Decreasing water storage capacity in Texas due to reservoir sedimentation

Reservoir sedimentation poses significant challenges for water storage, including drinking water supply, irrigation, recreations, flood control, and other uses. However, accurate quantification of present and future reservoir sedimentation remains a considerable challenge. One of the main obstacles is the lack of repeated reservoir capacity surveys that cover the same spatial domains and employ consistent pre- and post-processing methods. Additionally, incorporating intricate nonlinear morphodynamics into sedimentation quantification is nontrivial. In this study, we analyze repeated bathymetric survey data from 62 reservoirs in Texas (USA) that utilize consistent processing methods, provided by Texas Water Development Board (TWDB). We also investigate spatio-temporal changes in remotely sensed suspended sediment concentration data (1984-2018), which allow to quantify temporal changes in incoming sediment flux to reservoirs and trap efficiency. Assuming a linear sedimentation rate, our results indicate that the capacity of the studied reservoirs in Texas is projected to decrease by 16% in 2100, relative to their maximum in 1994, when the most recent dam construction was completed. Furthermore, we observe an increase in suspended sediment concentration in East Texas, while other regions show a decrease in general. These spatial patterns correspond to observed changes in land cover, land usage, and streamflow. Our findings suggest that reservoirs in East Texas experience more rapid sedimentation due to increased sediment flux. We demonstrate the importance of accounting for such nonlinear sedimentation dynamics to improve long-term projections of reservoir sedimentation. These insights are essential for sustainable surface water management in the future.