size (mm)

Percent Finer
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 31475.7 g 512Tare weight: 876.8 g 256

Net weight: 30598.9 g 64 0.0 0.00 100.00

32 2133.8 28.84 71.16

Gravel weight: 4740.5 g 16 1423.2 19.24 51.92

Sand weight: 2625.1 g 8 678.3 9.17 42.75

4 505.2 6.83 35.92

Portion analyzed: 7402.1 g 2 479.3 6.48 29.45

1 375.3 5.07 24.37

Remarks: 0.5 605.5 8.18 16.19

0.25 788.5 10.66 5.53

0.125 312.6 4.23 1.30

0.0625 63.9 0.86 0.44

<0.0625 32.6 0.44 0.00

TOTAL 7398.2

d 90 = 50.3 mm

d 84.1 = 43.7 mmd 65 = 25.6 mmd 50 = 13.8 mmd 35 = 3.62 mmd 15.9 = 0.49 mmd g = 4.63 mm

V g = 9.44 mm

G = 2.80

No. of Particles01783>100

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

~1/4 of sample analyzed, used splitter.

SIEVE ANALYSIS

T-1-A2Big Lost River (INEEL)August 25, 2000

Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWDecember 14, 2000Sediments collected during trenching ofthe Big Lost River.Poorly sorted sand to pebble-size sediment.

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

138  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 2  

139

Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 5314.1 g 512Tare weight: 110.8 g 256 0.0 0.00 100.00

Net weight: 5203.3 g 64 1317.4 25.34 74.66

32 1417.9 27.28 47.38

Gravel weight: 4187.0 g 16 640.9 12.33 35.05Sand weight: 999.1 g 8 503.8 9.69 25.36

4 307.0 5.91 19.45

Portion analyzed: 5203.3 g 2 243.0 4.67 14.78

1 243.4 4.68 10.09

Remarks: 0.5 293.3 5.64 4.45

0.25 166.9 3.21 1.24

0.125 38.1 0.73 0.51

0.0625 14.4 0.28 0.23

<0.0625 12.0 0.23 0.00

TOTAL 5198.1

d 90 = 148 mm

d 84.1 = 107 mmd 65 = 50.1 mmd 50 = 34.2 mmd 35 = 15.9 mmd 15.9 = 2.36 mmd g = 15.9 mm

V g = 6.74 mm

G = 2.10

Particle Characteristics

Remarks

BVT, AJWNovember 27, 2000Sediments collected during trenching ofPoorly sorted sand to cobble-size sediment.

SIEVE ANALYSIS

T-1-B1BLR SedimentsAugust 26, 2000the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

Cobble

Pebble

Very fine sand

Silt & clays

21246

Size

Class

Boulders

No of Particles0>100>100

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100 1000

Sediment size (mm)

Percent Finer
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 5659.6 g 512Tare weight: 110.8 g 256

Net weight: 5548.8 g 64

32

Gravel weight: 28.9 g 16 0.0 0.00 100.00

Sand weight: 2317.9 g 8 12.7 0.54 99.46

4 16.2 0.69 98.77

Portion analyzed: 2361.1 g 2 45.8 1.94 96.83

1 201.0 8.53 88.31

Remarks: 0.5 1217.5 51.64 36.66

0.25 582.1 24.69 11.97

0.125 223.6 9.48 2.49

0.0625 47.9 2.03 0.46

<0.0625 10.8 0.46 0.00

TOTAL 2357.6

d 90 = 1.15 mm

d 84.1 = 0.95 mmd 65 = 0.73 mmd 50 = 0.60 mmd 35 = 0.48 mmd 15.9 = 0.28 mmd g = 0.51 mm

V g = 1.84 mm

G = 0.96

No of Particles01079

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWNovember 24, 2000Sediments collected during trenching of

SIEVE ANALYSIS

T-1-B2Big Lost River (INEEL)August 26, 2000Moderately sorted granule. 

>100

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

140 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 2  

141

Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 3976.2 g 512Tare weight: 110.8 g 256

Net weight: 3865.4 g 64 0.0 0.00 100.00

32 847.9 21.94 78.06

Gravel weight: 2576.7 g 16 1038.5 26.87 51.19Sand weight: 1282.9 g 8 416.0 10.76 40.42

4 274.3 7.10 33.32

Portion analyzed: 3865.4 g 2 287.0 7.43 25.90

1 338.9 8.77 17.13

Remarks: 0.5 389.6 10.08 7.04

0.25 227.7 5.89 1.15

0.125 32.9 0.85 0.30

0.0625 6.8 0.18 0.12

<0.0625 4.8 0.12 0.00

TOTAL 3864.4

d 90 = 46.7 mm

d 84.1 = 38.7 mmd 65 = 22.8 mmd 50 = 14.8 mmd 35 = 4.71 mmd 15.9 = 0.92 mmd g = 5.97 mm

V g = 6.49 mm

G = 2.16

Particle Characteristics

Remarks

BVT, AJWNovember 24, 2000Sediments collected during trenching ofPoorly sorted sand to pebble-size sediment.

SIEVE ANALYSIS

T-1-B3Big Lost River (INEEL)August 26, 2000the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

Cobble

Pebble

Very fine sand

Silt & clays

0554

Size

Class

Boulders

No of Particles>100

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 1394.7 g 512Tare weight: 122.9 g 256

Net weight: 1271.8 g 64

32

Gravel weight: 22.2 g 16

Sand weight: 1123.5 g 8 0.0 0.00 100.00

4 22.2 1.75 98.25

Portion analyzed: 1271.8 g 2 123.5 9.71 88.54

1 182.0 14.31 74.23

Remarks: 0.5 181.8 14.30 59.93

0.25 187.4 14.74 45.20

0.125 193.5 15.22 29.98

0.0625 255.3 20.08 9.90

<0.0625 125.9 9.90 0.00

TOTAL 1271.6

d 90 = 2.22 mm

d 84.1 = 1.61 mmd 65 = 0.64 mmd 50 = 0.31 mmd 35 = 0.16 mmd 15.9 = 0.08 mmd g = 0.35 mm

V g = 4.57 mm

G = 1.52

No. of Particles0>100; 90% consol. clay95% consol. clay

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

Fine sand to pebble-size sediment.

Medium sand

SIEVE ANALYSIS

T-1-C1BLR SedimentsAugust 28, 2000

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWDecember 4, 2000Sediments collected during trenching ofthe Big Lost River.

95% consol. clay95% consol. clay

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10

Sediment size (mm)

Percent Finer

142  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 2  

143

Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 2399.7 g 512Tare weight: 122.8 g 256

Net weight: 2276.9 g 64

32

Gravel weight: 0.0 g 16Sand weight: 2273.4 g 8

4 0.0 0.00 100.00

Portion analyzed: 2276.9 g 2 0.9 0.04 99.96

1 5.4 0.24 99.72

Remarks: 0.5 42.0 1.85 97.88

0.25 1975.6 86.79 11.08

0.125 228.1 10.02 1.06

Sample collected outside of active 0.0625 21.4 0.94 0.12

<0.0625 2.8 0.12 0.00

TOTAL 2276.2

Well-sorted coarse sand.

d 90 = 0.47 mm

d 84.1 = 0.45 mmd 65 = 0.38 mmd 50 = 0.34 mmd 35 = 0.30 mmd 15.9 = 0.26 mmd g = 0.34 mm

V g = 1.32 mm

G = 0.81

channel.

Particle Characteristics

Remarks>100

Fine sand

Very coarse sand

Size

Class

Boulders

SIEVE ANALYSIS

T-1-C2BLR SedimentsAugust 28, 2000

Cobble

Pebble

Very fine sand

Silt & clays

Granule

Coarse sand

Medium sand

BVT, AJWDecember 4, 2000Sediments collected during trenching ofthe Big Lost River.

No. of Particles027

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10

Sediment size (mm)

Percent Finer
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 703.5 g 512

Tare weight: 116.5 g 256Net weight: 587.0 g 64

32

Gravel weight: 2.7 g 16Sand weight: 521.6 g 8 0.0 0.00 100.00

4 2.7 0.46 99.54

Portion analyzed: 587.0 g 2 3.1 0.53 99.01

1 10.7 1.82 97.19

Remarks: 0.5 19.1 3.25 93.93

0.25 45.1 7.69 86.25

0.125 281.7 48.01 38.24

0.0625 161.9 27.59 10.65

<0.0625 62.5 10.65 0.00

TOTAL 586.8

d 90 = 0.35 mm

d 84.1 = 0.24 mmd 65 = 0.18 mmd 50 = 0.15 mmd 35 = 0.12 mmd 15.9 = 0.07 mmd g = 0.13 mm

V g = 1.84 mm

G = 0.96

No. of Particles08>100; 95% consol. clay, silt

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

Medium sand

SIEVE ANALYSIS

T-1-C3BLR SedimentsAugust 28, 2000

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWDecember 4, 2000Sediments collected during trenching ofthe Big Lost River.

95% consol. clay, silt95% consol. clay, silt

Well-sorted medium sand.

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10

Sediment size (mm)

Percent Finer

144  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 2  

145

Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 6899.4 g 512Tare weight: 275.6 g 256

Net weight: 6623.8 g 64 0.0 0.00 100.00

32 2853.0 43.08 56.92

Gravel weight: 5217.0 g 16 1592.8 24.05 32.87Sand weight: 1393.6 g 8 554.9 8.38 24.49

4 216.3 3.27 21.22

Portion analyzed: 6623.8 g 2 165.7 2.50 18.72

1 125.0 1.89 16.83

Remarks: 0.5 346.6 5.23 11.60

0.25 644.5 9.73 1.87

0.125 95.5 1.44 0.43

0.0625 16.3 0.25 0.18

<0.0625 11.9 0.18 0.00

Poorly sorted sand to pebble-size TOTAL 6622.5

sediment.

d 90 = 54.5 mm

d 84.1 = 49.6 mmd 65 = 36.4 mmd 50 = 26.2 mmd 35 = 17.0 mmd 15.9 = 0.88 mmd g = 6.61 mm

V g = 7.51 mm

G = 2.81

Particle Characteristics

Remarks

Fine sand

Very coarse sand

Size

Coarse sand

Medium sand

SIEVE ANALYSIS

T-1-C4BLR SedimentsAugust 28, 2000BVT, AJWDecember 5, 2000Sediments collected during trenching of

Cobble

Pebble

Very fine sand

Silt & clays

Granule

Class

Boulders

the Big Lost River.

No. of Particles02582194>100

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 6158.4 g 512Tare weight: 275.2 g 256 0.0 0.00 100.00

Net weight: 5883.2 g 64 538.7 9.16 90.84

32 2828.4 48.10 42.74

Gravel weight: 4848.7 g 16 791.4 13.46 29.29Sand weight: 1018.4 g 8 389.5 6.62 22.66

4 300.7 5.11 17.55

Portion analyzed: 5883.2 g 2 290.5 4.94 12.61

1 328.3 5.58 7.03

Remarks: 0.5 211.8 3.60 3.42

0.25 122.5 2.08 1.34

0.125 50.5 0.86 0.48

Poorly sorted sand to cobble-size 0.0625 14.8 0.25 0.23

sediment. <0.0625 13.6 0.23 0.00

TOTAL 5880.7

d 90 = 63.2 mm

d 84.1 = 58.1 mmd 65 = 44.1 mmd 50 = 35.5 mmd 35 = 21.5 mmd 15.9 = 3.17 mmd g = 13.6 mm

V g = 4.28 mm

G = 1.79

No. of Particles012442166>100

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

Medium sand

Fine sand

SIEVE ANALYSIS

T-1-C5BLR SedimentsAugust 28, 2000

Very coarse sand

Granule

Coarse sand

BVT, AJWDecember 5, 2000Sediments collected during trenching ofthe Big Lost River.

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100 1000

Sediment size (mm)

Percent Finer

146  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 2  

147

Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 8641.8 g 512Tare weight: 275.3 g 256

Net weight: 8366.5 g 64 0.0 0.00 100.00

32 2696.9 32.25 67.75

Gravel weight: 6324.0 g 16 1348.0 16.12 51.63Sand weight: 2017.4 g 8 1578.9 18.88 32.74

4 700.2 8.37 24.37

Portion analyzed: 8366.5 g 2 316.4 3.78 20.59

1 173.7 2.08 18.51

Remarks: 0.5 580.7 6.94 11.56

0.25 698.6 8.35 3.21

0.125 200.9 2.40 0.81

Poorly sorted sand to pebble-size 0.0625 47.1 0.56 0.24

sediment. <0.0625 20.4 0.24 0.00

TOTAL 8361.8

d 90 = 51.6 mm

d 84.1 = 45.5 mmd 65 = 28.4 mmd 50 = 15.1 mmd 35 = 8.69 mmd 15.9 = 0.77 mmd g = 5.92 mm

V g = 7.69 mm

G = 2.38

Size

Particle Characteristics

Remarks Class

Fine sand

Very coarse sand

SIEVE ANALYSIS

T-1-C6BLR SedimentsAugust 28, 2000

Cobble

Pebble

Very fine sand

Silt & clays

Granule

Coarse sand

Medium sand

Boulders

the Big Lost River.

No. of Particles024105

BVT, AJWDecember 5, 2000Sediments collected during trenching of

>100

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 1470.9 g 512Tare weight: 122.8 g 256

Net weight: 1348.1 g 64

32

Gravel weight: 0.2 g 16Sand weight: 1295.9 g 8 0.0 0.00 100.00

4 0.2 0.01 99.99

Portion analyzed: 1348.1 g 2 2.9 0.22 99.77

1 15.5 1.15 98.62

Remarks: 0.5 59.9 4.44 94.18

0.25 458.8 34.03 60.14

0.125 593.8 44.05 16.10

0.0625 165.0 12.24 3.86

<0.0625 52.0 3.86 0.00

Well-sorted medium sand. TOTAL 1348.1

d 90 = 0.46 mm

d 84.1 = 0.41 mmd 65 = 0.28 mmd 50 = 0.21 mmd 35 = 0.17 mmd 15.9 = 0.12 mmd g = 0.22 mm

V g = 1.85 mm

G = 0.96

Particle Characteristics

Remarks>100; 90% consol. sed. & org.90% consol. sed. & org.Organics present

BVT, AJWDecember 5, 2000Sediments collected during trenching ofthe Big Lost River.

Fine sand

Very coarse sand

Granule

Coarse sand

SIEVE ANALYSIS

T-1-C7BLR SedimentsAugust 28, 2000

Cobble

Pebble

Very fine sand

Silt & clays

Medium sand

No. of Particles

Size

Class

Boulders

04; 100% consol. sediment90; 85% consol. sed. & org.

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10

Sediment size (mm)

Percent Finer

148  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 2  

149

Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 9426.6 g 512Tare weight: 275.9 g 256 0.0 0.00 100.00

Net weight: 9150.7 g 64 434.7 4.75 95.25

32 3966.2 43.37 51.88

Gravel weight: 6715.4 g 16 682.6 7.46 44.41Sand weight: 2423.5 g 8 998.5 10.92 33.49

4 633.4 6.93 26.57

Portion analyzed: 9150.7 g 2 466.2 5.10 21.47

1 375.2 4.10 17.37

Remarks: 0.5 757.5 8.28 9.08

0.25 710.7 7.77 1.31

0.125 99.8 1.09 0.22

0.0625 14.1 0.15 0.07

<0.0625 6.0 0.07 0.00

Coarse sand, gravel, and cobble. Poorly TOTAL 9144.9sorted. Located near bottom of trench.

d 90 = 58.9 mm

d 84.1 = 53.6 mmd 65 = 39.5 mmd 50 = 26.9 mmd 35 = 8.8 mmd 15.9 = 0.88 mmd g = 6.87 mm

V g = 7.80 mm

G = 2.85

Particle Characteristics

Remarks

Medium sand

SIEVE ANALYSIS

T-1-C8BLR SedimentsAugust 28, 2000

Fine sand

Very coarse sand

Granule

Coarse sand

Cobble

Pebble

Very fine sand

Silt & clays

Size

Class

Boulders BVT, AJW

December 5, 2000Sediments collected during trenching ofthe Big Lost River.

