Channel Stability of the Neosho River Downstream 

From John Redmond Dam, Kansas 

Prepared in cooperation with the 

KANSAS WATER OFFICE 

U.S. Department of the Interior 

U.S. Geological Survey 

USGS Fact Sheet FS–088-–99 

April 1999 

—Kyle E. Juracek 

The stability of the Neosho River 

channel downstream from John 

Redmond Dam, in southeast Kansas, 

was investigated using multi-date 

aerial photographs and stream-gage 

information. Bankfull channel width 

was used as the primary indicator 

variable to assess pre- and post-dam 

channel change. Five 6-mile river 

reaches and four stream gages were 

used in the analysis. Results indicated 

that the overall channel response to the 

altered streamflow regime and sediment 

load introduced by the dam has been 

minor. Aside from some localized 

channel widening, there was little postdam change in bankfull channel width. 

The lack of a pronounced post-dam 

channel response may be attributable 

to a substantial reduction in the 

magnitude of the post-dam annual peak 

flows in combination with the 

resistance to erosion of the bed and 

bank materials. Also, the channel may 

have been overwidened by a series of 

large floods that predated construction 

of the dam. 

Introduction 

The construction and operation of a 

reservoir can have a substantial effect 

on the stability of the river channel 

downstream from the dam. Since its 

completion in 1964, the downstream 

effect of John Redmond Dam on the 

Neosho River in southeast Kansas 

(fig. 1) has been much debated. 

Previous studies by the U.S. Army 

Corps of Engineers (COE) (1972) and 

the U.S. Geological Survey (USGS) 

(Studley, 1996) have indicated the 

possibility of channel widening. Also, 

anecdotal evidence of perceived 

channel widening has been provided by 

residents living along the Neosho River 

as far as 165 mi downstream from the 

dam. The available evidence, however, 

is not sufficient to conclude that John 

Redmond Dam has caused the Neosho 

River channel to change more than it 

otherwise would have changed without 

the dam. 

To determine the effect of John 

Redmond Dam, a study of the Neosho 

River that compares the channel before, 

during, and after completion of the dam 

was undertaken by the USGS in cooperation with the Kansas Water Office. 

The objective of this study was to 

determine whether or not the Neosho 

River channel has widened in response 

to the changes in flow regime and 

sediment load introduced by the dam. 

Pre- and post-dam channel stability was 

assessed using multi-date aerial 

photographs and streamgage information. 

Important issues related to the 

stability of the Neosho River channel 

include protection of riparian resources, 

protection of habitat for threatened and 

endangered species (for example, the 

Neosho Madtom, Noturus placidus), 

and bank stabilization as related to loss 

of property, general aesthetics, and 

recreation. The knowledge provided by 

this study will provide some of the 

information needed to best manage the 

Neosho River system. 

Description of Study Area 

The focus of this study was the 

middle 180-mile reach of the Neosho 

River between John Redmond Dam and 

the Kansas-Oklahoma State line 

(fig. 1). Throughout this reach the 

Neosho River is characterized by a 

meandering, gravel-bed channel. The 

channel slope averages about 1.2 feet 

per mile. Riverbank height varies from 

about 15 to 30 feet. The channel bed 

frequently is situated on bedrock. 

Alluvium in the Neosho River Valley 

averages about 25 feet in thickness and 

is typified by silt with a basal layer of 

sand and gravel that averages about 

3 feet in thickness. The channel-bank 

materials consist mostly of cohesive silt 

and clay and are relatively resistant to 

erosion compared to sand banks. Also, 

John Redmond Dam on the Neosho River near Burlington, southeast Kansas. 
the channel banks are typically covered 

by partial to complete mature tree cover 

which may enhance bank stability at 

some locations. 

Several tributaries contribute unregulated flow to the Neosho River downstream from John Redmond Dam. Also 

noteworthy are 12 overflow dams 

(fig. 1) that were constructed within the 

main-stem channel mostly in the 1930's 

or 1950's. Changes in the streamflow 

regime attributable to the operation of 

John Redmond Dam have included a 

decrease in the magnitudes of peak discharges (flows) and an increase in the 

magnitudes of low discharges (fig. 2) 

(Studley, 1996). Post-dam suspendedsediment concentrations are substantially reduced immediately downstream 

from the dam. 

Methods 

A stable river channel naturally 

meanders across its river valley over 

time while maintaining approximately 

the same cross-sectional shape. Therefore, changes in channel geometry may 

be used to infer channel instability. In 

this study, bankfull channel width was 

used as the primary indicator variable 

to assess channel change after the completion of the dam. 

