An integrated method to identify and evaluate the impact of hydropower development on terrestrial ecosystem

Abstract

Hydropower development has an important impact on the growth of vegetation in the basin, identifying and assessing the impact of engineering factors on vegetation dynamics is essential for sustainable watershed ecosystem management. In the paper, a integrated method coupling with Bfast, Theil-Sen Median and Mann-Kendall methods based on remote sensing was developed to identify the time and magnitude of abrupt changes for NDVI, judge the NDVI change trend and detect their potential drivers. Results showed that times of major abrupt changes of NDVI for areas around Wudongde, Baihetan, Xiluodu and Xiangjiaba hydropower stations were consistent with the construction and operation time of hydropower stations and the abrupt climate change time in the statistical yearbook. The proportion of areas with positive abrupt changes of NDVI around two early operational hydropower stations with 42.9 and 26.1% were higher than those around two newly operational hydropower stations with 12.9 and 25.8%. Results obtained from Theil-Sen Median and Mann-Kendall methods showed that areas with improved vegetation coverage for two early operational hydropower stations accounted for 83.99 and 80.21%. And those areas were mainly distributed along river direction (both sides of Jinsha river). Only 9.66 and 11.43% of areas had degraded vegetation, which indicated that the operation of hydropower stations can contribute to the recovery of regional NDVI. Results also indicated that the climate change may be a potential factor to promote regional vegetation growth. But, the growth rate of vegetation reached 0.000018 and 0.000024 caused by hydropower station operation was far higher than that between 0.000008 and 0.000010 caused by climate change. This work provides an important theoretical and technical support for ecological impact assessment of climate change and engineering construction.