Application And Applicability Evaluation Of WEPP Model In Rainfall Erosion And Snowmelt Erosion

Soil erosion is an important environmental issue faced by human development.Reasonable soil and water conservation measures can protect,improve and rationally allocate water and land resources,and ultimately achieve the purpose of preventing and controlling soil erosion.The soil erosion prediction model is an important frontier for scientific research on soil erosion and an important manifestation of quantitative research on soil erosion.The development and use of soil erosion models not only plays an important role in production practice,but also provides an important basis for the government to make decisions.Water Erosion Prediction Project WEPP(Water Erosion Prediction Project)is a new generation of soil erosion forecasting model.It pays attention to the application of WEPP model at the beginning of establishment and mainly concentrates on the purple soil area and the Loess Plateau area;WEPP model appraises the applicability of Northeast China.The application in the study is still relatively small,so it is necessary to evaluate the applicability of the WEPP model in the northeast region.This paper uses the measured precipitation and sediment production data from 11 rains during the 2015-2016 rainy season in the runoff plot of the Sujiatun Water and Soil Protection Science Experimental Station in Shenyang and the snowmelt runoff from 2015-2016 in the Meihekou Research District of Jilin Province.)Simulations were conducted under simulated conditions of rainfall erosion and snowmelt erosion.The main conclusions of this paper are as follows:(1)Through the sensitivity analysis of climate data,it is found that the simulation results of the WEPP model are only sensitive to the rainfall process parameters.Both the simulated values of runoff and soil erosion are most sensitive to rainfall,and the change multiple is approximately 2 times that of rainfall;through the soil sensitivity analysis,the simulation results of WEPP model show that the effective hydraulic conductivity,critical shear force and The rill soil is sensitive to erosivity.The runoff is only sensitive to the effective hydraulic conductivity and decreases with the increase of the effective hydraulic conductivity.The susceptibility factor for erosion is more and more complex.The erosion increases and increases with the increase of the critical shear force and effective hydraulic conductivity.Therefore,when using the WEPP model for simulation,only the main influence factor needs to be considered.(2)Soil database needs to determine soil physical and chemical properties mainly include sand content,clay content,gravel content,cation exchange capacity and organic matter content,etc.,and formulas are used to calculate the soil base value of the community as an effective hydraulic conductivity.The coefficient is 10.135 mm·h-1,the critical shear force of soil is 2.68 Pa,and the erodibility of rill soil is 0.022 s·m-1.On this basis,the soil parameters are calibrated using the cumulative error method.The calibration result is that the water conductivity coefficient is The critical shear of 5.8 mm·h-1 is 2.25 pa and the erodibility of rill soil is 0.035 s·m-1.(3)When using the WEPP model to simulate single rainfall erosion events,there is little difference between the predicted and observed values of runoff and sediment yield on the slope.In the eleven rainfall erosion events,the average relative error between simulated and measured values of runoff was 38.87%.The part where the relative error of runoff simulation results was less than 20% accounted for 18% of the total;the part where the relative error was less than 40% was Achieve 63%;82% of the relative error is less than %60;0.816 is effective to the runoff;the relative error of erosion is less than 20% of the simulation accounted for27% of the total;and the relative error is less than 40% Part of the ratio is 45%;the part with relative error less than 60% reaches 64% of the total;the validity of the model calculated using the Nash-stucliffe formula is ME = 0.712.The results show that the WEPP model has better simulated results for the sub-rainfall..(4)Selecting the WEPP model for the 4 crops of 2015-2016 rainfall in the planting crops for the corn cultivation method of conventional farming conditions,the average relative error of simulated and measured values of runoff is 43%,and the average relative error of erosion is24 %.(5)The simulation results of the WEPP model under different gradient slope lengths show that the simulated rainfall runoff has very little difference in simulation values,indicating that WEPP cannot simulate the change of runoff with slope length,simulated simulated rainfall erosion amount.The difference in simulated values with different gradient slope lengths indicates that the WEPP model can simulate the trend of soil erosion changes with slope length.The simulation of erosion is better than that of runoff,both of which follow the gradient slope length.Increase and increase.(6)The WEPP model’s simulated snowmelt runoff during the winter months of 2015 and2016 was 7.476 m3 and 8.644 m3.Compared with the measured values,the relative errors were 72% and 67%.The model simulated snowmelt erosion in 2015 and 2016 was 9.528 kg and 12.34 kg.Compared with the measured value,the relative error was 141% and 168%.