Semi-two dimensional numerical prediction of non-equilibrium sediment transport in reservoir using stream tubes and theory of minimum stream power

Abstract

This paper presents numerical modeling methods to predict long term reservoir sedimentation. The Generalized Stream Tube computer models for Alluvial River Simulation version 3.0 (GSTARS3) model which has capability of semi-two dimensional hydraulic computation and sediment routing by using stream tube concept combined with the theory of minimum stream power was implemented. In GSTARS3, non-equilibrium sediment transport equation is incorporated in accounting for the reservoir sedimentation processes. Capability of numerical simulation with and without applying stream tube concept, theory of minimum stream power, and non-equilibrium sediment transport equation was evaluated with nine years of sedimentation in the Kardeh Reservoir, Iran, and the best combinations of theories were investigated in this study. Simulated thalweg profile and channel geometry were compared to the measured results. From the comparisons, non-equilibrium sediment transport equation is preferably recommended method to predict reservoir sedimentation. The application of theory of minimum stream power improved the performance of model predictions significantly. In addition, simulations with three stream tubes were slightly better than the one with five stream tubes. Numerical simulations indicated that a semi-two dimensional modeling with non-equilibrium sediment transport equation, three stream tubes, and theory of minimum stream power is applicable to a long term prediction of reservoir sedimentation.