基于NDVI的水电站开发对植被的影响——以澜沧江梯级水电站开发为例

The Effects of Hydropower Stations Construction on Vegetation Dynamics Based on NDVI:A Case Study of Cascade Hydropower Stations of Lancang River

基于RS和GIS技术,利用1998—2012年SPOT NDVI数据建立近15 a澜沧江流域NDVI时序数据集,在收集该流域水电站建设概况资料的基础上,利用空间分析与统计方法、最大值合成法、一元趋势方法分析流域水电站周边植被覆盖的时空变化及其与土地利用的关系。结果表明：1998—2012年间,水电站的年最大NDVI值均保持在0.78~0.92之间;通过对比已建水电站在建设前、中、后期的年最大NDVI值随上下游距离梯度的变化趋势,水电站上、下游在建设前、建设中和建设后呈现出基本一致的波动变化;横向分析NDVI随岸边距离不同的变化情况,小湾水电站附近10 km范围内,随着岸边距离的增加,NDVI值缓慢增加,建设中的NDVI值要低于建设前后。上述结果表明,NDVI变化可以指示大坝建设对植被的影响。趋势分析表明,整个缓冲区内得到改善的面积占63%左右。Zonal Statistics结果表明,耕地、林地、草地的NDVI有所增加。本研究为探索多时段态NDVI监测水电站效应的可能性及水电开发的生态环境保护与恢复提供了一定的科学依据。

Based on RS and GIS technology,SPOT NDVI data from 1998 to 2012 was used to construct NDVI time series dataset of the Lancang River basin,this paper analyzed the spatio-temporal variation of vegetation cover by using the spatial analysis,statistical methods,MVC（ Maximum Value Composites） methods and trend method and relationships between NDVI and land use changes. The results showed that： timely,the annual MAX NDVI of each hydropower station was maintained between 0. 78 and 0. 92; spatially,through the comparison of dynamics of the annual MAX NDVI upstream and downstream before construction,during construction and after construction,the outcomes showed that the three curves had the same changing trend; according to variation of MAX NDVI with different distances along the shore,MAX NDVI which was near from Xiaowan hydropower station about 10 km increased slowly with distance along the shore,MAX NDVI which is during the construction of the hydropower station lower than before it,results above can show that the hydropower stations construction influenced on the local vegetation tempestuously. In this buffer,the improved areas were accounted for about 63%. Zonal Statistics showed that the NDVI of land,forest land and grassland has increased. This study provided the scientific basis with exploring the possibilities of using NDVI to monitor effect of hydropower stations construction and protection and resumption of ecological environment caused by hydropower stations construction.