土地覆被和气候变化的水文响应研究

Study on hydrologic response to land cover and climate change

采用分布式水文模型SWAT研究北京地区过去10 a间径流量剧减的主要原因。采用等高线→TIN→DEM的方法获取研究区分辨率较高的DEM图,基于DEM图提取流域边界、河网、子流域及相关属性,根据土壤类型与土地覆被类型的组合划分水文响应单元,实现下垫面的空间离散;采用校准和验证后率定的参数研究了10 a来气候变化和土地覆被变化对径流量的影响。研究表明:10 a间土地覆被变化的主要趋势是旱地城市化。过去10 a间,由于土地覆被变化导致北运河年均径流量增加了10%～20%,而气候变化导致年均径流量减少了约2/3。

The main reasons resulting in the acute decrease of runoff in Beijing are discussed by using a distributed hydrological model SWAT （Soil and Water Assessment Tool） , The grid DEM with higher resolution is obtained by transformation of contour lines-TIN-grid DEM, and basin boundary, drainage networks, and subbasins are extracted based on the DEM. The underlying surface is discretized according to the combination between soil types and land use categories. The effects of land cover change and climate change on runoff are studied in the past ten years by using the parameters determined during the periods of calibration and validation. The results show that the main trend of land cover change is urbanization of dry land from 1990 to 2000. The annual runoff of Beiyun River decreases by two thirds due to climate change from 1994 to 2003; however, one increases by 10%-20% due to land cover change.