土地利用变化对牤牛河流域径流的影响

摘要

土地利用变化对流域水资源配置及其循环过程有显著的影响,了解土地利用与径流的关系是流域水文学研究的重要内容.以牤牛河流域为研究区,基于SWAT分布式水文模型,利用流域DEM、土地利用、土壤、气象等数据,结合GIS和RS技术,并采用极端土地利用分析方法,对流域土地利用变化的径流响应进行定量研究与分析.结果表明:流域内1998年与2009年土地均以耕地、林地、未使用地为主,约占总面积的90%;相同的气象条件下,两期土地利用情景下年、月均径流量变化趋势一致,2009年土地利用情景下的年、月径流量较1998年略小,年均径流量减少605.5万m3;7,8月份月径流模拟减少量明显;土地植被覆盖度增大径流量减小,反之则增大;在极端土地利用情景下,径流量将发生剧烈变化.因此,在不考虑研究期间内气候变化等因素的条件下,土地利用变化是影响流域径流变化的主要因素.%Land use change plays an important role in catchment hydrology cycle and water resources allocation.Understanding the relationship between land use and runoff is an important research content of watershed hydrology.Based on SWAT model, combined with GIS and RS technology and adopting extreme land use analysis method, the runoff response to land use change in Mangniu Basin were analyzed quantitatively using various data derived from watershed DEM, land use, soil and meteorology.It was concluded that in 1998 and 2009, the land use in the basin mainly involved cultivated land, forest land, unused land, the three types of lands accounted for about 90% of the total area;under the same climate condition, monthly and annual runoff presented consistent trend under two different land use scenarios;the annual and monthly runoff in 2009 was slightly smaller than that of 1998, and the average annual runoff reduced by 6.055 million m3;the simulated monthly runoff in July and August decreased significantly;the runoff decreased with the increase of vegetation coverage and otherwise increased;under extreme land use condition, the runoff changes drastically.Therefore, if climate change and other factors are not considered during the study period, the change of land use is the main influential factor to the runoff change.