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Hydropower has been the leading source of renewable energy across the world, accounting for up to 71% of this supply as of 2016. This capacity was built up in North America and Europe between 1920 and 1970 when thousands of dams were built. Big dams stopped being built in developed nations, because the best sites for dams were already developed and environmental and social concerns made the costs unacceptable. Nowadays, more dams are being removed in North America and Europe than are being built. The hydropower industry moved to building dams in the developing world and since the 1970s, began to build even larger hydropower dams along the Mekong River Basin, the Amazon River Basin, and the Congo River Basin. The same problems are being repeated: disrupting river ecology, deforestation, losing aquatic and terrestrial biodiversity, releasing substantial greenhouse gases, displacing thousands of people, and altering people’s livelihoods plus affecting the food systems, water quality, and agriculture near them. This paper studies the proliferation of large dams in developing countries and the importance of incorporating climate change into considerations of whether to build a dam along with some of the governance and compensation challenges. We also examine the overestimation of benefits and underestimation of costs along with changes that are needed to address the legitimate social and environmental concerns of people living in areas where dams are planned. Finally, we propose innovative solutions that can move hydropower toward sustainable practices together with solar, wind, and other renewable sources.
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A Meta-Analysis of Environmental Tradeoffs of Hydropower Dams in the Sekong, Sesan, and Srepok (3S) Rivers of the Lower Mekong Basin
In Mekong riparian countries, hydropower development provides energy, but also threatens biodiversity, ecosystems, food security, and an unparalleled freshwater fishery. The Sekong, Sesan, and Srepok Rivers (3S Basin) are major tributaries to the Lower Mekong River (LMB), making up 10% of the Mekong watershed but supporting nearly 40% of the fish species of the LMB. Forty-five dams have been built, are under construction, or are planned in the 3S Basin. We completed a meta-analysis of aquatic and riparian environmental losses from current, planned, and proposed hydropower dams in the 3S and LMB using 46 papers and reports from the past three decades. Proposed mainstem Stung Treng and Sambor dams were not included in our analysis because Cambodia recently announced a moratorium on mainstem Mekong River dams. More than 50% of studies evaluated hydrologic change from dam development, 33% quantified sediment alteration, and 30% estimated fish production changes. Freshwater fish diversity, non-fish species, primary production, trophic ecology, and nutrient loading objectives were less commonly studied. We visualized human and environmental tradeoffs of 3S dams from the reviewed papers. Overall, Lower Sesan 2, the proposed Sekong Dam, and planned Lower Srepok 3A and Lower Sesan 3 have considerable environmental impacts. Tradeoff analyses should include environmental objectives by representing organisms, habitats, and ecosystems to quantify environmental costs of dam development and maintain the biodiversity and extraordinary freshwater fishery of the LMB.
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- Award ID(s):
- 1633756
- PAR ID:
- 10288963
- Date Published:
- Journal Name:
- Water
- Volume:
- 13
- Issue:
- 1
- ISSN:
- 2073-4441
- Page Range / eLocation ID:
- 63
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Hydropower dams have received increased global attention due to their detrimental socioenvironmental ramifications. Such attention has led to an increase in studies on the impacts of reservoir operation on river flow; however, a holistic understanding of the compounded effects of hydropower dams on different hydrological characteristics is lacking, especially for large river basins such as the Amazon where hydropower development is on the rise. Here, we mechanistically quantify the historical impacts of existing dams and the potential impacts of the collective operation of existing and planned dams on a basin‐wide scale in the Amazon for the 1981–2019 period. We build on the recently developed high‐resolution (3‐arcmin; ∼5 km) river‐floodplain‐reservoir model, the CaMa‐Flood‐Dam, which is enhanced to realistically simulate hydropower dam operation considering maximized power production. Flood simulations are further downscaled to 3 arc‐seconds (∼90 m) resolution to investigate the impacts of dams on fine‐scale flood dynamics across the basin. Results indicate that existing dams have substantially altered downstream river flow and flooding patterns across the Amazon River basin. Specifically, large dams in the Amazonian subbasins, including the Xingu, Madeira, and Tocantins, have altered downstream river flow amplitude by up to 3 orders of magnitude. Further, the collective operation of existing and planned dams could increasingly alter river flow patterns, causing ∼10% decrease in flood duration in many parts of the Amazon mainstem. Our results provide quantitative evidence on the severity of the hydrologic impacts of large hydropower dams and have important implications for sustainable hydropower operation and development in the Amazon and worldwide.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/w13010063
