U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2010–5226

Prepared in cooperation with the North Platte Natural Resources District

Quantifying Canal Leakage Rates Using a Mass-Balance 

Approach and Heat-Based Hydraulic Conductivity Estimates 

in Selected Irrigation Canals, Western Nebraska, 2007 

through 2009
Front cover:

Background, Looking upstream from the Interstate Canal near Mintle, Nebraska streamflow-gaging 

station. Photograph by Michael Anderson, U.S. Geological Survey. 

Back cover:

Top left, Acoustic Doppler current profiler measuring canal discharge, Interstate Canal, June, 2007. 

Photograph by Michael Anderson, U.S. Geological Survey. 

Top right, Stilling well installation, Interstate Canal, March, 2008. Photograph by Christopher Hobza, U.S. 

Geological Survey. 

Top right, Irrigation map of western Nebraska (Darton, 1903b, pl. 40).
Quantifying Canal Leakage Rates Using 

a Mass-Balance Approach and HeatBased Hydraulic Conductivity Estimates 

in Selected Irrigation Canals, Western 

Nebraska, 2007 through 2009 

By Christopher M. Hobza and Michael J. Andersen

Prepared in cooperation with the North Platte Natural Resources District

Scientific Investigations Report 2010–5226

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2010

This and other USGS information products are available at http://store.usgs.gov/

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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:

Hobza, C.M., and Andersen, M.J., 2010, Quantifying canal leakage rates using a mass-balance approach and heatbased hydraulic conductivity estimates in selected irrigation canals, western Nebraska, 2007 through 2009: U.S. 

Geological Survey Scientific Investigations Report 2010–5226, 45 p.
iii

Acknowledgments

The authors thank managers Ron Cacek, North Platte Natural Resources District, Kevin 

Adams, Farmers Irrigation District, and Dennis Strauch, Pathfinder Irrigation District, for 

providing field support during data collection. The authors also thank Scott Schaneman and 

Thad Kuntz of the North Platte Natural Resources District for their help with installation and 

data collection.
Blank Page
v

Contents

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

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

Purpose and Scope .............................................................................................................................2

Study Area Description .......................................................................................................................2

North Platte Valley Irrigation Canals .......................................................................................4

Hydrogeology ...............................................................................................................................4

Previous Groundwater and Surface-Water Interaction Studies ........................................7

Channel Infiltration and Recharge ...........................................................................................7

Methods and Approach ...............................................................................................................................8

Study Reach and Site Selection and Description ..........................................................................8

Mass-Balance Approach Calculation ............................................................................................10

Data Sources .............................................................................................................................10

Hydroacoustic Data Collection and Index-Velocity Computation ....................................10

The Use of Heat as a Tracer .............................................................................................................12

VS2DH Model Framework and Calibration ...........................................................................12

Monitoring Design and Data Collection ................................................................................13

Tri-State Canal near Mitchell, Nebr. .............................................................................13

Tri-State Canal at Spottedtail Creek, Nebr. ..................................................................15

Interstate Canal near University Lake, Nebr. ..............................................................16

Calculated Leakage Rates Using Mass-Balance Approach ...............................................................18

Tri-State Canal Leakage Rates ........................................................................................................18

Interstate Canal Leakage Rates ......................................................................................................23

Heat-Based Hydraulic Conductivity Estimates ......................................................................................25

Tri-State Canal near Mitchell, Nebr. ...............................................................................................25

Tri-State Canal at Spottedtail Creek, Nebr. ....................................................................................28

Interstate Canal near University Lake, Nebr. ................................................................................29

Leakage Rate Comparisons .......................................................................................................................32

Summary and Conclusions ........................................................................................................................35

References Cited .........................................................................................................................................36

Appendix 1. Sediment Core Locations and Lithologic Descriptions .................................................39

Figures

1. Location of study area within the North Platte Natural Resources District ......................3

2. Map showing selected study reaches and location of streamflow-gaging stations 

and temperature monitoring sites, Interstate and Tri-State Canals, western 

Nebraska .......................................................................................................................................5

3. Generalized geologic sections A–A’ and B–B’ showing principal geologic units ...........6

4. Generalized one-dimensional VS2DH model of water and heat transport through 

canal-bed sediment ...................................................................................................................12

5. Example subsurface temperature data from paired deep and shallow 

thermocouples: pre-processed, unfiltered data display an artificial diurnal 

variation, and post-processed, filtered data have had artificial diurnal variation 

removed .......................................................................................................................................14
vi

6. Generalized diagram (A) and map (B) of monitoring installation design used at site 

TCTEMP1, Tri-State Canal near Mitchell, Nebr. ....................................................................16

7. Generalized diagram (A) and map (B) of monitoring installation design used at site 

TCTEMP2, Tri-State Canal at Spottedtail Creek, Nebr. ........................................................18

8. Generalized diagram (A) and map (B) of monitoring installation design used at site 

ICTEMP, Interstate Canal near University Lake, Nebr. ........................................................20

9. Daily mean upstream discharge, downstream discharge, and bed leakage rate, 

Tri-State Canal, late June to September, 2007 ......................................................................21

10. Daily mean upstream discharge, downstream discharge, and bed leakage rate, 

Tri-State Canal, late June to early August, 2008 ...................................................................21

11. Daily mean upstream discharge, downstream discharge, and bed leakage rate, 

Tri-State Canal, early July to late August, 2009 ....................................................................22

12. Monthly mean streamflow of North Platte River at the Nebraska-Wyoming state 

line (streamflow-gaging station 06674500) and total monthly precipitation measured 

at Scottsbluff Airport, January 2007 through December 2009 ...........................................22

13. Daily mean upstream discharge, downstream discharge, and bed leakage rate, 

Interstate Canal, May to mid-August, 2007 ...........................................................................23

14. Daily mean upstream discharge, downstream discharge, and bed leakage rate, 

Interstate Canal, late April to early August, 2008 .................................................................24

15. Daily mean upstream discharge, downstream discharge, and bed leakage rate, 

Interstate Canal, early July to late August, 2009 ..................................................................24

16. Thermograph of sediment beneath Tri-State Canal from vertical sensor array 4 

during initiation of seasonal flow, June 2007 ........................................................................25

17. Groundwater level recorded near Tri-State Canal near Mitchell, Nebr., June 2007 ......26

18. Water temperature and stage in Tri-State Canal near Mitchell, Nebr., May through 

September, 2007 .........................................................................................................................26

19. Measured and simulated thermographs for saturated sediment at (A) 0.15 meter 

and (B) 0.76 meter beneath Tri-State Canal near Mitchell, Nebr., 2007 ............................27

20. Measured and simulated thermographs for saturated sediment at (A) 0.15 meter 

and (B) 0.76 meter beneath Tri-State Canal near Mitchell, Nebr., 2009 ............................28

21. Measured and simulated thermographs for saturated sediment (including a 

hypothetical top layer of silt) at (A) 0.15 meter and (B) 0.76 meter beneath Tri-State 

Canal near Mitchell, Nebr., 2008 .............................................................................................29

22. Water temperature and stage in Tri-State Canal at Spottedtail Creek, Nebr., 

May to October, 2009 .................................................................................................................30

23. Pressure head and temperature recorded 0.91 meter below Tri-State Canal at 

Spottedtail Creek, Nebr., May to October, 2009 ....................................................................30

24. Canal stage and hydraulic gradient measured beneath Tri-State Canal at Spottedtail 

Creek (A), discharge reported at Spottedtail Creek streamflow-gaging station, and 

precipitation recorded at Scottsbluff Airport (B), March to October 2009 ......................31

25. Example measured and simulated thermographs for saturated sediment at 

(A) 0.15 m and (B) 0.76 meter beneath Tri-State Canal at Spottedtail Creek, Nebr., 

2009 ..............................................................................................................................................32

26. Groundwater level and temperature recorded at monitoring well 420233103441301, 

Interstate Canal near University Lake, Nebr., April to October, 2008 ................................33

27. Canal water temperature and stage of Interstate Canal, April to mid-September, 

2008 ..............................................................................................................................................33

28. Measured thermographs of sediment beneath Interstate Canal near University 

Lake, Nebr., from selected depths in vertical sensor arrays, April to October, 2008 .....34
vii

29. Measured and simulated thermographs for saturated sediment at (A) 0.15 meter 

and (B) 0.76 meter beneath Interstate Canal near University Lake, Nebr., 

July 2008 ......................................................................................................................................34

Tables

1. Field names and locations of streamflow-gaging stations and temperature 

monitoring sites ............................................................................................................................9

2. Summary statistics for Acoustic Doppler Current Profiler (ADCP) measurements 

including percent difference between ADCP and computed discharge from 

Tri-State Canal and Interstate Canal streamflow-gaging stations, 2007–09 ....................11

3. Summary of hydraulic and thermal properties used in final VS2DH models for 

each temperature monitoring site ..........................................................................................13
viii

Conversion Factors

SI to Inch/Pound

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

meter (m) 3.281 foot (ft) 

kilometer (km) 0.6214 mile (mi)

Area

hectare (ha) 2.471 acre

hectare (ha) 0.003861 square mile (mi2

) 

square kilometer (km2

) 0.3861 square mile (mi2)

square meter (m2

) 10.76 square foot (ft2) 

Volume

cubic meter (m3

) 0.0008107 acre-foot (acre-ft) 

cubic hectometer (hm3

) 810.7 acre-foot (acre-ft) 

Flow rate

meter per second (m/s) 3.281 foot per second (ft/s) 

meter per day (m/d) 3.281 foot per day (ft/d)

cubic meter per second (m3

/s) 35.31 cubic foot per second (ft3/s)

centimeters per year (cm/yr) 0.3937 inch per year (in/yr) 

Hydraulic gradient

meters per meter (m/m) 1 feet per foot (ft/ft) 

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

°F=(1.8×°C)+32

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

°C=(°F-32)/1.8

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

(NAVD 88). 

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

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

Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L) 

or micrograms per liter (μg/L).
Abstract

The water supply in areas of the North Platte River 

Basin in the Nebraska Panhandle has been designated as 

fully appropriated or overappropriated by the Nebraska 

Department of Natural Resources (NDNR). Enacted legislation (Legislative Bill 962) requires the North Platte Natural 

Resources District (NPNRD) and the NDNR to develop an 

Integrated Management Plan (IMP) to balance groundwater 

and surface-water supply and demand in the NPNRD. A clear 

understanding of the groundwater and surface-water systems is 

critical for the development of a successful IMP. The primary 

source of groundwater recharge in parts of the NPNRD is from 

irrigation canal leakage. Because canal leakage constitutes a 

large part of the hydrologic budget, spatially distributing canal 

leakage to the groundwater system is important to any management strategy. Surface geophysical data collected along 

selected reaches of irrigation canals has allowed for the spatial 

distribution of leakage on a relative basis; however, the actual 

magnitude of leakage remains poorly defined. To address this 

need, the U.S. Geological Survey, in cooperation with the 

NPNRD, established streamflow-gaging stations at upstream 

and downstream ends from two selected canal reaches to allow 

a mass-balance approach to be used to calculate daily leakage 

rates. Water-level and sediment temperature data were collected and simulated at three temperature monitoring sites to 

allow the use of heat as a tracer to estimate the hydraulic conductivity of canal-bed sediment. Canal-leakage rates were estimated by applying Darcy’s Law to modeled vertical hydraulic 

conductivity and either the estimated or measured hydraulic 

gradient. This approach will improve the understanding of the 

spatial and temporal variability of canal leakage in varying 

geologic settings identified in capacitively coupled resistivity 

surveys. 

The high-leakage potential study reach of the Tri-State 

Canal had two streamflow-gaging stations and two temperature monitoring sites along its length. Calculated leakage rates 

from the mass-balance approach varied from year to year and 

were generally dependent on local climatic conditions, and 

the timing and magnitude of the initial seasonal diversion into 

the Tri-State Canal. Leakage rates ranged from 0.98 meter 

per day (m/d) on June 22, 2007, to about to 0 m/d during July 

2009. Drier conditions generally resulted in higher leakage 

rates because of reduced flow from Spottedtail Creek, lower 

groundwater levels near Spottedtail Creek, and no unmeasured 

flow entering the reach. Of the three years studied (2007–09), 

2007 was the driest, and therefore had the highest canal leakage rates.

The moderately low-leakage potential study reach of 

Interstate Canal had two streamflow-gaging stations and 

one temperature monitoring site along its length. Excluding 

the leakage calculations from early May 2007, leakage rates 

ranged from 0.08 to 0.7 m/d. Less variability in leakage from 

year to year indicates that climatic conditions may have less 

of an effect for Interstate Canal compared to Tri-State Canal. 

This may be because Interstate Canal was cut into the northern 

edge of the North Platte alluvial valley and consequently the 

canal bed is well above the local groundwater table resulting 

in a constant (1 meter per meter [m/m]) hydraulic gradient. 

Interstate Canal also does not receive any captured flow that 

can vary substantially year to year. 

Two temperature monitoring sites were installed within 

the high-leakage potential reach of Tri-State Canal. Site 

TCTEMP1 was established in 2007 where the water table 

was well below the canal-bed surface. The vertical hydraulic 

conductivity of the poorly sorted sand and gravel beneath site 

TCTEMP1 was estimated using a calibrated one-dimensional 

VS2DH model. Using a trial-and-error approach, the best-fit 

vertical hydraulic conductivity for the site TCTEMP1 model 

domain was 1.1 m/d. Site TCTEMP2 was established at the 

mouth of Spottedtail Creek where a shallow water table may 

restrict canal leakage. The mean vertical hydraulic conductivity estimated from the best-fit VS2DH model was 1.5 m/d; 

however, measured hydraulic gradients ranged from -0.14 to 

-0.07 m/m, resulting in canal leakage rates that ranged from 

0.1 to 0.2 m/d. Because hydraulic gradient only was collected 

at one point, it was not possible to spatially extrapolate this 

estimate to other parts of the high-leakage potential reach.

Quantifying Canal Leakage Rates Using a Mass-Balance 

Approach and Heat-Based Hydraulic Conductivity 

Estimates in Selected Irrigation Canals, Western 

Nebraska, 2007 through 2009

By Christopher M. Hobza and Michael J. Andersen
2 Quantifying Canal Leakage Rates Using a Mass-Balance Approach and Heat-Based Hydraulic Conductivity Estimates

Site ICTEMP is a temperature monitoring site that was 

established in 2008 to estimate the hydraulic conductivity of 

near-surface sediments, and to understand canal leakage and 

recharge mechanisms in a fractured Brule setting. Based on 

the thicknesses and modeled vertical hydraulic conductivities, an average vertical hydraulic conductivity of 0.74 m/d 

was computed. The vertical hydraulic conductivity of the least 

permeable layer had the greatest effect on the mean vertical hydraulic conductivity, and therefore, canal leakage. The 

hydraulic gradient is assumed to be 1 m/m because the bed of 

the canal is well above the water table along the study reach; 

therefore, the canal-leakage rate at site ICTEMP is estimated 

to be 0.74 m/d. 

Introduction

The water supply in areas of the North Platte River 

Basin in the Nebraska Panhandle has been designated as 

fully appropriated or overappropriated by the Nebraska 

Department of Natural Resources (NDNR). Enacted legislation (Legislative Bill 962) requires the North Platte Natural 

Resources District (NPNRD) and the NDNR to develop an 

Integrated Management Plan (IMP) to balance groundwater 

and surface-water supply and demand in the NPNRD (fig. 1) 

(Ostdiek, 2009). A clear understanding of the groundwater 

and surface-water systems is critical for the development of a 

successful IMP.

As part of the IMP, improved decision-making tools are 

needed to analyze the effects of different groundwater management strategies on base flow of the North Platte River. 

To fulfill that need, a groundwater model is being constructed 

(NPNRD groundwater model area, fig. 1) that will evaluate 

the effects of specific management options such as intentional groundwater recharge and changes in pumpage (S.M. 

Peterson, U.S. Geological Survey, oral commun., 2008). 

The primary source of groundwater recharge in parts of the 

NPNRD is from irrigation canal leakage (Verstraeten and 

others, 2001). Canals in the area leak approximately 40 to 

50 percent of the diverted surface-water into underlying aquifers (Luckey and Cannia, 2006).

Because canal leakage constitutes a large part of the 

hydrologic budget, spatially distributing canal leakage to 

the groundwater system is important to the accuracy of any 

groundwater model. Surface geophysical data collected 

along selected reaches of irrigation canals has allowed for 

the spatial distribution of leakage on a relative basis (Ball 

and others, 2006; Burton and others, 2009); however, the 

actual magnitude of leakage remains poorly defined. Before 

the release of this report, the relative distribution of canal 

leakage was estimated on the basis of interpreted lithology 

from test holes and capacitively coupled resistivity (CCR) 

surveys (Ball and others, 2006; Burton and others, 2009). 