Five 6-mile river reaches were 

selected for use in this study (fig. 1) 

with the objective being to obtain a 

spatially representative sample while 

avoiding, to the extent possible, 

localized human-caused or natural 

conditions that might obscure channel 

adjustment. Human-caused conditions 

include overflow dams (fig. 1), bridges, 

and channel modifications (for 

example, riprap). Natural conditions 

include split-channel locations and hard 

points (that is, locations where the 

channel is situated along the valley 

wall). Additional factors considered in 

the selection of the reaches included 

proximity to John Redmond Dam and 

the availability and usability of aerial 

photographs. 

For each reach, aerial photographs 

were obtained for three time periods—pre-dam (late 1930's), construction (early 1960's), and post-dam (early 

1990's). The bankfull channel area was 

interpreted from the aerial photographs 

for each time period and traced on a 

scale-stable mylar overlay. Primary 

indicators used in the delineation of the 

bankfull channel included breaks in 

slope, the tops of point bars, and 

changes in vegetation. The channel 

centerline was added, and all 

information was digitized. Mean 

bankfull channel width then was 

estimated for all reaches and dates as 

channel area divided by channel 

centerline length. 

To compare pre- and post-dam 

channel stability, the mean bankfull 

channel widths for all reaches and dates 

were tabulated, and pre- and post-dam 

differences were evaluated. For each 

reach, pre-dam change was computed 

as the percentage difference in mean 

bankfull channel width between the 

pre-dam and construction time periods. 

Similarly, post-dam change was 

computed for each reach as the 

percentage difference in mean bankfull 

channel width between the construction 

and post-dam time periods. The magnitude and direction of the changes were 

used to assess pre- and post-dam 

channel stability for the individual 

reaches as well as the entire system. 

Due to various potential sources of 

error in the use of aerial photographs to 

Figure 1. 

KANSAS 

OKLAHOMA 

MISSOURI 

ARKANSAS 

Study 

area 

Neosho River 

Basin 

Index map 

Arkansas 

River 

Neosho 

River 

4 

1 

EXPLANATION 

Current U.S. Geological Survey 

streamflow-gaging station—Number 

is map number used in table 1 

Discontinued U.S. Geological Survey 

streamflow-gaging station—Number 

is map number used in table 1 

Overflow dam 

0 

0 10 20 30 MILES 

10 20 30 KILOMETERS 

95° 

37° 

38° 

95°30' Burlington 

Le Roy 

Humboldt 

3 Iola

2 

4 

1 

Chanute 

Erie 

Chetopa 

OKLAHOMA 

KANSAS 

MISSOURI 

KANSAS 

Le Roy reach 

Iola reach 

Humboldt reach 

Erie reach 

Oswego reach 

Neosho 

River 

John Redmond 

Dam 

John Redmond 

Reservoir 

Base from U.S. Geological Survey digital data, 1:100,000, 1995 

Universal Transverse Mercator projection 

Zone 14 & 13 

Converted to Lambert Conformal Conic projection, 

Standard parallels 33° and 45°, central meridian -98°15' 

Boundary of 

Neosho River 

Basin 

Parsons 

Oswego 

Location of Neosho River Basin, study area, river reaches, and streamflow-gaging stations. 
measure bankfull channel widths, only 

a change in bankfull width of 10 percent or more was considered significant. 

Information from USGS 

streamflow-gaging stations (fig. 1, table 

1) was also analyzed to assess pre- and 

post-dam channel stability downstream 

from the dam. A comparison of preand post-dam conditions included an 

assessment of stage-discharge, discharge-width, discharge-area, and 

discharge-velocity relations. The 

Parsons gaging station was excluded 

from all analyses due to back-water 

effects from an overflow dam located 

2.7 miles downstream from the gage 

(fig. 1, map number 4). The gaging 

stations provide site-specific information at locations separate from the 

river reaches analyzed in this study. 

Results and Discussion 

The aerial-photograph analyses 

indicate that the construction and 

operation of John Redmond Dam has 

not resulted in a substantial and 

pervasive downstream widening of the 

Neosho River channel. The mean 

bankfull channel widths (table 2) show 

that, with the exception of the Iola 

reach (10-percent increase in width), 

post-dam changes have been minor 

(and may be attributable in part to 

measurement error). In comparison, 

relatively large pre-dam channel-width 

changes had occurred at the Le Roy, 

Humboldt, and Oswego reaches with 

respective increases of 15, 14, and 

10 percent. The fact that three of the 

four largest increases in mean bankfull 

channel width predate the dam may be 

indicative of a predam period of 

channel widening possibly associated 

with one or more large floods. 

