Quantification of Modeled Streamflows under Climate Change over the Flint River Watershed in Northern Alabama

This study quantified the impacts of climate change on water availability over the Flint River subwatershed (FRW) located in the Wheeler Lake Watershed (WLW) in northern Alabama. The observed climate data were obtained from the Alabama Mesonet Stations, and the modeled climate was obtained from multiple models, multiple scenarios, and multiple projections available through the World Climate Research Program's database. The hydrologic model, the soil and water assessment tool (SWAT), was calibrated and validated for the period of 2004 to 2013, based on daily meteorological forcing and monthly streamflow data. Various climate scenarios developed with respect to anticipated future climate until 2100, based on representative concentration pathways (RCPs), were forced into the calibrated SWAT model to quantify future water availability. The simulated average change in monthly streamflow varied from +23 to -46%, +29 to -48%, +40 to -48%, and +38 to -48% for scenarios RCP 2.6, RCP 4.5, RCP 6.0, and RCP 8.5, respectively; the simulated total annual streamflow varied from +18 to -28% for the same scenarios. However, average change in total annual streamflow based on all scenarios showed a decreasing streamflow pattern from -0.3 to -1.2% for future periods, except a slight increase of +0.17% at the end of this century. The simulated results that quantified water availability under changing future climate conditions can be used by water managers, stakeholders, and decision makers in planning and managing available water resources and their allocations based on users and water demands, and in considering alternatives for monitoring and mitigating long-term impacts. (C) 2017 American Society of Civil Engineers.