The Analysis Of Land Cover Change In Yang River Valley Based On The Remote Sensing Technique

Yang River, the upper river course in Yongding river system, and also the main water resources of Guanting Reservoir, lies in the south of Baxia district of Zhang Jiakou City. Yang River Valley is in the district of high population density and economic development center in Zhang Jiakou. At the same time, Yang River Valley has a characteristic geographic area condition around Beijing and Tianjin city, which is a natural ecologic and water-source protection barrier. The prominent contradiction between population and land leads to some manifestation such as LUCC, which is the direct one for the result of interaction between people and land. In order to interpret the problem of LUCC in this area, we use remote sensing technique and geographic information system technique to get the overall and systematic research and exploration of LUCC in Yang River Valley. At last, we get the land use classification chart of three period, which is useful for further research, for the guidance to the people's accurate exploration and exploitation to use natural resources, to protect ecological environment and also useful for offering reference to realize the constant use of land and constant development of social economics.On the basis of satellite image data of Sept.1987, Jul.1995 and May 2000, topographic map (Scale: 1/100,000), DEM data (1:250,000),"resource and environment database in China"of China Science Academy and other statistical data, the researched district is divided into six types: cultivated land, woodland, grassland, water area, construction land and non-cultivated land. On the software platform of Arcgis 9.0 and Erdas Imagine 9.1, geometrically correction, subset image and image enhancement are performed on the remote images. The interpreter symbols are established through the field survey knowledge, the drill districts are selected to transact classification under computer supervised to obtain the advance sort diagram. And the ultimate sort diagram of land utilization is achieved through the vector diagram of the advance sort diagram and the correction of the sort with human-machine interactive interpretation. The 1987-1995, 1995-2000 alteration diagram of land utilization is thus attained in Erdas Imagine, in which the sort diagram of land utilization is operated on with Matrix Analysis Function, hitherto the conversion matrix of land utilization of the two periods is established.The thesis seeks to make qualitative and quantitative analysis of the five aspects of the general characteristics of land use/land cover change , the dynamic transformation tendency of the type of land utilization, the transformation of land utilization extent, the matrix of land utilization transfer and landscape pattern. It clarifies the transformation of the land utilization type of the Yang River Valley of the 14 years. And it deciphers the power drive of the general characteristics of land use/land cover change from the four aspects of nature, population, economy and policy factors. Finally, it analyzes the environmental impact of land use/land cover change in the research area, including the change of ecosystem service value, the influence on the water quality in Guanting Reservior and the influence on the sandstorm in Beijing.The research of land utilization type of 1987 mainly focuses on grassland, cultivated land, and woodland; the one of 1995 mainly focuses on cultivated land, grassland, and woodland; the one of 2000 mainly on cultivated land, woodland, grassland and construction land. It can be descried through comparison that the cultivated land and construction land are being augmented and the grassland being abated. The trait of woodland and water area is increase after decrease, while the non-cultivated land is in reverse order. The ecosystem service value in the research area is inclined to descend; the increase of the cultivated land and construction land is closely connected with the pollution of the water quality in Guanting Reservior; the increase of cultivated land and the decrease of grassland greatly enhance the possibility of sandstorm.