Kansas Water Science Center
U.S. Geological Survey

Multiply  By  To obtain 

cubic foot per second (ft³/s)  0.02832  cubic meter per second 
foot (ft)  0.3048  meter 
foot per year (ft/yr)  0.3048  meter per year 
inch (in.)  2.54  millimeter 
mile (mi)  1.609  kilometer 
square mile (mi²)  2.590  square kilometer 
The streamflow regimen of the Neosho River downstream from John Redmond Dam in southeastern Kansas has changed significantly since the dam's completion in 1964. The controlled releases from the dam have decreased the magnitudes of peak discharges and increased the magnitudes of low discharges. The trends in river stage for selected discharges also have changed at two of the streamflowgaging stationsthose closest to the dam. There is a significant downward trend in the stages associated with the median annual peak discharges, but no significant trend in the stages associated with the annual mean discharges, which indicates that the river channel is increasing in width but not depth or that the flow velocity has increased at the streamflowgaging stations. Because there were no significant trends present in precipitation, mean annual discharge, or annual peak discharge, the changes are attributed to John Redmond Dam.
The Neosho River in southeastern Kansas flooded 57 times in the 34year period prior to 1964 (Department of the Army, Tulsa District Corps of Engineers, 1984), which resulted in numerous requests from the public to the U.S. Army Corps of Engineers for flood protection. The response to these requests was to build three floodcontrol dams in the Neosho River Basin ( fig. 1). The effect of one of the dams, John Redmond Dam (completed September 1964), on highflow frequency and channel geometry of the Neosho River was the focus of a 1year study (1995) conducted by the U.S. Geological Survery (USGS) in cooperation with the Kansas Water Office (KWO) and supported in part by the Kansas State Water Plan Fund. Results will contribute to improve understanding of the effects of dams on streams.
The purpose of this report is to describe changes in highflow frequency and channel geometry of the Neosho River after the construction of John Redmond Dam. The scope of this report includes the analysis of highflow frequency and stagedischarge relation changes at USGS streamflowgaging stations downstream from John Redmond Dam and a comparison of the results of analyses based on data collected before and after completion of the dam.
The data used to determine highflow frequencies and channel geometry were obtained from three currently operating USGS streamflowgaging stations downstream from John Redmond Dam. In addition to these three stations, a discontinued station, which was located at Strawn, Kansas (07182400), was included to further analyze the highflow frequency close to the dam. The discharge at the Strawn gage (operated from 1949 to 1963) should be comparable to what would have been recorded at the Burlington gage site if there would have been a gaging station at that site during that time period. The most current data was used whenever possible. The most current data are available for highflow frequencies through the 1993 water year and for channelgeometry changes through the 1994 water year. Table 1 lists the four stations, their distance downstream from John Redmond Dam, drainage area, and period of record. The location of the streamflowgaging stations is shown in figure 1.
A detailed description of the study area can be found in the Kansas Water Resource Board's Water Plan Study for the Neosho River Basin (Kansas Water Resources Board, 1961). The water plan study includes information on geology and soils as well as average annual precipitation and land use.
Map number ( fig. 1) 
USGS station number 
USGS station name  Distance downstream from John Redmond Dam (mi) 
Drainage area (mi²) 
Period of record (water years) 

1  07182400  Neosho River at Strawn, KS    3,015  194963 
2  07182510  Neosho River at Burlington, KS  5.3  3,042  196393 
3  07183000  Neosho River near Iola, KS  56.3  3,818  191893 
4  07183500  Neosho River near Parsons, KS  139.6  4,905  192293 
Highflow frequency curves are used to estimate the exceedance probability of selected discharges. The median (50percent exceedanceprobability) discharge and the standard deviation of the fitted distribution curve help to describe the characteristics of the streamflow. In this study, comparisons of two curves, one using data prior to closure of John Redmond Dam and one using data after dam closure, are made using the discharge magnitudes of the 2, 50, and 95percent exceedance probabilities as well as the standard deviation of each curve. Also, for this part of the report, the highflow frequency curve for Strawn is illustrated and compared with data from the Burlington gaging station (map number 2, figure 1) because of their close proximity and because the streamflowgaging station at Burlington was not installed until 1963.
The highflow frequency curves developed for the Neosho River downstream from John Redmond Dam illustrate how the discharge characteristics have changed since the dam was completed in September 1964. Highflow frequencies for 7day and 30day highflow discharges at the stations downstream from the dam for the period up to and including 1963 and the period 1965 through 1993 are shown in figures 2, 3, and 4. The differences for all stations are summarized in tables 2, 3, and 4. Since the closure of the dam, the discharge magnitudes associated with the upper end of the curves (lower exceedance probabilities) have been reduced, whereas those associated with the lower end of the curves (higher exceedance probabilities) have been increased. The magnitudes of the differences in the frequencies appear to be dependent upon the distance downstream from the dam. The differences are very large at Burlington, which is 5.3 mi downstream from the dam; they are much smaller at Parsons, which is about 140 mi downstream. This probably is due to a larger part of the drainage area being unregulated as the distance from the dam increases (approximately 27 mi² at Burlington and 1,863 mi² at Parsons). Also, the standard deviations of the logs of the 7day and 30day data are greatly reduced for the postdam period. This is attributed to the regulation of releases through the dam.
Discharge, in cubic feet per second  

