Study On Coupling Simulation And Optimal Allocation Of Surface Water In Well Canal Combined Irrigation Area In Yinbei Region

Aiming YinBei Drainage wells water ratio imbalance, causing ground water depth across the appropriate cause secondary salinization problem, select the benefits of agricultural area Li Village study area, field experiment and numerical simulation of a combination of well Soil water and groundwater and canal irrigation area variation, water balance, groundwater-surface water coupled modeling, surface water and groundwater optimal allocation for a more systematic study of Northern Yinchuan Irrigation provides a theoretical basis for saving technological transformation.The results of the study are as follows:(1) Using the groundwater balance principle to test the recharge and discharge of groundwater resources in the irrigation area of study is analyzed and calculated. The results showed that the irrigation experiment recharge is 157900 m3, excretion is 139100 m3, the groundwater in the positive equilibrium, equilibrium differential is 18800 m3, relative equilibrium difference of 13.51%. Recharge is greater than the excretion, made the irrigation area ground water level rise, groundwater depth over the critical depth of groundwater. And test irrigation evaporation is strong, and the groundwater salt with the capillary water rise to the surface, evaporation, water to make salt accumulation in soil on the surface, easy to result in secondary salinization of soil.(2) To test irrigation district groundwater and surface water system as a whole simulation analysis, considering the hydrogeological trial basis irrigated conditions on the establishment of groundwater-surface water coupling simulation model, the dual node mode of surface water and groundwater model coupling, calibration and validation of hydrogeological parameters, and by HydroGeoSphere software to solve the model, on irrigated water exercise test to make simulation analysis and prediction. After calibration and validation, to give parameters groundwater surface water coupled model of permeability coefficient K is 1.03 m/d, a porosity of 0.38, the Manning coefficient of 0.03 s/m1/3, the air pressure reciprocal 4.07m-1, porosity size distribution index of 1.19, residual saturation of 0.056. After calibration model during the validation period to calculate the change trend is relatively close to the water level and the measured values, the calculated groundwater level and the measured water level observation period error statistics index requirements.Show the structure of the boundary conditions of generalized aquifer, hydrogeological parameter selection is reasonable. The mathematical model can truly portray the characteristics of the study area groundwater system can be used for irrigation district groundwater depth forecast.(3) A comprehensive analysis of the transformation of the relationship between reproductive Groundwater Irrigation System test inputs and outputs, in March and April in the main irrigation period, the higher the degree of exploitation of groundwater, and in a centralized exploitation of groundwater level drop, high groundwater table about 2m, surface soil saturation control varies between 0.69 to 0.76 in. July and August is the largest canal irrigation period, groundwater levels increased significantly, groundwater depth up to lm, over ecological safety level, some high water saturation of soil surface area increased to 0.94 to 0.96. When in September and October to stop diversion headworks, the water table dropped again, the lowest reach 2.2m, saturation decreased to 0.68 or less.(4) A groundwater surface water optimal allocation model is proposed, which is coupled with the numerical simulation model of groundwater surface water. Coupling model from the regulation of groundwater and surface water and water distribution ratio, to determine the exploitation quantity of groundwater and surface water water diversion of, in order to optimize the configuration model of the objective function and constraint conditions as the basis, to reasonable groundwater depth control principle, the optimal output well and canal water supply ratio to improve the utilization of water resources, improve ecological environment.