Title
Impacts of Dam Operation on Vegetation Dynamics of Mid-Channel Bars in the Mid-Lower Yangtze River, China
Abstract
Vegetation dynamics on mid-channel bars (MCBs) is essential for supporting ecosystem functions and associated services in river systems, especially in dammed large rivers. Generally, there are two possible changing patterns that vegetation of MCBs downstream a dam would experience. On one hand, the vegetation area may shrink because of a decrease in the MCB area in the post-dam period, which has been observed in many rivers around the world. On the other hand, the MCB vegetation area may expand because flood disturbances would be weakened by dam operation. However, little evidence has been reported to clarify such confusion. Therefore, vegetation dynamics of MCBs in the mid-lower Yangtze River downstream the Three Gorges Dam (TGD; the world's largest dam) is selected as a case study to address the issue. Using long-term (1987-2017) Landsat archive images, this study reveals the spatiotemporal variations of vegetation area change intensities (VACIs; indicated by dynamic trends) on MCBs in the mid-lower Yangtze River. Results show that an overall VACI in the post-dam period (2003-2017) is about three times faster than that in the pre-dam period (1987-2002). In other words, the rate of vegetation colonization accelerated after the TGD operation began in 2003. Moreover, the VACIs in the post-dam period are size dependent, where large size MCBs are likely to gain higher VACIs: Small-sized MCBs (0.33 km(2)/yr), medium-sized MCBs (1.23 km(2)/yr), large-sized MCBs (1.49 km(2)/yr). In addition, VACIs of individual MCBs in the post-dam period are distance dependent, where the further a MCB was from the TGD, the higher the VACI. It is also suggested that the weakened flood disturbances in the post-dam could explain the rapid vegetation growth and colonization. This work is not only beneficial for managing and protecting MCBs downstream the TGD after its operation, but is also helpful in understanding vegetation dynamics of MCBs in other dammed river systems around the world.
Year
DOI
Venue
2021
10.3390/rs13204190
REMOTE SENSING
Keywords
DocType
Volume
Three Gorges Dam, flood disturbances, remote sensing monitoring, vegetation colonization, sandbars
Journal
13
Issue
Citations 
PageRank 
20
0
0.34
References 
Authors
0
7
Name
Order
Citations
PageRank
Xu Zhou100.68
Zhaofei Wen201.01
Yuanyang Huang300.34
Xuemei Yi400.34
Maohua Ma500.34
Tao Liao600.34
Shengjun Wu701.35