Future Climate Impacts on Streamflow and Stream Temperature in the Tennessee River Basin

Abstract:

Climate change is expected to alter streamflow and stream temperatures, such as mean values, seasonality and extreme events. These changes could affect human water use and in turn the reliability of power systems, since power generation is heavily water-dependent (either for cooling or for hydropower generation). Most research on future water availability, especially in terms of power system water use, has been conducted in the western U.S., while the southeastern U.S. has been less studied. As part of a larger study to evaluate the potential impacts of climate change on power demand and generation in the southeastern U.S., we implemented the Variable Infiltration Capacity (VIC) hydrologic model at 1/8 degree resolution, linked with the RBM water temperature model, in the Tennessee River basin, where intensive thermal- and hydro-power operations are conducted. A simple reservoir component is also incorporated in the modeling framework. The models are evaluated and calibrated against observed hydrologic data and stream temperatures over the historical period 1950-2010. Daily streamflow and stream temperatures are then simulated over the period 1950-2099, forced by climate projections from multiple global climate model (GCM) runs under RCP4.5 and RCP8.5 emission scenarios. Our results suggest that the modeling framework produces generally realistic simulations of streamflow and stream temperature, and reservoir operations play an important role in streamflow seasonality in this region. We present results on projected streamflow and stream temperatures in the region, with a specific focus on periods that are likely to stress energy demand and generation.