Geoscience

Optimization of Cascaded-reservoirs: Theory and Practice

The research achievements on “Upper Yangtze River reservoir-group optimal operation and its simulation decision supporting system” completed by Prof. Cheng Genwei, Institute of Mountain Hazards and Environment, CAS, has passed the appraisal recently. Three-Gorges Reservoir is of world-famous tremendous hydraulic engineering work. The research on cascaded reservoir optimization operation and its impact on the stream flow downstream are significant both in scientific and engineering aspects. The scientists of Institute of Mountain Hazards and Environment and Tsinghua University have eventually provided solution for the critical theoretic and technical issues on optimal operating rules for the large-scale cascaded reservoirs. The impact mechanism of impounding and releasing water of cascaded-reservoir upstream to river flow of the Three Gorges Reservoir, the long-term runoff forecasting theory and methodology under different confidence level, the controlling principle of limiting-water-level of reservoir on the flooding season, the best time of water storage for the Three Gorges Reservoir after flooding season,etc, have been explored and figured out. At the same time, the technical scheme and optimal operating regulations for the Three Gorges Reservoir have also been proposed. These achievements are of great scientific significance and engineering technical value. The dynamic model and decision-making supporting system on cascaded-reservoirs developed recently involves more than 50 large-scale reservoirs and catchments of area controlled over one million square kilometers in the upper Yangtze valley. Characterized by all-round supervising, the states of all reservoirs and subsequently carrying out flexible operating simulation, this system can fulfill long-term forecasting to daily stream flow in six months and the analog simulation to various operating schemes. It is regarded as the largest scale and the highest level reservoir group operating/simulation system, according to the scientific reference retrieval. The critical theories and technologies in the long-term forecasting of river flow, the determination principles forecasting confidence probability, the multi-stage limiting-water-levels on flood season based on the dynamic storage capacity, the dynamics model of flow and sediment to the Three Gorges reservoir have been studied and solution obtained, thus the results on the long-term runoff forecasting of complex reservoir group system and optimization scheduling and related technologies have been proposed. The system complexity and technical difficulty can be considered as a new “Three Gorges Project” in large-scale water resources controlling system.