No. of Particles013450>100

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100 1000

Sediment size (mm)

Percent Finer
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 5164.5 g 512Tare weight: 110.8 g 256

Net weight: 5053.7 g 64 0.0 0.00 100.00

32 1488.2 29.45 70.55

Gravel weight: 3473.7 g 16 729.6 14.44 56.12Sand weight: 1557.1 g 8 760.5 15.05 41.07

4 495.4 9.80 31.26

Portion analyzed: 5053.7 g 2 475.4 9.41 21.86

1 444.9 8.80 13.05

Remarks: 0.5 305.0 6.04 7.02

0.25 183.5 3.63 3.39

0.125 110.1 2.18 1.21

0.0625 38.2 0.76 0.45

<0.0625 22.9 0.45 0.00

TOTAL 5053.7

d 90 = 50.6 mm

d 84.1 = 44.0 mmd 65 = 24.5 mmd 50 = 12.1 mmd 35 = 5.21 mmd 15.9 = 1.25 mmd g = 7.42 mm

V g = 5.93 mm

G = 1.82

Particle Characteristics

Remarks

BVT, AJWNovember 27, 2000Sediments collected during trenching ofthe Big Lost River.Poorly sorted sand to pebble-size sediment.

Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

SIEVE ANALYSIS

T-1-D1BLR ChannelAugust 28, 2000

Cobble

Pebble

Very fine sand

Silt & clays

1446

Size

Class

Boulders

No. of Particles0>100

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

150 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 2  

151

Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 3830.4 g 512Tare weight: 110.8 g 256

Net weight: 3719.6 g 64

32

Gravel weight: 5.2 g 16 0.0 0.00 100.00Sand weight: 3711.5 g 8 2.9 0.08 99.92

4 2.3 0.06 99.86

Portion analyzed: 3719.6 g 2 8.7 0.23 99.63 >100

1 51.1 1.37 98.25

Remarks: 0.5 2028.3 54.53 43.72

0.25 1372.0 36.89 6.84

0.125 231.4 6.22 0.62

0.0625 20.0 0.54 0.08

<0.0625 2.9 0.08 0.00

TOTAL 3719.6

sediment.

d 90 = 0.90 mm

d 84.1 = 0.84 mmd 65 = 0.66 mmd 50 = 0.54 mmd 35 = 0.42 mmd 15.9 = 0.30 mmd g = 0.50 mm

V g = 1.67 mm

G = 0.92

No. of Particles0116

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

Sieving required two runs in shaker.

Medium sand

SIEVE ANALYSIS

T-1-D2BLR ChannelAugust 28, 2000

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWNovember 27, 2000Sediments collected during trenching ofthe Big Lost River.Bedded coarse sand and granule-size 

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10

Sediment size (mm)

Percent Finer
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 5546.0 g 512Tare weight: 110.8 g 256

Net weight: 5435.2 g 64

32 0.0 0.00 100.00

Gravel weight: 2027.0 g 16 209.0 6.68 93.32Sand weight: 1088.1 g 8 986.5 31.54 61.78

4 831.5 26.58 35.20

Portion analyzed: 3128.0 g 2 444.0 14.19 21.00

1 166.8 5.33 15.67

Remarks: 0.5 155.0 4.96 10.72

0.25 191.9 6.13 4.58

0.125 102.6 3.28 1.30

0.0625 27.8 0.89 0.41

<0.0625 12.9 0.41 0.00

TOTAL 3128.0

d 90 = 14.9 mm

d 84.1 = 13.1 mmd 65 = 8.59 mmd 50 = 5.88 mmd 35 = 3.96 mmd 15.9 = 1.03 mmd g = 3.67 mm

V g = 3.57 mm

G = 1.41

Particle Characteristics

Remarks

BVT, AJWNovember 27, 2000Sediments collected during trenching ofthe Big Lost River.Well-sorted pebble layer.

Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

SIEVE ANALYSIS

T-1-D3BLR ChannelAugust 28, 2000

Cobble

Pebble

Very fine sand

Silt & clays

No. of Particles015

Size

Class

Boulders

>100

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

152  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 2  

153

Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 5844.8 g 512Tare weight: 110.8 g 256

Net weight: 5734.0 g 64 0.0 0.00 100.00

32 1188.6 20.73 79.27

Gravel weight: 3904.4 g 16 1345.9 23.47 55.80Sand weight: 1796.2 g 8 933.2 16.27 39.52

4 436.7 7.62 31.91

Portion analyzed: 5734.0 g 2 244.0 4.26 27.65

1 342.3 5.97 21.68

Remarks: 0.5 643.2 11.22 10.47

0.25 346.1 6.04 4.43

0.125 158.4 2.76 1.67

0.0625 62.2 1.08 0.58

<0.0625 33.4 0.58 0.00

TOTAL 5734.0

d 90 = 45.8 mm

d 84.1 = 37.6 mmd 65 = 21.0 mmd 50 = 12.5 mmd 35 = 5.30 mmd 15.9 = 0.70 mmd g = 5.13 mm

V g = 7.33 mm

G = 2.28

No. of Particles01291>100>100

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

SIEVE ANALYSIS

T-1-D4BLR ChannelAugust 28, 2000

Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWNovember 27, 2000Sediments collected during trenching ofthe Big Lost River.Poorly sorted sand to pebble-size sediment.

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 3388.2 g 512Tare weight: 110.8 g 256

Net weight: 3277.4 g 64

32

Gravel weight: 0.6 g 16Sand weight: 1748.0 g 8 0.0 0.00 100.00

4 0.6 0.03 99.97

Portion analyzed: 1753.0 g 2 4.6 0.26 99.70 >100

1 45.5 2.60 97.11

Remarks: 0.5 314.1 17.92 79.19

0.25 1142.3 65.16 14.03

0.125 214.1 12.21 1.81

0.0625 27.4 1.56 0.25

<0.0625 4.4 0.25 0.00

TOTAL 1753.0

d 90 = 0.76 mm

d 84.1 = 0.60 mmd 65 = 0.43 mmd 50 = 0.37 mmd 35 = 0.31 mmd 15.9 = 0.26 mmd g = 0.39 mm

V g = 1.52 mm

G = 0.87

Particle Characteristics

Remarks

BVT, AJWNovember 27, 2000Sediments collected during trenching ofthe Big Lost River.Bedded coarse sand layer. 

Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

SIEVE ANALYSIS

T-1-D5BLR ChannelAugust 28, 2000

Cobble

Pebble

Very fine sand

Silt & clays

~1/2 of sample analyzed, used splitter.

No. of Particles

Size

Class

Boulders

06

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10

Sediment size (mm)

Percent Finer

154  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 2  

155

Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 464.7 g 512

Tare weight: 110.8 g 256Net weight: 353.9 g 64

32

Gravel weight: 7.6 g 16Sand weight: 98.5 g 8 0.0 0.00 100.00

4 7.6 6.31 93.69

Portion analyzed: 120.5 g 2 12.1 10.04 83.65

1 21.8 18.09 65.56

Remarks: 0.5 20.3 16.85 48.71

0.25 18.8 15.60 33.11

0.125 15.9 13.20 19.92

0.0625 9.6 7.97 11.95

<0.0625 14.4 11.95 0.00

TOTAL 120.5

d 90 = 3.10 mm

d 84.1 = 2.06 mmd 65 = 0.98 mmd 50 = 0.53 mmd 35 = 0.27 mmd 15.9 = 0.09 mmd g = 0.43 mm

V g = 4.84 mm

G = 1.57

No. of Particles036

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

Clay was described.

Medium sand

SIEVE ANALYSIS

T-1-DCLAY2BLR ChannelAugust 28, 2000

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWNovember 27, 2000Sediments collected during trenching of Big Lost River.Poorly sorted sand to pebble-sizesediment.

>100

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10

Sediment size (mm)

Percent Finer
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 24767.8 g 512Tare weight: 808.4 g 256

Net weight: 23959.4 g 64 0.0 0.00 100.00

32 974.8 19.06 80.94

Gravel weight: 3515.7 g 16 1086.1 21.24 59.70

Sand weight: 1560.5 g 8 883.7 17.28 42.42

4 571.1 11.17 31.25

Portion analyzed: 5115.3 g 2 406.6 7.95 23.30

1 246.3 4.82 18.48

Remarks: 0.5 207.3 4.05 14.42

0.25 398.4 7.79 6.63

0.125 214.3 4.19 2.44

0.0625 87.6 1.71 0.73

<0.0625 37.3 0.73 0.00

TOTAL 5113.5

d 90 = 44.5 mm

d 84.1 = 35.9 mmd 65 = 19.0 mmd 50 = 10.8 mmd 35 = 5.05 mmd 15.9 = 0.64 mmd g = 4.79 mm

V g = 7.49 mm

G = 2.25

No. of Particles0970>10020% consol. sediments

Size

Class

Boulders

Granule

Coarse sand

Cobble

Pebble

Very fine sand

Silt & clays

Medium sand

Fine sand

Very coarse sand

~1/4 of sample analyzed, used splitter.

SIEVE ANALYSIS

T-1-E1Big Lost River (INEEL)August 29, 2000BVT, AJWDecenber 19, 2000Sediments collected during trenching ofthe Big Lost River.

40% consol. sediments75% consol. sediments

Poorly sorted sand to pebble-size sediment.

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

156  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 2  157

0

1

2

3

4

5

6

7

8

DEPTH

IN FEET

T-2-B

L-2-A

T-2-A

L-2-C

113° 02' 40"

43°

31'

55"

43°

32'

113 113° 02' 45" ° 02' 50"

0 100 200 FEET

0 25 50 METERS

EXPLANATION

TRENCH LITHOLOGY

 Very fine to very coarse sand

 Silty sand

 Sand, granule, and cobbles

 Sand, granule, cobbles, and boulders

 Basalt bedrock

TRENCH PARTICLE-SAMPLING SITE AND 

 IDENTIFIER—T, transverse; L, lateral. 

 Particle analyses are shown in table 2 and appendix 2 

APPROXIMATE BOUNDARY OF TOP OF BANK

T-2-B

Site 3

constriction

Site 2

constriction

Base from Bureau of Reclamation

aerial photographs, written commun., 2001.

Figure 2–2. Lithology of selected trenches at site 2, Big Lost River upstream from Pioneer diversion structures, Idaho National 

Engineering and Environmental Laboratory, Idaho.
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 2973.2 g 512Tare weight: 110.8 g 256

Net weight: 2862.4 g 64

32

Gravel weight: 12.7 g 16

Sand weight: 1209.1 g 8 0.0 0.00 100.00

4 12.7 1.04 98.96

Portion analyzed: 1224.9 g 2 44.5 3.63 95.33 >100

1 87.4 7.14 88.19

Remarks: 0.5 123.3 10.07 78.13

0.25 619.8 50.60 27.53

0.125 310.4 25.34 2.19

0.0625 23.7 1.93 0.25

<0.0625 3.1 0.25 0.00

TOTAL 1224.9

d 90 = 1.19 mm

d 84.1 = 0.75 mmd 65 = 0.42 mmd 50 = 0.34 mmd 35 = 0.28 mmd 15.9 = 0.18 mmd g = 0.37 mm

V g = 2.04 mm

G = 1.01

Particle Characteristics

Remarks

BVT, AJWNovember 27, 2000Sediments collected during trenching ofthe Big Lost River.Wood found in sample.

Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

SIEVE ANALYSIS

L-2-A1BLR SedimentsAugust 24, 2000

Cobble

Pebble

Very fine sand

Silt & clays

No. of Particles

Size

Class

Boulders

065; some wood--3 pieces

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10

Sediment size (mm)

Percent Finer

158  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 2604.3 g 512Tare weight: 110.8 g 256

Net weight: 2493.5 g 64

32

Gravel weight: 408.3 g 16 0.0 0.00 100.00Sand weight: 2083.9 g 8 54.4 2.18 97.82

4 353.9 14.19 83.63

Portion analyzed: 2493.5 g 2 814.2 32.65 50.97

1 488.0 19.57 31.40

Remarks: 0.5 282.2 11.32 20.08

0.25 305.9 12.27 7.82

0.125 183.4 7.36 0.46

0.0625 10.2 0.41 0.05

<0.0625 1.3 0.05 0.00

TOTAL 2493.5

d 90 = 5.46 mm

d 84.1 = 4.09 mmd 65 = 2.69 mmd 50 = 1.93 mmd 35 = 1.14 mmd 15.9 = 0.39 mmd g = 1.27 mm

V g 3.22 mm

G = 1.32

Particle Characteristics

Remarks

BVT, AJWNovember 27, 2000Sediments collected during trenching ofthe Big Lost River.Moderately sorted, very coarse sandand pebble layer.

Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

SIEVE ANALYSIS

L-2-A2BLR SedimentsAugust 24, 2000

Cobble

Pebble

Very fine sand

Silt & clays

No. of Particles0

Size

Class

Boulders

69>100

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

Appendix 2  159
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 2426.2 g 512Tare weight: 110.8 g 256

Net weight: 2315.4 g 64

32

Gravel weight: 18.7 g 16 0.0 0.00 100.00

Sand weight: 1350.4 g 8 5.0 0.36 99.64

4 13.7 1.00 98.63

Portion analyzed: 1369.9 g 2 39.8 2.91 95.73 >100

1 262.3 19.15 76.58

Remarks: 0.5 850.9 62.11 14.47

0.25 153.6 11.21 3.26

0.125 37.8 2.76 0.50

0.0625 6.0 0.44 0.06

<0.0625 0.8 0.06 0.00

TOTAL 1369.9

d 90 = 1.63 mm

d 84.1 = 1.31 mmd 65 = 0.88 mmd 50 = 0.74 mmd 35 = 0.63 mmd 15.9 = 0.51 mmd g = 0.82 mm

V g = 1.61 mm

G = 0.90

No. of Particles0379

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

SIEVE ANALYSIS

L-2-A3BLR SedimentsAugust 24, 2000

Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWNovember 27, 2000Sediments collected during trenching ofthe Big Lost River.Wood fragments found during excavation;well-sorted granule layer.

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

160 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 4979.9 g 512Tare weight: 110.8 g 256

Net weight: 4869.1 g 64

32 0.0 0.00 100.00

Gravel weight: 746.9 g 16 148.5 5.46 94.54Sand weight: 1964.9 g 8 288.4 10.60 83.94

4 310.0 11.39 72.55

Portion analyzed: 2737.0 g 2 359.9 13.23 59.32

1 292.7 10.76 48.56

Remarks: 0.5 437.4 16.08 32.48

0.25 533.9 19.62 12.86

0.125 300.0 11.03 1.83

0.0625 41.0 1.51 0.33

<0.0625 8.9 0.33 0.00

TOTAL 2720.7

d 90 = 11.9 mm

d 84.1 = 8.08 mmd 65 = 2.69 mmd 50 = 1.10 mmd 35 = 0.56 mmd 15.9 = 0.28 mmd g = 1.50 mm

V g 5.39 mm

G = 1.68

No. of Particles013143>100

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

Medium sand

Very coarse sand

Granule

Coarse sand

SIEVE ANALYSIS

L-2-A4BLR SedimentsAugust 24, 2000BVT, AJWNovember 27, 2000Sediments collected during trenching ofthe Big Lost River.Poorly sorted sand to pebble-size sediment.

