| Changes in land-use change of the regional changes in land-use type and vegetation cover, soil erosion characteristics of the regional changes in land-use types and soil erosion intensity is an important basis for change. Soil erosion has become the worldwide serious environment problem, threatening the existence and development of humankind. In this paper, based on integrated on techniques and methods including ArcGIS, Remote sensing, with the theoretical support of soil erosion science. Taking the Longhe watershed as a case study area, the regional soil erosion states in2005and2010were evaluated. The spatio-temporal change features of the5years were analyzed. The study aimed at providing new ideas for regional soil erosion research, which is the necessary precondition for eco-construction of soil and water conservation and the establish and implement of environ menial protection. The main content of this paper are as following:1. The study analyzed the land use/cover change in the study area from2005to2010. Within the study period, the various land use/cover types were mainly paddy land, dry land and forest land, and they covered more than90%of the Longhe watershed, of which the area of the forest land covered more than50%. Settlements, industrial land, dry land, forest land, shrub and grass land showed a growth trend, and the increase range were respectively9.36%,0.26%,0.45%and1.48%, while paddy land and unused land represented a more substantial reduction.2. The distribution and variation of land use/cover in different altitudes and slopes in the study area from2005to2010had important significances on revealing the effects of soil erosion by land use/cover. According to the study of two periods, we concluded that in the study area the land use types were mainly distributed in the altitudes from500m to1000m, which covered55.3% of the study area, the following were in the elevation band from1000m to1500m, which covered24.4%of the study area, and there were few land cover types that distributed in the area whose altitudes were lower than200m and higher than1500m, and the percentages were respectively1.9%and2.3%. Most of the land use/cover types were distributed in the slope from15°to25°, and the percentage was32.8%, the following were in slope from8°to15°, which covered30.7%of the study area, and the percentage distributed in the slope from25°to35°had also reached15.5%, which were consistent with the mountainous terrain characteristics in the southern region of Fengdu County.3. The study then analyzed the soil erosion change in the study area from2005to2010. In the study area, the major types of soil erosion intensity were slightly eroded and slight erosion, and the percentages of the two periods were respectively80.52%and81.18%. During the study period, the soil erosion in the study area were showing improving trend, and the average soil erosion modulus had reduced from23.70t·hm-2·a-1to20.62t·hm-2·a-1, and the total amount of the soil erosion had reduced from1.95×10·a-1in2005to1.69×106t·a-1in2010.4. According to the soil erosion grade change of land use types from2005to2010, dry land area in the soil erosion grades had increased, and they were mainly due to the relocation of the counties, which resulted in the increase of land development and reclamation amount. On the contrary, paddy land area in the soil erosion had reduced, and they were related with that the paddy lands were mostly in valley flat areas, and they were occupied by urban development construction projects. The area of forest land had increased, and the soil erosion had been significantly improved, which were related with the closed forest policy in the study area.5. The study used GIS technology to overlay and analyzed the soil erosion with related environmental background factors including terrain slop, altitude, aspect and so on, and analyzed the relationships between soil erosion and these factors. The results showed that, soil erosion was mainly focused on hills and low mountain region whose relative elevations were from200m to500m, and the mountain region whose relative elevations were from500m to1500m. Soil erosion intensity showed increase characteristics with the increase of the slop. The soil erosion area higher than pole strength grades were concentrated in the slop more than15°, in the slop lower than5°there were mainly slightly eroded, and in the slop from5°to8°and from8°to15°,there were mainly slightly eroded and slight erosion. And the soil erosion in all slops were mainly slightly eroded and slight erosion. After governance of five years, the soil erosion situation in mountainous region and hilly region had improved, while which were still the fey areas of soil and water conservation work in the future. |
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