In many river systems 90 to 99 percent of significant bank erosion occurs 

during large floods. A large flood 

occurred in July 1951 when the Neosho 

River had a flow with an estimated 

500-year recurrence interval. The peak 

discharge during this flood at Strawn 

(fig. 1) was 400,000 cubic feet per 

second (The mean annual peak 

discharge for the period of record at 

Strawn is about 43,000 cubic feet per 

second). Interestingly, the three reaches 

that had the largest pre-dam increases 

in bankfull channel width also had the 

smallest post-dam changes in bankfull 

Figure 2. 

downstream from John Redmond Dam. Location of stations shown in figure 1. 

Downstream Effects of Dams 

on River Channels 

Primary changes introduced by a 

dam include a reduction in the river's 

sediment load as well as an alteration of 

the flow regime. Typical changes in the 

flow regime include a reduction in the 

magnitude of peak flows and a possible 

increase in the magnitude of low flows. 

Such artificially introduced changes 

may trigger an adjustment by the river 

as it attempts to re-establish an approximate equilibrium between the channel 

and the discharge and sediment load 

being transported. 

In general, rivers downstream from 

dams initially adjust by channel 

degradation. Typically, a river will 

scour, and thus lower, its channel bed as 

the sediment-depleted water emerging 

from the dam attempts to replenish its 

sediment load. Concurrently, the 

reduced magnitude of peak flows 

emerging from the dam eventually may 

result in channel narrowing as vegetation 

encroaches. An exception is the case 

where the channel bed is armored or 

situated on bedrock. Unable to effectively scour the resistent channel bed, the 

river may instead erode laterally and thus 

widen its channel. Typically, channel 

degradation initiates near the dam 

following closure and eventually may 

migrate a considerable distance 

downstream (Williams and Wolman, 

1984). 

The type, rate, duration, and 

downstream extent of channel degradation downstream from dams are 

controlled by a number of factors, 

including discharge, sediment load, bed 

and bank material composition, local 

bed-elevation control (for example, 

bedrock, armoring), channel geometry, 

climate, tributary inflow, and vegetation. 

Considerable variation in the type and 

rate of channel degradation may occur 

even between sites located close together 

due to the variability of the controlling 

factors. 

500,000 

100,000 

200,000 

300,000 

400,000 

Annual peak discharge, in cubic feet per second 

Neosho River at Strawn, KS 

(map number 1) 

Neosho River at Burlington, KS (map number 2) 

0 

Dam closure Dam closure Dam closure 

Neosho River near Iola, KS 

(map number 3) 

500,000 

100,000 

200,000 

300,000 

400,000 

0 1880 

1890 1900 1910 1920 

1930 

1940 1950 

1960 

1970 

1980 1990 

2000 

Water year 

500,000 

0 

100,000 

200,000 

300,000 

400,000 

Neosho River near Parsons, KS 

(map number 4) 

Annual peak discharges for U.S. Geological Survey streamflow-gaging stations 
--

References 

Studley, S.E., 1996, Changes in high-flow 

frequency and channel geometry of the 

Neosho River downstream from John 

Redmond Dam, Southeastern Kansas: 

U.S. Geological Survey Water-Resources 

Investigations Report 96–4243, 16 p. 

Williams, G.P., and Wolman, M.G., 1984, 

Downstream effects of dams on alluvial 

rivers: U.S. Geological Survey Professional Paper 1286, 83 p. 

U.S. Army Corps of Engineers, 1972, 

Memorandum of findings, riverbank 

stabilization study, Grand (Neosho) 

River, Kansas & Oklahoma, John 

Redmond Dam & Reservoir to KansasOklahoma State line: U.S. Army Corps 

of Engineers, September 1972, Tulsa, 

Oklahoma, 24 p. 

channel width. This may be due to the 

overwidened condition of the channel 

at these locations in response to the 

1951 and other pre-dam floods. 

The gaging-station analyses 

provided some indication of channel 

widening at Burlington in the years 

immediately following completion of 

John Redmond Dam in 1964. Results 

indicated an initial increase in channel 

width of about 10 to 20 feet, followed 

by apparent stabilization at this 

location. At Iola, channel width has not 

changed. However, an increase in flow 

velocity was indicated. The increase in 

velocity may be due to an increase in 

channel slope and (or) a decrease in 

channel roughness. 

