Water Resources Research Act Program

Details for Project ID 2020TX225B

Improving Surface Water Availability Estimates by Accounting for Projected Changes of Reservoir Evaporation: A Case Study in Upper Trinity River Basin

Institute: Texas
Year Established: 2020 Start Date: 2020-03-01 End Date: 2021-02-28
Total Federal Funds: $5,000 Total Non-Federal Funds: $10,000

Principal Investigators: Huilin Gao

Abstract: Texas regional water planning considers projected water demand and reservoir sedimentation when evaluating future surface water availability, but not the impacts of climate change on hydrologic conditions and reservoir evaporation losses. Our objective is to assess the effects of reservoir evaporative losses on reservoir firm yield and water supply reliability under different future climate change scenarios. A total of 12 major reservoirs in the Upper Trinity Basin (UTB) are selected as the study sites. UTB supplies water to about a quarter of Texas’ population, including the Dallas-Fort Worth Metropolitan. A distributed hydrological model with a reservoir module, which accounts for both energy budget and mass transfer in the calculation of open water evaporation, will be used in this research. The model is to be forced by statistically downscaled CMIP5 climate forcings to simulate future reservoir evaporation. The projected reservoir evaporation is then used to as input to Water Availability Model (WAM) – a tool to assess water availability for regional water planning – for estimating future reservoir firm yield and water supply reliability. Results from this research can inform modifications to existing reservoir operations and inform revisions to guidance material related to the regional water planning process in Texas.