Study On Optimization Of Water Resources Allocation In Shuangpai Reservoir Irrigation District Under Changing Environment

The Shuangpai Reservoir Irrigation District was built in the 1960s and is one of the first large-scale irrigation districts in Hunan Province.With the development of social economy,the changing environment has a great impact on the water cycle of the irrigation area.Climate change will affect the distribution of regional water resources in time and space,and human activities will affect the regional water cycle production and distribution mechanism.Changing environment is the main factor affecting the evolution of water cycle and the optimization of water resources allocation in irrigation districts.It is of great significance to study the allocation of water resources under changing environment and the efficient use and planning of water resources in irrigation districts.The dissertation takes Shuangpai Reservoir Irrigation District as the research object,and uses the large-system optimization analysis method to analyze the impact of changing environment on the water resources allocation optimization of Shuangpai Reservoir Irrigation District.The main research results of the thesis are as follows:(1)Analyze the water cycle elements in the Lishui River Basin and the Shuangpai Reservoir Irrigation District from the hydrological data from 1961 to 2014.The annual average precipitation and potential evapotranspiration of the Xiaoshui River Basin were unevenly distributed during the year.The interannual variation of precipitation showed an upward trend.The potential evapotranspiration showed a decreasing trend,and the interannual variation of runoff showed a decreasing trend.The average annual precipitation of Shuangpai Reservoir Irrigation District is 1334mm.The precipitation distribution in the flood season and non-flood season is quite different.The precipitation in the four seasons is obviously changed.The interannual variation of precipitation shows no obvious upward trend,and the interannual variation of potential evapotranspiration shows a downward trend.(2)Based on the actual supply and demand of water resources in the irrigation area,combined with economic and social development,the quota method and other methods are used to predict and calculate the water demand,industrial water demand,agricultural water demand and ecological water demand in the irrigation area.In the 2030 year of the design year(P=50%),the total water demand in the irrigation area is 21,599,800 m3,the available water resources is 28,832,500 m3;the dry water year(P=90%),the total water demand in the irrigation area is 272,608,700 m3,available.The amount of water resources is 258.17 million m3.(3)Based on the large system decomposition coordination theory,establish a multi-objective genetic algorithm water resource allocation optimization model,and analyze the water resource allocation optimization under three different scenarios:1 without considering the changing environment scenario,2 precipitation-potential evapotranspiration change scenario,3 crop planting Structural change scenarios.The results show that the water resources allocation optimization study under the three scenarios of Fengshui Year(P=50%)can meet the water demand of users in all departments of the irrigation district;the water shortage in the dry year(P=90%)irrigation area is not considered.The water shortage rate in the irrigation area is 9.83%,the precipitation decreases,the potential evapotranspiration increases,the water shortage in the whole irrigation area is 15.89%,and the crop planting structure optimization scenario,the water shortage in the whole irrigation area is 5.52%.