Study On The Landuse Change And Its Environmental Impact In Hangbu River Basin Of Anhui Province

Landuse change and land-cover change is a core field of global environmental change research. Study on landuse and land-cover change of different spatial & time scales is also one focus of geography recently. Land use change, due to modern agriculture development, industrialization and urbanization, has lots of impacts on water balance and environment, such as increasing downstream flooding, decreasing groundwater supply, drying wetlands, soil erosion, non-point pollutant increasing and so on. Soil erosion and non-point source pollution are two serious environmental issues. So it is very important to analyze water environment impacts and soil loss of land use change for land use plan and watershed management.By selecting Hangbu River Watershed in Chaohu Basin of Central of Anhui Province, east of China as study area, this paper analyzed the land use change of Shucheng County in the basin and found the key driving forces in over 50 years (from 1949 to 2000) firstly. Secondly, under the support of technology of remote sensing and geographical information system, this paper analyzed the land use changes and its non-point pollutant & soil loss in 1987 and 2000. The land use map of 1987 and 2000 are acquired by explaining the TM/ETM image. Some conclusions are drawn out.The land use had changed greatly from 1949 to 2000 in the Shucheng County. There are two phases of farmland change. The characteristics of land use change are computed by the use of statistical data. The research displays that, the main land use changes of Shucheng County are land use transformation among farmland and woodland, and the changes of nonagricultural lands and garden plot are slight during the half past century, and the land use change has different stage. The land use change character is that farmland was increasing from 1949 to 1957 and decreasing from 1958 to 2000, woodland was decreasing, and water land was increasing from 1949 to 1962 due to the construction of Longhekou reservoir and canals attached while fluctuating after 1962.Then by the methods of Factor Analysis, it is found out that, the natural factors are not the driving forces of the land sue change during nearly past half century and there are four main human factors including agricultural condition & yield, the cultivating structure of foodstuff crop, the cultivating structure of industrial crop and national political policy. The linear regression result showed total labor, peasant labor, pig raising quantity, the ratio of rice cultivating area to foodstuff cultivating area, totalcultivating area, and multi-cropping index are key driving factors of land use change during past over fifty years.Using precipitation daily serial (from 1967 to 1996), and soil category map, the average annual runoff of 1987 and 2000 can be stimulated based on different land use distribution by L-THIA Model (Long-term Hydrologic Impact Assessment). The model results express there is prominence pollution impacts of land use change. There is 1.91% increasing of annual average runoff from 38834.47×10~4m~3 in 1987 to 39574.87×10~4m~3 in 2000 during 13 years. In 1987, the total nitrogen loads is about 620.77t/a, and in 2000 about 714.44t/a. There are 15.09% increasing during 13 years. In 1987, the total phosphorus loads is about 22.53 t/a, and in 2000 about 29.05 t /a. There are 28.92% increasing during 13 years.Also, the soil erosion loss of study area in 1987 and 2000 is calculated using Universal Soil Loss Equation according to the different land use. The soil loss is 91.2163×10~4t/a in 1987 and 92.6751×10~4t/a in 2000. The annual average soil loss is 430.30t/km~2 in 1987 and 440.09 t/km~2 in 2000. The whole watershed belonged to light soil erosion area.Finally, some preventive counter measures are put forward.