Large ranges in vertical hydraulic conductivity, often of 

several orders of magnitude, exist among the various sediment textures present locally (Domenico and Schwartz, 

1998), which can affect the degree of leakage. Moreover, 

CCR surveys may not detect thin near-surface layers of fine 

sediment that can clog the bed (Sophocleous and others, 1995) 

and affect the rate of leakage. To address this need, the U.S. 

Geological Survey, in cooperation with the NPNRD, established streamflow-gaging stations at upstream and downstream 

ends from two selected canal reaches to allow a mass-balance 

approach to be used to calculate daily leakage rates. Waterlevel and sediment temperature data were collected and 

simulated at three temperature monitoring sites to estimate the 

hydraulic conductivity of canal-bed sediment. Canal-leakage 

rates were estimated by applying Darcy’s Law based on modeled vertical hydraulic conductivity and either the estimated or 

measured hydraulic gradient. This approach will improve 

the understanding of the spatial and temporal variability of 

canal leakage in varying geologic settings identified in CCR 

surveys. 

Purpose and Scope

This report presents canal-leakage rates for selected 

reaches of Tri-State and Interstate Canals in western Nebraska. 

Based on CCR profiles, Ball and others (2006) identified a 

reach where the Tri-State Canal cuts through a section of 

Quaternary alluvial sand and gravel as having a predominantly high-leakage potential reach. They interpreted a moderately low-leakage potential for a reach where Interstate Canal 

cuts through several outcrops of weathered and fractured 

Brule Formation of the White River Group of Tertiary age 

(referred to hereinafter as the Brule Formation). Differences 

in streamflow measured at upstream and downstream locations allow a mass-balance approach to quantify canal-leakage 

rates from 2007 through 2009. The report includes plots of 

average daily discharge and daily canal-leakage rates. At 

each study reach, continuous water temperature and waterlevel data were used as inputs to the groundwater-flow model 

VS2DH (Healy and Ronan, 1996) to estimate the mean 

vertical hydraulic conductivity of the canal-bed sediment. 

Example water temperature and water-level time-series plots 

are included in this report. Lithologic descriptions of sediment cores, including core depth, texture, and color also are 

presented. 

Study Area Description

The methods and approaches described in this report 

have been applied to two selected reaches of two irrigation 

canals, but potentially may be applied to other reaches of 

irrigation canals within the study area. For this reason, the 

study area for this report is considered to be the entire NPNRD 

groundwater model area (fig. 1), which is located within the 

NPNRD and encompasses approximately 393,000 hectares 

(ha) along the North Platte River west of Bridgeport, Nebr., to 

the Nebraska-Wyoming border. The North Platte Valley west 

of Bridgeport is characterized by bottomland, terraces with 
Introduction 3

Figure 1. Location of study area within the North Platte Natural Resources District. 

Lake Minatare

Lake Alice

Lake Minatare

weather station

Sioux

Goshen

Laramie

Scotts Bluff

Banner

Harrisburg

Bridgeport

Bayard

Alliance

Scottsbluff

Mitchell

Morrill

Torrington

Kimball

Cheyenne

Morrill

Box Butte

Sheridan

Garden

North

Platte River

North Platte RiverNorth Platte River

WYOMING

NEBRASKA

Boundary of North Platte Natural Resources District 

 groundwater model area (study area)

Dutch Flats area

Interstate Canal

Tri-State Canal

Canal

EXPLANATION

104°15'

42°15'

41°30'

45'

42°

104° 45' 30' 15' 103° 102°45'

Base from U.S. Geological Survey digital data, 1987, 1:100,000

Universal Transverse Mercator projection

Zone 13

Horizontal coordinate information is referenced to the North American

Datum of 1983 (NAD 83)

0 6 12 18 24 MILES

0 6 12 18 24 KILOMETERS

WYOMING

COLORADO

NEBRASKA

Platte River

Whalen Diversion Dam

Index map

North Platte Natural 

Resources District groundwater

model area

North Platte Natural 

Resources District 

Guernsey Reservoir

Pathfinder Reservoir

North Platte River
4 Quantifying Canal Leakage Rates Using a Mass-Balance Approach and Heat-Based Hydraulic Conductivity Estimates

upland areas, escarpments of tablelands north of the North 

Platte River, and footslopes south of the North Platte River 

(Verstraeten and others, 2001). The study area has a semi-arid 

climate with a large temperature range typical of mid-latitude 

continental locations. The mean annual precipitation at the 

Scottsbluff Airport was 41.5 centimeters (cm) for 1970–2000 

(National Oceanic and Atmospheric Administration, 2007). 

The long-term estimated mean annual evaporative demand 

near Mitchell, Nebr., was 40.6 centimeters per year (cm/year) 

(Luckey and Cannia, 2006). 

Based on 2005 information, land use in the study area is 

about 58 percent range and pasture land, 36 percent cropland 

(dryland and irrigated land), 3 percent wetland (open water 

and vegetated wetlands), 1.5 percent urban, 1.2 percent forest 

and woodlands, and 1 percent barren (Center for Advanced 

Land Management Information Technologies, 2007). The primary crops raised in the area are corn, beans, sugar beets, and 

alfalfa (Verstraeten and others, 2001). Crop water demands not 

satisfied by precipitation are supplemented either with surface 

water supplied by irrigation canals, or groundwater applied 

from center-pivot or gravity-irrigation systems (Verstraeten 

and others, 2001). 

North Platte Valley Irrigation Canals

Shortly after the Federal Reclamation Act was signed 

in 1902 (Bureau of Reclamation, 2009b), the Bureau of 

Reclamation North Platte Project was created to irrigate 

91,500 ha of the North Platte Valley in eastern Wyoming 

and western Nebraska. Since construction of Pathfinder 

Dam and Interstate Canal in 1905, Guernsey Reservoir and 

Whalen Diversion Dam (fig. 1) have been constructed along 

with 542 kilometers (km) of canals. The North Platte Project 

provides irrigation water to hay and cropland (Bureau of 

Reclamation, 2009b) through Interstate and Tri-State Canals, 

which are the largest of 19 canals in the study area, and supply 

water to 47,400 and 20,300 ha, respectively (Ball and others, 

2006). 

Interstate Canal, operated by Pathfinder Irrigation 

District (Mitchell, Nebr.), diverts water from the Whalen 

Diversion Dam, 55 km west of the Nebraska-Wyoming state 

line. Pathfinder Irrigation District owns a water right for 

44.5 cubic meters per second (m3

/s) (1,572 cubic feet per second [ft3

/s]) dated 1904, and also receives storage water from 

the Bureau of Reclamation North Platte Project (Nebraska 

Department of Natural Resources, 2009). Interstate Canal 

ends at the High Line Canal (not shown on map) and Lake 

Alice north of Scottsbluff, Nebr. Interstate Canal is located at 

the northern edge of the ancestral North Platte Valley and is 

bordered by rangeland and groundwater-irrigated cropland to 

the north. Interstate Canal is bordered to the south by groundwater- and surface-water-irrigated cropland. Interstate Canal 

cuts through multiple outcrops of the Brule Formation from 

the Nebraska-Wyoming state line east toward Scottsbluff (Ball 

and others, 2006) (fig. 1). 

Tri-State Canal, operated by Farmers Irrigation District 

(Scottsbluff, Nebr.), diverts water from the North Platte River 

about 10 km northwest of Morrill, Nebr., and ends at North 

Port Irrigation District (Bridgeport, Nebr.) in the eastern part 

of the study area near Bayard, Nebr. Farmers Irrigation District 

owns water rights for 40.7 m3

/s (1,438 ft3/s) dated from 1887 

and 1902. Farmers Irrigation District also has water rights 

to divert from several tributaries of the North Platte River 

and purchases surplus water from the North Platte Project 

(Nebraska Department of Natural Resources, 2009). Several 

streams flow into Tri-State Canal in the study area, including Sheep Creek, Akers Draw, Dry Spottedtail Creek, and 

Spottedtail Creek (fig. 2). 

The irrigation season is divided into two diversion 

periods: the hay run and the primary irrigation season. When 

water supplies are available, diversions from the North Platte 

River to the Interstate and Tri-State Canals commonly begin in 

April for early irrigation of hay fields and meadows (referred 

to as the hay run). Drought conditions can delay diversions 

until mid- to late May or June. Diversions for the hay run 

typically are much less than those during the primary irrigation season, which occurs from June through September. Even 

when water-supply conditions prevent the early irrigation of 

hay fields and meadows, Interstate Canal still diverts water to 

fill downstream lakes during April of each year to satisfy interstate decree requirements. Diversions cease each year around 

September 30, which coincides with the end of the growing 

season for row crops. Thereafter, Tri-State Canal continues to 

receive water from Akers Draw, Spottedtail Creek, and Tub 

Springs Drain (fig. 2) during a period that is locally referred 

to as natural flow. The quantity and duration of captured 

streamflow during natural flow varies annually and depends on 

climatic conditions. 

Hydrogeology

Previous investigations have described the geology and 

occurrence of groundwater within the study area (Darton, 

1903a, 1903b; Wenzel and others, 1946; Babcock and Visher, 

1951; Verstraeten and others, 1995; Verstraeten and others, 

2001; Ball and others, 2006). Generalized geologic sections 

within the Dutch Flats area (fig. 1) from Verstraeten and others 

(2001) are presented in figure 3. A more thorough discussion 

of the groundwater and surface-water interaction of the Dutch 

Flats area is presented by Verstraeten and others (2001). 

The shallowest groundwater system in the study area is 

the unconfined alluvial aquifer. The alluvial aquifer is composed of Quaternary sand and gravel that mantle the Brule 

Formation or Cretaceous sediment (not shown in crosssection). A subsurface ridge or “high” in the Brule Formation 

(referred to hereafter as Brule high) divides the alluvial aquifer 

into northern and southern parts between Interstate and TriState Canal (fig. 3). The Brule high separates the paleochannels of the ancestral North Platte Valley north of the bedrock 

high (the upland valley) from the present North Platte River 
Introduction 5Figure 2. Selected study reaches and location of streamflow-gaging stations and temperature monitoring sites, Interstate and Tri-State Canals, western Nebraska. 

Scottsbluff

Mitchell

Morrill

Henry

Sioux County Scotts Bluff County

Goshen County WYOMING

NEBRASKA

Lyman

Enterprise Canal

Winters Creek

Lake Alice

Base from U.S. Geological Survey digital data, 1987, 1:100,000Universal Transverse Mercator projectionZone 13Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83)

104°10' 35' 104° 5' 55' 103o 50' 45' 103o 40'

42°10'

41°55'

42°

5'

Sunflower Drain

uT b Springs

r D ni a

Durham Andrews Drain

0 2 4 6 8 MILES

0 2 4 6 8 KILOMETERS

-

North Platte River

C

r

k

k y e Univ re isty L kae i i Unversity Lake

Mintle

Akers Draw

Interstate Canal

Tri-State Canal

USBR 

t opS yr D det

at Ci keer l

Spot et t d Cli a

e r k e

Sheep C ee

Dry Sheep reek

TSUS

06674500

TSDS

ISUS

ISDS

TCTEMP1

TCTEMP2

ICTEMP

EXPLANATION

CanalHigh-leakage potentialModerately low-leakage  potentialStreamflow-gaging station  and field identifierStreamflow-gaging station  and numberTemperature monitoring  site and field identifierSpottedtail Creek  streamflow-gaging stationTrace of generalized geologic section 

06674500

ISUS

ICTEMP

USBR A’

B’

A

B

A A'
6 Quantifying Canal Leakage Rates Using a Mass-Balance Approach and Heat-Based Hydraulic Conductivity Estimates

Figure 3. Generalized geologic sections A–A’ and B–B’ showing principal geologic units. (Modified from Verstraeten and others, 2001.) 

Q U

South

B

North

B’

A’

North

Brule High

?

?

Q U

A

METERS South

1,100

1,120

1,140

1,160

1,180

1,200

1,220

1,240

1,260

1,280

1,300

1,320

1,100

1,120

1,140

1,160

1,180

1,200

1,220

1,240

1,260

1,280

1,300

1,320

North Platte River

North Platte River

Qu

Qu

Qu

Qu

Tc

Tc

Tb

Tb

Tb

Tb

Tri-State Canal

Interstate Canal

InterstateCanal

Tri-State Canal

0

0

1 2 3 4 MILES

1 2 3 4 KILOMETERS

EXPLANATION

System Geologic unit 

Groundwater level—Dashed where 

 approximated Undifferentiated alluvial, colluvial,

 and eolian deposits

Chadron Formation of the

 White River Group

Brule Formation of the

White River Group

Quaternary

Tertiary

Qu

Tb

Tc

Vertical datum is North American Vertical Datum of 1988

Trace of section shown in figure 2

Trace of section shown in figure 2

VERTICAL SCALE GREATLY EXAGGERATED
Introduction 7

(the bottomland). Alluvial aquifer thickness is extremely variable with a maximum thickness of more than 80 meters (m) 

(Cooperative Hydrology Study, 2007). Depth to water in the 

northern alluvial aquifer ranges from 1.5 to 24 m and typically 

is less than 6 m below land surface in the southern alluvial 

aquifer (Ball and others, 2006). 

The Brule Formation is used as a water source only 

when fractured or containing alluvial deposits (Luckey and 

Cannia, 2006). The unfractured horizontal hydraulic conductivity of this unit is low (1x10-7 to 1x10-6 meters/second 

[m/s]) (Barrash and Morin, 1987); however, where adequate 

water supplies exist the Brule Formation is considered part 

of the High Plains aquifer (not shown on map) (Gutentag and 

others, 1984). Sustainable yields to wells are dependent upon 

the number, size, and continuity of fractures, and the availability of recharge from a surface-water source or connection 

to alluvial aquifers (J.C. Cannia, U.S. Geological Survey, oral 

commun., 2007). 

Fracturing of the Brule Formation is largely limited to the 

upper parts (Harvey and Sibray, 2001). Approximately 100 km 

south of the study area, near Sidney, Nebr. (not shown on 

map), Sibray and Zhang (1994) reported a horizontal conductivity of 8x10-2 m/s and a vertical hydraulic conductivity of 

1x10-5 m/s for the upper Brule Formation based on analytical 

modeling of aquifer test data. Values reported for the lower 

Brule Formation were much less and ranged from 1x10-6 to 

1x10-8 m/s.

Groundwater movement in the study area generally is 

toward the North Platte River or its tributaries (Verstraeten and 

others, 2001). A Brule high in the western part of the study 

area causes groundwater flow to deviate from the predominant north-south direction. In the part of the alluvial aquifer 

between the Brule high and the North Platte River, groundwater moves from areas recharged by groundwater from the 

northern alluvial aquifer toward the North Platte River (Ball 

and others, 2006).

Previous Groundwater and Surface-Water 

Interaction Studies

Understanding the interaction of groundwater and 

surface-water systems is essential to sound water-resource 

management and policy (Winters and others, 1998). 

Groundwater/surface-water interaction and the effects of 

canals on the local hydrology have been a focus of study in 

the North Platte Valley since Darton (1903b) described the 

geology and water resources of the area. The interaction of 

groundwater and surface water has been explored by examining recharge, modeling results (Luckey and Cannia, 2006), and 

chemical transport. 

Recharge to the groundwater system in the study area 

from precipitation is much less than leakage from irrigation canals, laterals, and infiltration of applied irrigation 

water (Babcock and Visher, 1951; Harvey and Sibray, 2001; 

Verstraeten and others, 2001; Luckey and Cannia, 2006). 

Monitoring wells located near irrigation canals record 

groundwater-level rises shortly after surface water is diverted 

into irrigation canals, and typically record water-level declines 

after the diversions cease. During the irrigation season, leakage through canal beds affects the movement of groundwater by increasing the hydraulic head in the aquifer near the 

canals. As the groundwater hydraulic head near the canal 

increases, the overall hydraulic gradient of the groundwater 

flow system also increases. Subsequently, groundwater moves 

from recharge areas near the canals to discharge areas, which 

increases base flow of streams in the North Platte Valley. 

Wenzel and others (1946) reported that “prior to 1911 the 

aggregate discharge of all the tributaries to the North Platte 

River from the State line (Nebraska-Wyoming) to Bridgeport 

was less than 25,000 acre-feet a year; since 1927 it has in no 

year been less than 300,000 acre-feet.”

Irrigation system losses from canal and lateral leakage have been estimated for many of the canals in western 

Nebraska by Bishop-Brogden Associates (2002). System 

losses for Pathfinder and Farmers Irrigation Districts were 

estimated at 51 and 41 percent, respectively, of their diversion 

before reaching cropland. Of these calculated system losses, it 

was estimated that 71 percent is leakage from canals, and 29 

percent is leakage from laterals (Dennis Strauch, Pathfinder 

Irrigation District, oral commun., 2010). 

The strong connection between groundwater and surface 

water in the study area also has been reflected in water-quality 

and chemistry data. Locally, irrigation canals have caused 

seasonal changes in groundwater quality. Nitrate concentrations of shallow groundwater typically decrease in the irrigation season as a result of leakage and subsequent mixing 

with and dilution of shallow groundwater (Verstraeten and 

others, 2002). These localized effects are greatest for areas 

of, or adjacent to, Interstate Canal near the northernmost part 

of the valley and diminish southward toward Tri-State Canal. 