7day high flow  30day high flow  
Exceedance probability (percent) 
Predam (Strawn) 
Postdam (Burlington) 
Percentage differences 
Predam (Strawn) 
Postdam (Burlington) 
Percentage differences 
2.0  102,377  13,501  87  37,491  13,266  65 
50.0  8,306  10,813  +30  3,768  7,005  +86 
95.0  1,099  4,266  +288  321  2,064  +540 
Standard deviation of logs 
.533  .173  68  .580  .249  57 
Discharge, in cubic feet per second  

7day high flow  30day high flow  
Exceedance probability (percent) 
Predam  Postdam  Percentage differences 
Predam  Postdam  Percentage differences 
2.0  86,400  18,700  78  37,800  14,700  61 
50.0  11,800  13,000  +10  5,130  9,070  +77 
95.0  1,890  5,290  +180  746  2,890  +287 
Standard deviation of logs 
.456  .176  61  .472  .225  52 
Discharge, in cubic feet per second  

7day high flow  30day high flow  
Exceedance probability (percent) 
Predam  Postdam  Percentage differences 
Predam  Postdam  Percentage differences 
2.0  82,441  47,531  42  45,182  22,598  50 
50.0  19,201  20,635  +7  8,926  12,684  +42 
95.0  3,351  6,988  +108  1,329  3,590  +170 
Standard deviation of logs 
.397  .241  39  .436  .251  42 
Flowduration curves for the periods before and after the construction of John Redmond Dam are shown in figure 5. For specific durations, the highflow discharges have decreased subsequent to dam construction, and the medium to lowflow discharges have increased. The discharges rarely, if ever, become as low as they did prior to completion of the dam because, although the primary purpose for the dam is flood control, it also is used to regulate low flow for the purpose of maintaining water quality in the Neosho River.
Reservoir release operations are known to produce channel changes downstream from a dam
(Williams and Wolman, 1984). Other variables such as precipitation and streamflow also can
cause changes in the river channel. These variables, known as driving or forcing variables,
were tested for trend along with the response variable, stage. Changes with time in the
stagedischarge relation can be used to infer channel changes in the immediate vicinity of the
streamflowgaging station (Wahl and Weiss, 1995). These variables were analyzed for the
period up to the end of the 1963 water year and also for the period from 1965 through 1993,
which coincide with the periods before and after completion of John Redmond Dam. The forcing
variables considered in this study are described below:
The response variable tested for trend is the stream stage at selected discharge magnitudes. Two discharge magnitudes were selected. The annual mean discharge, or the average discharge for the period of record, was used because generally it reflects moderate to low discharges. The median annual peak discharge was used because it generally is about the same magnitude as the 2year flood recurrence interval and because it generally reflects high to moderate discharges.
The stagedischarge relation tables throughout the period of record for each station were used to determine the stream stage (height of water surface above a datum) of each of the selected discharges. The time variable associated with each stage is the year, month, and day in which the stagedischarge relation was put into effect; therefore, there is not a separate stage associated with each year but only a stage associated with each stagedischarge relation.
The test used to determine the presence of trends commonly is referred to as Kendall's tau trend test (Kendall, 1938; 1975). It is a nonparametric test that, in application, tests the null hypothesis that the data are random observations that are identically distributed and not time dependent; no assumption is made about the identity or form of the underlying distribution.
Under the null hypothesis, tau values significantly different from zero are not expected, and their occurrence casts doubt on the truth of the null hypothesis. The test consists of comparing the observed value of tau for the sample with a critical value from the theoretical distribution for tau. If the absolute value of tau for the sample is greater than the critical value, the null hypothesis is rejected; that is, the observed value of tau is too great to have been obtained plausibly by random sampling from a single distribution without time trends. If the observed absolute value of tau does not exceed the critcal value, the sample does not provide a basis for rejecting the null hypothesis.
The probability that tau will exceed the critical value when the null hypothesis is true is called the significance level (alpha) of the test; thus, the significance level is the probability of erroneously rejecting a true null hypothesis. High significance is associated with small values of alpha. In this study, an alpha value of 0.01 was used, representing a 1percent probability of erroneously rejecting the null hypothesis. The attained significance level for a particular test, or p value, indicates the strength of the test result when compared with the alpha value.Results from the trend tests on the forcing variables are summarized in table 5. Forcingvariable data are graphically illustrated in figures 7, 8, and 9. No apparent trend was present in any of the variables tested. The tau values were below the critical value, and the p values were all larger than the alpha value, which indicates that there is no evidence to reject the null hypothesis. These results indicate no climatological change causing changes in the stagedischarge relations at the streamflowgaging stations investigated in this report.
Variable tested  Period years in test 
Number of (water years) 
tau  p value 

