Reclamation's Research on Climate Change Impact on Reservoir Capacity

This study assesses the impacts of projected climate changes on reservoir sedimentation. Much attention has been paid to the impact of climate change on water supply (e.g., timing and magnitude of flows); however, little is known about the effects of climate change on reservoir sedimentation. Elephant Butte Reservoir on the Rio Grande in New Mexico was selected for this purpose. To predict the effects of climate change on reservoir sedimentation, several steps are involved. First, all of the 112 downscaled climate projections were divided into five categories, which provide average and extreme scenarios for reservoir sediment management and water operations. Second, hydrologic responses were simulated using the Variable Infiltration Capacity (VIC) hydrologic model to obtain the unimpaired flows at various gauging stations, which are then used to calculate regulated flows into the reservoir with the Upper Rio Grande Water Operations Model (URGWOM). Third, the total sediment load into the reservoir was calculated using the Bureau of Reclamation Automated Modified Einstein Procedure (BORAMEP), based on each sample's hydraulic properties, measured suspended load, and bed material gradation. Finally, sediment loads under the historical and climate change scenarios were calculated based on the adjusted rating curves.