Study Of Cascade Reservoir Operation In The Upper Hanjiang River In Response To Runoff Variation

Reservoir dispatching rules are simulated by the hydrological data sequence in reservoir design phase. Due to the global climate change, and human activities effect, watershed conditions change, and the hydrological data sequence consistency is destroyed. Reservoirs dispatching rules which designed in the reservoirs design phase did not apply to the new hydrological sequence.Therefore, the research of reservoir dispatching rules based on new hydrological sequence is necessary. In this paper, with Hanjiang River upstream Shiquan-Xihe-Ankang cascade reservoirs as objects, we studied operation rules of the cascade reservoirs in response to runoff change.The major research contents and accomplishments are as follows:(1) The runoff law of the upper reaches of Hanjiang River was analyzed. Based on wavelet analysis method, the inflow runoff of Shiquan Reservoir has 6 years and 23 years cycle, and Ankang Reservoir has 7 years, 17 years and 26 years cycle. By Kendall rank test, the runoff of Shiquan Reservoir and Ankang Reservoir shows a decreasing trend. By R/S analysis method, the runoff series of Shiquan Reservoir and Ankang Reservoir is sustainable.(2) The variation of runoff in the upper reaches of Hanjiang River was analyzed by using several methods, such as Moving t-test, Yamamoto, Mann-Kendall, Pettitt, Orderly Clustering Analysis, and Schwarz Information Criterion method. The result showed that the runoff mutation point occurred in 1990 in the Hanjiang River upstream. A fter the variation, the annual runoff of the basin was reduced, and the reduction period was mainly concentrated in the flood season.May to October after variation, runoff of Shiquan and Ankang were reduced by 39.20% and 30.80%, and the proportion decreased from 80.94% and 80.32% to 77.25% and 77.45%respectively. And the trend is changing.(3) Using the original design dispatching chart ofShiquan Reservoir and Ankang Reservoir,the scheduling of Hanjiang River upstream cascade reservoirs is simulated. The average annual generating capacity of Shiquan, Xihe and Ankang from 1954 to 1990 was 7.59, 6.06 and 2.15 billion kW·h respectively; from 1990 to 2005, the average annual generating capacity of Shiquan,Xihe and Ankang was 5.66,4.57 and 1.835 billion kWh respectively.(4) The improved reservoir operation chart after the change point of runoff established. A new scheduling graph is obtained by equal power methods and used to simulate the scheduling.It can be obtained that the average annual power generation of Shiquan, Xihe and Ankang hydropower stations were 5.69, 4.57 and 1.846 billion kW·h. The new scheduling graph relative to the original scheduling graph can increase the power generation benefits of cascade reservoirs.(5) The optimal reservoir operation chart after the change point of runoff established based on the new scheduling graph. By establishing an optimization model, and the Hanjiang River upstream cascade reservoirs joint optimization scheduling graph was obtained, and smulation and genetic algorithm method was used. The average annual generating capacity of Shiquan, Xihe and Ankang hydropower stations was 5.83, 4.62 and 1.859 billion kWh respectively. The efficiency of the cascade reservoirs power generation was greatly improved.