Optimal Allocation Of Water Resources In The Ziya River Basin Based On ET Management

With the development of economy and society,the demand for water resources increases sharply.Due to the limitation of total water resources,the contradiction between supply and demand of water resources becomes more and more prominent,resulting in serious over-exploitation of groundwater and deterioration of ecological environment.Therefore,this study focuses on the problem of water resource shortage,takes Ziya River Basin as an example,calculates the natural ET and artificial ET of the basin,evaluates the water shortage degree of the basin through the balance analysis of supply and consumption,and puts forward anoptimal allocation scheme of water resources based on ET,which provides theoretical basis and technical support for alleviating the contradiction between supply and demand of water resources in this region.The main contents and achievements of this study are as follows:(1)Natural ET calculation of Ziya River Basin based on SWAT modelIn the SWAT model,runoff observation data and remote sensing ET data were used to establish three scenarios at the watershed scale to calibrate the model,and the evapotranspiration in the Ziya River basin from 2005 to 2015 was simulated accurately,In particular,the natural ET in 2015 was 398.2mm,and the results of each simulated scenario were compared and analyzed.The conclusions are as follows:1)In ET simulation,the remote sensing ET data calibration model is superior to the runoff data calibration model in both the objective function and the total amount of simulated ET;2)In the case of good data,the multiple target variable calibration model is better than the single target variable calibration model.At the same time,the factors affecting the accuracy of ET simulation by the SWAT model were explored,mainly including terrain,precipitation and agricultural irrigation.(2)Artificial ET calculation of Ziya River BasinThe domestic ET and production ET were calculated by the quota method.In order to consider the impact of terrain,temperature,sunshine,precipitation,vegetation and other natural factors on the evaporation of irrigation water,the quota method combined with the SWAT model was used to calculate agricultural ET.Based on Landsat8 data,the planting areas of spring maize and winter wheat in the watershed were firstly extracted by two methods of NDVI time series decision tree and random forest.,the areas in the SWAT model where the land use was cultivated land were subdivided,and then the irrigation system was set according to the irrigation quota.Finally,the data of redivided cultivated land and crop irrigation system were input into the model to calculate the agricultural ET,and the agricultural ET was 57.46mm in 2015.(3)Optimal allocation of water resources based on ET controlFirstly,the current situation of the basin and the degree of water shortage and its spatial distribution in 2025 for the three typical frequency hydrological years of abundant,flat and dry were analysed through the water supply and consumption balance.Then,based on industrial structure adjustment of water between the three industries adjust the multi-objective optimization model and water consumption can be county space deployment of multi-objective optimization model.Through optimal allocation,water consumption can be saved by 814 million m~3;the use of industrial and agricultural efficient water-saving measures can reduce water consumption in the river basin by 1.031 billion m~3;and finally,through the transfer of water from outside the basin by 1.074 billion m~3,the balance of water supply and consumption of water resources can be realized.