Together, the aerial-photograph and 

gaging-station analyses indicate that the 

overall downstream response of the 

Neosho River channel to John 

Redmond Dam has been minor. With 

one exception, the five river reaches 

indicated little if any post-dam change 

in channel width. However, the apparent initial widening of the channel at 

the Burlington gage shows that localized widening has occurred. Such 

localized widening is also evident in a 

series of six COE cross sections located 

successively at intervals of about 1 mile 

immediately downstream from the 

dam. The cross sections, surveyed in 

1963, 1974, and 1983, indicate minor 

widening at one site (10 to 20 feet), 

moderate widening at one site (30 to 

40 feet), and little if any change at the 

remaining four sites (Harry Hartwell, 

U.S. Army Corps of Engineers, written 

commun., 1995). Localized widening 

may or may not be directly related to 

the operation of John Redmond Dam. 

The overall lack of a pronounced 

post-dam channel response may be 

attributable to several factors. First, 

there has been a substantial post-dam 

reduction in the magnitude of the 

annual peak discharges. A second 

factor is the strength of the bed and 

bank materials. Degradation of the 

channel bed has been limited due to the 

presence of bedrock and (or) coarse 

gravel, the latter of which would 

require large flows to transport. The 

channel banks consist mostly of 

cohesive silt and clay and are relatively 

resistant to erosion. Moreover, bank 

stability may be enhanced at some 

locations by partial to complete mature 

tree cover. Therefore, significant bank 

erosion (beyond site-specific occurrences) may only occur during large 

flows which have mostly been 

eliminated by the dam. 

A third factor is the pre-dam 

condition of the channel. As indicated 

by the five river reaches, there is some 

indication of a pre-dam widening of the 

channel, possibly due in part to the 

1951 flood. Thus, it is possible that the 

channel, at least in places, may have 

been in an overwidened condition at the 

time of dam construction. Thus, 

additional widening at such locations 

may be unlikely. In fact, there is some 

field evidence to indicate that a new 

lower flood plain may be forming 

within the confines of the original 

channel. Eventually, this may result in a 

narrowing of the channel. 

The findings of this study suggest 

two possibilities. First, the Neosho 

River is a relatively stable system that 

may only change significantly in 

response to extreme events. Second, it 

may be that insufficient time has 

transpired for pronounced channel 

changes to become manifest. Local 

residents' perception of channel 

widening may be correct at specific 

locations. However, also likely are 

instances where normal channel 

migration has been mistaken for 

channel widening, especially where 

property (for example, cropland and 

structures) has been lost or is 

threatened. 

Acknowledgments 

This study was made possible in part 

by funding from the Kansas State Water 

Plan Fund. The author also gratefully 

acknowledges the aerial photographs 

provided by the U.S. Department of 

Agriculture's Farm Service Agency, and 

the Geology Department and the 

Kansas Applied Remote Sensing 

Program, University of Kansas. 

For more information contact: 

District Chief 

U.S. Geological Survey 

4821 Quail Crest Place 

Lawrence, Kansas 66049–3839 

(785) 842–9909 

email: waucott@usgs.gov 

Map 

number 

(fig. 1) 

USGS 

station 

number USGS station name 

Distance 

downstream 

from John 

Redmond 

Dam (miles) 

Drainage 

area 

(square 

miles) 

Period of 

continuous 

record 

(water year) 

1 

2 

3 

4 

07182400 

07182510� 

07183000� 

07183500 

Neosho River at Strawn, KS 

Neosho River at Burlington, KS 

Neosho River near Iola, KS 

Neosho River near Parsons, KS 

5.3� 

56.3� 

139.6 

3,015� 

3,042� 

3,818� 

4,905 

1949–63 

1963–present 

1918–present 

1922–present 

Table 1. 

River 

reach 

(fig. 1) 

Distance 

downstream 

from dam 

(miles) 

Mean bankfull channel width (feet) 

(percent change from previous time period) 

Pre-dam Construction Post-dam 

Le Roy 

Iola 

Humboldt 

Erie 

Oswego 

23–29 

42–49 

63–69 

102–108 

146–152 

197� 

240� 

243� 

246� 

233 

226 (+15) 

236 (-2) 

276 (+14) 

253 (+3) 

256 (+10) 

233 (+3) 

259 (+10) 

266 (-4) 

269 (+6) 

256 (0) 

Table 2. -reach locations and mean bankfull channel widths 

U.S. Geological Survey (USGS) streamflow-gaging stations used in this study 

River