Simulating the hydrologic response to climate and landscape change using the Precipitation-Runoff Modeling System in the Apalachicola-Chattahoochee-Flint River Basin, southeastern United States

The Apalachicola-Chattahoochee-Flint (ACF) River Basin is home to multiple fish and wildlife species of conservation concern, is regionally important for water supply, and has been a recent focus of complementary water-resources, ecological, and climate-change research. The Southeast Regional Assessment Project (SERAP) was initiated in 2009 by the U.S. Geological Survey (USGS) National Climate Change and Wildlife Science Center to help environmental resource managers assess potential effects of climate and landscape change on ecosystems. Hydrologic models of varying spatial extents and resolutions are required to address varied local-to-regional water-resource management questions as required by the scope and limits of potential management actions. One component of the SERAP is development and calibration of a set of multi-resolution hydrologic models of the ACF River Basin. As part of SERAP, a hydrologic model was developed for the ACF River Basin using the USGS Precipitation Runoff Modeling System (PRMS). The PRMS hydrologic model simulates basin hydrology using daily timesteps, measured climatic data, and basin characteristics such as land cover and topography. Measured streamflow data, collected by the USGS, were used to calibrate and evaluate computed basin hydrology at 35 locations. Land cover projections of vegetation and urbanization were used in conjuction with results from three statistically downscaled General Circulation Models (Community Climate System Model version 3.0, Geophysical Fluid Dynamics Laboratory model version 2.1, and the Parallel Climate Model) to simulate potential future hydrologic conditions for two emissions scenarios (A1Fi and B1) in the ACF River Basin through year 2099. Initial results indicate increases in basin air temperature for both emissions scenarios and increases in surface runoff due to increased urbanization. Current stormwater management practices in urban areas include surface-water storage to decrease the effects of rapid runoff during storms, which is not accounted for in the urbanization projections. Therefore, additional simulations to determine the necessary amount of additional surface-water storage capacity to mitigate these increases in surface runoff were performed.