Remote Sensing And GIS Based Study On The Soil Wind Erosion In China

Based on remote sensing (RS) and GIS technique, with the method of climatology, statistics, Geo-statistics, and GIS, this dissertation analyze the process and intensity of wind erosion, wind erosion hazard, sandy desertification, driving forces of wind erosion, trend of wind erosion in the future and possible countermeasures of wind erosion in China using soil wind erosion data through RS investigation, land use and land cover data, soil data, meteorological data, digital elevation data(DEM), vegetation index, and various statistical data, also, the main driving factors of sand dust storm and their spatial-temporal changes is analyzed using multi-factor analysis.The content of this dissertation are as following:l.the analysis of driving forces of soil wind erosion in China: The establishment of spatial patterns of different erosion intensity with the analysis of spatial distribution of remote sensing derived soil wind erosion in China. The analysis of spatial patterns of factors that affect soil wind erosion, such as wind field intensity, soil water content, vegetation index, soil texture, earth surface slope, is carried out through data mining theories of GIS. Soil Wind Erosion Dynamic Index(SWEDI) is set up using the method of principle component analysis. SWEI has a close relation with current soil wind erosion data in China, thus can reflect the main influential factors, developing trend, dynamic mode and wind erosion intensity, and has a direct guidance in the control of sandy desertification.2.The description of spatial distributions of factors that influence soil wind erosion. With different models, the factors of wind field intensity, soil erodibilty, soil crust and snow cover is digitalized through soil database, weather data, and resource and environmental data of China. The spatial distributions of each factors are analyzed, and the sandy desertification control measures concerned with each factor are studied. 3. The analysis of the development of sand dust storm in China: Five regions with sand dust storm can be classified with a total area of 440 X 104km2. Three possible trajectories exist for sand dust storm that influences China. Sand dust storm frequency increases as the aggravation of soil wind erosion. In China, regions as the sand sources of dust storm are mainly bare-land, which account for 59.5% of total area of sand source area. However, 70 X 104 km2 of grassland became sources of sand dust because of soil wind erosion, which account for 30.4% of all sand dust sources, and 38% of all grassland in China. 5.2% of farmland are influenced by wind erosion and became sand sources of dust storm . The frequency of sand dust storm has a close relation with meanannual wind speed in the arid, and semi-arid area in China. Analysis show a sharp decrease in annual wind speed in most part of North China in recent ten years which is more obvious than that of temperature and precipitation, and this may lead to the decrease in sand dust storm frequency. Meteorological records in the past 50 years indicate that there has been a sharp decrease in sand dust storm frequency, which is in accordance with the decrease in annual mean wind speed. The transition of grassland to sandy land, or the expansion of farmland can all leads to the expansion of sand dust sources, which in turn will increase the intensity and frequency of sand dust storm. If observation data are credible, and if human activities can be controlled effectively, then under current climatic circumstance, the efficiency of many erosion control projects should be re-evaluated.4.The analysis of spatial-temporal changes in farmland and sandy desertification in oasis in China in recent lOyears: Land use dynamic changes in oasis in China in 1990-2000 are analyzed. The relationship between farmland expansion and sandy desertification is discussed.5. The analysis of wind erosion in Tibet: Results show that sandy land in Tibet is shrinking reflecting the transition of sandy land to wood land. This is the result of years of sandy land manag...