Fine sand

~1/2 sample analyzed, used splitter.

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

Appendix 2  161
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 1747.6 g 512Tare weight: 110.8 g 256

Net weight: 1636.8 g 64

32

Gravel weight: 10.0 g 16

Sand weight: 1596.1 g 8 0.0 0.00 100.00

4 10.0 0.61 99.39

Portion analyzed: 1636.8 g 2 44.7 2.73 96.66

1 71.3 4.36 92.30

Remarks: 0.5 137.3 8.39 83.91

0.25 857.2 52.37 31.54

0.125 399.8 24.43 7.12

0.0625 85.8 5.24 1.88

<0.0625 30.7 1.88 0.00

TOTAL 1636.8

d 90 = 0.83 mm

d 84.1 = 0.51 mmd 65 = 0.39 mmd 50 = 0.32 mmd 35 = 0.26 mmd 15.9 = 0.16 mmd g = 0.29 mm

V g 1.78 mm

G = 0.95

No of particles058

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWNovember 21, 2000Sediments collected during trenching of

SIEVE ANALYSIS

L-2-B1Big Lost River (INEEL)August 25, 2000Well-sorted coarse sand.

>100

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10

Sediment size (mm)

Percent Finer

162  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 3470.0 g 512Tare weight: 110.8 g 256

Net weight: 3359.2 g 64

32

Gravel weight: 14.9 g 16

Sand weight: 3330.5 g 8 0.0 0.00 100.00

4 14.9 0.45 99.55

Portion analyzed: 3359.2 g 2 51.1 1.53 98.03

1 102.3 3.06 94.97

Remarks: 0.5 1571.7 46.96 48.02

0.25 1453.6 43.43 4.59

0.125 143.1 4.28 0.31

0.0625 8.7 0.26 0.05

<0.0625 1.8 0.05 0.00

TOTAL 3347.2

d 90 = 0.93 mm

d 84.1 = 0.85 mmd 65 = 0.64 mmd 50 = 0.51 mmd 35 = 0.41 mmd 15.9 = 0.30 mmd g = 0.51 mm

V g 1.69 mm

G = 0.92

No of particles092

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWNovember 21, 2000Sediments collected during trenching of

SIEVE ANALYSIS

L-2-B2Big Lost River (INEEL)August 25, 2000Well-sorted coarse sand and granule layer.

>100

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10

Sediment size (mm)

Percent Finer

Appendix 2  163
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 4738.3 g 512Tare weight: 110.8 g 256 No of particles

Net weight: 4627.5 g 64 0.0 0.00 100.00 0

32 546.6 11.81 88.19 4

Gravel weight: 2353.0 g 16 1037.3 22.42 65.77 63Sand weight: 2266.1 g 8 329.5 7.12 58.65

4 439.6 9.50 49.15

Portion analyzed: 4627.5 g 2 539.5 11.66 37.49

1 583.3 12.61 24.88

Remarks: 0.5 459.9 9.94 14.94

0.25 550.9 11.91 3.03

0.125 113.3 2.45 0.59

0.0625 19.2 0.41 0.17

<0.0625 7.9 0.17 0.00

TOTAL 4627.0

d 90 = 35.6 mm

d 84.1 = 28.2 mmd 65 = 14.8 mmd 50 = 4.26 mmd 35 = 1.74 mmd 15.9 = 0.53 mmd g = 3.88 mm

V g 7.26 mm

G = 1.91

188>100

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWNovember 21, 2000Sediments collected during trenching of

SIEVE ANALYSIS

L-2-B3Big Lost River (INEEL)August 24, 2000Poorly sorted sand to pebble-size sediment.

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

164  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 7913.6 g 512Tare weight: 275.9 g 256

Net weight: 7637.7 g 64 0.0 0.00 100.00

32 206.9 2.71 97.29

Gravel weight: 4858.4 g 16 747.4 9.79 87.50Sand weight: 2756.7 g 8 2490.2 32.62 54.88

4 1413.9 18.52 36.37

Portion analyzed: 7637.7 g 2 786.9 10.31 26.06

1 506.4 6.63 19.43

Remarks: 0.5 600.7 7.87 11.56

0.25 665.7 8.72 2.84

0.125 157.9 2.07 0.77

0.0625 39.1 0.51 0.26

<0.0625 19.8 0.26 0.00

TOTAL 7634.9

d 90 = 19.1 mm

d 84.1 = 14.9 mmd 65 = 9.92 mmd 50 = 6.66 mmd 35 = 3.65 mmd 15.9 = 0.73 mmd g = 3.30 mm

V g 4.51 mm

G = 1.68

No. of Particles0358>100

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

SIEVE ANALYSIS

L-2-C1BLR sedimentsAugust 24, 2000

Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWDecember 4, 2000Sediments collected during trenching ofthe Big Lost River.Poorly sorted sand to pebble-size sediment.

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

Appendix 2  165
166  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho Sieve Cumulative Size Weight Percent Percent (mm) (g) Finer Finer Sample ID: Location: Date/Time: 8192 Analyzed by: 4096 Date/Time: 2048 1024 Gross weight: 3689.8 g 512 Tare weight: 113.6 g 256 Net weight: 3576.2 g 6432 Gravel weight: 205.9 g 16 Sand weight: 3366.4 g 8 0.0 0.00 100.00 4 205.9 5.76 94.24 Portion analyzed: 3576.2 g 2 249.8 6.99 87.25 1 454.2 12.70 74.55 Remarks: 0.5 1728.8 48.36 26.19 0.25 754.0 21.09 5.10 0.125 165.7 4.63 0.47 0.0625 13.9 0.39 0.08

<0.0625 2.9 0.08 0.00

TOTAL 3575.2

d 90 = 2.63 mm

d 84.1 = 1.68 mmd 65 = 0.87 mmd 50 = 0.70 mmd 35 = 0.57 mmd 15.9 = 0.36 mmd g = 0.77 mm

V g 2.17 mm

G = 1.04

Particle Characteristics

Remarks

BVT, AJWDecember 4, 2000Sediments collected during trenching ofthe Big Lost River.Well-sorted granule layer.

Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

SIEVE ANALYSIS

L-2-C2BLR sedimentsAugust 24, 2000

Cobble

Pebble

Very fine sand

Silt & clays

No. of Particles

Size

Class

Boulders

0>100

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10

Sediment size (mm)

Percent Finer
Appendix 2  

167

Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 1764.6 g 512Tare weight: 122.8 g 256

Net weight: 1641.8 g 64

32

Gravel weight: 177.7 g 16 0.0 0.00 100.00Sand weight: 545.8 g 8 95.7 12.86 87.14

4 82.0 11.02 76.13

Portion analyzed: 745.6 g 2 150.3 20.19 55.94 85% consol. clay

1 154.3 20.73 35.21

Remarks: 0.5 105.6 14.19 21.02

0.25 74.0 9.94 11.08

0.125 36.9 4.96 6.13

Poor sample due to consolidated clay. 0.0625 24.7 3.32 2.81

<0.0625 20.9 2.81 0.00

Poorly sorted sand to pebble-size TOTAL 744.4

materials. Clay described in sample.

d 90 = 9.33 mm

d 84.1 = 6.61 mmd 65 = 2.73 mmd 50 = 1.64 mmd 35 = 0.99 mmd 15.9 = 0.35 mmd g = 1.52 mm

V g 4.35 mm

G = 1.48

Remarks

Particle Characteristics

90% consol. clay90% consol. clay

BVT, AJWDecember 4, 2000Sediments collected during trenching ofthe Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

SIEVE ANALYSIS

L-2-C4BLR sedimentsAugust 24, 2000

Size

Class

Boulders

No. of Particles0

Cobble

Pebble

Very fine sand

Silt & clays

49; 60% consol. Clay50% consol. clay

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 26685.9 g 512Tare weight: 808.4 g 256 0.0 0.00 100.00

Net weight: 25877.5 g 64 504.3 7.50 92.50

32 1277.1 19.00 73.50

Gravel weight: 5274.9 g 16 1664.9 24.76 48.74

Sand weight: 1413.9 g 8 1195.5 17.78 30.96

4 633.1 9.42 21.54

Portion analyzed: 6724.8 g 2 411.2 6.12 15.42

1 291.2 4.33 11.09

Remarks: 0.5 250.2 3.72 7.37

0.25 258.6 3.85 3.53

0.125 153.5 2.28 1.24

0.0625 49.2 0.73 0.51

<0.0625 34.3 0.51 0.00

TOTAL 6723.1

d 90 = 58.4 mm

d 84.1 = 47.1 mmd 65 = 25.2 mmd 50 = 16.6 mmd 35 = 9.37 mmd 15.9 = 2.11 mmd g = 9.97 mm

V g 4.72 mm

G = 1.64

No of Particles0114104>100

Size

Class

Boulders

Granule

Coarse sand

Cobble

Pebble

Very fine sand

Silt & clays

Medium sand

Fine sand

Very coarse sand

~1/4 of sample analyzed, used splitter.

SIEVE ANALYSIS

M-2-A1Big Lost River (INEEL)August 29, 2000BVT, AJWDecember 19, 2000Sediments collected during trenching ofthe Big Lost River.Poorly sorted sand to cobble-size sediment.

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100 1000

Sediment size (mm)

Percent Finer

168  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 2039.2 g 512Tare weight: 110.8 g 256

Net weight: 1928.4 g 64

32

Gravel weight: 5.7 g 16Sand weight: 1918.5 g 8 0.0 0.00 100.00

4 5.7 0.30 99.70

Portion analyzed: 1928.4 g 2 26.2 1.36 98.35

1 41.0 2.13 96.22

Remarks: 0.5 81.2 4.21 92.01

0.25 1439.5 74.65 17.36

0.125 286.3 14.85 2.52

0.0625 44.3 2.30 0.22

<0.0625 4.2 0.22 0.00

TOTAL 1928.4

d 90 = 0.49 mm

d 84.1 = 0.46 mmd 65 = 0.39 mmd 50 = 0.34 mmd 35 = 0.29 mmd 15.9 = 0.23 mmd g = 0.33 mm

V g 1.41 mm

G = 0.84

Particle Characteristics

Remarks>100

BVT, AJWNovember 21, 2000Sediments collected during trenching ofWell-sorted coarse sand.

SIEVE ANALYSIS

T-2-A1Big Lost River (INEEL)August 24, 2000the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

Cobble

Pebble

Very fine sand

Silt & clays

No of particles

Size

Class

Boulders

031

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10

Sediment size (mm)

Percent Finer

Appendix 2  169
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 4058.2 g 512Tare weight: 110.8 g 256

Net weight: 3947.4 g 64

32

Gravel weight: 19.3 g 16

Sand weight: 3921.3 g 8 0.0 0.00 100.00

4 19.3 0.49 99.51

Portion analyzed: 3947.4 g 2 93.3 2.37 97.14

1 265.7 6.74 90.40

Remarks: 0.5 495.6 12.57 77.83

0.25 2876.9 72.97 4.86

0.125 161.3 4.09 0.77

0.0625 28.5 0.72 0.05

<0.0625 2.0 0.05 0.00

TOTAL 3942.6

d 90 = 0.98 mm

d 84.1 = 0.71 mmd 65 = 0.44 mmd 50 = 0.38 mmd 35 = 0.33 mmd 15.9 = 0.28 mmd g = 0.44 mm

V g 1.60 mm

G = 0.90

No of particles082

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWNovember 24, 2000Sediments collected during trenching of

SIEVE ANALYSIS

T-2-A2Big Lost River (INEEL)August 24, 2000Well-sorted coarse sand.

>100

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10

Sediment size (mm)

Percent Finer

170 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 4273.3 g 512Tare weight: 110.8 g 256

Net weight: 4162.5 g 64 0.0 0.00 100.00

32 249.1 5.99 94.01

Gravel weight: 1590.9 g 16 525.1 12.63 81.38Sand weight: 2561.8 g 8 462.0 11.11 70.27

4 354.7 8.53 61.74

Portion analyzed: 4162.5 g 2 389.2 9.36 52.37

1 570.8 13.73 38.64

Remarks: 0.5 981.9 23.62 15.03

0.25 492.9 11.86 3.17

0.125 109.6 2.64 0.54

0.0625 17.4 0.42 0.12

<0.0625 4.9 0.12 0.00

TOTAL 4157.6

d 90 = 25.7 mm

d 84.1 = 18.6 mmd 65 = 5.22 mmd 50 = 1.77 mmd 35 = 0.90 mmd 15.9 = 0.51 mmd g = 3.09 mm

V g 6.02 mm

G = 1.87

Particle Characteristics

Remarks

BVT, AJWNovember 24, 2000Sediments collected during trenching ofPoorly sorted sand to pebble-size sediment.

SIEVE ANALYSIS

T-2-A3Big Lost River (INEEL)August 24, 2000the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

Cobble

Pebble

Very fine sand

Silt & clays

438

Size

Class

Boulders

No of particles0>100

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

Appendix 2  171
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 8745.5 g 512Tare weight: 275.5 g 256

Net weight: 8470.0 g 64 0.0 0.00 100.00

32 1471.2 17.38 82.62

Gravel weight: 4433.8 g 16 677.0 8.00 74.62Sand weight: 4025.1 g 8 1387.9 16.40 58.22

4 897.7 10.61 47.62

Portion analyzed: 8470.0 g 2 700.6 8.28 39.34

1 751.8 8.88 30.46

Remarks: 0.5 1608.1 19.00 11.46

0.25 786.1 9.29 2.17

0.125 156.4 1.85 0.32

0.0625 22.1 0.26 0.06

<0.0625 5.1 0.06 0.00

TOTAL 8464.0

d 90 = 43.0 mm

d 84.1 = 33.9 mmd 65 = 10.7 mmd 50 = 4.67 mmd 35 = 1.43 mmd 15.9 = 0.59 mmd g = 4.47 mm

V g 7.60 mm

G = 1.95

Particle Characteristics

Remarks

BVT, AJWNovember 24, 2000Sediments collected during trenching ofModerately sorted granule and pebblesediment layer.

SIEVE ANALYSIS

T-2-A4Big Lost River (INEEL)August 25, 2000the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

Cobble

Pebble

Very fine sand

Silt & clays

1048

Size

Class

Boulders

No of particles0>100

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

172  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 1367.7 g 512Tare weight: 110.8 g 256

Net weight: 1256.9 g 64

32

Gravel weight: 28.8 g 16 0.0 0.00 100.00

Sand weight: 1184.0 g 8 10.8 0.86 99.14

4 18.0 1.44 97.70

Portion analyzed: 1256.9 g 2 31.9 2.54 95.16

1 72.3 5.77 89.39

Remarks: 0.5 187.4 14.95 74.45

0.25 558.6 44.55 29.90

0.125 250.9 20.01 9.89

0.0625 82.9 6.61 3.28

<0.0625 41.1 3.28 0.00

TOTAL 1253.9

d 90 = 1.08 mm

d 84.1 = 0.78 mmd 65 = 0.43 mmd 50 = 0.34 mmd 35 = 0.27 mmd 15.9 = 0.15 mmd g = 0.35 mm

V g 2.25 mm

G = 1.06

Particle Characteristics

Remarks>100

BVT, AJWNovember 24, 2000Sediments collected during trenching ofWell-sorted coarse sand.

