Study On The Low And Simulation Of Return Water In Gansu Jingtai Yellow River Electric-irrigated Area

The contradiction between the supply and demand of water resources in my country is increasing.With the increase in the demand for industrial water and urban domestic water,my country's agricultural water supply is more scarce.In addition,the agricultural water and land resources are not coordinated in time and space,so that the cultivated land resources cannot be efficiently used,which greatly reduces agricultural productivity.Therefore,the development of water-saving agriculture is an effective way to solve the shortage of agricultural water resources.The large amount of backwater generated in some irrigation areas of the Yellow River in China is one of the low efficiency of water resources utilization in irrigated agriculture in China.Therefore,studying the law of backwater in the Yellow River irrigation area and its prediction and efficient use are the effective ways to improve the efficiency of water resources utilization one.This article takes Jinghuang pumping irrigation area in Gansu Province as the research area.Based on the study of the law of water withdrawal and its influencing factors,the MIKE SHE distributed hydrological model is used to establish a hydrological simulation model that is consistent with the actual irrigation area.The main results achieved by simulation calculation are as follows:(1)On the annual scale,the surface retreat volume has a significant linear relationship with the diversion volume and groundwater depth,but the linear relationship with precipitation and evaporation is not obvious;on the monthly scale,the surface retreat volume and the diversion volume and groundwater level are The more obvious polynomial fitting relationship is not obvious with precipitation and evaporation.(2)The gray correlation analysis method is used to analyze the influence degree of each influencing factor of the surface retreat in the irrigation area on the annual scale,and it is shown that the water diversion,precipitation and evaporation in the irrigation area and the surface retreat in the irrigation area are ranked in order of their influence.It is:water diversion>groundwater depth>precipitation>evaporation.(3)Based on the meteorological and hydrological data,DEM altitude data,crop planting structure,soil type distribution,canal system distribution,water resource distribution,groundwater depth and aquifer thickness of the Jingtai electric-irrigated area,the MIKE SHE distributed hydrological model is adopted to successfully establish the water recession model and calculate the water recession flow.The surface water recession flow is calculated by the actual water recession volume and the Manning coefficient of slope flow,the crop growth characteristic parameters in the land use module,the saturated hydraulic conductivity and the saturated water content of different soil types in unsaturated zone,the horizontal and vertical hydraulic conductivity,storativity and water storage in the saturated zone,and the channel roughness coefficient of the open channel flow are all calibrated.(4)The model efficiency coefficient Ens,the water balance coefficient RE and the correlation coefficient r are used to evaluate the applicability of the model after the calibration.The results show that the model's simulation effect on the annual backwater volume is better than that on the monthly runoff.On the annual scale,The efficiency coefficients,water balance coefficients and correlation coefficients of the model during the period and verification period are better than the monthly scale.