Groundwater age dating has indicated that groundwater in 

the alluvium recharged less than 30 years ago and averaged 

9 years ago in the Dutch Flats area of the North Platte Valley 

(Verstraeten and others, 2002). 

Channel Infiltration and Recharge 

Evaluating and quantifying recharge from irrigation 

canals and ephemeral stream channels has been the focus 

of many groundwater recharge and availability studies. The 

primary sources of groundwater recharge in many arid and 

semiarid regions in many cases are seepage from ephemeral 

streambeds (Stonestrom and others, 2007) and leakage from 

canals (Verstraeten and others, 2001). Although ephemeral 

streams and seasonal canals have considerably different flow 

characteristics, they share many of the same unsaturated-zone 

flow processes, such as hysteretic effects of wetting and drying 

of sediments. Stonestrom and others (2007) reported numerous 

case studies examining groundwater recharge from ephemeral 

streambeds in arid and semiarid areas in the southwestern 

United States. Groundwater recharge is focused along stream 

and canal reaches because large amounts of water are available 
8 Quantifying Canal Leakage Rates Using a Mass-Balance Approach and Heat-Based Hydraulic Conductivity Estimates

for seepage and strong hydraulic gradients exist to drive seepage (Dages and others, 2008). 

Quantifying the amount of recharge from surface-water 

sources is more difficult for ephemeral streams than for irrigation canals because geologic, hydrologic, and meteorological 

conditions often are highly variable, (Stephens and others, 

1988), and therefore, manifest greater flow-rate variability in 

natural systems rather than managed conduits. The amount 

of recharge received by underlying aquifers from channel 

infiltration is affected by many factors, including bed sediment 

texture, depth to groundwater, channel geometry, available 

unsaturated-zone storage volume, flow duration and depth, 

volumetric soil-water content, and the presence of clogging 

layers (Robinson and Rohwer, 1957 1959; Stephens, 1996). 

Streamflow measurement can be difficult under these conditions because runoff events are often flashy and erosive, which 

creates operational problems for maintaining instrumentation 

(Stephens and others, 1988). 

In order for leakage through an irrigation canal or 

recharge from an ephemeral stream to occur, water must 

infiltrate the bed sediment and reach the water table. Onedimensional, steady-state, vertical flow of water through 

unsaturated homogenous porous media can be described with 

a form of Darcy’s Law (Hoffman and others, 2007):

q K

z = ( ) ∂

∂

+ 



 



 θ ψ 1 (1)

where,

q is the flux [length units/time units],

θ is the volumetric soil-water content [volume units/

volume units], 

K ( ) θ is the hydraulic conductivity [length units/time units] 

as a function of the volumetric soil-water content, 

ψ is the pressure head of the water [length units], and

z is the vertical dimension [length units].

Thus, determination of the rate of flow in the unsaturated 

zone requires knowledge of the hydraulic conductivity (which 

is dependent on the degree of saturation) and the pressurehead gradient (Hoffman and others, 2007). 

Recharge characteristics were studied with several 

techniques at various spatial and temporal scales along Rillito 

Creek in Arizona (not shown on map) (Hoffman and others, 

2007). A two-dimensional temperature and water-content 

array was used to examine the redistribution of water in the 

unsaturated zone. High infiltration rates were measured at the 

onset of infiltration because of high hydraulic conductivity 

in the underlying sandy sediment and low volumetric water 

content creating large capillary pressure-head gradients. 

Multidimensional flow was present with lateral velocities 

roughly equivalent to vertical velocities. Shortly after the 

onset of infiltration the near-surface sediment became saturated causing the strong capillary gradients to disappear. As 

capillary gradients disappeared, gravity became the dominant 

force in water movement, and flow primarily became vertical 

(Hoffman and others, 2007). The investigators reported that 

when saturated conditions persist, Darcy’s Law (Freeze and 

Cherry, 1979) can be used to calculate the flow rate, provided 

the hydraulic conductivity and hydraulic gradient are known. 

If a unit hydraulic gradient is assumed then the potential 

recharge rate becomes equivalent to the saturated hydraulic 

conductivity of the underlying sediment. 

Other investigations have studied recharge patterns from 

a drainage ditch and examined its effect on local groundwater 

levels using several transects of piezometers and tensiometers 

(Dages and others, 2008). During the initiation of flow in the 

ditch, the rates of leakage were high and large horizontal and 

vertical moisture gradients were measured. Sediment beneath 

the ditch quickly reached saturation extending to the water 

table, which created a large groundwater mound that extended 

beyond the banks of the ditch. A nearly instantaneous response 

of the water table was recorded at some distance from the 

ditch because the downward and laterally flowing water 

resulted in a synchronous pressure wave. This pressure wave 

propagated normally from the ditch, causing nearly instantaneous groundwater-level rises.

Methods and Approach

This section of the report describes the methods and 

approaches used to quantify canal leakage rates from two 

selected study reaches using a mass-balance approach and 

heat-based hydraulic conductivity estimates. Included in this 

section is the rationale for reach and site selection as well 

as brief descriptions of each study reach. The mass-balance 

approach used for this report is described including the additional data sources needed and the methods of hydroacoustic 

data collection and discharge computation. A brief introduction to the technique of using heat as a tracer and the VS2DH 

model framework and calibration procedures also are provided. The instrumentation used for each temperature monitoring site is described, as well as the monitoring design and the 

data-collection procedures.

Study Reach and Site Selection and Description

Two study reaches were chosen to represent contrasting 

areas with high and moderately low-leakage potential. Each 

study reach was of sufficient length that the potential leakage 

loss was greater than the expected uncertainty of the leakage calculation, yet minimizing the amount of unmeasured 

return flows, diversions, or additional variables that would 

increase the extraneous uncertainty of the calculated leakage. 

Interpretations of previously collected CCR profiles (Ball and 

others, 2006; Burton and others, 2009) indicate a predominantly high-leakage potential for the reach where Tri-State 

Canal cuts through a section of alluvial sand and gravel, and 

a moderately low-leakage potential where Interstate Canal 

cuts through outcrops of fractured and weathered bedrock of 
Methods and Approach 9

the Brule Formation. Capacitively coupled resistivity profiles 

(Ball and others, 2006) indicated that within the moderately 

low-leakage potential reach thin sand and silt deposits cover 

the Brule Formation in some areas. Harvey and Sibray (2001) 

collected water-level and water-quality data to determine 

the effect of canal leakage on the local hydrology of the 

University Lake area (fig. 2). In their study area, the upper part 

of the Brule Formation is weathered with localized fracturing 

(S.S. Sibray, University of Nebraska, oral commun., 2010) 

and is the primary source of recharge in this area providing 

water to the alluvial aquifer and the upper parts of the Brule 

Formation (Verstraeten and others, 2001). 

These selected reaches were bounded by streamflowgaging stations at upstream and downstream locations to allow 

a mass-balance approach to be used to calculate canal leakage rates. To accurately quantify canal leakage within the two 

selected study reaches, the determination of the exact streamflow-gaging station location required careful consideration of 

several variables. The selected reaches had to be of sufficient 

length that the leakage loss was greater than the dischargecomputation error of both streamgages; the total magnitude of 

unmeasured return flows, diversions, or other gains or losses 

had to be minimized; and the characteristics of the streamgaging cross-section had to be desirable, as defined by Rantz 

(1982). Within each study reach, at least one temperature monitoring site was selected for estimating the vertical hydraulic 

conductivity of various sediment textures. Within the highleakage potential reach, one site was established well above 

the water table, and one site was established where a shallow 

water table might restrict leakage by reducing the hydraulic 

gradient. Within the moderately low-leakage potential reach, 

one site was established to examine recharge mechanisms 

in a fractured Brule Formation setting. The surface area of 

each study reach was estimated by tracing the canal outlines 

from aerial photography and calculating the area in a geographic information system (GIS) at a scale of 1:1,500. Field 

identifiers and locations of the streamflow-gaging stations and 

temperature monitoring sites are listed in table 1.

The study reach of Tri-State Canal had two streamflowgaging stations and two temperature monitoring sites along 

its length. Streamflow-gaging stations TSUS (Tri-State Canal 

near Mitchell, Nebr., site 415812103493701) and TSDS (TriState Canal near Mintle, Nebr., site 415626103434001) were 

established in 2007 at upstream and downstream locations, 

respectively, along the study reach of Tri-State Canal (fig. 2). 

Based on GIS analysis of aerial photography, the study reach 

is 14.2 km long with an area of 32 ha. Within this reach, 

outflows include six minor laterals (turnouts) and one major 

lateral diversion; inflows include nine center-pivot return 

flows, two drainage ditch return flows, and flow received 

from Spottedtail Creek. Streamflow data for each streamflowgaging station are stored in the publicly accessible USGS 

National Water Information System (NWIS) database (http://

waterdata.usgs.gov/ne/nwis). Temperature monitoring sites 

were installed within this reach at site TCTEMP1 (Tri-State 

Canal near Mitchell, Nebr., site 415542103455301, fig. 2), 

established in 2007, and site TCTEMP2 (Tri-State Canal 

at Spottedtail Creek, Nebr., site 415834103483701, fig. 2), 

established in 2009. All continuous temperature and waterlevel data for the temperature monitoring sites are stored in the 

publicly accessible NWIS database.

The study reach of Interstate Canal had two streamflowgaging stations and one temperature monitoring site along its 

length. Streamflow-gaging stations ISUS (Interstate Canal 

near Rattlesnake Hill, Nebr., site 420327103464301) and ISDS 

(Interstate Canal near Mintle, Nebr., site 415922103404801) 

were established in 2007 at upstream and downstream locations, respectively (fig. 2). Based on GIS analysis of aerial 

photography the study reach is 14.5 km long with an area of 

28 ha. Within this reach outflows include 17 turnouts and two 

major lateral diversions; inflows include one drainage culvert. 

Site ICTEMP (Interstate Canal near University Lake, Nebr., 

Table 1. Field names and locations of streamflow-gaging stations and temperature monitoring sites.

[Datum used NAD83, North American Datum of 1983; temperature refers to temperature monitoring site; streamgage refers to streamflow-gaging station; all 

sites are in Nebraska]

Site name Site number Field identifier Site location Site type Year

established

Tri-State Canal

Tri-State Canal near Mitchell 415812103493701 TSUS 41o 58' 12" N, 103o 49' 37" W streamgage 2007

Tri-State Canal near Mintle 415626103434001 TSDS 41o 56' 26" N, 103o 43' 40" W streamgage 2007

Tri-State Canal near Mitchell 415542103455301 TCTEMP1 41o 55' 42" N, 103o 45' 53" W temperature 2007

Tri-State Canal at Spottedtail Creek 415834103483701 TCTEMP2 41o 58' 34" N, 103o 48' 37" W temperature 2009

Interstate Canal

Interstate Canal near Rattlesnake Hill 420327103464301 ISUS 42o 3' 27" N, 103o 46' 43" W streamgage 2007

Interstate Canal near Mintle 415922103404801 ISDS 41o 59' 22" N, 103o 40' 48" W streamgage 2007

Interstate Canal near University Lake 420233103441301 ICTEMP 42o 2' 33" N, 103o 44' 13" W temperature 2008
10 Quantifying Canal Leakage Rates Using a Mass-Balance Approach and Heat-Based Hydraulic Conductivity Estimates

site 420233103441301, fig. 2) is a temperature monitoring 

site that was established in 2008. All streamflow, continuous 

temperature, and water-level data for the streamflow-gaging 

stations and temperature monitoring sites are stored in the 

publicly accessible NWIS database. 

Mass-Balance Approach Calculation

Flow loss attributed to canal leakage was calculated using 

a mass-balance approach. In addition to the computed daily 

mean discharge from streamflow-gaging stations, other data 

were incorporated to compute canal leakage, including daily 

pan-evaporation rates from the Lake Minatare weather station 

(fig. 1; Bureau of Reclamation station WMNE, 2009), outflow 

diversions from the study reach as reported by Pathfinder 

and Farmers Irrigation Districts (Dennis Strauch, Pathfinder 

Irrigation District; Kevin Adams, Farmers Irrigation District; 

unpub. data, 2010), and daily discharge reported for the 

Spottedtail Creek streamflow-gaging station (fig. 2; Bureau 

of Reclamation station WSNE, 2009). Equations (2) and (3) 

quantify how daily mean leakage rates were calculated for 

each canal reach. 

[(QU – D – Ep

 +W) – QD]/A = daily mean leakage rate for

Tri-State Canal, in m/d (2)

[(QU – D – Ep) – QD]/A = daily mean leakage rate from 

Interstate Canal, in m/d (3)

where,

QU is the upstream daily mean discharge, in cubic meters per 

second,

D is the sum of reported outflow diversions from the study 

reach, in cubic meters per second,

Ep is the daily pan evaporation, in meters/day

W is the reported daily mean discharge from Spottedtail 

Creek, in cubic meters per second, 

QD is the downstream daily mean discharge, in cubic meters 

per second,

A is the estimated area (of the bed) of the study reach, in 

square meters, and irrigation drainage return flows 

are neglected.

Data Sources

Total daily evaporation was estimated using the reported 

pan evaporation rate from station WMNE multiplied by the 

estimated canal area for each reach and converted to daily 

average water loss in cubic meters per second. The Spottedtail 

Creek streamflow-gaging station is located 1.5 km upstream 

from Tri-State Canal. There may be differences between 

discharge reported at the streamflow-gaging station and the 

actual discharge from Spottedtail Creek into the canal. This 

could introduce some error into leakage estimates, especially 

in wet-weather conditions where intervening surface runoff 

and increased groundwater discharge would increase the discharge downstream from the streamflow-gaging station. Flow 

received from drainage returns was assumed to be minimal 

and to occur during short periods of wet-weather conditions, 

and, therefore, was not considered in the leakage calculation. 

The reach area used in the leakage calculations was the 

planimetric (map view) area rather than the wetted perimeter of each canal. The calculated map view area was more 

appropriate because most of the study reach of each canal was 

constructed well above the water table, and in some cases the 

canal banks were constructed above the original land surface; 

therefore, leakage from irrigation canals results in predominantly vertical water flow. 

Precipitation was recorded every 15-minutes at the 

upstream streamflow-gaging station within each study reach 

only when streamflow-gaging stations ISUS and TSUS were 

active. Precipitation would have been such a small component 

that it was not used in the mass-balance calculation. Recorded 

precipitation was used to assess local climatic conditions 

and the possibility when unmeasured flow from drainage 

returns or other unmeasured inputs could increase errors in 

leakage calculations. Measured precipitation also was examined to provide additional climatic context when using the 

recorded precipitation reported at the Scottsbluff Airport by 

the National Oceanic Atmospheric Administration National 

Climatic Data Center (http://gis.ncdc.noaa.gov/website/

ims-cdo/sod/viewer.htm, accessed March 1, 2010). 

Hydroacoustic Data Collection and IndexVelocity Computation

The methods of collecting and computing discharge have 

improved significantly since the U.S. Geological Survey began 

collecting streamflow data in 1889. Recent developments in 

the area of streamflow-monitoring technology have enhanced 

the quality of the data collected and the confidence in streamflow computation. Using sound waves, hydroacoustic instruments are capable of measuring the magnitude and direction 

of water velocity across an entire stream profile or part of the 

water column. These instruments emit an acoustic pulse at a 

known frequency. As the pulse travels horizontally and vertically through the water column a part of the emitted energy 

is reflected off particles (scatter) in the water and back to the 

instrument. Using the Doppler-shift principle, water speed 

and direction of flow are calculated by assessing the change in 

frequency of the returning pulse (Morlock and others, 2002). 

For this study, acoustic Doppler velocity meters 

(ADVMs) were secured within the surface-water column 

to measure water velocity and level (stage). Data collected 

from ADVMs were used in conjunction with independent 

acoustic Doppler current profiler discharge measurements 

to compute discharge. The ADVMs were oriented to emit 

a 2-beam horizontal signal to define water velocity and 

direction, and a single vertical beam to determine stage. 
Methods and Approach 11

The ADVM-measured water velocity was sampled in 10 

cells, which are user-specified increments of the stream 

cross-section. 

Sontek 1500 kHz Argonaut SL (YSI Sontek, San Diego, 

Calif.) ADVMs were deployed at upstream and downstream 

ends of each study reach. The Sontek Argonaut has a reported 

velocity measuring accuracy of 0.001 m/s. The ADVMs were 

secured to the end of a steel I-beam angled down the bank 

into the water column and oriented such that the vertical beam 

was perpendicular to the water surface. With this deployment 

configuration the ADVMs were not able to collect stage and 

velocity data at low-flow stages. ADVMs needed at least 

0.15 m of water above the vertical beam to accurately measure 

stage. 

