| For a long time, the Loess Plateau is one of the worst areas suffering soil erosion in theworld, especially the sandy area in the Yellow River Basin. Long-time soil erosion has causedexiguous vegetations, worsening environment and weak co-logical environment. Abundantsoil erosion has easily led to sediment deposition of stream channels in the lower area andraised many problems like floods. Therefore, the highpoint of scholars’ research subjects fromhome and abroad is building a model of soil erosion applicable to this area and using such amodel to simulate erosion and sediment, make a forecast about the soil erosion in the LoessPlateau, provide scientific evidences and to make improvement on regional ecologicalenvironment. It also becomes a pressing task for governing the Yellow River.Chabagou watershed is situated in the sandy area where waterfall and geographicfeatures are typical. Therefore the study on the adaptability of different erosion and sedimentyield model will be of great importance to the productive practice and the research on erosionand sediment in sandy areas. The thesis chooses different types of erosion models （empiricalmodel of watershed scale and distributed mechanism model） and compares watershedapplicability of different models and model applicability of different geomorphic unit with theaid of GIS and remote sensing technique. On one hand, the thesis analyzes the geomorphicunit of high sediment yield in order to take specific measures on protection and management;On the other hand, by extending the range of models application, the thesis aims at making amodel transplantation. The main research content and results of the thesis are as follows:（1）Choose two systems of high accuracy with different erosion mechanism model bycomparing the advantages, disadvantages and application of different models based on theconditions of the soil erosion model of Chabagou watershed. Analyze the two mechanism andmake improvement on the model systems.（2）Use two models to calculate the erosion and sediment yield under the mathematicalmodel system of soil loss in loess plateau. The results show that both the two models havehigh simulation accuracy. The higher the simulation accuracy, the more applicable to thecalculation of watershed annual sediment yield.（3）Analyze the erosion and sediment yield contribution in different soil via ArcGIS,among which open forest and moderate covering grassland have a sharp inhibition to erosionand sediment yield. The contribution of slope farmland is comparatively big and it suffers aserious sand loss. The two different models both have high accuracy on sediment yield modelin different soil and can be used in sand yield calculation.（4）Pick up the erosion unit of the Liangang slope, gully slope and ditch based on theDEM data. When the slope of the gully slope is within25o~45o, soil erosion can easily emergewith a biggest contribution. Compared with annual empirical model, precipitation mechanismmodel is applicable to the sediment yield calculation of gully slope unit. When used inLiangang slope unit and and ditch unit, both of the two models have high accuracy and can beused in its calculation of yield unit.（5）Heavy rain in Chabagou watershed is mainly in July, August and September, whenthe sand yield is fourth times larger than that in other months. It is of great importance to study the applicability model in heavy rains. Through comparative analysis it turns out thatprecipitation mechanism model has a higher accuracy than annual empirical model and ismore applicable to analog computation of sediment yield in heavy rains.By comparing the two different models, the thesis comes up with a result that Chabagouwatershed is the most suitable soil erosion model for sediment yield simulation and enlargesthe application range of the two models. The thesis also provides a certain help for themanagement of soil erosion in sandy area in the Yellow River Basin and make a guidance tothe study of erosion and yield in similar landscapes. |
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