| A complete soil erosion process should include erosion,deposition transport and deposition.However,the evaluation of soil erosion often pays attention to the study of deposition erosion,and the consideration of deposition deposition is obviously insufficient.Topography is an important factor affecting the occurrence of soil erosion,and the research on the relationship between soil erosion and topography has always been a hot topic in the academic circle.However,most of the current studies focus on the impact of topography on erosion,while the study of the impact of topography on depositionation has been neglected.Therefore,it is of great theoretical and practical significance to carry out the evaluation of soil erosion including the effect of topography on deposition deposition,and to fully understand the influence of topography on erosion,transportation and deposition,and to perfect the erosion and deposition yield models.This paper takes Ji river demonstration zone as an example,based on rainfall data,soil data,terrain data and TM remote sensing data,with the support of RS and GIS technology,the Moore algorithm is used to extract the erosion-deposition terrain index which can fully describe the influence of topography on the whole process of soil erosion,transportation and deposition,and based on the RUSLE model,the soil erosion-deposition factor banks of the Ji river demonstration zone in four typical years of 1997,2005,2010 and 2015 are established.Based on the RUSLE model,the evaluation and analysis of soil erosion in Ji river demonstration zone in typical years were carried out.The temporal and spatial characteristics of soil erosion-deposition in the Ji river demonstration zone from 1997 to 2015 are analyzed by coupling erosion-deposition terrain index with RUSLE model.The main findings of the study are as follows:(1)Extraction and analysis of erosion-deposition terrain index.The Moore algorithm is used to extract the erosion-deposition terrain index which characterizes the influence of topography on the whole process of soil erosion,transportation and deposition,the results of index extraction and its analysis show that the index can quantitatively express the influence of topography on erosion and deposition.(2)The soil erosion-deposition factor bank is established in the Ji river demonstration zone.Based on the factors and their algorithms in the RUSLE model and combined with the erosion-deposition terrain index algorithm,the soil erosion-deposition factor database of four periods in the Ji river demonstration zone is established,it provides a basis for the evaluation of soil erosion and the effective management of data in the study area.(3)Temporal and Spatial variation characteristics of soil erosion based on RUSLE Model.The soil erosion modulus in 1997,2005,2010 and 2015 in the Ji river demonstration zone were 1326.18 t/(km~2·a),2790.39 t/(km~2·a),2025.23 t/(km~2·a)and1366.32 t/(km~2·a).Soil erosion was mainly micro erosion and slight erosion.Before2005,soil erosion was transferred to higher erosion grade with an intensification trend.And after 2005 to lower erosion grade with an improvement trend.At different slope,with the increase of slope,soil erosion tends to be serious first and then moderate.The slope of 15°~45°is the main slope section of soil erosion distribution in the study area.At different elevations,soil erosion increased first and then decreased with elevation.Soil erosion in middle altitude area(1562m~1782m)and middle-low altitude area(1335m~1562m)was the most widely distributed and the intensity was the largest.(4)Temporal and spatial variation characteristics of soil erosion-deposition.The soil erosion-deposition situation in Ji river demonstration zone showed an increasing trend from 1997 to 2005,and a decreasing trend after 2005.Soil erosion-deposition was mainly micro-erosion and micro-deposition,and the whole is dominated by soil deposition.With the increase of slope,soil erosion-deposition tends to increase at first and then decrease.The soil erosion is mainly distributed on the slope of 15°~35°,and soil deposition is on the slope of 5°~35°.Soil erosion-deposition increased first and then decreased with the rise of altitude,all of them are mainly distributed in middle altitude area(1562m~1782m)and middle-low altitude area(1335m~1562m).Basedonerosion-depositionterrainindex,theevaluationofsoil erosion-deposition in Ji river demonstration zone can not only quantitatively express the amount of erosion and deposition,but also identify the possible sites of soil erosion and deposition,which makes up for the defect that RUSLE model can not calculate deposition deposition.It can provide theoretical support for the improvement of soil erosion prediction model. |
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