The Simulation Of Water Erosion Process In Loess Plateau Based On GeoCA

The loess plateau becomes one of the most serious area of soil erosion in China for its unique morphology and climate characteristics.Gully erosion,as one of the most common types of the soil erosion,is a major cause of soil erosion on the loess plateau,which plays an important role in shaping the loess plateau terrain.From aspects including the gully erosion mechanism,the impact factor,developing process monitoring,erosion and sediment yield prediction model of gully erosion,gully erosion a discussed in many ways by former research.However,because of the limitation of research methods and technical means,the researches gully erosion process in space and time are still insufficient.Geographical cellular automate(Geographical Celluar Automate,GeoCA)having a distinct temporal coupling characteristic,is suitable for dynamic process simulation of Geographical spatial system.The preliminary researches suggested that GeoCA can better simulate the development of gully in watershed of loess.This research aims to simulate the hydro-erosion process of gully based on DEMs,with GeoCA method,the artificial simulation watershed for experimental data,the formulation is given priority to with kinetic formula transformation rules,build the loess gully erosion of small watershed based on GeoCA CA model.On this basis,the simulation and analysis of small watershed gully erosion process,with specific examples demonstrate the validity of the model and simulation accuracy,and compared with the existing research methods.In this research,the main contents and conclusions are as follows:1.Build the GeoCA model of loess gully hydro-erosion of small watershedThis research design GeoCA transformation rules based on the physical process of gully hydro-erosion,in view of the basic theory of gully hydro-erosion and GeoCA.The emphasis is to study the mathematical model of the transformation rules and its expression.In line with the flow characteristics on DEMs,the model only considers the influence of the surface run-off on erosion process.According to the differences of erosion intensity,the gully erosion process is divided into slope surface erosion and gully erosion.Due to the complexity of the gully erosion process,the model make downward erosion in the process of water erosion process as the main simulation process.As discussed above,the implement process was designed and the GeoCA model of loess gully erosion of small watershed was implemented.2.The dynamic process simulation of the gully hydro-erosion CA modelIn this study,the artificial small watershed was applied as the experimental data to simulate the gully hydro-erosion process with the model.The experiment is divided into single phase and multiphase in the simulation of hydro-erosion process.And the multiphase simulation results were compared with measured results.The simulation results showed that no obvious changes in the shape of the valleys during the hydro-erosion process.Instead,the elevation values continuing downward trend.The great error concentrated along the gully shoulder lines,because of the model without consideration of lateral erosion and headward erosion.3.The validation of the gully hydro-erosion CA modelTo test and verify the simulation ability of the model,this study compared the simulation results with the measured results and date mining model’s simulation.And the comparison indicate that the model proposed in this research is better than others with the gully length,width,groove depth and the error of the measured results were less than 30%.In addition,the erosion intensity and erosion volume are smaller than the measured results.In comparison with the data mining model,this model has higher precision.Besides this model is closer to real erosion process,in terms of altitude changes.To sum up,this research based on the study of the gully erosion,combining with geographical cellular automata method,constructed gully hydro-erosion CA model,to solve the problem of the dynamic simulation of the gully erosion.This research distinguished the type of the gully hydro-erosion process.According to the differences of hydro-erosion in different terrain conditions,different model transformation rules were used,so as to improve the simulation of gully hydro-erosion process.