Study On Optimal Allocation Of Water Resources In The Sanyizhai Irrigation District

The population of China is very large.With the rapid development of social economy,the requirement for water resources is increasing rapidly.However,the total amount of water resources is limited,and the spatial and temporal features of water resources are uneven.The Sanyizhai Irrigation District is a large Yellow River irrigation project,locating in the east of Henan Province,where is short of water resources.Most of water resources are used for agricultural purposes,the development of society has been restricted by water shortage and the contradiction between the requirement and supply.Facing water resources shortage,low utilization efficiency and unreasonable structure of development,this paper,taking the Sanyizhai Irrigation District as the experimental area,studies the optimal allocation of regional water resources by using the method of system analysis.On the basis of investigations on water resources condition and the situation of development and utilization,this paper,combining with development plan of the Sanyizhai Irrigation District,predicts requirement for water resources and available water supply in planning year.According to the prediction results of water supply and requirement,an optimal allocation model of regional water resources is established,based on the system optimization theory,it is solved by genetic algorithm,the results can determine the water resources allocation schemes in planning level year.The main contents and achievements are as follows:(1)The basic data of geographical location,meteorological,social economy,water resources condition of water resources and water conservancy project are collected and sorted out,and the unreasonable development and utilization of water resources in the Sanyizhai Irrigation District is analyzed.The results show that a coexisting of water scarcity of engineering and quality,the utilization efficiency of water resources is low,and the development and utilization structure of water resources is unreasonable.(2)Based on the investigation on the current structure of water consumption in the irrigated area,combined with the development plans,taking a full account of the improvement of water-saving level and the adjustment of agricultural planting structure,the quota prediction method is used to predicte the water requirement.The results show that more than 80% of water requirement in the Sanyizhai Irrigation District is agricultural water requirement.Based on the current conditions of water resources and water conservancy projects,combined with the future goals of the Sanyizhai Irrigation District,thaking a full account of exploiting the potential capacity of water supply,this paper predicts available water supply in 2025 and 2030.The results show that,the Yellow River water and ground water will still be main sources of water in the Sanyizhai Irrigation District,the Yellow River water accounts for 52.21～53.41% of the total available water supply,the ground water accounts for37.55% ～38.41%.The development of the Sanyizhai Irrigation District is supported by the combination of the Yellow River water and ground water.The reclaimed water accounts for5.66～6.23%,while local surface water accounts for 2.45～4.11%.Without the support of the Yellow River water diversion,the Sanyizhai Irrigation District cannot operate normally,and unreasonable allocation of water diverted from the Yellow River can lead to excessive exploitation of ground water.There is potential for further development of reclaimed water and local surface water.(3)According to theory of optimal allocation of water resources,an optimal allocation model of regional water resources is established,which aims to maximize the comprehensive benefits of economy,society and ecology,based on the theory of sustainable development.The genetic algorithm is used to solve it,based on the theory of overall optimization of largescale system.The results show that,on the basis of achieving the maximum comprehensive benefits of the Sanyizhai Irrigation District,in normal year(P=50%),water supply can meet the domestic,ecological,industrial and agricultural water requirements.In dry year(P=75%),the overall water deficiency ratio of the irrigation area in 2025 is 6.01%,and the water deficiency ratio of agriculture is 6.97%.While the overall water deficiency ratio of the irrigation area in 2030(P=75%)is 2.90%,and the water deficiency ratio of agriculture is3.42%,water supply can meet the domestic,ecological and industrial water requirements.Research results can provide scientific basic for the irrigation area water management.