Ecological risks in downstream lakes exacerbated by the three Gorges reservoir

River regulation through reservoir construction is one of the greatest challenges to the natural flow state and ecological health of river systems globally. The Three Gorges Dam (TGD), the largest dam in the world, has been in operation since 2003 to regulate water resources downstream. However, mos...

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Main Authors: Xinxin Chen, Yaxin Guo, Junhong Zhang, Xiao Han, Weiya Huang, Yao Yue
Format: Article
Language:English
Published: Elsevier 2025-01-01
Series:Ecological Indicators
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Online Access:http://www.sciencedirect.com/science/article/pii/S1470160X24014985
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author Xinxin Chen
Yaxin Guo
Junhong Zhang
Xiao Han
Weiya Huang
Yao Yue
author_facet Xinxin Chen
Yaxin Guo
Junhong Zhang
Xiao Han
Weiya Huang
Yao Yue
author_sort Xinxin Chen
collection DOAJ
description River regulation through reservoir construction is one of the greatest challenges to the natural flow state and ecological health of river systems globally. The Three Gorges Dam (TGD), the largest dam in the world, has been in operation since 2003 to regulate water resources downstream. However, most of the current research on the TGD compares the post-2003 hydrologic patterns downstream of the TGD with the pre-2003 hydrologic patterns and lacks direct evidence of the TGD impacts on the downstream areas. In this paper, the ecological impacts of TGD on downstream large lakes are explored in terms of hydrological alteration degree, biodiversity, connectivity, and ecological surplus and ecological deficit by building a 1/2-dimensional nested model to simulate the hydrological processes with and without the TGD from 2008 to 2011. The results showed that (1) TGD storage led to a decrease in the number of high pulses at downstream stations, resulting in wetland degradation in the riverine region; (2) the SI (Shannon’s diversity index) based on hydrological calculations became smaller, indicating that the downstream biodiversity showed a decreasing trend; (3) the diversion ratio and the confluence ratio of Dongting Lake and the Yangtze River decreased at the same time, and the connectivity decreased, which would lead to an increase in the degree and frequency of droughts during the dry season;(4) after the regulation of the TGD, the low-risk months were transformed into medium-risk months of the Dongting Lake basin, indicating a deterioration of the ecological situation in this region. The study demonstrates that the construction of the TGD has exacerbated downstream water stress, while the degradation of wetlands and the reduction in biodiversity highlight the heightened pressure on ecological and environmental protection downstream of the TGD. The results of this study provide necessary information for evaluating the impact of the TGD project on large lakes downstream and provide feasible suggestions for water resource management and ecological protection in the Yangtze River basin to ensure the realization of sustainable development in the future.
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spelling doaj-art-1ff04515b8424c1e9f4bd856f5312fdf2025-01-31T05:10:38ZengElsevierEcological Indicators1470-160X2025-01-01170113041Ecological risks in downstream lakes exacerbated by the three Gorges reservoirXinxin Chen0Yaxin Guo1Junhong Zhang2Xiao Han3Weiya Huang4Yao Yue5Key Laboratory of Resources Conversion and Pollution Control of the State Ethnic Affairs Commission, College of Resources and Environmental Science, South-Central Minzu University, Wuhan 430074, ChinaState Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, ChinaKey Laboratory of Resources Conversion and Pollution Control of the State Ethnic Affairs Commission, College of Resources and Environmental Science, South-Central Minzu University, Wuhan 430074, China; Corresponding author.Wuhan Blue Sky and Green Field Consulting Design Co., Ltd., Wuhan 430070, ChinaKey Laboratory of Resources Conversion and Pollution Control of the State Ethnic Affairs Commission, College of Resources and Environmental Science, South-Central Minzu University, Wuhan 430074, ChinaKey Laboratory of Resources Conversion and Pollution Control of the State Ethnic Affairs Commission, College of Resources and Environmental Science, South-Central Minzu University, Wuhan 430074, ChinaRiver regulation through reservoir construction is one of the greatest challenges to the natural flow state and ecological health of river systems globally. The Three Gorges Dam (TGD), the largest dam in the world, has been in operation since 2003 to regulate water resources downstream. However, most of the current research on the TGD compares the post-2003 hydrologic patterns downstream of the TGD with the pre-2003 hydrologic patterns and lacks direct evidence of the TGD impacts on the downstream areas. In this paper, the ecological impacts of TGD on downstream large lakes are explored in terms of hydrological alteration degree, biodiversity, connectivity, and ecological surplus and ecological deficit by building a 1/2-dimensional nested model to simulate the hydrological processes with and without the TGD from 2008 to 2011. The results showed that (1) TGD storage led to a decrease in the number of high pulses at downstream stations, resulting in wetland degradation in the riverine region; (2) the SI (Shannon’s diversity index) based on hydrological calculations became smaller, indicating that the downstream biodiversity showed a decreasing trend; (3) the diversion ratio and the confluence ratio of Dongting Lake and the Yangtze River decreased at the same time, and the connectivity decreased, which would lead to an increase in the degree and frequency of droughts during the dry season;(4) after the regulation of the TGD, the low-risk months were transformed into medium-risk months of the Dongting Lake basin, indicating a deterioration of the ecological situation in this region. The study demonstrates that the construction of the TGD has exacerbated downstream water stress, while the degradation of wetlands and the reduction in biodiversity highlight the heightened pressure on ecological and environmental protection downstream of the TGD. The results of this study provide necessary information for evaluating the impact of the TGD project on large lakes downstream and provide feasible suggestions for water resource management and ecological protection in the Yangtze River basin to ensure the realization of sustainable development in the future.http://www.sciencedirect.com/science/article/pii/S1470160X24014985Hydrological alterationConnectivityBiodiversityEcological surplus and ecological deficit
spellingShingle Xinxin Chen
Yaxin Guo
Junhong Zhang
Xiao Han
Weiya Huang
Yao Yue
Ecological risks in downstream lakes exacerbated by the three Gorges reservoir
Ecological Indicators
Hydrological alteration
Connectivity
Biodiversity
Ecological surplus and ecological deficit
title Ecological risks in downstream lakes exacerbated by the three Gorges reservoir
title_full Ecological risks in downstream lakes exacerbated by the three Gorges reservoir
title_fullStr Ecological risks in downstream lakes exacerbated by the three Gorges reservoir
title_full_unstemmed Ecological risks in downstream lakes exacerbated by the three Gorges reservoir
title_short Ecological risks in downstream lakes exacerbated by the three Gorges reservoir
title_sort ecological risks in downstream lakes exacerbated by the three gorges reservoir
topic Hydrological alteration
Connectivity
Biodiversity
Ecological surplus and ecological deficit
url http://www.sciencedirect.com/science/article/pii/S1470160X24014985
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