Discharge is computed from cross-sectional area and 

velocity (Rantz, 1982). To compute discharge using an 

ADVM, the stage-dependant cross-sectional area must be 

established. Before each irrigation season a stage-area 

relation was defined by using a conventional leveling survey to measure distance and elevation across the channel at 

each ADVM deployment location. Level surveys were done 

annually to assess potential changes in the channel geometry 

that may have occurred during the previous irrigation season, 

because routine channel maintenance may affect the stage-area 

relation. The level survey data was processed with a USGS 

program, AreaComp (Rehmel, 2002), to determine the stage to 

cross-sectional area relation. Staff gages were installed at each 

streamflow-gaging station to allow verification of the ADVM 

recorded stage readings.

The ADVMs were programmed to measure and record 

stage and velocity at 15-minute intervals. Velocity data were 

averaged over a 3-minute interval before recording. Horizontal 

water velocity typically was sampled in ten 0.91-m cells across 

the channel. After canal diversions began, a beam check was 

run to verify that no obstructions were in the cross-section that 

could bias the velocity data. All data collected were logged 

on the internal memory of the ADVM and an external data 

collection platform (DCP). Logged DCP data were transmitted 

hourly through the Geostationary Operational Environmental 

Satellites (GOES). The uploaded data were then stored in publicly accessible NWIS-Web (http://waterdata.usgs.gov/nwis). 

Acoustic Doppler current profilers (ADCPs) were 

used independently to measure the discharge of each canal. 

Individual ADCP measurements were collected for a range 

of stages (Morlock and others, 2002). The ADCP used was 

a Teledyne RD Instruments (Poway, Calif.) 1200 kHz Rio 

Grande, with reported accuracy of 0.25 percent of the measured velocity. The ADCP was mounted to a measuring 

catamaran tethered to a pulley system spanning the canal at 

each streamflow-gaging station. Summary statistics for ADCP 

measurements collected at each streamflow-gaging station, 

including percent difference between measured and computed 

discharge, are summarized in table 2. 

 To collect a complete velocity profile, the instrument 

was moved across the channel, perpendicular to the principal 

direction of flow. The water velocity was sampled in cells that 

were integrated to determine the total discharge for a single 

measurement (velocity times area, summed for all cells). The 

reported total discharge for an independent ADCP measurement was the mean discharge calculated from at least four 

velocity profiles or transects. If any of the transects were not 

within 5 percent of the computed mean, then four more transects were collected before the mean discharge was calculated 

and reported. For a more thorough discussion of using ADCP 

procedures for measuring discharge including field data collection and processing, refer to Mueller and Wagner (2009). 

Computing discharge from recorded ADVM velocity and 

stage measurements and independent ADCP measurements 

requires the application of the index-velocity method. This 

index-velocity method of calculating stream discharge relies 

on the assumed relation between the current velocity of some 

specific increment of the stream cross-section and the total 

stream discharge. To compute discharge the indexed velocity 

is multiplied by the stage-dependant cross-sectional area to 

determine the total discharge. The accuracy of each indexvelocity rating depends on multiple factors including: stability 

of the channel geometry at the site, the accuracy of the crosssectional area measurement, accuracy of stage and velocity 

measurements, and accuracy of the independent discharge 

measurements (Morlock and others, 2002). The development 

of the index-velocity ratings and the discharge computation 

was completed in accordance with the methods and guidelines 

Table 2. Summary statistics for Acoustic Doppler Current Profiler (ADCP) measurements including percent difference between ADCP 

and computed discharge from Tri-State Canal and Interstate Canal streamflow-gaging stations, 2007–09.

[ADCP, Acoustic Dopper Current Profiler; discharge is given in cubic meters per second; ABS, absolute value]

Field identifier Number of ADCP 

measurements

Discharge, measured by ADCP ABS percent difference between the measured 

ADCP and computed discharge

Maximum Minimum Median Maximum Minimum Median

TSUS 15 35.6 13.4 23.8 3.96 0.21 1.62

TSDS 15 34.8 13.4 29.2 4.14 .34 1.63

ISUS 26 24.3 9.20 17.2 4.57 .13 1.93

ISDS 21 20.4 11.4 15.6 5.55 .02 1.79
12 Quantifying Canal Leakage Rates Using a Mass-Balance Approach and Heat-Based Hydraulic Conductivity Estimates

reported in Mueller and Wagner (2009) and Morlock and 

others (2002). 

The Use of Heat as a Tracer

The effectiveness of using heat as a tracer in groundwater 

and surface-water interaction studies has been well established. Heat tracer techniques have been applied successfully 

to determine streambed hydraulic conductivity (Essaid and 

others, 2007; Eddy-Miller and others, 2009; Zamora, 2008), 

assess diurnal and annual variability in groundwater/surfacewater exchanges (Cox and others, 2007; Ronan and others, 

1998), and determining groundwater recharge from ephemeral streams (Constantz and others, 2002). The practicality 

of using heat as a tracer has improved substantially in recent 

years because of improvements in data-collection equipment 

and computational capabilities (Stonestrom and Constantz, 

2003). For more detail on the use of this technique in studies 

of groundwater and surface-water interaction and groundwater 

transport refer to Stonestrom and Constantz (2003), Andersen 

(2006), Blasch and others (2007), Constantz and others 

(2002), and Constantz (2008). 

VS2DH Model Framework and Calibration

Numerical modeling of continuous sediment temperature 

data allows canal leakage to be quantified. The groundwater 

flow and transport model VS2DH (Healy and Ronan, 1996) 

was used to simulate flow and estimate the vertical hydraulic 

conductivity of the canal-bed sediment at the temperature 

monitoring sites. VS2DH is a finite-difference model that 

uses a modified version of the advection-dispersion equation 

expressed in terms of water temperature (Healy and Ronan, 

1996). Flow through the unsaturated zone is solved using a 

modified version of the Richards equation (Chow and others, 

1988) that assumes hydraulic conductivity is a temperaturedependent variable because of viscosity effects. VS2DH 

required continuous records of the water temperature, canal 

stage, groundwater level, and sediment temperature at multiple depths beneath the canal bed (Stonestrom and Constantz, 

2003). A one-dimensional grid was created, with the top of the 

grid representing canal-bed water interface with changing temperature and stage. Model parameters, such as hydraulic conductivity, were adjusted, such that, the timing and amplitude 

of the diurnal temperature peaks of the simulated temperatures 

matched measured temperatures. Estimated canal leakage was 

the calculated flux determined from the best-fit model.

Creating a useful VS2DH model involves specifying 

a model domain and boundary conditions that adequately 

represent the physical system at each temperature monitoring site. The physical characteristics of the model were based 

on a number of data sources collected at each site, including 

continuous sediment cores, CCR profiles, continuous water 

temperature, and water-level data. One-dimensional VS2DH 

models were constructed for each temperature monitoring site 

based on flow through canal-bed sediment that was assumed 

to be primarily vertical. With this configuration, non-vertical 

(referred to hereinafter as multidimensional) flow of water was 

ignored, and only the vertical hydraulic conductivity of the 

shallow bed sediment was estimated. The top boundary of the 

model was at the canal-bed water interface and was assigned 

specific-head and specific-temperature boundary conditions 

based on measured canal stages and canal water temperatures. 

The bottom boundary was assigned specific-head and specifictemperature conditions on the basis of recorded groundwater 

levels and temperatures. The sides of the model domain were 

specified as no flow boundaries. Model domains thus were 

to represent the subsurface from the canal-bed surface to the 

groundwater table before the irrigation season. The thickness 

of model domains were based on elevation data collected at 

each site with a real time kinematic global positioning system 

(RTK GPS) with a vertical precision of plus or minus (±) 5 

cm. A generalized one-dimensional VS2DH model is shown 

in figure 4. 

Model domains for each VS2DH model were subdivided 

into a series of rows each assigned a sediment texture on the 

basis of described lithology of continuous sediment cores collected at each temperature monitoring site. Lithologic descriptions of collected sediment cores are included in appendix 1 of 

this report. Estimates of thermal and hydraulic properties, such 

as thermal conductivity of saturated sediment, porosity, and 

heat capacity of water, were based on published values from 

Niswonger and Prudic (2003) and Healy and Ronan (1996). 

Thermal properties were held constant for all the sediment textures used in each simulation and are summarized in table 3. 

Figure 4. Generalized one-dimensional VS2DH model of water 

and heat transport through canal-bed sediment. 

Upper boundary—Temperature

and pressure head are 

specified

Lower boundary—Temperature

and pressure head are 

specified

No flow boundary

14.2 meters Poorly sorted 

sand and gravel

Model domain subdivided 

into rows
Methods and Approach 13

Porosity values were estimated based on published values 

documented by Lapalla and others (1987) and are summarized 

in table 3. 

All irrigation seasons were divided into 15- or 30-minute 

intervals called recharge periods, each having unique upper 

and lower boundary conditions based on measured water-level 

and water temperature data. Start date for model simulation 

periods for each temperature monitoring site was indicated for 

each irrigation season by a recorded rise in groundwater levels. 

This rise was interpreted to signal that shallow sediment was 

saturated and flow predominantly was vertical. Model estimates of the vertical hydraulic conductivity of the canal-bed 

sediment involved a trial-and-error approach to obtain the best 

fit between the simulated and measured sediment temperature 

profiles. After each model simulation, the simulated temperatures from user-specified observation points were plotted and 

visually compared to the measured data from each corresponding depth. The vertical hydraulic conductivity of the modeled 

sediment textures was adjusted between simulations (trials) 

until the timing and amplitude of the diurnal temperature 

peaks agreed between the simulated and measured temperatures. The estimated average vertical hydraulic conductivity of 

each canal-bed sediment texture is reported from the best-fit 

model for each temperature monitoring site (table 3).

Monitoring Design and Data Collection 

Tri-State Canal near Mitchell, Nebr.

Using CCR profiles and continuous sediment cores, Ball 

and others (2006) reported that underlying Tri-State Canal 

near temperature monitoring site TCTEMP1 is approximately 

15 m of unsaturated poorly sorted sand and gravel. Vertical 

sensor arrays were installed at various locations across the 

canal bed to examine potential differences in measured temperatures with different sensor deployment designs. 

Sediment temperature gradients were determined by 

measuring temperature at multiple depths beneath the canal 

in separate vertical sensor arrays. Sediment temperature 

data were collected with a subset of type-E thermocouples 

in four vertical sensor arrays. All thermocouple junctions 

were soldered together and covered with heat shrink tubing 

to insulate the junction from the environment. A direct-push 

Geoprobe® (Salina, Kans.) coring rig collected a sediment 

core at the location of each vertical sensor array. Vertical 

sensor arrays 1 and 2 were installed inside two open 6.1-m 

long, 2.5-cm diameter polyvinyl chloride (PVC) pipes, and 

arrays 3 and 4 were installed inside of two 3.05-m open holes 

in direct contact with the sediment. Vertical sensor arrays 1 

and 2 collected sediment temperature data at 0.15, 0.38, 0.76, 

1.52, and 3.05 m below the canal-bed surface, and vertical 

sensor arrays 3 and 4 collected sediment temperature data at 

0.15, 0.23, 0.38, 0.76, and 1.52 m below the canal-bed surface. 

All sensor arrays were backfilled with native material after 

installation. Thermocouples were connected to two Campbell 

Scientific® (Logan, Utah) CR10X data loggers housed inside 

a steel enclosure at the top of the canal bank. The data loggers 

were placed inside a styrofoam cooler and wrapped in bubble 

wrap to reduce the effects of temperature gradients that could 

develop on the wiring panel of the data logger.

Although Type-E thermocouples have 1.0 degrees Celsius 

(oC) accuracy for a 0 to 900 oC temperature range (Omega 

Engineering, 2008), diurnal temperature noise as large as 2 oC 

was present in measured data in all thermocouples. This noise 

is the result of temperature gradients that develop along the 

Table 3. Summary of hydraulic and thermal properties used in final VS2DH models for each temperature monitoring site.

[cm3, cubic centimeters; W/m oC, watts per meter degrees Celsius; J/m3 oC, Joules per cubic meter degrees Celsius; m/d, meters per day]

Sediment texture Porosity1

(cm3/cm3)

Thermal conductivity of 

saturated sediment2

(W/m oC)

Heat capacity of 

water3 at 20 oC 

(J/m3

 oC)

Modeled vertical

hydraulic conductivity 

(m/d)

TCTEMP1

Poorly sorted sand and gravel 0.375 2.1x106 4.2x106 1.1

Silt loam .43 2.1x106 4.2x106 .17

TCTEMP2

Medium sand .375 2.1x106 4.2x106 17

Fine sand .375 2.1x106 4.2x106 1.1

ICTEMP

Medium sand .375 2.1x106 4.2x106 17

Fine sand .375 2.1x106 4.2x106 2.1

Silt and weathered Brule .43 2.1x106 4.2x106 .69

1

 From Lapalla and others, 1987.

2

 From Healy and Ronan, 1996.

3

 From Niswonger and Prudic, 2003.
14 Quantifying Canal Leakage Rates Using a Mass-Balance Approach and Heat-Based Hydraulic Conductivity Estimates

thermocouple wire and on the wiring panel of the data logger. 

To reduce diurnal noise, a reference thermistor replaced one of 

the thermocouples on the wiring panel on each data logger, so 

that the thermocouples referenced this thermistor rather than a 

thermistor remote from the wiring panel. Data from the deepest subsurface thermocouples indicated that this modification 

decreased the diurnal temperature noise to 0.3 oC. To remove 

any artificial diurnal temperature variations, all thermocouple 

data were post-processed using a technique described by 

Mihevc and others (2002) and Hobza (2008). This technique 

assumes that temperature changes in sediment near the deepest 

thermocouple are the result of seasonal warming and cooling. 

Any diurnal temperature variations in the measured data for 

the deepest thermocouple are considered to be artificial, and 

are the result of temperature gradients that have developed on 

the wiring panel of the data logger. To correct for the artificial diurnal variation, daily temperature data recorded by the 

deepest thermocouple at 4:00 a.m. were fit with a series of 

polynomial functions. Data measured at 4:00 a.m. were chosen 

because this is when temperature gradients on the data logger 

wiring panel are assumed to be the smallest. The difference 

between the measured data from the deep thermocouple and 

the fitted data was calculated for each time step. This difference was subtracted from all other thermocouple data from the 

same vertical array to produce data sets with minimal noise. 

An example of pre-processed, unfiltered and post-processed, 

filtered temperature data is shown in figure 5.

To collect data sets free of artificial diurnal noise, and 

assess the effectiveness of the thermocouple data post-processing, additional sediment temperature data were collected with 

HOBO® Tidbit temperature loggers for the 2008 and 2009 

irrigation seasons. The HOBO® Tidbit temperature logger 

(Onset Computer Corp., Pocasset, Mass.) is a self-logging 

thermistor accurate to ±0.2 oC within a -5 to 37 oC temperature 

range (Onset Computer Corp., http://www.onsetcomp.com/

products/data-loggers/tbi32-0537). Self-logging thermistors measure an electrical resistance which is dependent on 

the temperature of the surrounding environment and do not 

require an external reference temperature (Stonestrom and 

Blasch, 2003). HOBO® temperature loggers were deployed 

inside of a stainless-steel sand point and were suspended at 

depths corresponding to the some of the depths of the subsurface data collected by the thermocouples in all four vertical 

sensor arrays. 

Figure 5. Example subsurface temperature data from paired deep and shallow thermocouples: pre-processed, unfiltered data display 

an artificial diurnal variation, and post-processed, filtered data have had artificial diurnal variation removed. 

0

5

10

15

20

25

17 18 19 20 21 22 23 24 25 26 27 28 29 30 1 2 3 4 5 6

June

2007

July

SEDIMENT TEMPERATURE, IN DEGREES CELSIUS

Deep thermocouple, unfiltered data

Deep thermocouple, filtered data

Shallow thermocouple, filtered data

Shallow thermocouple, unfiltered data

Data from vertical sensor array 1 at TCTEMP1
Methods and Approach 15

In addition to sediment temperature data, canal water 

temperature data were measured during each irrigation season. 

A HOBO® Tidbit temperature logger was deployed inside of 

a section of pipe anchored to the bed of the canal. Following 

its disturbance July 7, 2008, the HOBO temperature logger ceased operation for the remainder of the 2008 irrigation 

season. 

Canal-stage data were collected using an In-situ LevelTROLL® 500 (In-Situ Inc., Fort. Collins, Colo.) vented-cable 

transducer located inside a stilling well. The transducer was 

placed 0.76 m above the elevation of the canal bed. A monitoring well was installed near the temperature monitoring site and 

instrumented with a second In-situ Level-TROLL® 500 to continuously record groundwater levels. In-situ Level-Troll 500 

pressure transducers are accurate to 0.02 m (In-situ Inc., http://

www.in-situ.com/products/Water-Level/Level-TROLL-Family/

Level-TROLL-500-Instrument/overview). Manual water-level 

measurements were collected to verify the accuracy of the 

groundwater-level record. All continuous data collected at 

this site were recorded at 15-minute intervals throughout the 

duration of the study. A generalized diagram and map of the 

installation design for site TCTEMP1 is shown in figure 6. 