SIEVE ANALYSIS

T-2-A5Big Lost River (INEEL)August 25, 2000the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

Cobble

Pebble

Very fine sand

Silt & clays

No of particles0

Size

Class

Boulders

7116

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

Appendix 2  173
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 341.8 g 512

Tare weight: 110.8 g 256Net weight: 231.0 g 64

32

Gravel weight: 0.0 g 16Sand weight: 204.5 g 8

4 0.0 0.00 100.00

Portion analyzed: 231.0 g 2 1.9 0.83 99.17

1 5.7 2.48 96.69

Remarks: 0.5 13.0 5.66 91.03

0.25 45.1 19.64 71.39

0.125 86.3 37.59 33.80

0.0625 52.5 22.87 10.93

<0.0625 25.1 10.93 0.00

TOTAL 229.6

d 90 = 0.48 mm

d 84.1 = 0.39 mmd 65 = 0.22 mmd 50 = 0.17 mmd 35 = 0.13 mmd 15.9 = 0.07 mmd g = 0.17 mm

V g 2.32 mm

G = 1.08

No of particles0

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWNovember 24, 2000Sediments collected during trenching of

SIEVE ANALYSIS

T-2-A6Big Lost River (INEEL)August 25, 2000Well-sorted medium sand.

99>100

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10

Sediment size (mm)

Percent Finer

174  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 2  175

Figure 2–3. Lithology of selected trenches at site 3, Big Lost River upstream of Pioneer diversion structures, Idaho National Engineering and 

Environmental Laboratory, Idaho.

0

1

2

3

4

5

6

DEPTH

IN FEET

T-3-A L-3-A

113° 02' 40"

43°

31'

55"

43°

32'

113° 113 02' 45" ° 02' 50"

0 100 200 FEET

0 25 50 METERS

Site 3

constriction

Site 2

constriction

EXPLANATION

TRENCH LITHOLOGY

 Very fine to very coarse sand

 Silty sand

 Sand, granule, and cobbles

 Sand, granule, cobbles, and boulders

 Basalt bedrock

TRENCH PARTICLE-SAMPLING SITE AND 

 IDENTIFIER—T, transverse; L, lateral. 

 Particle analyses are shown in table 2 and appendix 2 

APPROXIMATE BOUNDARY OF TOP OF BANK

T-3-A

Base from Bureau of Reclamation

aerial photographs, written commun., 2001.
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 1893.1 g 512Tare weight: 110.8 g 256

Net weight: 1782.3 g 64 0.0 0.00 100.00

32 461.0 8.24 91.76

Gravel weight: 3795.0 g 16 1428.9 25.53 66.23Sand weight: 1782.3 g 8 1165.8 20.83 45.41

4 739.3 13.21 32.20

Portion analyzed: 5601.0 g 2 482.6 8.62 23.58

1 262.3 4.69 18.89

Remarks: 0.5 281.7 5.03 13.86

0.25 520.5 9.30 4.56

0.125 192.9 3.45 1.11

0.0625 42.3 0.76 0.36

<0.0625 19.9 0.36 0.00

TOTAL 5597.2

d 90 = 30.5 mm

d 84.1 = 26.0 mmd 65 = 15.4 mmd 50 = 9.32 mmd 35 = 4.63 mmd 15.9 = 0.66 mmd g = 4.15 mm

V g 6.26 mm

G = 2.05

No of Particles04103>100

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWNovember 29, 2000Sediments collected during trenching of 

SIEVE ANALYSIS

L-3-A1BLR SedimentsAugust 23, 2000Poorly sorted sand to pebble-sizesediment layer.

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

176  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 6829.3 g 512Tare weight: 110.8 g 256

Net weight: 6718.5 g 64 0.0 0.00 100.00

32 588.0 8.75 91.25

Gravel weight: 4341.3 g 16 1668.6 24.84 66.40Sand weight: 2346.6 g 8 1185.1 17.64 48.76

4 899.6 13.39 35.36

Portion analyzed: 6718.5 g 2 658.4 9.80 25.56

1 447.6 6.66 18.90

Remarks: 0.5 487.5 7.26 11.64

0.25 530.4 7.90 3.74

0.125 172.4 2.57 1.18

0.0625 50.3 0.75 0.43

<0.0625 28.7 0.43 0.00

TOTAL 6716.6

d 90 = 30.9 mm

d 84.1 = 26.2 mmd 65 = 15.1 mmd 50 = 8.40 mmd 35 = 3.90 mmd 15.9 = 0.75 mmd g = 4.44 mm

V g 5.91 mm

G = 1.89

Particle Characteristics

Remarks

BVT, AJWNovember 29, 2000Sediments collected during trenching ofPoorly sorted sand to pebble-sizesediment layer.

SIEVE ANALYSIS

L-3-A2BLR SedimentsAugust 23, 2000the Big Lost River Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

Cobble

Pebble

Very fine sand

Silt & clays

5135

Size

Class

Boulders

No. of Particles0>100>100

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

Appendix 2  177
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 5271.5 g 512Tare weight: 110.8 g 256

Net weight: 5160.7 g 64 0.0 0.00 100.00

32 96.7 1.84 98.16

Gravel weight: 3671.6 g 16 1001.5 19.04 79.12Sand weight: 1542.9 g 8 1550.4 29.47 49.65

4 1023.0 19.45 30.20

Portion analyzed: 5260.7 g 2 398.7 7.58 22.63

1 286.0 5.44 17.19

Remarks: 0.5 306.7 5.83 11.36

0.25 350.7 6.67 4.69

0.125 134.8 2.56 2.13

0.0625 66.0 1.25 0.87

<0.0625 46.0 0.87 0.00

TOTAL 5260.5

sediment layer.

d 90 = 23.8 mm

d 84.1 = 19.2 mmd 65 = 11.5 mmd 50 = 8.07 mmd 35 = 4.75 mmd 15.9 = 0.86 mmd g = 4.06 mm

V g 4.73 mm

G = 1.72

No. of Particles0276>100

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWNovember 29, 2000Sediments collected during trenching of

SIEVE ANALYSIS

L-3-A3BLR SedimentsAugust 23, 2000Artillery shell fragments found in sample.Poorly sorted sand to pebble-size

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

178  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 2431.2 g 512Tare weight: 110.8 g 256

Net weight: 2320.4 g 64

32 0.0 0.00 100.00

Gravel weight: 783.1 g 16 164.9 7.11 92.89Sand weight: 1461.3 g 8 320.1 13.80 79.10

4 298.1 12.85 66.25

Portion analyzed: 2320.4 g 2 314.4 13.55 52.70

1 282.3 12.17 40.53

Remarks: 0.5 261.5 11.27 29.26

0.25 260.0 11.21 18.05

0.125 188.5 8.12 9.93

0.0625 154.6 6.66 3.27

<0.0625 75.8 3.27 0.00

TOTAL 2320.2

sediment layer.

d 90 = 13.8 mm

d 84.1 = 10.3 mmd 65 = 3.75 mmd 50 = 1.72 mmd 35 = 0.71 mmd 15.9 = 0.21 mmd g = 1.46 mm

V g 7.03 mm

G = 1.89

Particle Characteristics

Remarks

BVT, AJWNovember 29, 2000Sediments collected during trenching ofArtillery shell fragments found in sample.Poorly sorted sand to pebble-size

SIEVE ANALYSIS

L-3-A4BLR SedimentsAugust 23, 2000the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

Cobble

Pebble

Very fine sand

Silt & clays

013

Size

Class

Boulders

No. of Particles218>100

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

Appendix 2  179
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 3431.3 g 512Tare weight: 110.8 g 256

Net weight: 3320.5 g 64

32

Gravel weight: 49.7 g 16 0.0 0.00 100.00

Sand weight: 1406.0 g 8 7.2 0.48 99.52

4 42.5 2.81 96.71

Portion analyzed: 1513.0 g 2 92.0 6.09 90.62

1 125.8 8.32 82.30

Remarks: 0.5 302.5 20.01 62.29

0.25 493.9 32.68 29.61

0.125 281.7 18.64 10.97

0.0625 110.1 7.28 3.69

<0.0625 55.7 3.69 0.00

TOTAL 1511.4

d 90 = 1.90 mm

d 84.1 = 1.16 mmd 65 = 0.55 mmd 50 = 0.39 mmd 35 = 0.28 mmd 15.9 = 0.15 mmd g = 0.42 mm

V g 2.78 mm

G = 1.18

No. of Particles06211

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWNovember 29, 2000Sediments collected during trenching of

SIEVE ANALYSIS

L-3-A5BLR SedimentsAugust 23, 2000~1/2 sample analyzed, used splitter.Artillery shell fragments found in sample.Poorly sorted sand to pebble-sizesediment layer.

>100

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

180 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 889.4 g 512

Tare weight: 110.8 g 256Net weight: 778.6 g 64

32

Gravel weight: 78.3 g 16 0.0 0.00 100.00

Sand weight: 590.7 g 8 1.2 0.15 99.85

4 77.1 9.92 89.93

Portion analyzed: 778.6 g 2 99.8 12.84 77.09

1 73.4 9.44 67.65

Remarks: 0.5 50.3 6.47 61.18

0.25 46.0 5.92 55.26

0.125 117.8 15.15 40.11

0.0625 203.4 26.16 13.94

<0.0625 108.4 13.94 0.00

TOTAL 777.4

d 90 = 4.02 mm

d 84.1 = 2.92 mmd 65 = 0.75 mmd 50 = 0.20 mmd 35 = 0.11 mmd 15.9 = 0.07 mmd g = 0.44 mm

V g 6.66 mm

G = 2.11

Particle Characteristics

Remarks

BVT, AJWNovember 29, 2000Sediments collected during trenching ofCarbonate present in fine-grainedmaterial.

SIEVE ANALYSIS

L-3-A6BLR SedimentsAugust 23, 2000the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

Cobble

Pebble

Very fine sand

Silt & clays

No. of Particles0

Size

Class

Boulders

1>100

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

Appendix 2  181
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 3968.5 g 512Tare weight: 110.8 g 256

Net weight: 3857.7 g 64

32

Gravel weight: 114.0 g 16 0.0 0.00 100.00Sand weight: 592.2 g 8 10.4 1.37 98.63

4 103.6 13.64 84.99

Portion analyzed: 762.6 g 2 126.5 16.66 68.33

1 74.9 9.86 58.47

Remarks: 0.5 57.6 7.58 50.88

0.25 161.6 21.28 29.60

0.125 112.5 14.81 14.79

0.0625 59.1 7.78 7.01

<0.0625 53.2 7.01 0.00

TOTAL 759.4

sediment layer with some clay.

d 90 = 5.16 mm

d 84.1 = 3.85 mmd 65 = 1.58 mmd 50 = 0.49 mmd 35 = 0.30 mmd 15.9 = 0.13 mmd g = 0.71 mm

V g 5.41 mm

G = 1.70

No. of Particles020>100

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWNovember 29, 2000Sediments collected during trenching of

SIEVE ANALYSIS

L-3-A7BLR SedimentsAugust 23, 2000Artillery shell fragments found in sample.Poorly sorted sand to pebble-size

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

182  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 6161.0 g 512Tare weight: 110.8 g 256

Net weight: 6050.2 g 64

32 0.0 0.00 100.00

Gravel weight: 750.9 g 16 133.6 5.40 94.60Sand weight: 1721.3 g 8 328.4 13.26 81.34

4 288.9 11.67 69.67

Portion analyzed: 2480.8 g 2 351.0 14.18 55.49

1 504.7 20.39 35.11

Remarks: 0.5 602.6 24.34 10.76

0.25 228.4 9.23 1.54

0.125 29.6 1.20 0.34

0.0625 5.0 0.20 0.14

<0.0625 3.5 0.14 0.00

TOTAL 2475.7

sediment layer.

d 90 = 12.6 mm

d 84.1 = 9.24 mmd 65 = 3.18 mmd 50 = 1.66 mmd 35 = 1.00 mmd 15.9 = 0.58 mmd g = 2.31 mm

V g 4.00 mm

G = 1.45

Particle Characteristics

Remarks

BVT, AJWNovember 29, 2000Sediments collected during trenching of ~1/3 sample analyzed, used splitterPoorly sorted sand to pebble-size

SIEVE ANALYSIS

L-3-A8BLR SedimentsAugust 23, 2000the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

Cobble

Pebble

Very fine sand

Silt & clays

015

Size

Class

Boulders

No. of Particles167 & piece of shell casing>100

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

Appendix 2  183
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 7243.5 g 512Tare weight: 110.8 g 256

Net weight: 7132.7 g 64 0.0 0.00 100.00

32 68.2 3.25 96.75

Gravel weight: 1091.3 g 16 229.5 10.95 85.80Sand weight: 1002.8 g 8 468.1 22.32 63.48

4 325.5 15.52 47.95

Portion analyzed: 2102.2 g 2 275.5 13.14 34.81

1 265.3 12.65 22.16

Remarks: 0.5 292.9 13.97 8.19

0.25 139.0 6.63 1.56

0.125 25.7 1.23 0.34

0.0625 4.4 0.21 0.13

<0.0625 2.7 0.13 0.00

TOTAL 2096.8

sediment layer.

d 90 = 20.9 mm

d 84.1 = 15.2 mmd 65 = 8.39 mmd 50 = 4.38 mmd 35 = 2.02 mmd 15.9 = 0.73 mmd g = 3.34 mm

V g 4.55 mm

G = 1.54

No. of Particles0121>100

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWNovember 29, 2000Sediments collected during trenching of

SIEVE ANALYSIS

L-3-A9BLR SedimentsAugust 23, 2000~1/4 sample analyzed; used splitterPoorly sorted sand to pebble-size

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

184  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 1825.3 g 512Tare weight: 110.8 g 256

Net weight: 1714.5 g 64

32

Gravel weight: 19.6 g 16 0.0 0.00 100.00

Sand weight: 930.5 g 8 13.0 1.30 98.70

4 6.6 0.66 98.04

Portion analyzed: 997.9 g 2 9.0 0.90 97.13

1 12.8 1.28 95.85

Remarks: 0.5 62.9 6.30 89.55

0.25 230.1 23.06 66.49

0.125 476.3 47.73 18.77

0.0625 139.4 13.97 4.80

<0.0625 47.9 4.80 0.00

TOTAL 998.0

d 90 = 0.53 mm

d 84.1 = 0.42 mmd 65 = 0.24 mmd 50 = 0.20 mmd 35 = 0.16 mmd 15.9 = 0.11 mmd g = 0.21 mm

V g 1.98 mm

G = 1.00

No. of Particles0644

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWNovember 29, 2000Sediments collected during trenching of

SIEVE ANALYSIS

L-3-A11BLR SedimentsAugust 23, 2000Organic matter present in sample.Well-sorted medium sand.

