Study On The Relationship Between Landscape Pattern And Soil Erosion In Yanhe River Basin Based On "Source - Sink" Theory

Soil erosion is one of the main hazards which influence soil and water conservation, vegetation growth even the sustainable development of the area, the loess plateau region in China and even in the world is most serious soil erosion areas in a region. Yanhe basin is the important position in the loess plateau, so the water loss and soil erosion situation cannot allow ignoring. Chinese government invested a lot of manpower to the loess plateau region and capital for soil and water management working. After years of persistence, soil erosion and ecological environment of the region began to change. The soil erosion effect generated by the landscape pattern and it is an important problem in soil erosion research; it has important reference value in the soil and water conservation as the goal of watershed land layout and management optimization. Landscape pattern analysis method and analysis method of soil erosion model are two important ways in the study of soil erosion effect caused by the landscape pattern change. Therefore, this article choose yanhe basin which in loess plateau area as the research object, analyzing the effects of spatial and temporal variations of soil erosion in the basin and the influence on the landscape pattern change. Collecting history research achievements in the study area, remote sensing image, DEM data, rainfall data, soil property data, and combined with RS and GIS technology, based on the erosion, Analysis of the study area from1990to2000during the change laws of soil erosion characteristics. At the same time, based on the "source" and "sink" landscape theory, transfer land use/cover pattern to the "source""sink" landscape pattern, finally using comparison with landscape space load index method, analyzes the basin soil erosion processes and the response mechanism of the landscape pattern, get the following results:(1)The dynamic changes of the landscape pattern within20years, and the simulation of the landscape pattern over the next20yearsReturning farmland to forest and grass measures effect the landscape types, it makes the woodland and grassland area in the basin showing a rising trend in the past20years, cultivated land area had a corresponding reduced. This prompted the Yanhe basin landscape structure been optimized, for the development of the basin ecological environment has the obvious role in promoting. Using CA-Markov model, simulating Yanhe basin landscape pattern in the next20years, we found that in the coming20years, forest land, grassland area has a small decrease, degree of cultivated land area of micro float up. This could be that in the next period, the development of the landscape pattern and suitable with the development of economy and ecology system in the basin(2)The extraction of Yanhe basin soil erosion factors and soil erosion estimation and its predictionThrough research and analyze soil erosion condition in the study area, combining previous research results, consider ting the comprehensive of yanhe river basin vegetation, hydrology, soil, rainfall and other natural environment factors which affect the overall status of soil erosion in the basin, choose a suitable RUSLE model for calculating river basin. Then using RS and GIS technology extract the influence of each factor of soil erosion, and use grid computing, statistics shows the change of the river basin and the amount of soil erosion over the past20years. At the same time, using the CA-Markov model simulates the change of the amount of soil erosion in the next20years.(3) The interaction of landscape pattern and soil erosion in the basin is studiedIn this paper, from the view of landscape ecology, on account of the theory of "source" and "sink "landscape, the pattern of land use/cover change into "source""sink" landscape pattern, Finally by comparison with landscape space load index method, the response mechanism of the Yanhe basin soil erosion and landscape pattern were discussed. Results show that during the20years from1990to2010, each area landscape contrast load index (slope, relative height) a general trend of reducing in Yanhe basin:Different slope range and relative height range is in declining, the percentage of arable land, Woodland and grassland area percentage in a rising trend, And the distribution of woodland and grassland are more inclined to the slope and a relatively high place, the landscape pattern configuration is relatively more reasonable, the contrast gradient load index contrast and relative height load index and the basin soil erosion modulus presented positive correlation in Yan he basin from1990to2010, it indicates that soil erosion and, landscape pattern "source""sink" formed the good interaction in the basin. At the same time, through simulating watershed landscape pattern and the amount of soil erosion in the future20years, we found that landscape pattern began to rationalize in the basin. By changing the "source" and "sink" landscape pattern on the slope, relative height of the relative position and size of the percentage,it can reduce the incidence of the soil erosion, increased the block effect of the soil erosion process.