Supporting At-Risk Aquatic Species Management with Hydrologic Projections

Projections of ecologically relevant metrics defining changes in hydrologic regime are key to understanding aquatic species’ risk under climate and land use change. Large scale modeling efforts covering the Continental United States (CONUS) at high-resolution can provide information relevant to multiple species in a basin and aid in identifying high-risk areas that require priority attention. Here we use the new CONUS-wide implementation of the U.S. Geological Survey NHM-PRMS hydrologic model in order to understand the variation of change in daily flow regime (magnitude, frequency, timing, rate of change, and duration) driven by climate change and land use change. Understanding these drivers of hydrologic change is critical even in highly managed flow environments as variations in input will drive operational decisions. We investigate the applicability of this data in impounded reaches in the southeastern United States which are often seen as risk hot spots for aquatic species due to flow modification and potential climate change. We also compare the projected changes in flow regime with proposed listings for aquatic species under the Endangered Species Act and a range of aquatic vulnerability indexes for native species. The broad scale of this hydrologic dataset allows for a novel comparison across the region of how priority and risk are currently aligned and where management and climate driven changes may correspond.