Time-Based Estimation of Reservoir Sedimentation Impacts

Existing empirical methods to predict reservoir sediment distribution are largely based on the original reservoir shape. To describe reservoir sediment distribution, one usually compares the original reservoir capacity and surface area as functions of the water depth to a future reservoir capacity and surface area. Examination of survey data of 23 reservoirs of Bureau of Reclamation found that area reduction method (ARM) produces the best results with existing Bureau of Reclamation data. Further examinations show that the reservoir type determined only from the reservoir shape usually does not always produce the best sediment distribution fitting compared to reservoir survey data. Reservoir sedimentation pattern depends not only on the reservoir shape, but also on reservoir operation rules, water surface levels, and sediment size distribution. Several reservoir operation parameters are presented in an attempt to relate sediment distribution with reservoir operations. Initial results show that sediment distribution is more complex than what simple parameters can present. Reservoir shape, defined as slope of the depth-capacity curve on log-log coordinates, presents the best correlation with the sediment distribution. Poor correlations between proposed reservoir operation parameters and sediment distribution were found. Sediment size distribution would likely improve the results, but this data is not available for the majority of the reservoirs analyzed in this study.