Research On The Erosion Dynamic Model Of The Slope And Gully Ecosystem

Soil erosion is one of the most serious environmental problems today.In the past two or three decades,the use of nonlinear methods to explore the erosion dynamics of ecosystems has been a hot issue for many scholars.Aiming at the problem of soil erosion in slope and gully ecosystem,this thesis studied the feedback mechanisms among the factors of water,soil and vegetation,and establishes a four-variables differential dynamic model of surface water-soil water-vegetation-soil erosion.Based on the calibration of model parameters,the dynamic model was applied in actual field,taking the Taipingzhai watershed as an example,and numerical simulation was conducted to study the soil erosion in this watershed.The main research results are as follows:(1)Based on the dynamic models of vegetation patterns as proposed by Gilad and Rietkerk et al.,terrain factors were introduced into the dynamic model to describe the soil erosion dynamics in the slope and gully ecosystem.Numerical simulation of the surface water-soil water-vegetation-soil erosion dynamic model was carried out based on the coupled map lattice method,promoting the consistence between simulation process and the actual ecological processes.(2)The data obtained in the small watershed of Taipingzhai Village by setting up a field weather station,UAV scanning terrain,ring knife sampling and artificial rainfall experiments were used to determine part of parameters of the model.By comparing the simulation results with the actual results,the parameters of the model were adjusted and optimized in order to determine the final values.This makes the simulation results more realistic and more targeted.(3)Via performing simulation with application of the dynamic model on the basis of manually setting terrain conditions,the results show that the microtopography affects the distribution of vegetation and erosion.Vegetation self-organization and sediments deposition will eventually occur in lower terrain areas.(4)The spatial and temporal distributions of vegetation and erosion were predicted by simulation under the actual terrain conditions.It was found that the vegetation spontaneously gathered in the gully with abundant water,and the vegetation biomass at the bottom of the gully was obviously higher than other areas.The erosion was positively correlated with the slope gradient,and the two walls of the gully was the most seriously eroded.This makes the gully expands outwards and the gully wall becomes steeper with time.Based on the differential dynamic model of surface water,soil water,vegetation and soil,this thesis discussed the changes of vegetation patterns and gully landform under the long-term interactions between vegetation growth and soil erosion,providing a theoretical basis for predicting the co-evolution of vegetation and landform on sloped gully.