>100; lots of organicsOrganic matterOrganic matterOrganic matterOrganic matter

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

Appendix 2  185
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 2799.2 g 512Tare weight: 110.8 g 256

Net weight: 2688.4 g 64

32 0.0 0.00 100.00

Gravel weight: 1513.0 g 16 144.4 5.37 94.63Sand weight: 1172.0 g 8 714.5 26.59 68.04

4 654.1 24.34 43.70

Portion analyzed: 2688.4 g 2 559.0 20.80 22.90

1 345.5 12.86 10.04

Remarks: 0.5 194.1 7.22 2.82

0.25 59.8 2.23 0.60

0.125 10.7 0.40 0.20

0.0625 2.9 0.11 0.09

<0.0625 2.4 0.09 0.00

TOTAL 2687.4

sediment layer. 

d 90 = 14.2 mm

d 84.1 = 12.2 mmd 65 = 7.34 mmd 50 = 4.79 mmd 35 = 2.99 mmd 15.9 = 1.37 mmd g = 4.08 mm

V g 2.98 mm

G = 1.23

No. of particles012 -- Pieces of shell casing>100

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWNovember 29, 2000Sediments collected during trenching of

SIEVE ANALYSIS

L-3-A12BLR SedimentsAugust 23, 2000Sediments are red in color -- iron stainingPoorly sorted sand to pebble-size 

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

186  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 4183.2 g 512Tare weight: 110.8 g 256

Net weight: 4072.4 g 64

32

Gravel weight: 25.4 g 16 0.0 0.00 100.00

Sand weight: 1952.0 g 8 4.3 0.22 99.78

4 21.1 1.07 98.72

Portion analyzed: 1983.2 g 2 138.2 6.99 91.73

1 604.4 30.55 61.18

Remarks: 0.5 1003.6 50.73 10.44

0.25 187.8 9.49 0.95

0.125 15.3 0.77 0.18

0.0625 2.7 0.14 0.04

<0.0625 0.8 0.04 0.00

TOTAL 1978.2

d 90 = 1.92 mm

d 84.1 = 1.68 mmd 65 = 1.09 mmd 50 = 0.86 mmd 35 = 0.70 mmd 15.9 = 0.54 mmd g = 0.95 mm

V g 1.77 mm

G = 0.94

Particle Characteristics

Remarks>100

BVT, AJWNovember 29, 2000Sediments collected during trenching of~1/2 of sample analyzed; used splitter.Well-sorted granule layer.

SIEVE ANALYSIS

T-3-A1BLG SedimentsAugust 23, 2000the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

Cobble

Pebble

Very fine sand

Silt & clays

No. of particles0

Size

Class

Boulders

3123

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

Appendix 2  187
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 2003.6 g 512Tare weight: 110.8 g 256

Net weight: 1892.8 g 64

32 0.0 0.00 100.00

Gravel weight: 48.6 g 16 37.7 1.99 98.01

Sand weight: 1841.7 g 8 8.4 0.44 97.56

4 2.5 0.13 97.43

Portion analyzed: 1892.8 g 2 5.5 0.29 97.14

1 18.2 0.96 96.18

Remarks: 0.5 260.7 13.78 82.40

0.25 1320.3 69.76 12.64

0.125 209.9 11.09 1.55

0.0625 27.1 1.43 0.12

<0.0625 2.2 0.12 0.00

TOTAL 1892.5

d 90 = 0.73 mm

d 84.1 = 0.54 mmd 65 = 0.42 mmd 50 = 0.36 mmd 35 = 0.31 mmd 15.9 = 0.26 mmd g = 0.37 mm

V g 1.45 mm

G = 0.85

No. of Particles01412

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWNovember 29, 2000Sediments collected during trenching of

SIEVE ANALYSIS

T-3-A2BLR SedimentsAugust 23, 2000Well-sorted coarse sand layer. 

>100

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

188  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 8187.2 g 512Tare weight: 110.8 g 256

Net weight: 8076.4 g 64

32 0.0 0.00 100.00

Gravel weight: 896.6 g 16 246.7 10.70 89.30Sand weight: 1404.6 g 8 334.8 14.52 74.78

4 315.1 13.67 61.11

Portion analyzed: 2313.3 g 2 412.5 17.89 43.22

1 459.2 19.92 23.30

Remarks: 0.5 215.1 9.33 13.97

0.25 222.5 9.65 4.32

0.125 84.4 3.66 0.66

0.0625 10.9 0.47 0.19

<0.0625 4.3 0.19 0.00

TOTAL 2305.5

d 90 = 16.7 mm

d 84.1 = 12.5 mmd 65 = 4.87 mmd 50 = 2.60 mmd 35 = 1.50 mmd 15.9 = 0.58 mmd g = 2.68 mm

V g = 4.65 mm

G = 1.53

Particle Characteristics

Remarks

BVT, AJWNovember 29, 2000Sediments collected during trenching of~1/4 of sample analyzed; used splitter.Poorly sorted sand to pebble-sizesediment layer.

SIEVE ANALYSIS

T-3-A3BLR sedimentsAugust 23, 2000the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

Cobble

Pebble

Very fine sand

Silt & clays

No. of Particles014

Size

Class

Boulders

194>100

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

Appendix 2  189
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 9421.5 g 512Tare weight: 110.8 g 256

Net weight: 9310.7 g 64 0.0 0.00 100.00

32 178.1 4.86 95.14

Gravel weight: 1889.4 g 16 268.3 7.32 87.82Sand weight: 1743.7 g 8 787.8 21.50 66.31

4 655.2 17.88 48.43

Portion analyzed: 3668.4 g 2 481.9 13.15 35.28

1 285.9 7.80 27.47

Remarks: 0.5 229.8 6.27 21.20

0.25 487.7 13.31 7.89

0.125 205.1 5.60 2.29

0.0625 53.3 1.45 0.84

<0.0625 30.7 0.84 0.00

TOTAL 3663.8

d 90 = 19.7 mm

d 84.1 = 14.2 mmd 65 = 7.60 mmd 50 = 4.25 mmd 35 = 1.95 mmd 15.9 = 0.38 mmd g = 2.32 mm

V g 6.12 mm

G = 1.91

No. of Particles0322>100

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

the Big Lost River. Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWNovember 29, 2000Sediments collected during trenching of

SIEVE ANALYSIS

T-3-A4BLR SedimentsAugust 23, 2000~1/2 of sample analyzed.Poorly sorted sand to pebble-size sediment layer.

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

190 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 2  191

Figure 2–4. Lithology of selected trenches at site 4, Big Lost River upstream of Pioneer diversion structures, Idaho National 

Engineering and Environmental Laboratory, Idaho.

0

1

2

3

4

5

6

7

8

DEPTH

IN FEET 

T-4-A 

113° 03' 40"

43°

31'

35"

113 113° 03' 45" ° 03' 50"

43°

31'

40"

0 100 200 FEET

0 25 50 METERS

EXPLANATION

TRENCH LITHOLOGY

 Silty sand

 Sand, granule, cobbles,

 and boulders

 Basalt bedrock

TRENCH PARTICLE-SAMPLE

 SITE AND IDENTIFIER—

 T, transverse. Particle analyses

 are shown in table 2 and appendix 2

APPROXIMATE BOUNDARY OF

 TOP OF BANK

T-4-A
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 30452.2 g 512Tare weight: 795.5 g 256 0.0 0.00 100.00

Net weight: 29656.7 g 64 1615.6 20.48 79.52

32 898.4 11.39 68.13

Gravel weight: 5620.3 g 16 1208.5 15.32 52.81

Sand weight: 2251.3 g 8 1106.6 14.03 38.78

4 791.2 10.03 28.75

Portion analyzed: 7895.8 g 2 601.5 7.63 21.13

1 556.6 7.06 14.07

Remarks: 0.5 689.7 8.74 5.33

0.25 304.1 3.86 1.47

0.125 74.8 0.95 0.52

0.0625 24.6 0.31 0.21

<0.0625 16.8 0.21 0.00

TOTAL 7888.4

d 90 = 130 mm

d 84.1 = 87.3 mmd 65 = 27.8 mmd 50 = 13.9 mmd 35 = 6.16 mmd 15.9 = 1.20 mmd g = 10.2 mm

V g = 8.53 mm

G = 2.11

No. of Particles02583>100

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

~1/4 of sample analyzed.sediment layer.

SIEVE ANALYSIS

T-4-A1BLR SedimentsJune 21, 2001

Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWJune 26, 2001Sediments collected during trenching ofthe Big Lost River.Poorly sorted sand to cobble-size

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.1 1 10 100 1000

Sediment size (mm)

Percent Finer

SA

192  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Figure 2–5. Lithology of selected trenches at site 4, Big Lost River upstream of Pioneer diversion structures, Idaho National 

Engineering and Environmental Laboratory, Idaho.

EXPLANATION

TRENCH LITHOLOGY

 Silty sand

 Sand, granule, cobbles,

 and boulders

 Basalt bedrock

TRENCH PARTICLE-SAMPLE

 SITE AND IDENTIFIER—

 T, transverse. Particle analyses

 are shown in table 2 and appendix 2

APPROXIMATE BOUNDARY OF

 TOP OF BANK

T-4-A

0

1

2

3

4

5

6

7

DEPTH

IN FEET

113° 03' 05"

43°

31'

50"

113 113° 03' 10" ° 03' 15"

T-5-A

0 100 200 FEET

0 25 50 METERS

Appendix 2  193
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 34634.3 g 512Tare weight: 929.8 g 256

Net weight: 33704.5 g 64 0.0 0.00 100.00

32 2382.7 26.74 73.26

Gravel weight: 6187.2 g 16 1562.3 17.53 55.73

Sand weight: 2715.3 g 8 1344.4 15.09 40.64

4 897.8 10.08 30.56

Portion analyzed: 8919.0 g 2 629.5 7.06 23.50

1 570.1 6.40 17.10

Remarks: 0.5 957.9 10.75 6.35

0.25 463.2 5.20 1.15

0.125 78.4 0.88 0.27

0.0625 16.2 0.18 0.09

<0.0625 8.1 0.09 0.00

TOTAL 8910.6

d 90 = 49.4 mm

d 84.1 = 42.4 mmd 65 = 23.1 mmd 50 = 12.3 mmd 35 = 5.43 mmd 15.9 = 0.93 mmd g = 6.28 mm

V g = 6.75 mm

G = 2.04

No. of particles01597>100

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

~1/4 of sample analyzed.sediment layer.

SIEVE ANALYSIS

T-5-A1BLR SedimentsJune 21, 2001

Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWJune 26, 2001Sediments collected during trenching ofthe Big Lost River.Poorly sorted sand to pebble-size 

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10 100

Sediment size (mm)

Percent Finer

S5-A

194  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Sieve Cumulative

Size Weight Percent Percent

(mm) (g) Finer Finer

Sample ID:Location:Date/Time:

8192

Analyzed by: 4096Date/Time: 2048

1024

Gross weight: 1868.8 g 512Tare weight: 110.2 g 256

Net weight: 1758.6 g 64

32

Gravel weight: 12.6 g 16Sand weight: 528.0 g 8 0.0 0.00 100.00

4 12.6 2.19 97.81

Portion analyzed: 575.9 g 2 24.5 4.26 93.55

1 60.7 10.55 82.99

Remarks: 0.5 97.9 17.02 65.97

0.25 133.0 23.13 42.84

0.125 121.2 21.07 21.77

Poorly sorted sand to pebble-size 0.0625 90.7 15.77 6.00

<0.0625 34.5 6.00 0.00

TOTAL 575.1

d 90 = 1.58 mm

d 84.1 = 1.08 mmd 65 = 0.49 mmd 50 = 0.31 mmd 35 = 0.19 mmd 15.9 = 0.097 mmd g = 0.32 mm

V g = 3.34 mm

G = 1.29

>100 (50% consolidated clay

No. of particles060 (30% consolidated clay)

Size

Class

Boulders

Cobble

Pebble

Very fine sand

Silt & clays

SIEVE ANALYSIS

T-5-A2BLR SedimentsJune 21, 2001

Medium sand

Fine sand

Very coarse sand

Granule

Coarse sand

BVT, AJWJune 26, 2001Sediments collected during trenching ofthe Big Lost River.

60% consolidated clay & silt

80% consolidated clay & silt

sediiment layer.

Particle Characteristics

Remarks

Cumulative Semilogarithmic Size 

0

80604020

100

0.01 0.1 1 10

Sediment size (mm)

Percent Finer

S5-B

Appendix 2  195
This page intentionally left blank.

196  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 3  197

Appendix 3 

Field-Surveyed Map of the Saddle Area at Site 1 on the Big Lost River 

Upstream of the Pioneer Diversion Structures, Idaho National Engineering and 

Environmental Laboratory
Figure 3–1. Location of the saddle area elevation-sampling sites at site 1 on the Big Lost River upstream of Pioneer diversion 

structures, Idaho National Engineering and Environmental Laboratory, Idaho.

33.82

33.98

36.31

37.23 34.06

36.52

36.15

32.78

34.01

34.01

35.38

34.56

32.07 30.59

28.22

28.17

31.52

35.05

34.66

34.65

34.60

33.11

31.52

31.51

32.73

33.67 33.38 33.92

33.66 31.65

29.79

27.67

28.03

32.75

29.77 29.81

29.34 33.15

29.53

33.21 33.93

33.78

33.72

31.41

32.29

33.28

31.37

29.10

28.49

28.51

28.61 28.62

29.01

35.54

34.66

34.81

33.69

33.64

35.03

36.26

35.32

35.99

36.56

35.67

34.92

28.62

31.89

35.84

36.34

35.31

113° 03' 27" 03' 26" 03' 25" 03' 24" 03' 23" 03' 22" 113° 03' 21"

43° 31' 52"

31' 51"

31' 50"

31' 49"

31' 48"

31' 47"

31' 46"

43° 31' 45"

0 100 200 FEET

0 25 50 METERS

Base from Dean Ostenaa (Bureau of 

Reclamation; aerial photographs,

 written commun., 2001).

EXPLANATION 

ELEVATON-SAMPLING SITE

 AND ELEVATION—Add

 5,000 feet to get total

 elevation number. Lowest

 elevation is on the saddle ridge

 in the saddle area. Datum

 is North American Vertical

 Datum of 1988

APPROXIMATE BOUNDARY OF

 THE LEFT BANK OF BIG LOST

 RIVER

Saddle

area

32.29

198  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 3  199

Land-surface points GPSed in the Saddle area of the INEEL (Shaded points denote points 

within Saddle area). See previous figure for location of points and saddle area. See 

appendix figure 3-1 for location of saddle area to the study area. 