The VS2DH model domain extended from the elevation 

of the top of the canal bed to the water table elevation immediately before canal diversion for the hay run and primary 

irrigation seasons. The model domain varied slightly depending on the elevation of the water table before diversion into 

Tri-State Canal. The entire model domain was subdivided into 

500 rows and was assigned a single lithologic unit composed 

of poorly sorted sand and gravel based on data from continuous sediment cores (appendix 1), CCR data, and a test-hole 

log recorded during monitoring-well installation. The irrigation season was subdivided into 15-minute periods called 

recharge periods that had unique upper and lower boundary 

conditions. Canal-stage and water temperature data were 

inputs for the upper boundary condition of each model simulation. Differences between the elevation of the canal bed and 

the elevation of the stage transducer were added to the stage 

record to determine the pressure head at the canal-bed surface. 

Continuous groundwater-level and groundwater-temperature 

data were inputs for the lower boundary condition of each 

model simulation. The difference between the pre-diversion 

groundwater-level elevation and recorded groundwater elevation was the pressure head exerted at the lower model boundary for each recharge period.

Tri-State Canal at Spottedtail Creek, Nebr.

Site TCTEMP2 was located immediately downstream 

from the confluence of Tri-State Canal with Spottedtail Creek 

where discharge received from Spottedtail Creek submerges 

the canal bed, and it potentially creates a groundwater mound 

beneath the canal. Within this reach the higher water table 

would decrease the hydraulic gradient and potentially reduce 

canal leakage. This condition is believed to be spatially 

anomalous as most of the reach is dry during the non-irrigation 

season. The headwaters of Spottedtail Creek are south of 

Interstate Canal, approximately 8 km upstream from Tri-State 

Canal. The Bureau of Reclamation operates a streamflowgaging station about 1.5 km above site TCTEMP2. Leakage 

from Interstate Canal increases local groundwater levels and 

contributes to the base flow of Spottedtail Creek (Harvey 

and Sibray, 2001). Historical discharge data indicate that 

Spottedtail Creek is an intermittent stream at the streamflowgaging station; however, discharge was continuous for the site 

TCTEMP2 period of record.

Site TCTEMP2 was designed to measure the shallow 

groundwater level beneath Tri-State Canal in order to compute 

the hydraulic gradient. Canal-stage data were collected using 

an In-situ Level-TROLL® 100 nonvented transducer deployed 

inside of a 0.2-m long section of PVC pipe attached to the 

sounding weight. Pressure-head data were collected with an 

In-situ Level-TROLL® 100 nonvented transducer deployed in 

a stainless-steel sand point 0.91-m below the canal bed. The 

cap of the sand point was sealed water tight, and the sandpoint screen was covered with pipe wrap except for the bottom 0.15 m, which was open to the canal-bed sediment. The 

distance between the transducers was 0.91 m and was assumed 

to remain fixed. Data collected from both nonvented transducers were corrected for changes in barometric pressure as 

monitored using an In-situ Baro-TROLL pressure sensor. The 

calculated accuracy of both nonvented transducers after barometric pressure correction is ±0.03 m (In-situ Inc., http://www.

in-situ.com/products/Water-Level/BaroTROLL-Instruments/

Rugged-BaroTROLL-Instrument/overview). Sediment temperature data were collected with HOBO® TidbitV2 temperature loggers (±0.2 oC in a 0 to 50 oC range; Onset Computer 

Corp., http://www.onsetcomp.com/products/data-loggers/utbi001) deployed inside of a stainless-steel sand point at depths 

of 0.15, 0.23, 0.38, and 0.76 m below the canal-bed surface. 

Water temperature was collected with a HOBO® TidbitV2 

temperature logger attached to the top of a sounding weight 

placed on the bed of the canal to ensure the temperature logger 

remained in the water column. Continuous sediment cores 

were collected by manually driving a Geoprobe® core barrel into the saturated sediment to a depth of 0.91 m beneath 

the canal-bed surface. A generalized diagram and map of the 

installation design used at site TCTEMP2 is shown in figure 7. 

A one-dimensional VS2DH model was created using 

the continuous sediment core (appendix 1), and the waterlevel and water temperature data collected from May through 

September 2009. The model domain was subdivided into 

200 rows and extended from the top of the canal bed to the 

level of the lower transducer. Stage and canal water temperature data were inputs for defining the upper boundary condition of each model simulation. Continuous pressure-head and 

groundwater-temperature data were inputs for defining the 

lower boundary condition of each model simulation. Because 

the model boundary was set at the location of the lower 

transducer, the recorded groundwater level was equal to the 

pressure head exerted at the lower model boundary for each 

recharge period. 
16 Quantifying Canal Leakage Rates Using a Mass-Balance Approach and Heat-Based Hydraulic Conductivity Estimates

Interstate Canal near University Lake, Nebr.

Sediment temperature data were collected with a series 

of type-T thermocouples (Omega Engineering, 2010) in two 

vertical sensor arrays beneath the canal bed (VA1 and VA2), 

and two vertical sensor arrays immediately south of Interstate 

Canal (VA3 and VA4) (fig. 8). The placement of the thermocouple sensor arrays was chosen to examine vertical and 

lateral leakage of canal water. Type-T thermocouples have a 

reported precision of ±0.5 oC for a range of temperatures 

from 0 to 900 oC (Omega Engineering, 2010). At sensor array 

VA1, thermocouples collected data 0.15, 0.23, 0.38, 1.52, and 

Figure 6. Generalized diagram (A) and map (B) of monitoring installation design used at site TCTEMP1, Tri-State Canal near Mitchell, 

Nebr. 

Monitoring well Stilling well

Vertical sensor array

HOBO® Tidbit temperature logger

Groundwater level

Thermocouples

Canal

A

HOBO® Tidbit temperature logger

Grou

Thermocouples

Not to scale
Methods and Approach 17

4.5 m below the canal-bed surface. At sensor array VA2, thermocouples collected sediment temperature data at 0.15, 0.23, 

0.38, 0.61, and 5.49 m below the canal-bed surface. South 

of the canal, thermocouples at sensor array VA3 collected 

sediment temperature data at 7.01, 7.47, 7.92, 8.38, 8.83, and 

9.14 m below land surface. At sensor array VA4, sediment 

temperature data were collected at 7.92, 8.53, 8.83, and 9.14 m 

below land surface south of the canal. 

Boreholes at vertical sensor arrays were backfilled with 

native material after installation. Sensor arrays were connected to two Campbell Scientific CR10X data loggers housed 

inside a steel enclosure at the top of the canal bank. Reference 

Cook Oil Road

Spring Creek Road

Tri-State Canal

VA2

VA3 VA1

VA4

103°46'30" 20" 10" 46' 50" 40" 103°45'30"

41°56'

50"

40"

41°55'30"

Base from U.S. Department of Agriculture, Aerial Photography Field Office

Digital orthophotography, 2007, 1:100,000

Universal Transverse Mercator projection

Zone 13

Horizontal coordinate information is referenced to the North American

Datum of 1983 (NAD 83)

Flow

EXPLANATION

VA3 Vertical sensor array 

 and number

TCTEMP1 

B

0

0

0.1 0.2 KILOMETER

0.1 0.2 MILE

Figure 6.—Continued.
18 Quantifying Canal Leakage Rates Using a Mass-Balance Approach and Heat-Based Hydraulic Conductivity Estimates

thermistors were wired to the panels of the data loggers, as for 

site TCTEMP1. Diurnal temperature noise as large as 0.5 oC 

was present in measured data from all thermocouples. These 

data were adjusted as previously described in Tri-State Canal 

near Mitchell, Nebr., section of this report. Additional sediment temperature data were collected with HOBO temperature 

loggers deployed inside of a stainless-steel sand point. These 

temperature loggers collected sediment temperature at 0.15, 

0.23, 0.38, and 0.76 m below the canal-bed surface.

Canal water temperature also was monitored continuously. A HOBO® Tidbit temperature logger was deployed 

inside of a section of pipe anchored to the bed of the canal. 

Canal stage data were collected using an In-situ LevelTROLL® 500 vented-cable transducer placed inside of a stilling well. A monitoring well was installed near the temperature 

monitoring location and instrumented with an In-situ LevelTROLL® 500 vented-cable transducer to continuously record 

groundwater levels. Water level also was measured manually 

to verify the groundwater-level record. Continuous data were 

recorded at 15-minute intervals throughout the study. A generalized diagram and map of the installation design used at site 

ICTEMP is shown in figure 8. 

A one-dimensional VS2DH model was constructed 

based on the lithology of the collected sediment cores at site 

ICTEMP (appendix 1). The model domain was subdivided 

into 500 rows and comprised three layers corresponding to different sediment types: 0.3 m of medium sand, overlying 1.0 m 

of fine sand, overlying 14.2 m of silt and weathered Brule 

Formation (appendix 1). The model domain extended from 

the top of the canal bed to the water table elevation measured 

immediately before the start of the 2008 diversions into the 

canal. The entire irrigation season was divided into 15-minute 

recharge periods. Inputs defining the upper boundary condition of each simulation were canal stage and canal water temperature data. Inputs defining the bottom boundary condition 

of each simulation were continuous records of groundwater 

level and groundwater temperature. The difference in elevation 

between the pre-diversion groundwater-level elevation and 

recorded groundwater elevation is the pressure head exerted at 

the lower boundary for each recharge period.

Calculated Leakage Rates Using MassBalance Approach

Tri-State Canal Leakage Rates

Daily mean computed discharge from rated ADVM for 

the TSUS and TSDS streamflow-gaging stations is shown 

in figures 9 through 11 for a selected period each year. The 

minimum computed discharge from Tri-State Canal was 

13.2 m3/s (465 ft3/s), reported at the TSDS streamflow-gaging 

station on May 16, 2008 (not shown), and the maximum 

reported discharge was 36.5 m3/s (1,290 ft3/s) reported at the 

TSUS streamflow-gaging station on July 9, 2007. In general, 

higher flows were reported during the 2007 irrigation season 

in response to drier conditions and greater demands for irrigation water. Reported daily mean diversions to laterals within 

the study reach ranged from 0 to 0.19 m3

/s (0 to 6.8 ft3/s) and 

typically were greatest from late July into early August when 

water demands were greatest. Evaporative water loss was less 

than 1 percent of the computed daily leakage, but was still 

included in the calculation. 

Daily mean leakage rates are plotted in figures 9 through 

11 for the 2007 to 2009 irrigation seasons. Canal-leakage rates 

were not reported for periods of record not bracketed by discharge measurements. During such periods, the larger uncertainty in the computed daily mean discharge at each streamflow-gaging station potentially could mask canal leakage. 

Figure 7. Generalized diagram (A) and map (B) of monitoring 

installation design used at site TCTEMP2, Tri-State Canal at 

Spottedtail Creek, Nebr. 

EXPLANATION

Canal bed

Sounding weight

Temperature logger

Pressure transducer

0.91 meter

0.03

meter

0.15

0.15

0.38

0.08

0.15

Not to scale

Water level

A
Calculated Leakage Rates Using Mass-Balance Approach 19

Leakage, thus, was calculated only for the period between the 

first and last ADCP discharge measurement each year.

Computed leakage rates (hereinafter referred to as leakage rates), given in units of meters per day, are defined as 

discharge loss per unit of bed area. Leakage rates varied from 

year to year and usually were dependent on local climatic conditions, and the timing and magnitude of the initial seasonal 

diversion into Tri-State Canal. Leakage rates ranged from 

0.98 m/d on June 22, 2007, to about 0 m/d during July 2009. 

Generally speaking, drier local conditions resulted in higher 

leakage rates. Of the three years studied (2007–09), 2007 

was the driest. Only 23.8 cm of precipitation was recorded 

the entire year at the Scottsbluff Airport (fig. 12) (National 

Oceanic and Atmospheric Administration, 2010). Of the total 

annual precipitation, 9.8 cm was recorded during the irrigation 

season from May through September 2007. Climatic conditions also are reflected in the pre-diversion season (October to 

April) discharge of the North Platte River (fig. 12). The discharge of the North Platte River during these months mainly 

is base flow from groundwater discharge. During the diversion 

season, reservoir releases to satisfy surface-water irrigation 

demands increase the river’s discharge, masking base flow. 

North Platte River discharge for April and May 2007 (0.36 

and 0.077 m3

/s, respectively) were the lowest monthly mean 

discharges recorded during the study period.

Water-supply conditions were so severe in 2007 that no 

hay run took place, and diversions into Tri-State Canal were 

delayed until late June. Hay runs occurred in 2008 and 2009; 

however, they were not included in mass-balance computation 

of leakage rates because the stage was too low for ADVMs to 

103°49 '20" 103°49 ' 103°48 '40" 103°48 '20" 103°48 '

41°58'40"

41°58'20"

Tri-State Canal

Spottedtail Creek

Base from U.S. Department of Agriculture, Aerial Photography Field Office

Digital orthophotography, 2007, 1:100,000

Universal Transverse Mercator projection

Zone 13

Horizontal coordinate information is referenced to the North American

Datum of 1983 (NAD 83)

0

0 0.1

0.2

0.2 MILE

Highway 29

0.4 KILOMETER

Flow

TCTEMP2

B

Figure 7.—Continued. 
20 Quantifying Canal Leakage Rates Using a Mass-Balance Approach and Heat-Based Hydraulic Conductivity Estimates

Figure 8. Generalized diagram (A) and map (B) of monitoring installation design used at site ICTEMP, Interstate Canal near University 

Lake, Nebr. 

Stilling well

Thermocouples

Top of Brule Formation

Direction of regional groundwater flow

HOBO® Tidbit

temperature loggers

Not to scale

Groundwater level

Monitoring well

Canal bed

VA4 VA3 VA2 VA1

A

Sand point

Flow

42°02'40"

42°02'30"

VA1

VA2

VA3

VA4

Base from U.S. Department of Agriculture, Aerial Photography Field Office

Digital orthophotography, 2007, 1:100,000

Universal Transverse Mercator projection

Zone 13

Horizontal coordinate information is referenced to the North American

Datum of 1983 (NAD 83)

ICTEMP

InterstateCanal

0

0

0.1 0.2 KILOMETER

0.1 0.2 MILE

103°44 '30" 103°44 '20" 103°44 '10" 103°44 ' 103°43 '50"

EXPLANATION

VA3 Vertical sensor array 

 and number

B
Calculated Leakage Rates Using Mass-Balance Approach 21

0

0.25

0.5

0.75

1

1.25

1.5

1.75

2

0

5

10

15

20

25

30

35

40

6/15 7/1 7/15 8/1 8/15 9/1 9/15

DAILY MEAN LEAKAGE RATE, IN METERS PER DAY

DAILY MEAN DISCHARGE, IN CUBIC METERS PER SECOND

Tri-State Canal near Mitchell, site 415812103493701 (site TSUS)

Tri-State Canal near Mintle, site 41562610343001 (site TSDS)

Computed mean leakage rate for intervening reach

2007

Upstream

Downstream

Figure 9. Daily mean upstream discharge, downstream discharge, and bed leakage rate, Tri-State Canal, late June to September, 2007. 

Figure 10. Daily mean upstream discharge, downstream discharge, and bed leakage rate, Tri-State Canal, late June to early August, 

2008. 

0

0.25

0.5

0.75

1

1.25

1.5

1.75

2

0

5

10

15

20

25

30

35

40

7/1 7/15 8/1 8/15

Tri-State Canal near Mitchell, site 415812103493701 (site TSUS)

Tri-State Canal near Mintle, site 415626103434001 (site TSDS)

Computed mean leakage rate for intervening reach

DAILY MEAN LEAKAGE RATE, IN METERS PER DAY

DAILY MEAN DISCHARGE, IN CUBIC METERS PER SECOND

2008

Upstream

Downstream
22 Quantifying Canal Leakage Rates Using a Mass-Balance Approach and Heat-Based Hydraulic Conductivity Estimates

-0.25

0

0.25

0.5

0.75

1

1.25

1.5

1.75

2

0

5

10

15

20

25

30

35

40

7/15 8/1 8/15 9/1

Tri-State Canal near Mitchell, site 415812103493701 (site TSUS) 

Tri-State Canal near Mintle, site 415626103434001 (site TSDS)

Computed mean leakage rate for intervening reach

DAILY MEAN LEAKAGE RATE, IN METERS PER DAY

DAILY MEAN DISCHARGE, IN CUBIC METERS PER SECOND

2009

Upstream

Downstream

Negative values indicate gains in flow for the intervening reach

0

2

4

6

8

10

12

14

16

18

0 20

10

20

30

40

50

60

PRECIPITATION, IN CENTIMETERS

MONTHLY MEAN DISCHARGE, IN CUBIC METERS PER SECOND

Monthly mean streamflow 

 of the North Platte River 

 at the Nebraska-Wyoming 

 state line

Total monthly precipitation 

 at Scottsbluff Airport

2007 2008 2009

J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D

Figure 11. Daily mean upstream discharge, downstream discharge, and bed leakage rate, Tri-State Canal, early July to late August, 

2009. 

