流域土地利用/覆盖与植被变化的水文响应模拟研究

A Simulation-based Research on the Hydrological Response of Land Use/Cover and Vegetation Changes in Watershed Scale

以鄱阳湖的主要水源区梅江流域作为研究区,利用分布式机理性环境水文模型SWAT,探讨人类活动背景下植被变化对流域水文特征的影响。以遥感获取的叶面积指数(LAI)表征流域的植被状态数据,并通过控制性模拟来研究流域土地利用/覆盖、植被状态的改变导致的流域水文特征响应。模拟结果表明:在1987-2001年的15 a中,虽然流域的土地利用/覆盖变化很小,但由于植被叶面积指数的变化,导致了流域年径流总量5.4%的增加,其中枯水期的增量为10.2%,丰水期则为2.6%;土地利用/覆盖和植被变化对流域水文过程的影响主要表现在暴雨强度相同的情况下,植被变化对流域流量的影响呈非线性变化趋势,其中对中等程度的暴雨影响最大;植被增加具有明显的使暴雨洪峰出现时间滞后的效应,同时也使洪水之后的"退水"过程变得平缓。

This paper presented a research on the hydrological responses of watershed-scale land use/cover and vegetation changes under the background of human activities with Meijiang watershed as study area using physically-based and parameter-distributed hydrological model SWAT.Leaf area index（LAI） got from remote sensing technology was used in this simulation in the format of plant growth database in SWAT to express the watershed vegetation situation.Variable-controlled method was used to simulate the response of watershed hydro-characteristics and hydro-processes to land use/cover and vegetation changes.The results show that annual runoff in Meijiang watershed increases 5.4%（which is 10.2% during dry season,2.6% during wet season） because of the changes of vegetation in 15 years（1987-2001）.On the other hand,the results also show that the impact of vegetation change to water flow in Meijiang watershed has a nonlinear tendency,which means watershed water flow increases with the increasing of LAI of vegetation but the increment of water flow is the largest due to vegetation change in medium rainstorm.The increasing of LAI will obviously result in time delay effect of flood peak and gentle water-flow recession characteristics.