A Case Study on Predicting River Valley Deformation Following Reservoir Impoundment

Valley contraction poses a significant threat to high-arch dams, making the prediction of valley deformation a critical task in assessing the long-term performance of dams. The Baihetan dam is currently undergoing compression due to valley contraction, and its complex control mechanisms present major challenges in predicting valley deformation. This paper proposes a hybrid model to predict valley deformation in Baihetan, which integrates numerical simulation and statistical analysis to identify the main causes of river valley deformation and make predictions based on extrapolation. A transient numerical seepage model has been used to comprehensively characterize the complex seepage field in the Baihetan dam site area over nearly a decade following impoundment. The hybrid model was developed based on this foundation to determine the contribution of each factor using monitoring data. The model can then be used for time series extrapolation to predict long-term deformation. By June 2028, the valley near the dam is projected to experience a deformation rate of less than 1 mm per month, with a maximum contraction of approximately 26.7 mm. This study provides a basis for assessing the long-term operational safety of the Baihetan and offers valuable reference for similar studies on valley deformation.