Figure 12. Monthly mean streamflow of North Platte River at the Nebraska-Wyoming state line (streamflow-gaging station 06674500) 

and total monthly precipitation measured at Scottsbluff Airport, January 2007 through December 2009.
Calculated Leakage Rates Using Mass-Balance Approach 23

collect accurate velocity and stage data. Each year, calculated 

leakage rates were greatest when flow was first diverted into 

the canal system. Because the first diversions into Tri-State 

Canal in 2008 and 2009 were hay runs from which discharge 

was not measured, the calculated leakage rates were smaller 

than those in 2007. Discharge within part of the study reach 

of Tri-State Canal was greater in 2009 after the hay run and 

before the primary irrigation season than in 2007 or 2008 

because of captured flow from Akers Draw and Spottedtail 

Creek, and to deliver water to Northport Canal (not shown on 

map). This sustained early wetting of the canal was a potential 

cause of the lower canal-leakage rates recorded during the 

early part of the irrigation season in 2009 as compared to 2007 

and 2008. 

Interstate Canal Leakage Rates

Daily mean computed discharges from ADVM ratings for 

the ISUS and ISDS streamflow-gaging stations are presented 

in figures 13 through 15 for a selected period of each year. 

The minimum computed discharge from Interstate Canal was 

9.97 m3/s (352 ft3/s) reported at the ISDS streamflow-gaging 

station on May 16, 2009 (not shown), and the maximum 

discharge was 26.8 m3/s (945 ft3/s) reported at the ISUS 

streamflow-gaging station on July 27, 2007. In general, higher 

discharges occurred during the 2007 irrigation season in 

response to drier conditions and greater demands for irrigation 

water. Reported daily mean diversions to laterals within the 

study reach on Interstate Canal ranged from 0.57 to 6.5 m3

/s 

(20 to 230 ft3/s). The larger diversions to laterals [typically 2.8 

to 5.7 m3/s (100 to 200 ft3/s)] were reported during the primary 

irrigation season from mid-July to early August when water 

demands were highest. 

Computed leakage for the 2007–09 irrigation seasons 

is plotted in figures 13 through 15. Just as for Tri-State Canal, 

leakage was calculated only for the period between the first 

and last ADCP discharge measurement each year. Although 

the index discharge was within five percent of discharge measurements, the recorded 2007 irrigation-season flows indicated 

there were gains in discharge within the study reach of as 

much as 0.27 m3/s (9.4 ft3/s). This is unlikely because the only 

inflow is a drainage culvert that would only flow during wetweather conditions. Apparent gains in flow may be the result 

of relative proximity to Lake Alice where high water levels 

may cause backwater conditions and alter the index velocitydischarge relation for part of an irrigation season, and thus, 

introduce error in the mass-balance calculations. Excluding the 

leakage calculations from early May 2007, the leakage rates 

ranged from 0.08 to 0.7 m/d. Less variability in leakage from 

-0.25

0

0.25

0.5

0.75

1

1.25

1.5

1.75

2

0

5

10

15

20

25

30

4/15 5/1 5/15 6/1 6/15 7/1 7/15 8/1 8/15

DAILY MEAN LEAKAGE RATE, IN METERS PER DAY

DAILY MEAN DISCHARGE, IN CUBIC METERS PER SECOND

Interstate Canal near Rattlesnake Hill, site 420327103464301 (site ISUS)

Interstate Canal near Mintle, site 415922103404801 (site ISDS)

Computed mean leakage rate for intervening reach

2007

Upstream

Downstream

Negative values indicate gains in flow for the intervening reach

Figure 13. Daily mean upstream discharge, downstream discharge, and bed leakage rate, Interstate Canal, May to mid-August, 2007. 
24 Quantifying Canal Leakage Rates Using a Mass-Balance Approach and Heat-Based Hydraulic Conductivity Estimates

0

0.25

0.5

0.75

1

1.25

1.5

1.75

2

0

5

10

15

20

25

30

4/15 5/1 5/15 6/1 6/15 7/1 7/15 8/1 8/15 9/1 9/15

DAILY MEAN LEAKAGE RATE, IN METERS PER DAY

DAILY MEAN DISCHARGE, IN CUBIC METERS PER SECOND

Interstate Canal near Rattlesnake Hill, site 420327103464301 (site ISUS)

Interstate Canal near Mintle, site 415922103404801 (site ISDS)

Computed mean leakage rate for intervening reach

2008

Upstream

Downstream

0

0.25

0.5

0.75

1

1.25

1.5

1.75

2

0

5

10

15

20

25

30

7/15 8/1 8/15 9/1

Interstate Canal near Rattlesnake Hill, site 420327103464301 (site ISUS)

Interstate Canal near Mintle, site 415922103404801 (site ISDS)

Computed mean leakage rate for intervening reach

DAILY MEAN LEAKAGE RATE, IN METERS PER DAY

DAILY MEAN DISCHARGE, IN CUBIC METERS PER SECOND

2009

Upstream

Downstream

Figure 14. Daily mean upstream discharge, downstream discharge, and bed leakage rate, Interstate Canal, late April to early August, 

2008. 

Figure 15. Daily mean upstream discharge, downstream discharge, and bed leakage rate, Interstate Canal, early July to late August, 

2009. 
Heat-Based Hydraulic Conductivity Estimates 25

year to year indicates that climatic conditions may have less 

of an effect for Interstate Canal compared to Tri-State Canal. 

This may be because Interstate Canal was cut into the northern 

edge of the North Platte alluvial valley and consequently the 

canal bed is well above the local groundwater table resulting 

in a constant (-1 m/m) hydraulic gradient. Interstate Canal also 

does not receive any captured flow that can vary substantially 

year to year. 

Heat-Based Hydraulic Conductivity 

Estimates

Tri-State Canal near Mitchell, Nebr.

Seasonal flow patterns in Tri-State Canal affected the 

temperature patterns of the shallow sediment beneath the 

canal. Each year before the initial diversion into Tri-State 

Canal, diurnal variations in sediment temperature in shallow 

thermocouples and thermistors occurred because of daytime 

heating and nighttime cooling. A disruption in the diurnal 

temperature cycle in the shallow thermocouples or thermistors signaled the arrival of canal water. This disruption in the 

temperature cycle was recorded in deeper thermocouples at 

only slightly later times compared to shallow thermocouples 

because of the infiltration of water to these depths (fig. 16). 

The amplitude of the diurnal temperature cycle was dampened 

at depth as heat was transferred from the canal water to the 

surrounding sediments. 

Measured groundwater level rises typically occurred 

within 24 hours after flow arrived at a temperature monitoring 

site at the start of an irrigation season (fig. 17). Groundwater 

levels rose continuously when canal flows approached maximum capacity until diversions were decreased in September. 

Small diurnal water temperature variations (1.0 to 1.5 oC) 

were measured when canal flow was near maximum capacity 

(fig. 18). The temperature and stage sensors were above the 

surface of the water when the canal stage was below 0.76 m. 

This low-stage condition of Tri-State Canal was restricted to 

periods when the canal was delivering water only to Northport 

Canal (not shown on map) or a natural flow period following 

the primary irrigation season when canal flow was sustained 

by captured flow. Larger diurnal variations in temperatures of 

the canal water and shallow bed sediment were measured during lower discharge periods. 

The vertical hydraulic conductivity of the poorly sorted 

sand and gravel beneath site TCTEMP1 is estimated using 

a calibrated VS2DH model. Based on the trial-and-error 

approach, the best-fit vertical hydraulic conductivity for the 

entire site TCTEMP1 model domain was 1.1 m/d. This value 

6/13 5

10

15

20

25

30

35

6/14 6/15 6/16 6/17 6/18 6/19

2007

Thermocouple, depth below

 canal surface

0.15 meter

0.23 meter

0.38 meter

0.76 meter

1.52 meters

No flow Flow

SEDIMENT TEMPERATURE, IN DEGREES CELSIUS

Figure 16. Thermograph of sediment beneath Tri-State Canal from vertical sensor array 4 during initiation of seasonal flow, June 2007.
26 Quantifying Canal Leakage Rates Using a Mass-Balance Approach and Heat-Based Hydraulic Conductivity Estimates

1,201.6

1,201.8

1,202

1,203

1,202.2

1,202.4

1,202.6

1,202.8

5/30 6/1 6/3 6/5 6/7 6/9 6/11 6/13 6/15 6/17 6/19 6/21 6/23 6/25 6/27 6/29 7/1 7/3

ELEVATION, IN METERS ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988

Groundwater level

No Flow Flow

2007

-1

-0.5

0

0.5

1

1.5

2

-10

0

10

20

30

40

50

CANAL STAGE, IN METERS

May June July August September October

2007

WATER TEMPERATURE, IN DEGREES CELSIUS

No flow Flow Canal stage

Canal water

 temperature

Figure 17. Groundwater level recorded near Tri-State Canal near Mitchell, Nebr., June 2007. 

Figure 18. Water temperature and stage in Tri-State Canal near Mitchell, Nebr., May through September, 2007.
Heat-Based Hydraulic Conductivity Estimates 27

falls within the range of hydraulic conductivities for sand and 

gravel given by Domenico and Schwartz (1998). Example 

plots of measured and simulated sediment temperatures are 

shown in figures 19 through 21. Precise estimation of the 

vertical hydraulic conductivity was difficult because of the 

relatively small diurnal variation in canal water temperature. 

Model fits were best for temperature sensors shallower than 

0.76 m when flow was vertical. Below a depth of 0.76 m, flow 

in canal-bed sediment most likely became multidimensional 

as indicated by dampened diurnal cycles in measured data 

relative to simulated. Hoffman and others (2007) reported a 

similar interpretation when modeling channel infiltration with 

a one-dimensional VS2DH model. 

The calibrated model was able to fit simulated to measured subsurface temperatures collected in 2007 and 2009 

(figs. 19 and 20); however, the simulations for May and June 

2008 did not produce satisfactory results (not shown). Model 

simulations were not attempted for the period after July 7 

because the sensor recording canal water temperature was 

disturbed and ceased collecting data. The sediment diurnal 

temperature cycles measured for thermistors and thermocouple 

arrays were much more dampened compared to simulated 

temperatures. The dampened temperature cycles indicate 

reduced leakage rates through canal-bed sediments. Because 

it is unlikely that the vertical hydraulic conductivity of the 

underlying canal-bed sediments had changed, a reduction in 

leakage may have been caused by a lower hydraulic-conductivity layer that was deposited over sensor arrays. During site 

visits occurring between diversion periods, evidence of localized scouring and deposition of sediment on the canal bed was 

observed. Deposition of sediment over sensor arrays likely 

would dampen measured diurnal sediment temperature cycles 

and potentially could reduce canal leakage. Sediment deposition may be localized such that it may not affect the leakage 

rates of an entire reach. 

Additional model simulations included a hypothetical 

sediment layer having a lower vertical hydraulic conductivity 

layer and positioned on top of the calibrated model domain, 

Figure 19. Measured and simulated thermographs for saturated sediment at (A) 0.15 m and (B) 0.76 meter beneath Tri-State Canal near 

Mitchell, Nebr., 2007.

18

19

20

21

22

23

24

25

SATURATED SEDIMENT TEMPERATURE, IN DEGREES CELSIUS

Measured at 

 depth of 0.76

 meter

Simulated at 

 depth of 0.76

 meter

Measured at 

 depth of 0.15 

 meter

Simulated at 

 depth of 0.15

 meter

18

19

20

21

22

23

24

25

6/23 6/25 6/27 6/29 7/1

A

B

2007
28 Quantifying Canal Leakage Rates Using a Mass-Balance Approach and Heat-Based Hydraulic Conductivity Estimates

though no field data collected support this hypothesis. The 

hypothetical layer was a 10-cm layer of silt loam with a vertical hydraulic conductivity of 0.17 m/d above the sensor arrays. 

The amplitude and timing of simulated temperature peaks 

matched measured data for the 0.15- and 0.23-m sensors; 

however, measured diurnal sediment temperature cycles below 

these depths are dampened compared to simulated temperatures (fig. 21). This may be attributed to the lower conductivity 

layer reducing leakage rates such that the diurnal temperature 

cycle is masked in the canal-bed sediments deeper than 0.23 m 

resulting in poor model fits. 

Tri-State Canal at Spottedtail Creek, Nebr.

The seasonal flow patterns of Tri-State Canal affected 

the measured temperature of the canal water and the shallow 

groundwater at site TCTEMP2. Lower flows at site TCTEMP2 

coincided with larger diurnal variability in canal water temperatures (fig. 22). Measured groundwater temperature did 

not display diurnal variation in water temperature, but rather 

seasonal warming and cooling in response to changes in 

canal water temperature. Measured pressure head beneath 

Tri-State Canal closely resembled measured canal stage 

(fig. 23). 

The hydraulic gradient for the period of data collection ranged from -0.14 to -0.07 m/m indicating continued 

leakage to the groundwater system (fig. 24A). The hydraulic 

gradient increased during the hay run and peaked in June 

before the primary irrigation season. This increase in hydraulic gradient is most likely a result of the groundwater level 

rising in response to increases in local precipitation and 

base flow from Spottedtail Creek (fig. 24B). Several peaks 

in canal stage were the result of sharp increases in discharge 

in Spottedtail Creek during storm runoff. Throughout the 

primary irrigation season, canal stage and hydraulic gradient 

18

19

20

21

22

23

24

25

18

19

20

21

22

23

24

25

7/6 7/8 7/10 7/12

SATURATED SEDIMENT TEMPERATURE, IN DEGREES CELSIUS

Measured at 

 depth of 0.15 

 meter

Simulated at 

 depth of 0.15

 meter

Measured at 

 depth of 0.76

 meter

Simulated at 

 depth of 0.76

 meter

A

B

2009

Figure 20. Measured and simulated thermographs for saturated sediment at (A) 0.15 meter and (B) 0.76 meter beneath Tri-State Canal 

near Mitchell, Nebr., 2009.
Heat-Based Hydraulic Conductivity Estimates 29

were inversely related indicating that higher canal stages 

induced greater potential for losses to the groundwater 

system. 

The simulation period for VS2DH-based estimation of 

vertical hydraulic conductivities started when canal stage was 

steady and near its maximum during the primary irrigation 

season, which are conditions when leakage primarily would 

be vertical and the effects of multidimensional flow would 

be minimized. Description of the sediment core indicated 

a 0.25-m layer of medium sand overlying a 0.66-m layer 

of fine sand (appendix 1). Sediment layer thicknesses were 

adjusted from the thicknesses reported in appendix 1 because 

of incomplete sample recovery. The best-fit modeled vertical 

hydraulic conductivity estimated for this flow condition was 

17 m/d for the medium sand layer and 1.1 m/d for the fine 

sand layer (mean of 1.5 m/d). An example simulated thermograph produced using the previously stated vertical hydraulic 

conductivities plotted with measured thermographs is shown 

in figure 25. Both hydraulic conductivities agree well with 

published ranges for fine and medium sand (Domenico and 

Schwartz, 1998). 

Interstate Canal near University Lake, Nebr.

Diversion into Interstate Canal at the start of 2008 irrigation also resulted in sharp rises in groundwater levels recorded 

in the observation well (fig. 26). Changes in canal discharge 

result in near instantaneous responses in groundwater level. 

The high degree of synchrony suggests that fractures in the 

Brule Formation are present. Measured groundwater temperatures ranged from about 17.5 to 18.2 oC. A strong seasonal 

variation is clear within the irrigation season. Canal water 

temperature during the irrigation season varied from 4 to 25 oC 

and displayed a diurnal variability of 2 oC in the period of 

record (fig. 27). 

Figure 21. Measured and simulated thermographs for saturated sediment (including a hypothetical top layer of silt) at (A) 0.15 meter 

and (B) 0.76 meter beneath Tri-State Canal near Mitchell, Nebr., 2008.

18

19

20

21

22

23

24

25

SATURATED SEDIMENT TEMPERATURE, IN DEGREES CELSIUS

18

19

20

21

22

23

24

25

6/24 6/26 6/28 6/30

Measured at 

 depth of 0.15 

 meter

Simulated at 

 depth of 0.15

 meter

Measured at 

 depth of 0.76

 meter

Simulated at 

 depth of 0.76

 meter

A

B

2008
30 Quantifying Canal Leakage Rates Using a Mass-Balance Approach and Heat-Based Hydraulic Conductivity Estimates

0

0.5

1

1.5

2

2.5

0

5

10

15

20

25

30

5/1 5/15 9/15 10/1 10/15 6/1 6/15 7/1 7/15 8/1 8/15 9/1

CANAL STAGE, IN METERS

CANAL WATER TEMPERATURE, IN DEGREES CELSIUS

Canal stage

Canal water temperature

2009

0

0.5

1

1.5

2

2.5

3

0

5

10

15

20

25

Pressure head at 0.91 meter below canal bed

Groundwater temperature

PRESSURE HEAD, IN METERS

GROUNDWATER TEMPERATURE, IN DEGRESS CELSIUS

2009

5/1 5/15 9/15 10/1 10/15 6/1 6/15 7/1 7/15 8/1 8/15 9/1

Figure 22. Water temperature and stage in Tri-State Canal at Spottedtail Creek, Nebr., May to October, 2009.

