Experimental And Numerical Simulation Of Influence On Overland Flow And Water Infiltration By Crack Networks In Soil

Overland flow and groundwater coupled model is one of most important in hydrological modeling.Reviewing the coupled model of surface water and groundwater,Surface-Matrix-Crack(SMC model)is established to simulate the overland flow and the soil water with the presence of crack networks.SMC model couples the surface runoff model and the soil water flow model,and the overland flow is described by the two-dimensional diffusion wave equation;the soil water flow model is based on the concept of double permeability model,and the soil water flow is divided into two forms,which is in the matrix regions and in the fracture network.Richards' model and the single-fracture water flow channel water motion equation is used to describe the two soil water flow movement.In this paper,dye tracer experiment was carried out(slope angle equals to 10 degrees),and the artificial crack network was used.Overland flow and soil water flow data are obtained through the experiment,which are used in the calibration and verification stage of SMC model.According to dye-tracing experiment,the simulated area is edited.The relationship between the simulated value and measured value is evaluated by trial and error method,and mathematical evaluation index.Through adjust model parameters,the optimal parameters were obtained.Comparing the traditional model,the SMC model is better,and the simulation evaluation index is better than the traditional model.SMC model can accurately simulate the soil water flow and overland flow.Through the influential analysis of the SMC model parameters,the results show that:(1)The change of Manning coefficient has great influence on the simulation of overland flow;when the coefficient changes greatly,saturation decreases with the coefficient decreases.(2)The change of saturated hydraulic conductivity has a great influence on the overland flow and saturation.Coefficient changes greatly,saturation decreases with the decrease of the coefficient.(3)Overland flow increases with the increase of shape parameter.Saturation will decrease as a whole with the increase of shape parameter.Among the four model parameters,the reciprocal of inhale has the greatest influence on the simulation of overland flow movement,and the simulated value of overland flow increases with the increase of the reciprocal of inhale.The surface-matrix-crack coupled model will improve the understand of farmland water movement and solute transport law,and it has important application value for guiding agricultural irrigation and improving agricultural water use efficiency.