Abstract
The Three Gorges Dam (TGD) has received increasing attention with respect to its potential effects on downstream hydro-ecosystems. Poyang Lake is the largest freshwater lake downstream of the TGD, and it is not immune to these impacts. Here, we combine hydrological observations, remote sensing, a geographic information system (GIS), and landscape ecology technology to investigate the variability and spatial pattern of the hydro-ecological alterations to Poyang Lake induced by the operation of the TGD. It was found that the TGD caused significant hydro-ecological alterations across the Poyang Lake wetland. Specifically, the TGD operation altered the seasonal inundation pattern of Poyang Lake and significantly reduced the monthly inundation frequencies (IFs), which were especially notable (~30–40%) from September to November. Spatially, the declining IFs led to an increase in the mudflat area that is suitable for the growth of vegetation. The vegetation area increased by 58.82 km2 and 463.73 km2 in the low- and high-water season, respectively, with the most significant changes occurring in the estuary delta of the Ganjiang and Raohe rivers. The results also indicated that the changes in the inundation pattern and floodplain vegetation have profoundly altered the structure and composition of the wetland, which has resulted in increased landscape diversity and a gradual increase in the complexity of the ecosystem composition under the influence of regulation of the TGD. Such results are of great importance for policymakers, as they may provide a reference for wetland water resource planning and landscape restoration in an operational dam environment.
Highlights
Floodplain wetlands are the most productive and valuable ecosystems on earth [1]
The primary objective of this study is to provide an extensive assessment of the hydro-ecological impacts on Poyang Lake wetland associated with the Three Gorges Dam (TGD) construction
This study provides a comprehensive assessment of the hydro-ecological impacts on Poyang Lake following the TGD operation using remote sensing and geographic information system (GIS) analysis techniques
Summary
Floodplain wetlands are the most productive and valuable ecosystems on earth [1] They play a vital role in the biosphere and have regional ecological and environmental functions, such as flood mitigation, food production, water purification, and wildlife habitat [2,3,4]. Despite their immeasurable value, floodplain wetlands are considerably disturbed and endangered by human activities, which include land reclamation, dam construction, and other regulatory measures [5,6,7]. Dam operation can directly alter the wetland inundation magnitude, duration, frequency, and rate by modifying the seasonality of Remote Sens. 2017, 9, 1069; doi:10.3390/rs9101069 www.mdpi.com/journal/remotesensing
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