[Latitude and longitude, in degrees (o), minutes (’), and seconds (”), are based on the North American Datum of 1983; 

land-surface elevations are based on the North American Vertical Datum of 1988] 

Field no. Latitude Longitude

Land-surface

elevation (feet) 

1 43o

 31’ 44.390520” 113o 03’ 23.499555” 5,034.65

2 43o

 31’ 43.901199” 113o 03’ 23.486698” 5,033.66

3 43o

 31’ 43.496611” 113o 03’ 23.465170” 5,033.93

4 43o

 31’ 42.929625” 113o 03’ 23.414791” 5,033.78

5 43o

 31’ 42.240115” 113o 03’ 23.601051” 5,034.66

6 43 o 31’ 43.462634” 113 o 03’ 23.914255” 5,032.75

7 43 o 31’ 43.437876” 113 o 03’ 22.874606” 5,033.21

1402 43o

 31’ 41.892714” 113o 03’ 25.817010” 5,028.49

1403 43o

 31’ 41.700719” 113o 03’ 25.546928” 5,028.61

1404 43o

 31’ 41.381800” 113o 03’ 25.007009” 5,034.92

1405 43o

 31’ 40.979651” 113o 03’ 24.623281” 5,035.99

1406 43o

 31’ 40.826262” 113o 03’ 24.198113” 5,036.26

1407 43o

 31’ 40.702427” 113o 03’ 23.562208” 5,035.32

1408 43o

 31’ 40.650549” 113o 03’ 22.917951” 5,033.69

1409 43o

 31’ 41.163888” 113o 03’ 22.498980” 5,033.64

1410 43o

 31’ 41.376313” 113o 03’ 23.051822” 5,035.03

1411 43o

 31’ 41.587658” 113o 03’ 23.524103” 5,035.54

1412 43o

 31’ 41.871904” 113o 03’ 24.150855” 5,034.81

1413 43o

 31’ 42.220892” 113o 03’ 24.708473” 5,029.01

1414 43o

 31’ 42.532173” 113o 03’ 25.152051” 5,029.11

1415 43o

 31’ 42.967764” 113o 03’ 24.924155” 5,029.53

1416 43o

 31’ 42.869201” 113o 03’ 24.289355” 5,029.34

1417 43o

 31’ 42.766289” 113o 03’ 23.849702” 5,033.15

1418 43o

 31’ 42.645601” 113o 03’ 23.223508” 5,033.72

1419 43o

 31’ 42.675940” 113o 03’ 22.600929” 5,033.28

1420 43o

 31’ 42.882702” 113o 03’ 21.925800” 5,031.37

1421 43o

 31’ 43.395043” 113o 03’ 22.008337” 5,031.41

1422 43o

 31’ 43.425152” 113o 03’ 22.480975” 5,032.29

1423 43o

 31’ 43.426917” 113o 03’ 24.245954” 5,029.77

1424 43o

 31’ 43.374137” 113o 03’ 24.895574” 5,029.81

1425 43o

 31’ 43.885301” 113o 03’ 25.177827” 5,027.67

1426 43o

 31’ 44.015599” 113o 03’ 24.615400” 5,029.79

1427 43o

 31’ 44.044086” 113o 03’ 24.186861” 5,031.65

1428 43o

 31’ 44.056980” 113o 03’ 23.893684” 5,033.38

1429 43o

 31’ 44.112055” 113o 03’ 23.512476” 5,033.92

1430 43o

 31’ 44.189928” 113o 03’ 22.884283” 5,033.67

1431 43o

 31’ 44.265052” 113o 03’ 22.275899” 5,032.73

1432 43o

 31’ 44.477261” 113o 03’ 21.738004” 5,031.52

1433 43o

 31’ 44.932760” 113o 03’ 21.963346” 5,031.51
200 Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho

1434 43o

 31’ 44.840983” 113o 03’ 22.563704” 5,033.11

1435 43o

 31’ 44.748063” 113o 03’ 23.016536” 5,034.60

1436 43o

 31’ 44.683994” 113o 03’ 23.542476” 5,034.66

1437 43o

 31’ 44.632239” 113o 03’ 23.986205” 5,035.05

1438 43o

 31’ 44.446866” 113o 03’ 24.593131” 5,031.52

1439 43o

 31’ 44.264159” 113o 03’ 25.243131” 5,028.03

1440 43o

 31’ 44.568154” 113o 03’ 25.816542” 5,028.17

1441 43o

 31’ 44.942268” 113o 03’ 25.331705” 5,032.07

1442 43o

 31’ 45.215596” 113o 03’ 24.824076” 5,034.01

1443 43o

 31’ 45.457830” 113o 03’ 24.472409” 5,035.38

1444 43o

 31’ 45.733164” 113o 03’ 23.979734” 5,036.52

1445 43o

 31’ 45.877906” 113o 03’ 23.582829” 5,034.06

1446 43o

 31’ 45.284955” 113o 03’ 24.118903” 5,036.52

1447 43o

 31’ 45.137956” 113o 03’ 24.343990” 5,036.15

1448 43o

 31’ 46.412314” 113o 03’ 24.659299” 5,033.82

1449 43o

 31’ 46.203697” 113o 03’ 24.708019” 5,033.98

1450 43o

 31’ 46.055273” 113o 03’ 24.793510” 5,036.31

1451 43o

 31’ 45.951375” 113o 03’ 24.833764” 5,037.23

1452 43o

 31’ 45.554673” 113o 03’ 25.079404” 5,034.56

1453 43o

 31’ 45.175142” 113o 03’ 25.445438” 5,032.78

1454 43o

 31’ 44.903310” 113o 03’ 25.796107” 5,030.59

1455 43o

 31’ 44.692546” 113o 03’ 26.066813” 5,028.22

1456 43o

 31’ 41.967825” 113o 03’ 25.771712” 5,028.51

1457 43o

 31’ 41.716390” 113o 03’ 25.523144” 5,028.62

1458 43o

 31’ 41.264079” 113o 03’ 25.168218” 5,035.67

1459 43o

 31’ 40.865486” 113o 03’ 24.744063” 5,036.56

1460 43o

 31’ 40.117261” 113o 03’ 25.043463” 5,035.31

1461 43o

 31’ 40.299931” 113o 03’ 25.564767” 5,036.34

1462 43o

 31’ 40.534201” 113o 03’ 26.004518” 5,035.84
Appendix 4  201

Appendix 4

HEC-RAS, HEC-6, and TRIM2D Model Results for a Peak Flow of 100 Cubic 

Meters per Second on the Big Lost River Upstream of the Pioneer Diversion 

Structures, Idaho National Engineering and Environmental Laboratory
Appendix 4–1. HEC-RAS simulation at a flow of 100 cubic meters per second

[Abbreviations: W.S. elev, water-surface elevation; Vel chnl, average flow velocity in channel; ft, foot; ft/s, foot per second; W/m2, watt per squared meter]

Cross 

section

W.S. elev 

(ft)

Thalweg 

(ft)

Flow depth 

(ft)

Vel chnl 

(ft)

Stream 

power 

(W/m2)

108 5,033.4 5,025.8 7.6 4.06 13.0

107 5,033.0 5,025.4 7.6 4.21 15.4

106 5,032.8 5,024.5 8.3 4.12 15.6

105 5,032.6 5,023.5 9.1 4.10 16.2

104 5,032.1 5,022.9 9.2 4.60 20.8

103 5,031.7 5,023.4 8.3 5.12 18.7

102 5,031.7 5,023.3 8.4 4.04 10.0

101 5,031.7 5,023.8 7.8 3.16 5.5

100 5,031.6 5,023.7 7.9 3.19 4.2

99 5,031.5 5,022.1 9.4 2.91 6.4

98 5,031.5 5,022.9 8.6 2.57 4.5

97 5,031.5 5,022.1 9.4 2.08 3.6

96 5,031.4 5,021.6 9.8 2.97 7.8

95 5,030.8 5,021.9 8.9 5.41 19.7

93 5,030.0 5,020.9 9.1 3.25 14.7

90 5,029.1 5,020.5 8.6 4.28 30.0

86 5,028.5 5,018.1 10.4 4.05 20.1

85 5,028.4 5,017.3 11.1 4.66 23.8

84 5,026.7 5,015.2 11.5 10.77 193.3

83 5,027.1 5,015.0 12.1 8.64 90.8

82 5,027.3 5,017.3 10.0 7.09 49.7

81 5,027.1 5,017.3 9.8 7.67 108.6

80 5,027.2 5,017.9 9.3 5.81 26.3

79 5,027.1 5,016.5 10.6 6.04 30.0

78 5,027.1 5,015.6 11.5 5.76 26.9

77 5,026.8 5,016.7 10.1 6.07 31.9

76.5 5,026.4 5,016.7 9.7 7.51 60.3

76 5,026.2 5,016.1 10.1 7.10 50.8

75 5,026.2 5,015.9 10.3 5.48 24.0

74 5,026.3 5,014.7 11.6 3.95 15.6

73 5,026.2 5,015.3 10.9 3.81 7.8

72 5,026.0 5,014.7 11.3 4.56 12.6

71 5,025.6 5,015.2 10.4 5.94 30.3

70.5 5,025.1 5,014.5 10.6 6.95 50.7

70 5,024.5 5,014.0 10.5 7.50 62.4

69 5,024.0 5,013.9 10.1 7.02 85.0

68 5,024.2 5,012.1 12.1 4.57 26.0

67 5,024.3 5,012.6 11.7 3.38 5.9

66 5,024.2 5,010.8 13.4 3.96 8.7

65 5,024.2 5,010.9 13.3 3.59 6.3

64 5,024.1 5,013.4 10.7 4.30 11.3

63 5,023.9 5,012.3 11.6 5.06 31.8

62 5,023.9 5,013.0 10.9 3.93 9.8

61 5,023.9 5,012.3 11.6 3.49 6.1

Cross 

section

W.S. elev 

(ft)

Thalweg 

(ft)

Flow depth 

(ft)

Vel chnl 

(ft)

Stream 

power 

(W/m2)

60.5 5,023.9 5,012.1 11.8 2.75 4.8

60 5,023.8 5,011.6 12.2 4.01 8.2

59 5,023.8 5,007.8 16.0 3.45 6.5

58 5,023.7 5,009.3 14.4 4.34 10.1

57 5,023.7 5,010.4 13.3 3.84 12.3

56 5,023.6 5,008.8 14.8 5.04 26.5

55 5,023.6 5,008.3 15.3 5.00 14.6

54 5,023.4 5,006.2 17.2 5.96 46.1

53 5,022.8 5,005.5 17.3 8.49 142.5

52.5 5,021.8 5,005.7 16.1 11.28 340.8

52 5,018.6 5,005.9 12.7 17.50 1,384.3

51.75 5,015.1 5,006.9 8.2 22.31 3,008.6

51.5 5,020.7 5,007.9 12.8 9.12 179.7

51.25 5,020.9 5,008.8 12.1 7.61 103.3

51 5,021.1 5,009.7 11.4 6.74 72.8

50.5 5,020.8 5,009.4 11.4 7.74 114.1

50 5,019.5 5,009.2 10.3 11.77 608.1

49.5 5,019.7 5,009.3 10.4 9.55 234.2

49 5,019.9 5,009.4 10.5 7.82 126.7

48 5,020.0 5,009.4 10.6 7.16 88.8

47 5,020.1 5,011.0 9.1 5.58 40.7

46 5,020.1 5,010.5 9.6 5.05 30.2

45 5,020.1 5,010.3 9.8 4.61 24.2

44 5,019.8 5,009.6 10.2 5.65 42.9

43 5,018.9 5,009.9 9.0 8.02 163.9

42 5,018.6 5,009.3 9.3 7.40 132.8

41 5,018.5 5,009.1 9.4 6.45 88.5

40 5,018.6 5,009.7 8.9 5.04 39.0

36 5,018.6 5,008.7 9.9 4.30 22.6

35 5,018.6 5,008.4 10.2 3.80 15.0

34 5,018.3 5,007.9 10.4 5.26 41.5

33 5,018.1 5,007.2 10.9 6.72 82.4

32 5,017.9 5,007.7 10.2 6.79 69.4

31 5,018.0 5,006.6 11.4 5.12 20.9

30 5,017.8 5,007.2 10.6 5.74 26.0

29 5,017.4 5,007.7 9.7 7.09 43.5

28 5,017.2 5,007.4 9.8 7.62 54.5

26 5,017.0 5,007.4 9.6 7.71 55.1

23 5,016.7 5,006.6 10.1 7.02 54.3

20 5,016.1 5,006.2 9.9 7.21 44.2

13 5,015.9 5,005.5 10.4 6.35 25.9

8 5,015.7 5,004.9 10.8 4.65 137.1

3 5,014.1 5,002.0 12.1 8.36 175.7

1 5,011.4 4,998.7 12.7 13.22 636.7

202  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 4  203

Appendix 4–2. HEC-6 simulation at a flow of 100 cubic meters per second

[Abbreviations: W.S. elev, water-surface elevation; Vel chnl, average flow velocity in channel; ft, foot; ft/s, foot per second; W/m2, watt per squared meter]

Cross 

section

W.S. elev 

(ft)

Thalweg 

(ft)

Flow 

depth (ft)

Vel chnl 

(ft)

Stream 

power 

(W/m2)

108 5,034.20 5,027.90 6.30 2.89

107 5,033.70 5,024.60 9.10 2.75

106 5,033.30 5,024.30 9.00 2.97

105 5,033.20 5,023.00 10.20 3.01

104 5,032.60 5,022.10 10.50 3.18

103 5,032.10 5,022.30 9.80 3.60

102 5,031.50 5,024.10 7.40 4.47

101 5,031.30 5,025.50 5.80 3.97

100 5,031.30 5,026.00 5.30 2.85

99 5,031.30 5,022.20 9.10 2.57

98 5,031.30 5,023.10 8.20 2.28 5

97 5,031.30 5,022.10 9.20 2.38

96 5,031.20 5,021.40 9.80 2.91

95 5,030.90 5,020.90 10.00 3.98

93 5,030.10 5,019.10 11.00 2.73

90 5,028.40 5,020.00 8.40 5.48

86 5,027.50 5,017.00 10.50 4.32

85 5,027.30 5,016.70 10.60 5.08

84 5,026.50 5,011.10 15.40 8.25 339

83 5,026.60 5,010.50 16.10 7.49

82 5,026.50 5,015.40 11.10 7.52

81 5,026.30 5,015.00 11.30 7.20

80 5,026.60 5,014.10 12.50 4.90

79 5,026.00 5,016.60 9.40 6.97

78 5,026.10 5,012.40 13.70 6.00

77 5,025.90 5,014.50 11.40 5.60

76.5 5,025.80 5,013.10 12.70 6.44

76 5,025.70 5,012.70 13.00 6.08 46

75 5,025.20 5,017.00 8.20 6.92

74 5,025.50 5,011.60 13.90 4.03

73 5,025.00 5,018.70 6.30 5.91

72 5,025.00 5,012.10 12.90 4.89 24

71 5,024.50 5,013.00 11.50 6.53

70.5 5,024.20 5,010.90 13.30 6.29

70 5,023.70 5,011.90 11.80 7.51

69 5,023.50 5,011.60 11.90 6.47

68 5,023.30 5,015.30 8.00 6.27

67 5,023.50 5,012.60 10.90 3.96

66 5,023.20 5,012.10 11.10 5.57

65 5,023.30 5,010.90 12.40 4.11

64 5,022.90 5,015.00 7.90 6.22

63 5,022.80 5,010.60 12.20 5.83

62 5,022.70 5,013.00 9.70 5.72

61 5,022.60 5,014.00 8.60 5.48

Cross 

section

W.S. elev 

(ft)

Thalweg 

(ft)

Flow 

depth (ft)

Vel chnl 

(ft)

Stream 

power 

(W/m2)

