密云水库流域植被覆盖度变化对输沙量的影响

Impact of vegetation coverage change on sediment loads in Miyun Reservoir Basin

封闭流域中,泥沙的产生是多种因素相互作用,相互制约的结果,而在这些众多的环境影响因素中,植被是土壤侵蚀中最重要的环境控制因子,目前,植被覆盖度变化对输沙量的影响一直是区域生态环境研究中比较热门的话题。文章使用遥感(Remote Sensing(RS))、地理信息系统(Geographic Information System(GIS))与统计分析相结合的方法评价了密云水库流域内2个子流域出口处2002年至2005年植被覆盖度变化对输沙量的影响。密云水库流域多为山地,其降雨具有明显的季节性。本文的主要目的在于分析2002年至2005年植被覆盖度变化对流域输沙量的影响,并分析了植被覆盖度变化对气候改变及人类活动的综合影响,结果表明:在密云水库流域内,输沙量是降雨情况和人为因素引起的地表植被覆盖度变化情况的综合反映,人口增长、经济发展和城市化是密云水库流域内引起土地利用变化和地表植被覆盖度变化的主要驱动力。并且,输沙量可以被看作是一个很好的指标来定量分离出生物生理和人为的影响,并从中能够找出在流域生态系统中获得显著结果关键的临界点。研究结果对制定流域的合理开发和管理计划将有所帮助。

It is well known that the sediment generation in the watershed scale is a result of interaction and mutual restraints among many factors. Among these environment factors, vegetation is the most important factor which plays an important role in the soil erosion process. The impact of vegetation coverage change on sediment loads in non-contributing area is always a hot topic recently. In this paper, we evaluate the impacts of vegetation coverage change on sediment loads at the outlets of two sub-catchments of the Miyun Reservoir by integrating Remote Sensing and Geographic Information System （GIS） with statistical analysis. The Miyun Reservoir Basin is characterized by a mountainous and hilly topography and a seasonal rainy climate. The primary goal of this paper is to help a better understanding of vegetation coverage change and its driving forces. We discuss spatiotemporal variations in rainfall and sediment loads and identify factors contributing to those variations, analyze the comprehensive impacts of vegetation coverage change on changing climate and human activities, and conclude that the changing rates of vegetation coverage and climate regimes are primary factors for sediment loads in the Miyun Reservoir Basin, and the sediment discharge might be viewed as a good indicator to quantitatively separate the biophysical and anthropogenic influences and identify critical thresholds leading to dramatic conse- quences upon watershed eco-system. And it should be quite helpful for a reasonable watershed development and management plan.