Research On Water Movement Of Rainfall Infiltration Runoff System In Slope Under The Arbor-Shrub-Hedge-Gutter Method

Soil erosion is very serious in Northwest China. Besides the existence of water erosion, wind erosion is also very serious. They have seriously affected agricultural production in the region. To improve the serious conditions of water erosion and wind erosion in the Northwest China, Professor Sun Xihuan proposed the method of water conservation in arbor-shrub-hedge-gutter, which can effectively control soil erosion including water erosion and wind erosion. It is a new treatment method that is suit for the regions in Northern where soil erosion is most serious. Meanwhile it is a method of controlling water erosion and wind erosion which combines soil and water conservation engineering measures with biological ones. In this paper, with the method of combining of experiments and numerical simulation, we studied water movement of rainfall infiltration runoff system on slopes in the-arbor-shrub-hedge-gutter. The main research findings are as follows.1. The research on the soil water movement test of the arbor shrub hedge gutter channel is based on the self-developed apparatus of the arbor shrub hedge gutter channel. The results show that the horizontal and vertical wetting front advancing distances increase with the increase of infiltration time while the horizontal and vertical wetting infiltration velocities decrease with the increase of infiltration time. At the same time, we find the relation between the horizontal and vertical wetting front advancing distances and infiltration time is the function of logarithmic. The horizontal soil moisture of the arbor shrub hedge gutter channel agrees at different time, and all decrease with the increase of horizontal distance. The longer the time of infiltration, the greater the moist scope of soil moisture. In the vertical direction, the distribution trend of the soil moistures is consistent at different time. All decrease as the increase of the bottom distance of the water storage ditch. At different time, the moist scope of soil moisture is different. The longer the infiltration time is, the greater the soil moisture moist scope is.2. According to the characteristics of the soil water moisture of the arbor shrub hedge gutter channel and the principles of soil water dynamics, we established the two-dimensional mathematical model of the soil water moisture movement of the arbor shrub hedge gutter channel, applied the finite element method to solve the nonlinear partial differential equations and used the results to verify the model. The results show that using this method to simulate the arbor shrub hedge gutter channel of soil water movement process is feasible. At the same time, the analog computation of soil water movement of the arbor shrub hedge gutter channel is conducted under conditions of different amounts of water into the ditch, groove widths, initial soil water moisture contents and diameters of horizontal storage water pipe and burial depths of horizontal storage water pipe shrubbery hedge gully channel storage. The results show that the rule of two-dimensional distribution of the arbor shrub hedge gutter channel of soil water is consistent. Both take water ditch and horizontal lie tube as the center to spread around. The farther away they are from water ditch and horizontal lie tube, the smaller the soil moisture content. With the increase of the amount of water into ditch, the width of bottom of trench, the initial soil water moisture content, the diameter of horizontal storage water pipe, the burial depth of horizontal storage water pipe, the moist scope of the arbor shrub hedge gutter channel of soil water is larger. The two-dimensional distribution of the arbor shrub hedge gutter channel of soil water can be described by exponential function, and the correlation coefficients of over0.9.3. On the basis of analysis of the arbor shrub hedge gutter ditch slope rainfall infiltration and runoff storage characteristics, we established the water movement model of the system of the arbor shrub hedge gutter slope rainfall infiltration and runoff storage which is composed of the simulation of slope runoff wave motion model and the simulation of soil water movement and the channel slope of soil water movement equation of two-dimensional the arbor shrub hedge gutter ditch slope rainfall infiltration runoff storage model, and used the finite element method to solve it. Meanwhile, the model considered the slope rainfall runoff and the slope surface water infiltration process. And they combined with strong coupling model. Therefore, it can simulate the process of slope runoff, the processes of the slope and channel movement in the soil. Furthermore, we used experimental data to study the model. The results show that the model calculation of the runoff process and measured values are in good agreement. The error between the calculated and the measured runoff is small, and the maximum is no more than10%. Thus, it shows this model can be used to simulate the process of slope rainfall runoff.4. We used the motion model of the arbor shrub hedge gutter slope rainfall infiltration and runoff storage for water flow systems to analyze the different slope, roughness, antecedent soil moisture content, rainfall intensity and slope surface runoff under rainfall conditions. The results show that the greater the slope, the greater the slope surface flow. The larger the slope surface roughness, the smaller the production flow. The greater the antecedent soil moisture content, the greater the slope surface flow. The greater the rainfall intensity, the greater the slope surface flow; The more the rainfall, the greater the slope surface flow. The relation between the slope surface flow and the slope, roughness of slope surface, antecedent soil moisture content, rainfall intensity, and rainfall was found to be the function of exponentiation, and the correlation coefficients of over0.9.