The Soil Erosion Pattern And Dynamic Of E Zhuang Watershed Based On Information Technology

This paper has chosen EZhuang watershed of the typical northern territory rocky mountain areas as the study region. Remote sensing (RS) images of four typical periods (1990,1995,2000,2005) are the main information sources. Based on"3S"technology (RS,GIS,GPS) and soil and water conservation theory and method, through the methods of man-machine interaction interpretation and investigation in the open air, this paper has analyzed the function of vital environmental factors in the process of soil erosion. According to the soil erosion grading standards of the Ministry of Water Conservation (SL190-96), this paper has researched the soil erosion situation, temporal and spatial dynamics and the relationship of the environmental factors and soil erosion. And the main results are as follows:1. The present situation characteristics of soil erosion are grasped.In EZhuang watershed, the type of soil erosion is water erosion. Mild erosion is the main soil erosion intensity type, and moderate and serious erosion is only in some areas. In 2005, the area of soil erosion is 3504.76hm2, accounting for 38.26% of total area. The areas of different soil erosion intensity are: mild erosion is 1794.45hm2, accounting for 19.59%; moderate erosion is 826.93hm2, accounting for 9.03%; serious erosion is 699.38hm2, accounting for 7.64%; extremely erosion is 183.99hm2, accounting for 2.01%. The area of mild erosion accounts for 51.2% of the erosion area, and mainly distributes in the center and north of the watershed; the area of moderate and serious erosion accounts for 43.5%, mainly distributes in the south of watershed.In the comparison of 1990, the soil erosion area reduces 3698.79hm2 (net reduction of 51.3%) significantly during 15 years in the watershed, and reduces 246.59hm2 annually; the soil erosion intensity decreased obviously, the decreasing order of different soil erosion intensity are: moderate erosion (2360.42hm2) > serious erosion (680.99hm2) > mild corrosion (340.82hm2) > extremely erosion (316.57hm2). It shows that: the comprehensive management of soil and water conservation which is based on the unit of EZhuang watershed from 1980s has alleviated effectively the happening and development of soil erosion, and has improved obviously the ecological environment.2. The temporal and spatial dynamical characteristics of soil erosion are exploredâ‘ The main soil erosion intensity type is mild erosion and moderate erosion in different periods, and the area of the two kinds of erosion accounts for over 74% of soil erosion. The soil erosion area decreases gradually along with the time, from 7203.55hm2 of 1990 to 6854.31hm2 of 1995, to 6417.22hm2 of 2000, to 3504.75hm2. The soil erosion intensity reduces gradually along with the time. In other words, high-intensity level of soil erosion transfers to low-intensity level of soil erosion and micro erosion. The area of extremely erosion,serious erosion and moderate erosion reduces continuously. But mild erosion area increases (1990~2000) at first, and then reduces (2000~2005). And micro erosion area increases gradually. Different periods (1990~1995,1995~2000,2000~2005) have different reducing area of soil erosion intensity and the areas are respectively 1012.31 hm2,713.57 hm2,3207.93 hm2.â‘¡The spatial pattern of soil erosion in the watershed has changes along with the time. The regions of soil erosion intensity with enhancing mainly distribute in Yanziling Region, Taipingshan Region of Shangqueyu Region and Yanmenzhai Region of Luoquanyu in the south of watershed; northern Shipozhai Region in Shangdongdaoping and Guzhongyu Region nearby Taihe Reservoir in the center of watershed are mainly cultivated with Huangyan on the slope, low-coverage forest and grassland. The regions of soil erosion intensity with reducing are mainly in center and north of the watershed, and they are mainly forest,relatively high-covered grassland and terracing. The soil erosion intensity has no change basically in the farmland,dry land and difficult improved region in both sides of the river.It shows that: The efficiency of managing soil erosion is different because of different goals and measures of managements in various periods, but the efficiency of managing soil erosion in EZhuang watershed increases significantly day by day. 3. The relationship between soil erosion and the major environmental factors is revealed.â‘ The soil erosion and the way of land utilization are closely related. Moderate erosion,serious erosion and extremely erosion mainly distributes in the low-covered forest land,low-covered grass land and cultivated with Huangyan farmland on the slope.â‘¡Vegetation coverage is a key factor to determine the soil erosion intensity. Mild erosion mainly distributes in moderate coverage and relatively high coverage; moderate erosion,serious erosion and extremely erosion mainly distributes in low coverage, relatively low coverage and moderate coverage.â‘¢The soil erosion and the slope are closely related. The soil erosion area mainly distributes in pitch slope, steep slope and anxious slope and so on. The larger the slope is, the more the area of high-intensity soil erosion. For example, serious erosion mainly distributes in the steep slope and anxious slope and steep slope area accounts for above 66% of total serious erosion area; extremely erosion mainly distributes in steep slope, anxious slope and anxious steep slope and anxious slope accounts for above 68.80% of total extremely erosion area.