Streamflow Depletion Investigations in the Republican River Basin: Colorado, Nebraska, and Kansas

Abstract

Water is a critical resource in the Great Plains. This study examines the changes in long-term mean annual streamflow in the Republican River basin. In the past decades this basin, shared by three states, Colorado, Nebraska, and Kansas, displayed decreased streamflow volumes as the river enters Kansas across the Nebraska-Kansas border compared to values preceding the 1950s. A recent lawsuit filed by Kansas challenges water appropriations in Nebraska. More than half of the source area for this water, however, lies outside of Nebraska. Today a higher percentage of the annual flow is generated within Nebraska (i.e., 75% of the observed mean annual streamflow at the NE-KS border) than before the 1950s (i.e., 66% of the observed mean annual streamflow) indicating annual streamflow has decreased more dramatically outside of Nebraska than within the state in the past fifty years.