Abstract:
Analysis of the land use and land cover changes (LUCC) and its driving factors in water conservation zones is essential for the development of sustainable water resource strategies. Miyun Reservoir is the most important drinking water source for Beijing Municipality, the capital of China with a population of more than 20 million.In recent decades,the inflow to the reservoir has shown a decreasing trend,which has seriously threatened the security of water use in Beijing. According to researches, LUCC is generally assumed to be responsible for changes in water yield of catchments. In order to explore the evolution process and driving factors of landscape changes in water source protection zones of the metropolitan area, Hongmenchuan watershed located in Miyun County was selected as the research object. The characteristics and the dynamic evolution of landscape patterns during 1990 to 2005 were analyzed by applying landscape ecological method and Markov model on the basis of the land use information from remote sensing. Combined with Grey forecast model of GM (1, 1) and the principal components analysis, the driving force of landscape changes were discussed from three aspects of the socio-economic, the natural conditions and regional policy and the population, respectively. Brief conclusions can be drawn as follows: major LULC changes in the period from 1990 to 2005 include declines of water area, and major increases in urban area. Moreover, the rapid reduction of water area and the continued increase of construction land were the most obvious features of the landscape changes in Hongmenchuan watershed during the period of 1990-2005. Changes of comprehensive dynamic degree of land use in different periods indicated that land use change rate showed an accelerated increasing trend. Landscape fragmentation increased significantly and patches distribution of various landscape types tend to be gathered, which lead to the patches shape more complicated. Based on the predictable results, the water area will be reduced by 67.5% in 2020 and inevitably exacerbate the contradictions of water use in the watershed. Although the forests cover falls to 73.81%, it still meets the appropriate forest coverage for water conservation. Changes of precipitation were the main reason for the change of water area, and regional policy was the basic reason for the changes of forest area and forest structure. Human factors may be the major driving force of the increase of construction land and the conversion of unused land, water area to farmland. The results can provide important benchmarks for assessing the signi?cance of human activities, regional policy on the regional land use and land cover change, and also finally put forward a scientific reference for sustainable utilization, development and management of land resource in this region.