Annual precipitation  
Climatic region 6, eastcentral Kansas  18951994  100  +0.04  0.51 
Climatic region 9, southeast Kansas  18951994  100  +.11  .10 
Annual mean discharge  
at Burlington, Kansas (07182510) Postdam 
196593  28  .08  .55 
near Iola, Kansas (07183000) Predam Postdam 
191864 196593 
54 29 
+.07 +.05 
.42 .68 
near Parsons, Kansas (07183500) Predam Postdam 
192264 196593 
43 29 
0 +.11 
.99 .39 
Annual peak discharge  
at Burlington, Kansas (07182510) Postdam 
196593  29  .05  .68 
near Iola, Kansas (07183000) Predam Postdam 
191864 196593 
58 29 
.10 +.18 
.27 .16 
near Parsons, Kansas (07183500) Predam Postdam 
192264 196593 
43 28 
.01 +.24 
.92 .07 
The results of the trend tests on the stage data are summarized in table 6, and plots of the stage data are presented in figure 10. There was little or no trend in the stages associated with the mean annual discharges at all three stations downstream from John Redmond Dam. This probably is because the preferred location for gaging stations is where there will be stable control for low to medium discharges, which means that there is little chance that the channel will scour or degrade at medium to low stages. The median annual peakdischarge stages did show trends at Burlington and Iola. There is a relatively large negative trend just downstream from the dam at Burlington (0.104 ft/yr). Farther downstream at the Iola gaging station, the trend is not as large (0.046 ft/yr), and at the Parsons gaging station, there was no evidence of a trend in the median annual peak stages.
Because the stages are declining at the higher discharges and not at the lower discharges, it can be assumed that the channel is either widening rather than deepening or the flow velocity has increased. Also, the results of the trend tests show that there is a decrease in the magnitudes of the trends as the distance downstream from the dam increases and less proportion of the drainage area is regulated by the dam. Factors that could be affecting the scouring of the upper part of the channel cross section are the procedures used for reservoir releases, increased construction of levees downstream from the dam, channelization of sections of the river, and changes in land use along the flood plain. All of these factors can change the average velocity of the streamflow and (or) change the duration of higher streamflows, which generally will change the amount of scour or deposition.Although these data indicate that some scouring is occurring at two of the streamflowgaging stations, it is only a starting point in determining the amount of channel change in the Neosho River channel. A more definitive analysis of channelgeometry changes could be accomplished with surveys of channel cross sections.
A description of the effects of John Redmond Dam on the highflow frequency and channel geometry of the Neosho River downstream from the dam is presented in this report. Longterm data from four U.S. Geological Survey streamflowgaging stations were used to calculate 7day and 30day highflow frequencies and to determine the river stages for the annual mean discharges and the median annual peak discharges for each streamflowgaging station for the periods before and after completion of the dam.
Highflow frequency and flowduration results show that there has been a change in highflow frequencies since completion of John Redmond Dam. Discharge magnitudes during periods of low flow have increased, and both the magnitude and frequency of high flows have decreased.
A Kendall's tau test for trend was applied to the forcing variables (precipitation, annual mean streamflow, and annual peak discharge) at each of the streamflowgaging stations. These forcing variables, except for precipitation, were only tested to determine if there were trends within the pre and postdam periods. Precipitation was tested to determine any climatic trends. The results of the trend test indicate that there is no significant trend in the data and, therefore, there is no evidence of climatic effects on the changes found in the highflow frequencies. Kendall's tau trend test also was used to test for trends in the river stages for the annual mean discharges and the median annual peak discharges at each of the streamflowgaging stations. The results of the test indicate that there is a downward trend at the two streamflowgaging stations closest to the dam and that the magnitudes of the trends decrease as the distance downstream from the dam increases.
For additional information contact:
Kyle Juracek
U.S. Geological Survey
4821 Quail Crest Place
Lawrence, KS 660493839
Telephone: (785) 8323527
Fax: (785) 8323500
Email: kjuracek@usgs.gov