Spatial and Temporal Variations in Precipitation and Runoff in the Upper Saline River Drainage Basin, Kansas, 1956-1987

The precipitation/runoff relationship in the Upper Saline River drainage basin (Northwest Kansas) affects streamflow which has declined both spatially and temporally. The Theissen polygon method, for determining the effective uniform depth of precipitation, is used to calculate annual precipitation values over the drainage basin and selected subdivisions of the basin. Stream discharge data from two gaging stations are compiled and converted from volumetric units to linear units, enabling comparison among hydrologic values. A runoff ratio is used to quantify the precipitation/runoff relationship. Slope and land usage practices are areally categorized to determine their percentage distribution and influences on runoff. A double-mass analysis of cumulative precipitation and runoff values allows temporal and spatial variations in the runoff ratio to be determined within the basin and selected subdivisions. The analysis shows a gradual streamflow decrease in the eastern part of the basin and a sharp decline in the western part. Precipitation patterns, slope, and land usage practices are the primary factors affecting runoff and streamflow.