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Research on Rainfall Erosivity in Jiangsu Province

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Tutor: JiangXiaoSan
School: Nanjing Agricultural College
Course: Environmental Science
Keywords: Rainfall erosivity,Soil erosion,Geostatistics,Spatial distribution,System develo
CLC: S157.1
Type: Master's thesis
Year:  2011
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Abstract:
Soil erosion has become one of the most important eco-environmental problems in the world, and is increasingly attracting worldwide attention and study. It causes not only the destruction of soil resources, water pollution, and river channelerosion also cause the siltation of lakes and reservoirs, even increase the chance of flooding. Soil and water resources are the basements for human survival and development, so, extensive and severe soil erosion will directly affect the sustainable development of the society.Soil erosion is affected by many factors.The rainfall of the climatic factors is the main motivating factor. Rainfall erosivity (Rainfall Erosivity, referred as the R value) reflects the rainfall on the potential of soil erosion, so,rainfall erosivity factor is an power indicator for evaluating this potential. As an important indicator in USLE,R value between different regions is also an important indicator, which leads to the difference of soil erosion the interregional characteristics in different regions. Binding it with the factors such as soil, topography, crop cover and management factors we could predict the soil loss quantity in some regions. Therefore, the study of spatial and temporal distribution of rainfall erosivity and an accurate assessment of the potential effect of rainfall on soil erosion will play a positive role in prediction of soil erosion and in development of soil and water conservation planning. This thesis has finished based on mentioned above. The main conclusions are as follows:1) The mean accuracy of the rainfall and raininess model with the kinetic energy and raininess model is 91.56%. This is an ideal result and the model can be implicated in Jiangsu Province. Moreover, besides the result, a simple rainfall model with the advantage of convenient acquisition of raw data, and simple processing is built and its mean accuracy with the rainfall and raininess model is 92.81%, so, it is of great applicability in Jiangsu province.2) The best choice of spatial interpolation methods about spatial and temporal distribution of rainfall erosivity has a positive significance on the soil loss forecasting and soil and water conservation planning. In this paper, such research which combined different geostatistic spatial interpolation methods and comparative errors are preceded on the basis of the analysis of the rainfall records of 260 stations in Jiangsu Province from 2001 to 2006 used Bu-arithmetic. Result showed that the Ordinary Kriging method of second-order trend, Spherical semi-variogram model performed better than other interpolation methods, this is an ideal result and can be implicated in Jiangsu Province.3) The space distribution of rainfall erosivity in Jiangsu Province is not homogeneous, with a distinct high value area and a low value area. The value of R raried greatly from 2001 to 2006. It reached a maximum value of 372.15 MJ·mm/(hm2·h·a) in 2003 and it reached the Minimum value of 168.98 MJ·mm/(hm2·h·a) in 2004. The high rainfall erosivity regions appeared in the northern and southwestern of Jiangsu Province especially in Lianyungang and other cities, so that the government should pay attention to strengthen the prevention and monitoring of soil erosion.4) Based on the principle of setting up the rainfall stations location in the work of soil and water conservation, the representative stations were verified using the chosen Geostatistics method. The result indicated the feasibility of the location principle. The Ordinary Kriging method guaranteed that the accuracy of the temporal and spatial distribution of rainfall erosivity based on the less number of representative stations coincided with the accuracy based on most rainfall stations.5) A small rainfall erosion analysis system was developed based on JAVA and ArcGIS Engine. The program should be available because it integrated the rainfall erosivity calculation and analysis functions. The calculation, interpolation and map-making of rainfall erosivity can be quickly and easily expanded by use of the program file used. The system can provide a convenient, fast way to the subsequent analysis for soil erosion, due to its fast achieving reliable running and higher work efficiency.
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