| Drought has been a major problem for mankind, especially in the northwest. As the drought situation becoming more and more prominent, the role of reservoirs in drought resistance research is becoming more and more prominent, and the reasonable dispatching of reservoirs is of great significance in drought resistance and disaster reduction. The study is conducted on the drought resistance of Fengjiashan reservoir in Wei River Basin and aims to alleviating watershed drought through reservoir regulation. The main methods and conclusions are as follows:(1) Based on the meteorological and hydrological indicators to construct comprehensive drought index of Fengjiashan reservoir, the entropy weight method and the fuzzy comprehensive evaluation method are used to calculate the comprehensive drought index CDI of the irrigation area, evaluate the drought grade according to the regional drought grade standard and analyze drought characteristics of reservoir area. The results are as follows: the drought degree is increasing slowly as a whole, and the number of drought in the 1990s is increasing rapidly, which is the most severe drought period. The most severe drought periods are in 1986,1995 and 1997;The drought in the irrigation area is mainly concentrated in spring and autumn.(2) The minimum water deficit is established by the study. The DP (dynamic planning) is used to solve the model, based on reservoir water level, the average monthly rainfall, the average monthly inflow of reservoirs and the monthly average water level are selected as the sample values. The weight coefficient of each sample factor is determined by expert judgment method and Fisher’s optimal segmentation method is used to determine drought stages. The whole year is divided into four staging: January to March, April to June, July to October, November to December. The long series of drought and reservoir optimized water level results is used to determine the drought limit level corresponding to the different drought grades.(3) Firstly, the typical year of Fengjiashan reservoir is determined by the appropriate method.Based on the optimal operation of the reservoir and considering the staging drought limit level,the drought-resistant dispatching model of Fengjiashan reservoir is established, and the dynamic programming method is used to solve the model. Analyzing from the water shortage (long series,programming method is used to solve the model. Analyzing from the water shortage (long series, typical year, continuous dry series) and the water assurance rate of the results before and after drought resistance scheduling, the results show that the water shortage is mainly concentrated during the 1990s, and the average water deficit of the long series before and after drought resistance scheduling is respectively from 3.35 percent to 2.69 percent, which is 0.66 percent lower than that before the scheduling. The water deficit in the special dry season and the partial dry season after drought resistance scheduling is respectively 2.91 percent and 10.86 percent lower than that before the drought resistance scheduling. In the normal flow year, which reduces 9.23 million m3. In the rich and special rich hydrological year, the water is enough before and after the drought resistance scheduling. In the series of dry years, and the average water deficit is 2.77 percent lower than that before the drought resistance scheduling. The annual guarantee rate of all types of water after drought resistance scheduling is higher than that of the before, which is respectively 2.3 percent and 4.5 percent higher than that before the scheduling on consumption water and agricultural water and the guarantee rate of production water and ecological water is the same. |
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