基于遥感的黄土高原林草植被变化对河川径流的影响分析

从黄土高原不同地貌区降雨产流机制入手,分析了林草植被影响流域水循环的可能环节;利用20世纪70年代以来不同时期的土地利用和植被盖度解译成果,以及同期实测的降雨和径流数据、供用水数据等,引入林草植被覆盖率、径流系数、产洪系数和基流系数等概念,从流域尺度上构建了林草植被覆盖率与河川径流的定量响应关系,结果发现,在半湿润或半干旱的黄土区,径流系数和产洪系数都将随林草植被的改善而减少,气候越干旱、径流或洪量减少越多;与同气候带的黄土区相比,盖沙黄土区林草植被改善所导致的减水量更大。不过,当林草植被覆盖率大于60%后,产洪系数变化减缓;最终河川径流将稳定在大于基流的某阈值附近。

Influences of shrubs-herbs-arbor vegetation coverage on the runoff based on the remote sensing data in Loess Plateau

The impact of vegetation coverage on flood or runoff yield in the Loess Plateau has been extensively studied, but the research has been primarily based on observations from slope runoff plots or secondary forest regions. This paper is based on vegetation information from remote sensing images, measured rainfall and runoff data and water consumed from the related basin in Loess Plateau over nearly 50 years. By introducing the concepts of runoff yield coefficient, flood yield coefficient, base flow yield coefficient, and the percentage of effective vegetation, we proposed the quantitative relation between vegetation coverage extracted from remote sensing images and runoff yield at the watershed scale. The response relations reveal that the runoff yield and flood volume will decrease with the increase of shrubs-herbs-arbor vegetation, especially in the dryer region, and the reduction of the runoff in sand-covered loess region is even more than that in the loess region with similar climate. But the flood volume will be kept at a stable level, when the percentage of effective vegetation is larger than 60%. The river's runoff will be stable at a threshold, which is more than its base-flow at last, with a further increase of vegetation.