60.5 5,022.50 5,016.70 5.80 4.49

60 5,022.50 5,010.40 12.10 4.86

59 5,022.30 5,009.00 13.30 5.57

58 5,022.30 5,008.90 13.40 5.36

57 5,022.30 5,011.30 11.00 5.73

56 5,022.10 5,008.40 13.70 6.23 54

55 5,022.00 5,007.10 14.90 6.23

54 5,021.90 5,003.10 18.80 6.50

53 5,021.60 5,002.10 19.50 9.82

52.5 5,020.90 5,001.10 19.80 11.39

52 5,020.30 5,001.60 18.70 12.46 3,440

51.75 5,019.80 5,002.10 17.70 9.33

51.5 5,020.50 5,003.30 17.20 7.24

51.25 5,020.90 5,004.50 16.40 6.17

51 5,021.00 5,005.70 15.30 5.21

50.5 5,021.20 5,006.90 14.30 6.59

50 5,020.90 5,007.50 13.40 8.81

49.5 5,020.30 5,008.10 12.20 6.25

49 5,020.60 5,006.30 14.30 5.36

48 5,020.70 5,004.50 16.20 6.34

47 5,020.50 5,009.40 11.10 3.91

46 5,020.80 5,007.20 13.60 5.42

45 5,020.50 5,011.50 9.00 4.21

44 5,020.60 5,010.30 10.30 5.07

43 5,020.40 5,008.70 11.70 6.13

42 5,020.00 5,008.90 11.10 5.15 40

41 5,020.00 5,008.30 11.70 4.85

40 5,020.00 5,009.10 10.90 5.78

36 5,019.90 5,012.80 7.10 8.08

35 5,019.50 5,012.90 6.60 3.90

34 5,019.70 5,013.90 5.80 5.40

33 5,019.50 5,013.10 6.40 5.39 41

32 5,019.50 5,007.10 12.40 4.60

31 5,019.40 5,007.80 11.60 3.61

30 5,019.40 5,005.40 14.00 4.17

29 5,019.20 5,006.40 12.80 5.55

28 5,019.00 5,007.90 11.10 5.68

26 5,018.90 5,006.70 12.20 4.76

23 5,019.00 5,006.10 12.90 5.75

20 5,018.50 5,005.00 13.50 5.08 64

13 5,017.60 5,005.60 12.00 4.10

8 5,017.10 5,007.10 10.00 6.83

3 5,015.80 5,003.80 12.00 6.63

1 5,014.90 5,000.30 14.60 13.23
Appendix 4–3. TRIM2D simulation at a flow of 100 cubic meters per second

[Abbreviations: W.S. elev, water-surface elevation; ft, foot; ft/s, foot per second; W/m2, watt per squared meter]

Cross 

section

W.S. elev 

(ft)

Thalweg 

(ft)

Flow 

depth (ft)

Velocity (ft/s) Stream power (W/m2)

Thalweg Channel Overbank Used Thalweg Channel Overbank Used Remarks

108 5,032.94 5,027.49 5.45 5.96 6.61 – 5.96 111.5 – – 111.5

107 5,032.94 5,025.49 7.45 5.15 5.68 – 5.15 43.3 57.5 58.0 57.5 Left bank

106 5,032.64 5,025.49 7.15 4.36 – 6.59 4.36 88.5 – – 88.5 Meander (left 

bank)

105 5,032.02 5,025.49 6.53 5.43 – 8.49 5.43 100.4 195.1 – 195.1 Meander (left 

bank)

104 5,031.79 5,025.49 6.30 8.16 – 8.44 8.16 153.8 196.3 – 196.3 Meander (left 

bank)

103 5,031.33 5,023.49 7.84 5.48 7.58 – 5.48 55.8 130.4 – 130.4

102 5,031.43 5,023.49 7.94 5.99 6.83 – 5.99 65.8 110.9 – 110.9

101 5,031.30 5,025.49 5.81 5.85 6.13 – 5.85 66.2 76.6 – 76.6

100 5,031.20 5,023.72 7.48 5.01 5.04 – 5.01 38.4 47.1 87.1 47.1 Right bank

99 5,031.13 5,023.49 7.64 2.83 – 5.03 2.83 6.9 30.2 51.3 30.2 Right bank

98 5,031.20 5,023.49 7.71 2.14 – 4.10 2.14 3.0 9.5 26.5 9.5 Right bank

97 5,031.23 5,023.49 7.74 0.82 – 3.85 0.82 0.2 8.1 20.7 8.1 Right bank

96 5,031.16 5,023.49 7.67 1.90 – 3.87 1.90 2.9 14.4 20.8 14.4 Right bank

95 5,030.84 5,023.49 7.35 4.42 – 5.52 4.42 31.1 51.6 – 51.6 Right bank

93 5,030.34 5,023.49 6.85 4.83 6.24 – 4.83 35.4 98.8 – 98.8 Right bank

90 5,030.25 5,021.49 8.76 3.19 – 5.07 3.19 9.4 10.6 72.8 10.6 Left bank

86 5,029.43 5,021.49 7.94 5.58 – 9.41 5.58 52.0 417.8 – 417.8 Right bank

85 5,028.90 5,018.24 10.66 7.86 8.01 – 7.86 132.5 147.3 – 147.3

84 5,028.41 5,017.48 10.93 8.91 9.04 – 8.91 189.8 258.8 – 258.8

83 5,028.34 5,017.48 10.86 8.88 9.12 – 8.88 188.6 229.4 – 229.4

82 5,028.31 5,017.48 10.83 8.31 8.57 – 8.31 154.6 185.2 – 185.2

81 5,027.85 5,019.48 8.37 9.45 – 10.66 9.45 247.3 425.5 – 425.5 Left bank

80 5,028.04 5,019.48 8.56 7.63 7.73 – 7.63 128.9 134.6 – 134.6

79 5,027.62 5,019.48 8.14 8.69 – – 8.69 195.0 202.0 – 202.0

78 5,027.65 5,017.48 10.17 7.15 8.05 – 7.15 112.4 149.8 – 149.8

77 5,027.36 5,017.48 9.88 7.09 7.41 – 7.09 99.1 112.8 – 112.8

76 5,027.36 5,017.48 9.88 5.85 7.22 – 5.85 55.5 104.6 – 104.6

76.5 5,027.39 5,017.48 9.91 5.23 6.67 – 5.23 39.8 82.3 – 82.3

75 5,027.33 5,015.48 11.85 5.89 6.07 – 5.89 53.5 58.4 – 58.4

74 5,027.33 5,015.47 11.86 5.68 5.88 – 5.68 51.0 56.5 – 56.5

73 5,027.46 5,015.48 11.98 3.84 4.52 – 3.84 14.8 25.4 – 25.4

72 5,027.42 5,017.48 9.94 2.54 4.29 – 2.54 4.5 21.9 – 21.9

71 5,027.29 5,015.48 11.81 4.19 4.42 – 4.19 19.2 23.1 42.6 23.1 Right bank

70.5 5,026.67 5,017.48 9.19 7.13 7.14 – 7.13 103.3 – 124.8 103.3 Right bank

70 5,025.55 5,017.48 8.07 9.39 9.90 – 9.39 258.8 289.3 – 289.3

69 5,025.09 5,015.68 9.41 8.77 – 10.37 8.77 237.3 336.9 – 336.9 Right bank

68 5,024.41 5,014.27 10.14 8.55 – 10.79 8.55 170.1 448.8 – 448.8 Left bank

67 5,024.18 5,015.48 8.70 8.08 – 10.09 8.08 152.7 381.9 – 381.9 Left bank

66 5,024.34 5,013.55 10.79 8.50 8.74 – 8.50 180.6 212.2 – 212.2

65 5,024.41 5,013.15 11.26 8.03 8.10 – 8.03 138.4 139.7 – 139.7

64 5,024.37 5,014.07 10.30 7.07 7.20 – 7.07 97.1 101.3 – 101.3

63 5,023.81 5,015.48 8.33 8.09 – – 8.09 155.7 – – 155.7

62 5,023.91 5,015.48 8.43 7.00 7.20 – 7.00 101.0 115.2 – 115.2

61 5,023.95 5,015.48 8.47 6.28 7.11 – 6.28 72.6 105.4 – 105.4

60.5 5,024.01 5,015.48 8.53 5.86 6.13 – 5.86 58.7 67.1 – 67.1

60 5,023.91 5,013.51 10.40 5.58 6.38 – 5.58 49.4 71.3 – 71.3

59 5,023.75 5,011.48 12.27 6.48 6.49 – 6.48 70.3 87.2 – 87.2

58 5,023.78 5,011.48 12.30 6.21 – – 6.21 62.9 – – 62.9

57 5,023.85 5,011.64 12.21 4.46 5.70 – 4.46 20.3 50.3 53.3 50.3 Left bank

56 5,023.65 5,013.48 10.17 6.59 6.83 – 6.59 78.9 91.6 – 91.6

204  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Appendix 4  205

Cross 

section

W.S. elev 

(ft)

Thalweg 

(ft)

Flow 

depth (ft)

Velocity (ft/s) Stream power (W/m2)

Thalweg Channel Overbank Used Thalweg Channel Overbank Used Remarks

55 5,023.39 5,013.48 9.91 7.44 – – 7.44 138.1 – – 138.1

54 5,022.73 5,011.71 11.02 10.70 – 12.76 10.70 326.4 – – 326.4 Right bank

53 5,022.31 5,011.60 10.71 12.71 – 13.69 12.71 558.5 – – 558.5 Left bank

52.5 5,021.75 5,011.48 10.27 12.14 – – 12.14 389.9 407.4 – 407.4

52 5,021.75 5,011.48 10.27 10.03 – 15.52 10.03 327.1 – 1,841.0 327.1 Right bank

51.75 5,021.68 5,011.48 10.20 9.56 11.67 – 9.56 241.1 302.5 1,038.0 302.5 Right bank

51.5 5,021.72 5,011.48 10.24 9.73 10.48 – 9.73 316.0 – – 316.0

51.25 5,021.85 5,011.48 10.37 10.57 10.62 – 10.57 323.2 – – 323.2

51 5,021.94 5,011.48 10.46 10.63 – – 10.63 327.7 – – 327.7

50.5 5,021.91 5,011.48 10.43 10.78 – – 10.78 342.1 – – 342.1

50 5,021.81 5,011.48 10.33 11.23 11.53 – 11.23 387.8 425.0 – 425.0

49.5 5,021.81 5,011.54 10.27 10.83 – – 10.83 351.9 – – 351.9

49 5,021.75 5,011.48 10.27 10.36 10.66 – 10.36 307.7 333.9 – 333.9

48 5,021.85 5,011.48 10.37 10.15 10.19 – 10.15 287.4 291.6 – 291.6

47 5,021.94 5,011.51 10.43 9.10 9.79 – 9.10 211.3 260.3 – 260.3

46 5,021.98 5,011.51 10.47 8.61 – – 8.61 176.5 – – 176.5

45 5,022.01 5,011.64 10.37 8.32 – – 8.32 164.1 – – 164.1

44 5,021.91 5,013.48 8.43 6.86 7.21 – 6.86 94.5 110.1 – 110.1

43 5,021.72 5,011.58 10.14 4.56 – 7.67 4.56 26.8 136.5 149.0 136.5 Right bank

42 5,021.49 5,011.48 10.01 2.54 – 8.26 2.54 9.1 146.7 226.6 146.7 Right bank

41 5,021.55 5,011.48 10.07 5.59 – 8.03 5.59 48.2 115.1 226.9 115.1 Right bank

40 5,020.99 5,011.48 9.51 1.02 – 8.26 1.02 0.3 20.1 201.0 20.1 Left bank

36 5,020.96 5,011.48 9.48 0.94 – 8.36 0.94 0.2 16.7 217.4 16.7 Left bank

35 5,020.99 5,011.48 9.51 0.91 – 8.75 0.91 0.2 40.3 252.4 40.3 Left bank

34 5,020.93 5,010.89 10.04 5.81 – 9.13 5.81 56.0 120.3 299.9 120.3 Left bank

33 5,020.83 5,009.90 10.93 5.35 – 9.15 5.35 41.1 101.6 288.8 101.6 Left bank

32 5,020.93 5,009.48 11.45 4.39 – 8.74 4.39 22.5 88.7 238.4 88.7 Left bank

31 5,020.67 5,009.48 11.19 3.33 – 6.38 3.33 9.9 54.9 75.8 54.9 Right bank

30 5,020.14 5,010.69 9.45 5.48 – 7.48 5.48 50.1 114.9 – 114.9 Right bank

29 5,020.21 5,011.18 9.03 6.34 7.49 – 6.34 72.1 121.7 – 121.7

28 5,019.98 5,011.48 8.50 6.21 – 7.95 6.21 69.8 97.8 146.0 97.8 Right bank

26 5,019.58 5,011.48 8.10 7.97 – 8.57 7.97 154.1 173.5 187.0 173.5 Right bank

23 5,019.02 5,010.30 8.72 6.69 – 8.57 6.69 102.2 181.7 – 181.7 Right bank

20 5,018.70 5,009.48 9.22 2.50 – 7.98 2.50 7.9 139.2 144.7 139.2 Right bank

13 5,018.30 5,011.50 6.80 3.67 – 8.25 3.67 20.7 109.5 189.4 109.5 Right bank

8 5,018.04 5,007.48 10.56 4.10 – 6.77 4.10 33.2 43.8 103.9 43.8 Right bank

3 5,016.10 5,007.57 8.53 5.30 – 11.41 5.30 68.8 367.6 484.3 367.6 Right bank

1 5,013.02 5,005.90 7.12 2.66 – 23.59 2.66 38.4 – 4,141.2 38.4 Right bank

Appendix 4–3. TRIM2D simulation at a flow of 100 cubic meters per second—Continued

[Abbreviations: W.S. elev, water-surface elevation; ft, foot; ft/s, foot per second; W/m2, watt per squared meter]
y

Calculation of TRIM2D inflow into model reach (upstream of HEC-RAS model reach)

Simulated Q = 100 m3/s)

Variables

v1 = x coordinate in metersv2 = y coordinate in metersv3 = Zv4 = etav5 = uv6 = vv7 = H in meters

p = Power W/m2

z = land-surface elevation in feet

eta = water-surface elevation in feet

distance= distance across the section

Distance Resultant velocit

v1 v2 v3 v4 v5 v6 v7 p z eta (m) (ft) (m/s) (ft/s) Depth (ft) Area (ft2) Qi (ft3/s)

511.4702 286.4551 16.76 16.75045 0.018004 -0.000228 0 0.000208 5045.987 5045.956 0 0 0 0 0 0 0

512.4077 286.4551 16.69681 16.62902 0.022545 0 0 0.00035 5045.779 5045.557 1.875095 6.151886 0 0 0 0 0

513.4234 286.4551 16.48934 16.43947 0.045106 0.239418 0.080441 1.999636 5045.099 5044.935 3.906448 12.81643 0 0 0 0 0

514.5172 286.4212 16.05373 16.4 0.13455 1.043353 0.647896 26.21276 5043.67 5044.806 6.09511 19.99708 1.051993 3.45142 1.135869 4.078137 7.037683

515.5329 286.4551 15.28002 16.39467 0.215758 1.671069 1.595308 59.34823 5041.131 5044.788 8.127595 26.66534 1.68494 5.528018 3.656923 15.97978 71.74474

516.4704 286.4551 14.40399 16.39 0.237214 2.011067 2.348394 89.96438 5038.257 5044.773 10.00269 32.81722 2.025009 6.64373 6.515812 40.08453 243.9494

517.6423 286.4551 13.7969 16.38358 0.239038 2.333467 2.67 132.428 5036.265 5044.752 12.34656 40.50708 2.345678 7.695795 8.486485 65.25986 467.8977

518.5018 286.4551 13.72 16.38 0.239054 2.426898 2.664983 148.2068 5036.013 5044.74 14.0654 46.14631 2.438643 8.000798 8.727051 48.53554 380.9213

519.5174 286.4551 13.72 16.37772 0.235516 2.41587 2.66 146.2806 5036.013 5044.733 16.09675 52.81085 2.427323 7.963657 8.719606 58.18662 464.4588

