Study On Simulation And Response Law Of Soil Water Movement Under Different Underlying Surfaces And Rainfall Conditions

As an important part of water resources,soil water plays an important role in crop growth,regional soil and water conservation,and improvement of the ecological environment.Rainfall is the main source of replenishment of soil water in the northern region.Underlying surface conditions affect the movement of soil water.Therefore,the movement of soil water under undisturbed soil conditions is more valuable for research.The soil moisture dynamic change in the North China Rocky Mountainous Region is highly representative,which can provide a basis for the study of the dynamic law of soil moisture movement in typical regional rocky mountainous regions.In this paper,typical rainfalls are selected to study the response of soil water of two test plots with different underlying surfaces to rainfall under actual rainfall conditions;a model of soil water transport in the study area is established,and the soil hydraulic characteristics parameters of the study area are determined by calibration and verification;Analyze the effect of the four factors of soil permeability coefficient,potential evaporation coefficient,different rainfall and different rainfall duration on regional soil water migration,explore the response law of soil water migration under different underlying surface conditions and rainfall conditions,and finally get the following law:(a)The soil layer in the watershed is 0-10 cm as a rapidly changing layer of water,20cm-50 cm as an active layer of water,and below 60 cm as a stable layer of water;The soil particle mechanical composition of the two test plots is different,the pine forest plot with lush trees has a larger permeability coefficient than the shrub grassland and the vegetation coverage is high,so the pine forest plot The homogeneity is high,and the response to rainfall is consistent.The heterogeneity of the upper and lower sections of the barren slope area is significant.The response time of the soil water in the upper and lower sections of the deep soil layer is reduced by 0.5h-1h,and the difference in peak increment speed exceeds 20%;(b)Establish a soil moisture transport model within the region.The root mean square error(RMSE)is less than 2%,mean absolute error(MAE)is about 1.5%,and the relative error(RE)is controlled within 10%;The applicability of hydras-2d software to the soil water movement in North China earth rock mountain area is of great reference significance to the simulation of soil water movement in other semi-arid earth rock mountain areas,and also provides technical support for regional soil and water conservation and the establishment of disaster early warning mechanisms.(c)The correlation between the evaporation rate and the response time and the peak increase rate of soil water is low,and the Pearson correlation coefficient does not exceed 0.2;the Pearson correlation coefficient on the response time of soil water to rainfall at 50 cm soil thickness: soil permeability coefficient> rainfall duration> rainfall> evaporation rate,soil permeability coefficient and rainfall duration are strongly correlated with the response time of soil water to rainfall,Pearson correlation coefficient is higher than 0.9;rainfall,rainfall duration and permeability coefficient are significantly correlated with the peak increase rate of soil moisture,the highest correlation coefficients are 0.781,0.625 and 0.992,respectively.To study the effect of different underlying surface conditions and rainfall conditions on the response of soil water movement,to provide theoretical and technical reference for the further development of regional soil and water conservation and the effective use of water resources.