Figure 23. Pressure head and temperature recorded 0.91 meter below Tri-State Canal at Spottedtail Creek, Nebraska, May to October, 

2009.
Heat-Based Hydraulic Conductivity Estimates 31

Recorded sediment temperatures, both from thermocouples and thermistors, displayed diurnal cycles that became 

dampened with depth. Sediment temperature data from 

the deeper thermocouples, installed in the weathered Brule 

Formation, mainly recorded only seasonal variations in sediment temperature (sensor array VA1, 4.5 m), near that of the 

groundwater temperature of 18 oC. The arrival of canal water 

during the hay run or primary irrigation season produced an 

abrupt change in the temperature pattern of sensors installed 

in the sediment beneath the canal (fig. 28). Sediment temperatures from sensor arrays VA3 and VA4 indicate nearly constant 

temperature in the weathered Brule Formation, varying less 

than 1 oC. Canal leakage at site ICTEMP may primarily be 

vertical because of the relatively low variability in recorded 

sediment temperature data from sensor arrays VA3 and VA4. 

Based on the relatively flat sediment temperature response and 

the change in groundwater levels, it is thought that groundwater movement through the shallow Brule Formation beneath 

Interstate Canal would bypass the VA3 and VA4 sensor arrays. 

Temperature changes in sediment from advective heat transport, as seen for sensor array VA1 (4.5 m depth), would have 

caused an obvious departure from this seasonal heating and 

cooling temperature pattern (fig. 28).

The vertical hydraulic conductivities of the sediment layers were estimated using calibrated one-dimensional VS2DH 

models. After using a trial-and-error approach for calibration, 

the average vertical hydraulic conductivities were estimated 

at 17 m/d for the medium sand unit, 2.1 m/d for the fine sand 

unit, and 0.69 m/d for the silt and weathered Brule Formation. 

The estimated hydraulic conductivities agree well with 

published ranges for medium and fine sand (Domenico and 

Schwartz, 1998) and weathered Brule Formation (Barrash and 

Morin, 1987). The simulated sediment temperatures were in 

closest agreement with measured temperatures at shallow thermocouples and thermistors where flow primarily was vertical 

(fig. 29). Below 0.76 m, flow likely became multidimensional, 

0

0.5

1

1.5

2

2.5

-0.16

-0.12

-0.08

-0.04

0

CANAL STAGE, IN METERS

HYDRAULIC GRADIENT, IN METERS PER METER

Canal stage

Hydraulic gradient

A

5/1 5/15 6/1 6/15 7/1 7/15 8/1 8/15 9/1 9/15 10/1 10/15

5/1 5/15 6/1 6/15 7/1 7/15 8/1 8/15 9/1 9/15 10/1 10/15

0

0.2

0.4

0.6

0.8

1 0

1

2

3

4

5

DAILY MEAN DISCHARGE, 

IN CUBIC METERS PER SECOND

DAILY PRECIPITATION, IN CENTIMETERS

Spottedtail Creek streamflow-

 gaging station

Precipitation at Scottsbluff

 Airport

B

2009

Figure 24. Canal stage and hydraulic gradient measured beneath Tri-State Canal at Spottedtail Creek (A), discharge reported at 

Spottedtail Creek streamflow-gaging station, and precipitation recorded at Scottsbluff Airport (B), March to October 2009. (Sources of 

data: stream discharge from Bureau of Reclamation, 2009; precipitation data from National Oceanic and Atmospheric Administration, 

2009.) 
32 Quantifying Canal Leakage Rates Using a Mass-Balance Approach and Heat-Based Hydraulic Conductivity Estimates

and recorded data indicated dampened diurnal temperature 

cycles. 

Leakage Rate Comparisons

Reach-average leakage rates calculated using the massbalance approach along the high-leakage potential reach of 

Tri-State Canal varied from year to year and were generally 

dependent on local climatic conditions, and the timing and 

magnitude of the initial seasonal diversion into Tri-State 

Canal. Leakage rates ranged from 0.98 m/d on June 22, 2007, 

to about to 0 m/d in July 2009. Drier conditions usually 

resulted in higher leakage rates because of reduced flow from 

Spottedtail Creek, lower groundwater levels near Spottedtail 

Creek, and little unmeasured flow entering the reach.

Within the high-leakage potential reach the water table 

was well below the bed of the canal for most of the reach. 

Leakage rates calculated using the mass-balance approach can 

be compared to the heat-based vertical hydraulic conductivity 

estimates using Darcy’s Law if the hydraulic gradient for the 

entire reach can be estimated. Assuming a hydraulic gradient 

of 1 m/m at site TCTEMP1, the canal-leakage rate is 1.1 m/d. 

This assumption does not apply at site TCTEMP2, where the 

groundwater table was near the canal bed, and the hydraulic 

gradient was variable. Multiplying the calculated mean vertical hydraulic conductivity of 1.5 m/d by the hydraulic gradient 

yielded leakage rates that ranged from 0.1 to 0.2 m/d. This 

indicates that a shallow water table at site TCTEMP2 near the 

mouth of Spottedtail Creek restricted canal leakage. Because 

hydraulic gradient was determined for one point, it is not 

appropriate to spatially extrapolate leakage-rate estimates to 

the entire study reach. Reach-average leakage rates calculated 

using the mass-balance approach indicates that climatic conditions can affect canal-leakage rates. 

Reach-average leakage rates calculated using the massbalance approach along the moderately low-leakage potential 

reach of Interstate Canal ranged from 0.1 to 0.7 m/d. Less 

variability in leakage from year to year indicates that climatic 

conditions may have less of an effect for Interstate Canal compared to Tri-State Canal. This may be because Interstate Canal 

was cut into the northern edge of the North Platte alluvial 

Figure 25. Example measured and simulated thermographs for saturated sediment at (A) 0.15 m and (B) 0.76 meter beneath Tri-State 

Canal at Spottedtail Creek, Nebr., 2009.

18

19

20

21

22

23

24

25

18

19

20

21

22

23

24

25

8/4 8/6 8/8 8/10 8/12

SEDIMENT TEMPERATURE, IN DEGREES CELSIUS

Measured at depth 

of 0.15 meter

Simulated at depth 

of 0.15 meter

Measured at depth 

of 0.76 meter

Simulated at depth 

of 0.76 meter

A

B

2009
Leakage Rate Comparisons 33

1,261

1,262

1,263

1,264

1,265

1,266

17.4

17.6

17.8

18

18.2

18.4

Groundwater level

Groundwater temperature

GROUNDWATER LEVEL, IN METERS ABOVE NORTH AMERICAN VERTICAL DATUM OF 1988

GROUNDWATER TEMPERATURE, IN DEGREES CELSIUS

No Flow Flow

4/1 4/15 5/1 5/15 6/1 6/15 7/1 7/15 8/1 8/15 9/1 9/15 10/1

2008

No Flow Flow

0

0.5

1

1.5

2

-10

-5

0

5

10

15

20

25

30

35

40

45

Canal stage

Canal water temperature

CANAL STAGE, IN METERS

CANAL WATER TEMPERATURE, IN DEGREES CELSIUS

2008

4/1 4/15 5/1 5/15 6/1 6/15 7/1 7/15 8/1 8/15 9/1 9/15 10/1

Figure 26. Groundwater level and temperature recorded at monitoring well 420233103441301, Interstate Canal near University Lake, 

Nebr., April to October, 2008. 

Figure 27. Canal water temperature and stage of Interstate Canal, April to mid-September, 2008. 
34 Quantifying Canal Leakage Rates Using a Mass-Balance Approach and Heat-Based Hydraulic Conductivity Estimates

0

5

10

15

20

25

30

35

40

VA1 0.15 meter

Tidbit 0.76 meter

VA1 4.5 meters 

VA3 7.01 meters

VA4 9.14 meters

Depth below canal bed

 (VA, vertical sensor array;

 Hobo Tidbit® temperature logger)

No Flow Flow

SEDIMENT TEMPERATURE, IN DEGREES CELSIUS

4/1 5/1 5/31 6/30 7/30 8/29 9/28

2008

17

18

19

20

21

22

23

Measured at depth 

of 0.15 meter

Simulated at depth 

of 0.15 meter

17

18

19

20

21

22

23

7/16 7/18 7/20 7/22

SATURATED SEDIMENT TEMPERATURE, IN DEGREES CELSIUS

Measured at depth 

of 0.76 meter

Simulated at depth 

of 0.76 meter

A

B

2008

Figure 28. Measured thermographs of sediment beneath Interstate Canal near University Lake, Nebr., from selected depths in vertical 

sensor arrays, April to October, 2008. 

Figure 29. Measured and simulated thermographs for saturated sediment at (A) 0.15 meter and (B) 0.76 meter beneath Interstate Canal 

near University Lake, Nebraska, July 2008. 
Summary and Conclusions 35

valley and consequently the canal bed is well above the local 

groundwater table. Interstate Canal also does not receive any 

captured streamflow that can vary substantially year to year. 

Comparing leakage rates calculated from the massbalance approach for the moderately low-leakage potential 

reach of Interstate Canal to the heat-based estimates requires a 

mean vertical hydraulic conductivity to be calculated and the 

hydraulic gradient to be estimated. Based on sediment layer 

thicknesses and modeled vertical hydraulic conductivities 

(table 3), a daily leakage rate of 0.74 m/d was estimated for 

site ICTEMP. The vertical hydraulic conductivity of the least 

permeable layer had the greatest effect on the mean vertical hydraulic conductivity, and therefore, canal leakage. The 

hydraulic gradient is assumed to be 1 m/m because the bed of 

the canal is well above the water table along the study reach; 

therefore, the canal-leakage rate at site ICTEMP is estimated 

to be 0.74 m/d. 

Summary and Conclusions

The water supply in areas of the North Platte River 

Basin in the Nebraska Panhandle has been designated as 

fully appropriated or overappropriated by the Nebraska 

Department of Natural Resources (NDNR). Enacted legislation (Legislative Bill 962) requires the North Platte Natural 

Resources District (NPNRD) and the NDNR to develop an 

Integrated Management Plan (IMP) to balance groundwater 

and surface-water supply and demand in the NPNRD. A clear 

understanding of the groundwater and surface-water systems is 

critical for the development of a successful IMP. The primary 

source of groundwater recharge in parts of the NPNRD is from 

irrigation canal leakage. Because canal leakage constitutes a 

large part of the hydrologic budget, spatially distributing canal 

leakage to the groundwater system is important to any management strategy. Surface geophysical data collected along 

selected reaches of irrigation canals has allowed for the spatial 

distribution of leakage on a relative basis; however, the actual 

magnitude of leakage remains poorly defined. To address this 

need, the U.S. Geological Survey, in cooperation with the 

NPNRD, established streamflow-gaging stations at upstream 

and downstream ends from two selected canal reaches to allow 

a mass-balance approach to be used to calculate daily leakage 

rates. Water-level and sediment temperature data were collected and simulated at three temperature monitoring sites to 

allow the use of heat as a tracer to estimate the hydraulic conductivity of canal-bed sediment. Canal-leakage rates were estimated by applying Darcy’s Law to modeled vertical hydraulic 

conductivity and either the estimated or measured hydraulic 

gradient. This approach will improve the understanding of the 

spatial and temporal variability of canal leakage in varying 

geologic settings identified in capacitively coupled resistivity 

surveys. 

The high-leakage potential study reach of the Tri-State 

Canal had two stream gages and two temperature monitoring sites along its length. Streamflow-gaging stations TSUS 

(Tri-State Canal near Mitchell, Nebr., site 415812103493701) 

and TSDS (Tri-State Canal near Mintle, Nebr., site. 

415626103434001) were established in 2007 at upstream and 

downstream locations, respectively, along the study reach 

of Tri-State Canal. Calculated leakage rates from the massbalance approach varied from year to year and were generally dependent on local climatic conditions, and the timing 

and magnitude of the initial seasonal diversion into Tri-State 

Canal. Leakage rates ranged from 0.98 m/d on June 22, 2007, 

to about to 0 m/d during July 2009. Generally speaking, drier 

local conditions resulted in higher leakage rates. Of the three 

studied (2007–09), 2007 was the driest with only 23.8 cm of 

precipitation recorded the entire year.

The moderately low-leakage potential study reach of 

Interstate Canal had two stream gages and one temperature 

monitoring site along its length. Streamflow-gaging stations 

ISUS (Interstate Canal near Rattlesnake Hill, Nebr., site 

420327103464301) and ISDS (Interstate Canal near Mintle, 

Nebr., site 415922103404801) were established in 2007 at 

upstream and downstream locations, respectively. Excluding 

the leakage calculations from early May 2007, the leakage 

rates ranged from 0.08 to 0.7 m/d. Less variability in leakage 

from year to year indicates that climatic conditions may have 

less of an effect for Interstate Canal compared to Tri-State 

Canal. This may be because Interstate Canal was cut into the 

northern edge of the North Platte alluvial valley and consequently the canal bed is well above the local groundwater table 

resulting in a constant (1 m/m) hydraulic gradient. Interstate 

Canal also does not receive any captured flow that can vary 

substantially year to year. 

Two temperature monitoring sites were installed within 

the high-leakage potential reach of Tri-State Canal. Site 

TCTEMP1 was established in 2007 where the water table 

was well below the canal-bed surface. The vertical hydraulic 

conductivity of the poorly sorted sand and gravel beneath site 

TCTEMP1 was estimated using a calibrated one-dimensional 

VS2DH model. Using a trial-and-error approach, the bestfit vertical hydraulic conductivity for site TCTEMP1 model 

domain was 1.1 m/d. Model fits were best for temperature 

sensors shallower than 0.76 m when flow was primarily vertical. Below a depth of 0.76 m, flow in canal-bed sediment most 

likely became multidimensional as measured data display 

dampened diurnal temperature cycles relative to simulated 

temperatures. Site TCTEMP2 (Tri-State Canal at Spottedtail 

Creek, Nebr., site 415834103483701) was established in 2009 

at the mouth of Spottedtail Creek where a shallow water table 

may restrict canal leakage. The mean vertical hydraulic conductivity estimated from the best-fit VS2DH model was 1.5 

m/d; however, measured hydraulic gradients ranged from -0.14 

to -0.07 m/m, resulting in canal leakage rates that ranged from 

0.1 to 0.2 m/d. Because hydraulic gradient only was collected 

at one point, it was not appropriate to spatially extrapolate this 

estimate to other parts of the high-leakage potential reach.

Site ICTEMP (Interstate Canal near University Lake, 

Nebr., site 420233103441301) is a temperature monitoring 

site that was established in 2008 to estimate the hydraulic 
36 Quantifying Canal Leakage Rates Using a Mass-Balance Approach and Heat-Based Hydraulic Conductivity Estimates

conductivity of near-surface sediments, and to understand 

canal leakage and recharge mechanisms in a fractured Brule 

setting. Based on the thicknesses and modeled vertical hydraulic conductivities, an average vertical hydraulic conductivity of 

0.74 m/d was computed. The vertical hydraulic conductivity of 

the least permeable layer had the greatest effect on the mean 

vertical hydraulic conductivity, and therefore, canal leakage. 

The hydraulic gradient is assumed to be 1 m/m because the 

bed of the canal is well above the water table along the study 

reach; therefore, the canal-leakage rate at site ICTEMP is 

estimated to be 0.74 m/d. 