520.6894 286.4551 13.72 16.37545 0.229295 2.29332 2.66 125.43 5036.013 5044.725 18.44062 60.50071 2.304755 7.561532 8.712161 67.02391 520.2794

521.5488 286.4551 13.72 16.37226 0.221469 2.164889 2.657705 105.8115 5036.013 5044.715 20.15945 66.13994 2.176188 7.139724 8.701717 49.15932 361.3519

522.5645 286.4551 13.72 16.37 0.210522 1.973558 2.655449 80.66249 5036.013 5044.708 22.19081 72.80448 1.984755 6.511662 8.694336 58.01756 396.0101

523.502 286.4551 13.72274 16.37 0.199754 1.702833 2.655449 53.2092 5036.022 5044.708 24.0659 78.95637 1.714509 5.62503 8.685357 53.51418 324.7426

524.4396 286.4551 13.81116 16.37 0.181513 1.353796 2.642262 27.65988 5036.312 5044.708 25.941 85.10826 1.36591 4.481333 8.395348 54.32338 274.5059

525.6115 286.4551 14.1708 16.37 0.138915 0.965811 2.408734 10.32994 5037.492 5044.708 28.28487 92.79812 0.97575 3.201279 7.215447 69.09567 265.4176

526.549 286.4551 14.84374 16.37 0.087012 0.753209 1.95302 5.160195 5039.7 5044.708 30.15996 98.95 0.758219 2.487594 5.007543 37.59722 106.9429

527.4085 286.4551 15.72286 16.37 0.038812 0.416177 1.211738 2.1002 5042.584 5044.708 31.8788 104.5892 0.417983 1.371334 2.123261 8.132564 15.69149

528.6585 286.4551 16.82465 16.69058 0.003586 0.019635 0.177569 0.004607 5046.199 5045.759 34.37892 112.7917 0 0 0 0 0

529.5961 286.4212 17.06936 16.87953 0 0 0 0 5047.002 5046.379 36.25525 118.9477 0 0 0 0 0530.5336 286.4551 16.93272 16.82425 0 0 0 0 5046.554 5046.198 38.13157 125.1036 0 0 0 0 0

531.393 286.4551 16.82465 16.78376 0 0 0 0 5046.199 5046.065 39.8504 130.7428 0 0 0 0 0

Calculated Q = 3901.0 ft3/s

Calculated Q = 110.5

m3/s

Simulated Q = 100 m3/s

Distance across channel, in feet from left bank Distance across channel, in feet from left bank

inflow upstream of HEC-RAS model reach

50485046504450425040503850365034

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140

Elevation, in feet

Water-Surface ElevationGround Point

0123456789

0 20 40 60 80 100 120 140

Flow depth, in feetDepth

206  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
y

Calculation of TRIM2D flow—middle of model reach (near cross section 80)

Simulated Q = 100 m3/s

Variables

v1 = x coordinate in metersv2 = y corrdinate in metersv3 = Zv4 = etav5 = uv6 = vv7 = H in meters

p = Power W/m2

z = land-surface elevation in feet

eta = water-surface elevation in feet

distance= distance across the section

Distance Resultant velocit

v1 v2 v3 v4 v5 v6 v7 p z eta (m) (ft) (m/s) (ft/s) Depth (ft) Area (ft2) Qi (ft3/s)

1530.547 681.6219 11.089 10.99486 0 0 0 0 5027.381 5027.072 0 0 0 0 0 0 0

1530.572 680.6237 10.87899 10.7577 0 0 0 0 5026.692 5026.294 2.242113 7.356014 0 0 0 0 0

1530.547 679.5008 10.60095 10.4546 0 0 0 0 5025.78 5025.3 4.226937 13.8679 0 0 0 0 01530.572 678.565 10.30723 10.27101 0.480899 0.015113 0.13705 12.28244 5024.816 5024.698 5.975453 19.6045 0 0 0 0 0

1530.547 677.4421 9.881496 10.22907 1.657691 0.053287 0.56652 92.07049 5023.42 5024.56 8.20838 26.93038 1.658547 5.441428 1.140392 4.177185 11.364931530.521 676.5063 9.472222 10.23212 2.254965 0.063444 0.984821 165.152 5022.077 5024.57 9.956896 32.66698 2.255857 7.401105 2.493192 10.42221 66.9238

1530.547 675.321 8.936058 10.23746 2.55312 0.06108 1.550563 204.6111 5020.318 5024.587 12.19901 40.02299 2.553851 8.378775 4.269789 24.87429 196.2567

1530.547 674.51 8.521597 10.23907 2.707104 0.036609 2.010474 223.5495 5018.958 5024.593 13.94752 45.75959 2.707352 8.882389 5.634856 28.40949 245.1905

1530.521 673.5118 7.97755 10.23958 2.889425 -0.01744 2.467123 253.4349 5017.173 5024.594 15.93235 52.27148 2.889478 9.479915 7.42138 42.51038 390.2943

1530.521 672.4513 7.656103 10.23958 3.010137 -0.06149 2.619584 280.5051 5016.118 5024.594 17.91717 58.78337 3.010765 9.877838 8.475901 51.76067 500.9851

1530.521 671.5155 7.62 10.23958 3.014464 -0.08458 2.619584 281.84 5016 5024.594 20.15929 66.13939 3.01565 9.893866 8.594342 62.78447 620.678

1530.521 670.3926 7.62 10.23958 2.931194 -0.1118 2.619584 259.5844 5016 5024.594 22.14411 72.65128 2.933326 9.623771 8.594342 55.9654 546.1562

1530.521 669.3944 7.62282 10.23958 2.741389 -0.13481 2.619584 213.7015 5016.009 5024.594 24.12893 79.16317 2.744702 9.004928 8.585117 55.99544 521.56111530.495 668.3963 7.83676 10.2401 2.379577 -0.13841 2.601689 142.8296 5016.711 5024.596 26.11376 85.67506 2.383599 7.820208 7.884834 58.18541 489.4887

1530.469 667.4605 8.360832 10.24061 1.840288 -0.10865 2.223052 73.36879 5018.431 5024.598 28.10891 92.22083 1.843493 6.048205 6.167106 57.23429 396.87441530.495 666.4623 9.069747 10.2401 1.385882 -0.04137 1.530253 33.39891 5020.757 5024.596 30.34184 99.54671 1.386499 4.548881 3.839516 53.70527 284.55971530.521 665.4641 9.745418 10.23958 1.185995 0.009009 0.81213 26.10439 5022.973 5024.594 32.09035 105.2833 1.186029 3.891171 1.621096 6.363094 26.85242

1530.521 664.5284 10.2075 10.24194 0.591862 0.008833 0.256316 13.4717 5024.489 5024.602 34.08551 111.8291 0 0 0 0 0

1530.495 663.5302 10.5001 10.38129 0 -0.00189 0.005401 2.82E-06 5025.449 5025.059 36.31843 119.155 0 0 0 0 0

1530.469 662.532 10.68947 10.61179 0 0 0 0 5026.07 5025.816 38.30326 125.6669 0 0 0 0 01530.469 661.5963 10.81134 10.74805 0 0 0 0 5026.47 5026.263 39.79187 130.5508 0 0 0 0 01530.469 660.5357 10.93032 10.87032 0 0 0 0 5026.861 5026.664 42.0248 137.8766 0 0 0 0 0

Calculated Q = 4297.2 ft3/s

Calculated Q = 121.7 m3/s

Simulated Q = 100 m3/s

Distance across channel, in feet from left bank Distance across channel, in feet from left bank

50285026502450225020501850165014

0 20 40 60 80 100 120 140

Water-Surface ElevationGround Point

0123456789

0 20 40 60 80 100 120 140

Near cross section 80

Elevation, in feet

Flow depth, in feet

Appendix 4  207
Calculation of TRIM2D outflow (near cross section 23)

Simulated Q = 100 m3/s

Variables

v1 = x coordinate in metersv2 = y corrdinate in metersv3 = Zv4 = etav5 = uv6 = vv7 = H in meters

p = Power W/m2

z = land-surface elevation in feet

eta = water-surface elevation in feet

distance= distance across the section

v1 v2 v3 v4 v5 v6 v7 p z eta (m) (ft) (m/s) (ft/s) Depth (ft) Area (ft2) Qi (ft3/s)

2221.593 1038.478 8.23 8.23 0 0 0 0 5018.001 5018.001 0 0 0 0 0 0 02221.492 1037.362 8.23 8.23 0 0 0 0 5018.001 5018.001 2.242113 7.356014 0 0 0 0 0

2221.492 1036.369 8.23 8.23 0 0 0 0 5018.001 5018.001 4.226937 13.8679 0 0 0 0 0

2221.593 1035.501 8.23 8.23 0 0 0 0 5018.001 5018.001 5.975453 19.6045 0 0 0 0 0

2221.593 1034.384 8.172436 8.065903 0 0 0 0 5017.813 5017.463 8.20838 26.93038 0 0 0 0 02221.492 1033.516 7.946122 7.727882 0 0 -0.02662 0 5017.07 5016.354 9.956896 32.66698 0 0 0 0 02221.593 1032.399 7.483761 7.457913 0.627909 -0.03954 0.191941 15.2552 5015.553 5015.468 12.19901 40.02299 0.629153 2.06415 0 0 02221.492 1031.531 7.089612 7.449605 1.428496 -0.087 0.595841 56.36017 5014.26 5015.441 13.94752 45.75959 1.431143 4.69535 1.181236 3.388141 11.45107

2221.492 1030.539 6.556287 7.457222 2.015771 -0.11247 1.241667 111.873 5012.51 5015.466 15.93235 52.27148 2.018906 6.623708 2.955847 13.47012 76.23451

2221.492 1029.546 5.862433 7.46 2.446219 -0.07258 1.946273 168.2894 5010.234 5015.475 17.91717 58.78337 2.447295 8.029184 5.24132 26.68952 195.5393

2221.39 1028.43 5.286687 7.463751 2.728532 -0.04032 2.28 219.2011 5008.345 5015.487 20.15929 66.13939 2.72883 8.952854 7.142646 45.54831 386.7516

2221.39 1027.437 5.18 7.462423 2.824468 -0.06925 2.28 242.89 5007.995 5015.483 22.14411 72.65128 2.825317 9.269414 7.488395 47.63786 434.0349

2221.39 1026.445 5.172196 7.46 2.867292 -0.10175 2.295608 253.6663 5007.969 5015.475 24.12893 79.16317 2.869097 9.413047 7.506096 48.82123 456.05042221.39 1025.453 5.132739 7.46 2.829389 -0.10263 2.361244 241.8677 5007.84 5015.475 26.11376 85.67506 2.83125 9.288878 7.635541 49.30033 461.0056

2221.492 1024.46 5.108664 7.462615 2.684148 -0.0918 2.403132 205.7177 5007.761 5015.484 28.10891 92.22083 2.685718 8.81141 7.722998 50.26678 454.92162221.492 1023.344 5.376297 7.471479 2.452614 -0.09352 2.330764 158.8329 5008.639 5015.513 30.34184 99.54671 2.454396 8.052481 6.87392 53.4676 450.8359

2221.39 1022.475 5.65861 7.4811 2.276483 -0.08876 1.983002 133.8724 5009.565 5015.544 32.09035 105.2833 2.278213 7.474452 5.979224 36.86668 286.2132

2221.492 1021.483 5.802843 7.502843 1.993507 -0.08154 1.710173 96.49072 5010.038 5015.616 34.08551 111.8291 1.995174 6.545846 5.577397 37.82353 265.1486

2221.492 1020.366 5.941625 7.521251 1.54129 -0.09016 1.682156 46.21441 5010.493 5015.676 36.31843 119.155 1.543925 5.065371 5.18251 39.41287 228.8157

2221.492 1019.374 6.187307 7.524916 1.281187 -0.08481 1.481518 26.50743 5011.3 5015.688 38.30326 125.6669 1.283992 4.212571 4.388443 25.99162 120.5744

2221.492 1018.63 6.379032 7.523065 1.180978 -0.06773 1.271241 21.7365 5011.929 5015.682 39.79187 130.5508 1.182918 3.880966 3.753341 16.78011 67.90524

2221.492 1017.513 6.63255 7.52 1.071838 -0.02489 0.992534 17.58768 5012.76 5015.672 42.0248 137.8766 1.072127 3.517476 2.911488 18.24554 67.49428

2221.492 1016.521 6.833769 7.512813 0.736127 -0.00611 0.779336 8.985763 5013.421 5015.648 44.00963 144.3885 0.736152 2.415198 2.227855 12.28168 36.4316

2221.39 1015.528 7.02732 7.503902 0.071074 -0.00436 0.567151 1.049939 5014.055 5015.619 46.00478 150.9343 0.071207 0.233618 1.563771 8.062626 10.678212221.39 1014.536 7.201315 7.503902 -0.35598 0.01703 0.387227 0.980474 5014.626 5015.619 47.9896 157.4462 0.356384 1.169239 0.992839 4.606337 3.2310162221.39 1013.544 7.367412 7.506515 -0.33085 0.041048 0.224539 0.957161 5015.171 5015.628 49.97443 163.9581 0.333384 1.093779 0.456453 1.225927 1.387148

2221.39 1012.551 7.534588 7.522099 -0.14842 0.020917 0.07395 0.315316 5015.72 5015.679 51.95925 170.47 0.149884 0.491746 0 0 0

2221.492 1011.311 7.742434 7.652434 0 0.000466 0 4.26E-08 5016.402 5016.106 54.44855 178.637 0.000466 0.001529 0 0 0

2221.39 1010.442 7.898673 7.808673 0 0 0 0 5016.914 5016.619 56.19707 184.3736 0 0 0 0 02221.39 1009.326 8.092895 8.002895 0 0 0 0 5017.551 5017.256 58.42999 191.6995 0 0 0 0 02221.39 1008.333 8.266036 8.176036 0 0 0 0 5018.12 5017.824 60.41482 198.2113 0 0 0 0 02221.39 1007.465 8.420674 8.334072 0 0 0 0 5018.627 5018.343 62.15154 203.9092 0 0 0 0 02221.39 1006.473 8.60263 8.515406 0 0 0 0 5019.224 5018.938 64.13636 210.4211 0 0 0 0 0

Calculated Q = 4014.7 ft3/s

Calculated Q = 113.7 m3/s

Simulated Q = 100 m3/s

te from left bank efni,lennahcssorca ecnat siD te from left bank efni,lennahcssorca ecnat siD

Distance Resultant velocity

50205018501650145012501050085006

0 25 50 75 100 125 150 175 200 225

Water-Surface ElevationGround Point 0

123456789

0 25 50 75 100 125 150 175 200 225

Near cross section 23

Flow depth, in feet

Elevation, in feet

208  Hydraulic Characteristics of Bedrock Constrictions and Model Evaluation of Flood Flows, Big Lost River, Idaho
Manuscript approved for publication, May 2, 2007

Prepared by the USGS Publishing Network

Robert Crist

Linda Rogers

Sharon Wahlstrom

For more information concerning the research in this report, contact the 

Director, Idaho Water Science Center 

230 Collins Road 

Boise, Idaho 83702-4520

http://id.water.usgs.gov
SIR 2007–5080 Berenbrock and others Hydraulic Characteristics of Bedrock Constrictions and an Evaluation of One- and Two-Dimensional Models of Flood Flow on the Big Lost River at the Idaho National Engineering and Environmental Laboratory, Idaho