Estimates of Flow Duration and Peak-Discharge Frequency for Kansas Stream Locations

Streamflow statistics of flow duration and peak-discharge frequency were estimated for 4,771 individual locations on streams listed in the Kansas Surface Water Register. These statistics included the flow-duration values for 10%, 25%, 50%, 75%, and 90% as well as the mean flow value. Peak-discharge frequencies were estimated for the 2-, 5-, 10-, 25-, 50-, and 100-year floods.

Least-squares multiple regression techniques were used, along with Tobit analyses, to develop equations for estimating flow-duration values and the mean flow for uncontrolled stream locations. The drainage areas of 149 U.S. Geological Survey streamflow-gaging stations in Kansas and parts of surrounding states that were uncontrolled by large reservoirs were used in the regression analyses. Significant climatic and basin characteristics, in order of importance in the regression analyses, were drainage area, mean annual precipitation, mean basin permeability, and mean basin slope. Regression equations used to estimate peak-discharge-frequency values at ungaged locations were obtained from a previous report.

The regression equations and an interpolation procedure were used to compute flow durations, mean flow, and estimates of peak-discharge frequency for locations along uncontrolled streams listed in the Kansas Surface Water Register. Flow durations, mean flow, and peak-discharge frequency determined at available gaging stations were used to interpolate the regression-estimated flows for the stream locations where available. The locations that were uncontrolled by reservoirs were interpolated using data from gaging stations weighted according to the drainage area and the bias between the regression-estimated and gaged flow information. At controlled locations on Kansas streams, the streamflow information was interpolated between gaging stations using only gaged data weighted by drainage area.