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Appendix 1—Sediment Core Locations and Lithologic 

Descriptions
Blank Page
Appendix 1 41

Appendix 1. Sediment core locations and lithologic descriptions of vertical sensor arrays at temperature monitoring sites.—Continued

[site names: TCTEMP1, Tri-State Canal near Mitchell, site number 415542103455301; TCTEMP2, Tri-State Canal at Spottedtail Creek, site number 

41583410348370; ICTEMP, Interstate Canal near University Lake, site number 420233103441301; Legal descriptions: T., township; R., range; S., section; 

ABCD, for example, are codes for the quarter section, quarter–quarter section, quarter–quarter–quarter section, and quarter–quarter–quarter–quarter section; 

A, B, C, and D, respectively, where A is northeast, B is northwest, C is southwest, and D is southeast quarter of the next larger unit; Munsell color codes from 

X-rite, 2000; %, percent; cm, centimeter; m, meter]

Depth interval,

in meters below 

canal-bed surface

Lithology of indicated core interval at indicated site Munsell color

(color description)

TCTEMP1 – Vertical sensor array 1 (location T.23N R.56W S.36BAAA or latitude 41.92826o N, longitude 103.76466o W)

0–0.55 No sample

0.55–1.16 Sand, medium, moderately sorted, well rounded to rounded, interbedded coarse sand to fine gravel, 

rounded to sub-angular, range (0.48–1.90 cm), lenses of clayey silt, dark brown, medium plasticity, 85% quartz, 10% feldspar, 5% mafic

2.5Y 7/3

1.16–1.38 No sample

1.38–1.97 Sand, medium to coarse, poorly sorted, well rounded to rounded, interbedded fine to coarse gravel, 

rounded to sub-angular, range (0.48–3.81 cm), 85% quartz, 10% feldspar, 5% mafic

2.5Y 7/3

1.97–2.0 Clayey silt, medium plasticity 2.5Y 5/3

2.0–2.4 Sand, medium to coarse, poorly sorted, well rounded to rounded, interbedded fine gravels, rounded, 

range (0.48–1.90 cm), 75% quartz, 20% feldspar, 5% mafic

2.5Y 7/3

2.4–3.6 Sand, medium to coarse, poorly sorted, well rounded to rounded, interbedded fine to coarse gravel, 

rounded, range (0.48–2.54 cm), 85% quartz, 10% feldspar, 5% mafic

2.5Y 7/3

3.6–3.8 No sample

3.8–4.1 Sand, fine to medium, well rounded to rounded, poorly sorted, traces of organic silt, dark brown, 

interbedded fine to coarse gravel, rounded to sub-angular, range (0.48–2.54 cm), 90% quartz, 

5% feldspar, 5% mafic

2.5Y 7/3

4.1–4.4 Sand, fine, well sorted, well rounded, interbedded medium to coarse sand, rounded, 95% quartz, 

2% feldspar, 3% mafic

2.5Y 7/3

4.4–4.8 Sand, medium to coarse, well rounded to rounded, poorly sorted, interbedded fine to coarse gravel, 

rounded to sub-angular, range (0.48–2.03 cm), 90% quartz, 5% feldspar, 5% mafic

2.5Y 7/3

4.8–6.0 Sand, medium to coarse, well rounded to rounded, poorly sorted, interbedded fine to coarse gravel, 

rounded to sub-angular, range (0.48–1.90 cm), 85% quartz, 10% feldspar, 5% mafic 

2.5Y 7/3

TCTEMP1 – Vertical sensor array 2 (location T.23N R.56W S.36BAAA or latitude 41.92828o N, longitude 103.76472o W)

0–0.44 No sample

0.44–0.61 Sand, fine to medium, moderately sorted, well rounded to rounded, traces of intermixed clayey silt, 

brown, medium plasticity, interbedded coarse sand to fine gravel, rounded, range (0.20–1.27 cm), 

90% quartz, 5% feldspar, 5% mafic

2.5Y 7/3

0.61–1.16 Sand, medium to coarse, poorly sorted, well rounded to rounded, interbedded fine gravel, rounded, 

range (0.48–1.27 cm), 80% quartz, 15% feldspar, 5% mafic

2.5Y 7/3

1.16–1.33 No sample

1.33–1.72 Sand, medium to coarse, poorly sorted, well rounded to rounded, interbedded fine to coarse gravel, 

rounded to sub-angular, range (0.48–2.54 cm), 80% quartz, 15% feldspar, 5% mafic

2.5Y 7/2

Appendix 1
42 Quantifying Canal Leakage Rates Using a Mass-Balance Approach and Heat-Based Hydraulic Conductivity Estimates

Appendix 1. Sediment core locations and lithologic descriptions of vertical sensor arrays at temperature monitoring sites.—Continued

[site names: TCTEMP1, Tri-State Canal near Mitchell, site number 415542103455301; TCTEMP2, Tri-State Canal at Spottedtail Creek, site number 

41583410348370; ICTEMP, Interstate Canal near University Lake, site number 420233103441301; Legal descriptions: T., township; R., range; S., section; 

ABCD, for example, are codes for the quarter section, quarter–quarter section, quarter–quarter–quarter section, and quarter–quarter–quarter–quarter section; 

A, B, C, and D, respectively, where A is northeast, B is northwest, C is southwest, and D is southeast quarter of the next larger unit; Munsell color codes from 

X-rite, 2000; %, percent; cm, centimeter; m, meter]

Depth interval,

in meters below 

canal-bed surface

Lithology of indicated core interval at indicated site Munsell color

(color description)

TCTEMP1 – Vertical sensor array 2 (location T.23N R.56W S.36BAAA or latitude 41.92828o N, longitude 103.76472o W)—Continued

1.72–2.4 Sand, fine to medium, moderately sorted, well rounded, interbedded coarse sand to fine gravel, 

rounded to sub-angular, range (0.20–1.27 cm), trace of intermixed clay, light brown, medium 

plasticity, occasional coarse gravel, angular, range (2.54–3.81 cm), 90% quartz, 5% feldspar, 

5% mafic

2.5Y 7/3

2.4–2.75 Sand, fine, well sorted, well rounded, occasional interbedded coarse sand to fine gravel, rounded to 

sub-angular, range (0.20–1.27 cm), 90% quartz, 5% feldspar, 5% mafic

2.5Y 6/3

2.75–3.3 Sand, fine to medium, poorly sorted, well rounded to rounded, interbedded coarse sand to fine to 

coarse gravel, rounded to sub-angular, range (0.20–1.27 cm), lenses of clayey silt, light brown, 

medium plasticity, 2.54 cm in length, 85% quartz, 10% feldspar, 5% mafic

2.5Y 7/3

3.3–3.6 Sand, fine to medium, well sorted, well rounded to rounded, occasional interbedded fine gravel, 

rounded, 90% quartz, 5% feldspar, 5% mafic

2.5Y 8/2

3.6–4.0 Sand, fine to medium, well rounded to rounded, poorly sorted, interbedded coarse sand to fine 

gravel, rounded to sub-angular, range (0.20–1.27 cm), 85% quartz, 10% feldspar, 5% mafic

2.5Y 7/3

4.0–4.3 Sand, fine, well sorted, well rounded to rounded, occasional interbedded fine gravel, rounded to 

sub-angular, 95% quartz, 2% feldspar, 3% mafic

2.5Y 8/3

4.3–4.8 Sand, medium to coarse, rounded to sub-angular, poorly sorted, interbedded fine to coarse gravel, 

rounded to sub-angular, range (0.20–3.81 cm), 80% quartz, 15% feldspar, 5% mafic

2.5Y 7/3

4.8–5.0 No sample

5.0–5.9 Sand, fine to medium, well rounded to rounded, poorly sorted, interbedded coarse sand to fine 

gravel, rounded to sub-angular, range (0.20–1.27 cm), 80% quartz, 15% feldspar, 5% mafic

2.5Y 7/2

5.9–6.0 Sand, fine, well sorted, well rounded, 95% quartz, 2% feldspar, 3% mafic 2.5Y 6/3

TCTEMP1 – Vertical sensor array 3 (location T.23N R.56W S.36BAAA or latitude 41.92825o N, longitude 103.76469o W)

 0–0.21 No sample

0.21–1.16 Sand, medium to coarse, poorly sorted, well rounded, interbedded fine to coarse gravel, range 

(0.48–3.81 cm), contains a lense of silty clay, fine, medium plasticity, 85% quartz, 10% feldspar, 

5% mafic

2.5Y 7/3

1.16–2.4 Sand, fine to medium, poorly sorted, well rounded to rounded, interbedded coarse sand to fine to 

coarse gravel, rounded to sub-angular, range (0.48–5.08 cm), 85% quartz, 10% feldspar, 5% 

mafic

2.5Y 7/3

2.4–2.6 No sample

2.6–3.3 Sand, fine to medium, poorly sorted, well rounded to rounded, interbedded coarse sand to fine 

to coarse gravel, rounded to sub-angular, range (0.48–2.03 cm), 85% quartz, 10% feldspar, 

5% mafic

2.5Y 7/3

3.3–3.6 Sand, fine to medium, well sorted, well rounded, 95% quartz, 2% feldspar, 3% mafic 2.5Y 7/3

TCTEMP1 – Vertical sensor array 4 (location T.23N R.56W S.36BAAA or latitude 41.92831° N, longitude 103.76467° W)

 0–0.35 No sample

0.35–0.67 Sand, fine, moderately sorted, well rounded to rounded, interbedded medium sand, rounded to subangular, traces of clayey silt, organic, medium plasticity, 95% quartz, 3% feldspar, 2% mafic2.5Y 4/2

0.67–1.16 Sand, medium, poorly sorted, well rounded to rounded, interbedded coarse sand to fine gravel, 

rounded to sub-angular, 90% quartz, 5% feldspar, 5% mafic

2.5Y 7/3
Appendix 1 43

Appendix 1. Sediment core locations and lithologic descriptions of vertical sensor arrays at temperature monitoring sites.—Continued

[site names: TCTEMP1, Tri-State Canal near Mitchell, site number 415542103455301; TCTEMP2, Tri-State Canal at Spottedtail Creek, site number 

41583410348370; ICTEMP, Interstate Canal near University Lake, site number 420233103441301; Legal descriptions: T., township; R., range; S., section; 

ABCD, for example, are codes for the quarter section, quarter–quarter section, quarter–quarter–quarter section, and quarter–quarter–quarter–quarter section; 

A, B, C, and D, respectively, where A is northeast, B is northwest, C is southwest, and D is southeast quarter of the next larger unit; Munsell color codes from 

X-rite, 2000; %, percent; cm, centimeter; m, meter]

Depth interval,

in meters below 

canal-bed surface

Lithology of indicated core interval at indicated site Munsell color

(color description)

TCTEMP1 – Vertical sensor array 4 (location T.23N R.56W S.36BAAA or latitude 41.92831° N, longitude 103.76467° W)—Continued

1.16–1.4 No sample

1.4–2.2 Sand, medium, poorly sorted, well rounded to rounded, interbedded coarse sand, fine to coarse 

gravel, rounded to sub-angular, range (0.48–3.81 cm), lenses of medium sand, well sorted, well 

rounded, 90% quartz, 5% feldspar, 5% mafic

2.5Y 7/3

2.2–2.4 Sand, fine to medium, well sorted, well rounded, occasional interbedded coarse sand, rounded, 90% 

quartz, 5% feldspar, 5% mafic

2.5Y 7/3

2.4–3.3 Sand, fine to medium, poorly sorted, well rounded to rounded, interbedded, coarse sand, rounded, 

fine to coarse gravel, rounded to sub-angular, range (0.48–3.81 cm), 90% quartz, 5% feldspar, 

5% mafic

2.5Y 7/3

3.3–3.6 Sand, medium to coarse, poorly sorted, rounded to sub-angular, interbedded fine gravel, rounded to 

sub-angular, range (0.48–1.90 cm), 80% quartz, 15% feldspar, 5% mafic

2.5Y 7/3

TCTEMP2 – (location T.23N R.56W S.10CBDC or latitude 41.97611° N, longitude –103.81028oW)

0–0.41 No sample

0.41–0.58 Sand, medium, moderately sorted, well rounded, saturated, 95% quartz, 2% feldspar, 3% mafic 2.5Y 7/3

0.58–0.74 Sand, fine, well sorted, well rounded, organic, lense of sandy clay at the top of the interval, 

saturated, 95% quartz, 2% feldspar, 3% mafic

2.5Y 3/1

0.74–0.91 Sand, fine, well sorted, well rounded, saturated, 90% quartz, 10% mafic 2.5Y 5/1

ICTEMP – Vertical sensor array 1 (location T.24N R.55W S.20BBCB or latitude 42.0429° N, longitude 103.73714oW)

 0–0.80 No sample

0.80–1.16 Sand, medium, rounded, moderately sorted, interbedded coarse sand, rounded to sub-rounded, 

90% quartz, 5% feldspar, 5% mafic

2.5Y 7/3

1.16–1.99 No sample

1.99–2.32 Silt, fine, sandy silt towards the top, sand content decreases with depth (5% sand), silt is more compacted than previous interval, hard, soft when broken apart2.5Y 7/3

2.32–3.48 Silt, soft, slight sand content (5%), 90% quartz, 5% feldspar, 5% mafic 10YR 6/4

3.48–3.98 Sandy silt, medium, (40% sand), rounded, 90% quartz, 5% feldspar, 5% mafic 10YR 5/4

3.98–4.64 Silt, soft, slight sand content (5%), 90% quartz, 5% feldspar, 5% mafic, mafic content increases to 

10–15% toward the bottom

10YR 5/4

ICTEMP – Vertical sensor array 2 (location T.24N R.55W S.20BBCB or latitude 42.04285° N, longitude 103.73714° W)

0–0.51 No sample

0.51–0.88 Sand, medium, poorly sorted, rounded to sub-rounded, interbedded coarse sand to fine gravel, 

sub-rounded, occasional coarse gravel, sub-rounded, range (1.9–3.5 cm), clayey silt lense at 

0.84 m (2.5Y 4/2), sand becomes finer from 0.84–0.88 m, 80% quartz, 15% feldspar, 5% mafic

2.5Y 7/2

0.88–0.94 Clayey silt, dark brown (20–25% clay) 10YR 4/2
44 Quantifying Canal Leakage Rates Using a Mass-Balance Approach and Heat-Based Hydraulic Conductivity Estimates

Appendix 1. Sediment core locations and lithologic descriptions of vertical sensor arrays at temperature monitoring sites.—Continued

[site names: TCTEMP1, Tri-State Canal near Mitchell, site number 415542103455301; TCTEMP2, Tri-State Canal at Spottedtail Creek, site number 

41583410348370; ICTEMP, Interstate Canal near University Lake, site number 420233103441301; Legal descriptions: T., township; R., range; S., section; 

ABCD, for example, are codes for the quarter section, quarter–quarter section, quarter–quarter–quarter section, and quarter–quarter–quarter–quarter section; 

A, B, C, and D, respectively, where A is northeast, B is northwest, C is southwest, and D is southeast quarter of the next larger unit; Munsell color codes from 

X-rite, 2000; %, percent; cm, centimeter; m, meter]

Depth interval,

in meters below 

canal-bed surface

Lithology of indicated core interval at indicated site Munsell color

(color description)

ICTEMP – Vertical sensor array 2 (location T.24N R.55W S.20BBCB or latitude 42.04285° N, longitude 103.73714° W)—Continued

0.94–1.16 Silt, brown (5% clay) 10YR 5/3

1.16–2.16 Silt, soft, brown to light brown 10YR 6/4

2.16–2.32 No sample

2.32–3.21 Silt, soft, brown 10YR 6/4

3.21–3.48 No sample

3.48–4.20 Silt, soft, brown, sandy silt lense between 4.10–4.17 m 10YR 5/4

4.20–4.64 Silt, soft, more homogenous, more compact than previous interval 10YR 5/4

4.64–5.06 No sample

5.06–5.34 Sandy silt (5% clay), 85% quartz, 5% feldspar, 10% mafic 10YR 5/4

5.34–5.80 Silt, hard, with pieces of compacted siltstone, calcium deposits 10YR 5/4

ICTEMP – Vertical sensor array 3 (location T.24N R.55W S.20BBCB or latitude 42.04269° N, longitude 103.73722° W)

0–1.16 Sandy silt, fine, 10–15% sand, soft, occasional interbedded siltstone chips, white, interbedded roots, 

sand content decreases below 0.60 m to 5% sand, 90% quartz, 5% feldspar, 5% mafic 

10YR 6/4

1.16–1.74 No sample

1.74–2.32 Silt, fine, soft, slight sand content (5% fine sand), some interbedded roots, 90% quartz, 5% feldspar, 

5% mafic

10YR 6/4

2.32–3.48 No sample

3.48–4.64 Silt, soft, slight sand content (5% fine sand), 90% quartz, 5% feldspar, 5% mafic 10YR 6/4

4.64–5.14 No sample

5.14–5.8 Silt, soft, slight sand content (5% fine sand), 90% quartz, 5% feldspar, 5% mafic 10YR 6/4

5.8–6.96 Silt, soft, slightly more sand content (5–10% fine sand), 85% quartz, 5% feldspar, 10% mafic 10YR 6/4

6.96–8.12 Silt, darker color than previous interval, more weathered 10YR 5/4

8.12–8.92 Silt, harder, chunky, occasional appearance of interbedded siltstone chips, hard 10YR 5/4

8.92–9.2 Silt, hard, chunky, greater appearance of siltstone chips, hard 10YR 5/4

ICTEMP – Vertical sensor array 4 (location T.24N R.55W S.20BBCB or latitude 42.04264° N, longitude –103.73726° W)

0–0.26 No sample

0.26–0.57 Sandy silt, fine, interbedded roots, 85% quartz, 5% feldspar, 10% mafic 2.5Y 6/4

0.57–1.16 Sandy silt, fine, 10% fine sand, interbedded roots, 90% quartz, 5% feldspar, 5% mafic 2.5Y 7/4

1.16–1.57 No sample

1.57–2.32 Silt, soft, fine, sand content (5–10%), silt becomes more compacted below 2 m, 90% quartz, 

5% feldspar, 5% mafic

2.5Y 7/4
Hobza and Andersen—Quantifying Canal Leakage Rates Using a Mass-Balance Approach and Heat-Based Hydraulic Conductivity Estimates—SIR 2010–5226