Streamflow Impacts of Management and Environmental Change in the Upper Wabash River Basin

Abstract

In recent years, there is an ongoing debate regarding the causes of observed streamflow change across the Midwest. In the Wabash River basin in Indiana, streamflow trends due to changes in land management and climate are potentially masked by the effect of flood control reservoirs constructed in the mid-1960s. To investigate the impact of environmental changes on streamflow, historical daily data were used to estimate daily naturalized streamflow for six sites in the Upper Wabash basin. Annual statistics calculated from daily average streamflow show that reservoir management has resulted in 36% and 38% decreases in annual maxima series (AMS) and Richards-Baker flashiness index (RBI), respectively, and a 21% increase in annual minima (MIN) for the Wabash River at Lafayette between 1971 and 2000. Analysis of the naturalized streamflow time series from 1968 to 2014 indicates that there is an increasing trend in MIN and mean annual flow (MAF) across the watershed, as well as an increasing trend in the RBI and AMS. These trends are consistent with streamflow trends detected in other studies throughout the region.