Calculation Of Water Inflow For The Jinpen Reservoir On The Heihe River In Xi'an City

Xi'an is a central city in western China, and its safety of water supply is an important factor which has always been related to the economic and social sustainable development. The Jinpen reservoir on the Heihe river is the key water supply project. Under the background of global change, the change in water inflow for the Jinpen reservoir this paper will affect the insurance degree for water supply. For runoff time series, the variation characteristic of is analyzed and the correction calculation is conducted to confirm the change of water inflow for the Jinpen reservoir. The research results will provide reference for the local government in Xi'an about water supply security.Combined with the analysis, this paper gets the following results:(1)Runoff variation characteristics: This paper uses the ordered clustering analysis and sliding T test method to obtain that the mutation is 1990, and the runoff distribution during the year is very uneven, which in June to Octobers, accounting for 73.8% of the annual runoff.Then, it uses the Kendall rank test method to prove that the runoff of the Heiyukou generally presents a decreasing trend, and the decreasing trend of runoff series in year, spring, summer,winter is significant,while it isn't significant in winter. It also uses the R/S analysis to show the lasting is stronger among each runoff sequences(annual, spring, summer, autumn and winter),that is, the future runoff is still in a decreasing state.(2)Precipitation variation characteristics: The precipitation in the study area isn't obvious,and precipitation assigned during the year is extremely uneven, which in June to Octobers,accounting for 75.8% of the annual precipitation. Precipitation in the study area is not consistent with runoff, and there is no obvious decreasing trend between them, so the precipitation of the study area doesn't cause the runoff decreasing.(3)Evaporation variation characteristics: the evaporation of the study area shows a decreasing trend in general, and the decreasing trend of the evaporation series in the year,spring, summer, autumn and winter orders year, winter, summer, autumn and spring.Evaporation assigned during the year is extremely uneven , There is no different tendency to change the evaporation and runoff in the study area, so the evaporate of the study area doesn't cause the runoff decreasing.(4)Terrain information extraction: Based on the DEM method of extracting the watershed information, this paper uses the Arcgis software combined with DEM to extract the topographic information such as grid flow matrix, accumulated runoff volume, river network, confluence length, natural sub-watershed, topographic index.(5)Runoff correction calculation: The study area is divided into six sub-basins. The runoff series is divided into the series before and after the mutation point. Using the genetic algorithm to optimize the parameters, verify the applicability of TOPMODEL model in the study area. By model calculation, the reduction /correction value of the water storage of Jinpen Reservoir during the study period is 550 million m3 and 396 million m3.