Environmental Effect of Land Cover Change A case study of coal mining areas in Beijing,China

摘要

For a long time, global environmental change has become a focus all over the world. Environmental change not only alters the local natural landscape, but also will long impact the local or even large-scale ecosystem. While, the primary manifestation of environmental change is the land use/land cover change. In this study, taking Mentougou district in the west of Beijing for example, the temporal and spatial evolution of land cover change and its environmental effect were discussed through the integration of GIS techniques, laboratory experiments, field survey and automatic-extracting information of land cover change from remotely sensed data during the period from 1988 to 2004. The results indicated that the longtime exploitation of coal resources brought about the change of original land use/land cover and initiated a series of environmental problems, which were shown as follows: (1)The areas of coal waste, unused land and town industry-mining land increased, of forest-grass land decreased, which made soil erosion aggravating. In addition, huge gangue took up farmland, which seriously destroyed the whole landscape, gave rise to the change of original characteristic of underlying surface, aggravated the frangibility of ecosystem in coal mining area, and further impacted eco-safety of coal mining area. (2)A great deal of coal wastes chronically piled up in the open air, which released harmful gas, also destroyed original atmospheric composition, and resulted in atmospheric pollution. In the meanwhile, these gases changed heat efficiency of atmosphere, which further led to the annual mean temperature of Mentougou district increasing year after year, but the annual average rainfall decreasing. Moreover, efflorescence of coal gangue caused small sand rising, which had a strong impact on the air quality of Mentougou district and Beijing city. (3)Heavy metal pollution of Cr and Pb elements in coal gangue around each colliery was relative severe, which polluted soil, surface water and groundwater. (4)Coal resources were mined for long time, which incurred persistently decline of groundwater level, and further resulted in the shortage of water resource, badly impacted on the residential living. (5)Land-cover change of the coal mining area induced a good many geologic hazards, such as ground subsidence and crack, and so on.