The Soil Erosion Dynamical Changes Analysis In Fenhe Drainage Basin

With the development of social economy, human unreasonable exploitation and utilization of natural resources has made many vegetation is damaged. Soil erosion becomes global ecological and environmental issue. The research on the soil erosion has been done in the word. Due to the restriction of technological development levels the research mainly focuses on the quantitative and qualitative aspects, whereas seldom on dynamic applications. Soil erosion and its dynamic change research in typical regions is a rapid and effective research method by using remote sensing and GIS technology in this paper.Fenhe River is the2nd tributary of Yellow River, the soil erosive degree in the Fenhe drainage area has direct influence on the development of lower stream channel in Yellow River. Taking Fenhe drainage as a research object and remote sensing images in1976,1973and2009as the-different period main information source, this paper acquires reliable vegetation index, slope and land use data through interpretation and field survey verification combined with auxiliary data and "3S" technology. According to the soil erosion classification standard (SL190-2007) released by Ministry of Water Resources, soil erosion data at three phases in the research area are achieved through soil erosion type and intension classification by using ArcGIS spatial analysis function. Finally, the status, spatial distribution types, transformation rules and the relations among main environmental and ecological factors in Fenhe drainage area are systematically studied. The main contents include:(1) The soil erosion problems in the research area and the previous traditional technology limitations are firstly illustrated. Due to its own technological characteristics,"3S" technology has incomparable advantages in soil erosion information acquisition than other technologies.(2) The vegetation coverage classification map in the research area is produced by applying remote sensing and GIS technology; combined with natural influencing factors, such as land use data, geomorphology, slope, soil texture and so on, the land use status map is achieved. Applying slope classification map and vegetation coverage classification map, the soil erosion intension classification information is completed based on the soil erosion classification standards released by the Ministry of Water Resources. In order to improve the accuracy of the soil erosion classification, different methods are selected for extracting different ground objects according to the spectral characteristics of the images and the ground objects characteristics in the information extraction from remote sensing data, main include visual interpretation,NDVI, supervised classification,the relations among the spectrums, MNDVI, maximum likelihood method, and unsupervised classification. Finally, the man-computer interpretation is conducted by combing the above extracted information, so as to improve the accuracy of the extracted information.(3) Aided by "3S" technology, this paper conducted dynamic and quantitative spatial and temporal change analysis to the soil erosion data in1976,1993and2009in Fenhe drainage area. Through analysis to the soil erosion status and areas change characteristics in three phases, this paper analyzed and summarized the soil erosion intensity and temporal and spatial variation area transformation characteristics of different degrees, the type change ratio of soil erosion intensity. Based on these, this paper analyzed the relation between soil erosion and slope in the30years and the change influence of land use means to the intensity change of soil erosion. Results show:land use characteristics are different for different soil erosion intensity; the research area mainly distributes moderate erosion and mild erosion, then low erosion; the soil erosion area decreases rapidly with the increase of the erosion intensity.Finally, this paper summarized the technical measures for recovery and manages of soil erosion status and ecological restoration, so as to provide reference and basis not only for further planning and control, establishing ecological reserve rules properly and exploiting resources, but also for further improve ecology and environment, social and economic sustainable development.