Study on channel-forming process and a mathematical model for conservation storage for long-term utilized reservoirs

Abstract

ABSTRACT It was conventionally believed that a large multi-purpose reservoir would eventually be abandoned because of the sediment deposition caused by the long-term elevation of water level. The concept of the reservoir life was introduced based on this convention. The concept of long-term utilization of reservoirs was first proposed by some Chinese researchers, who also investigated the sedimentation process during the long-term operation of reservoirs and applied the long-term operation strategy in the planning and operation practices for large reservoirs. Based on the general law of reservoir sedimentation, the mechanism of the long-term utilization of reservoirs was discussed in this paper. The channel-forming process for long-term utilized reservoirs was investigated, the first and the second channel-forming discharges were introduced, and the formation of the relative equilibrium longitudinal channel profile and cross-section was analysed. A quantitative relation was derived for the conservation cross section and storage with respect to the sediment discharge period and the control water level. A mathematical model was developed for the long-term utilization of reservoirs. As a case study, this model was applied to the planning of the long-term utilization of the Three Gorges Reservoir.