Flood alleviation works have been built to move large volumes of water quickly from one area to another to protect against flooding. However, this leads to downstream flooding, causing a chain reaction that necessitates a cascade of alleviation works further downstream. These works have resulted in the destruction of riverine, riparian and floodplain habitats.
Cascading flood alleviation works disrupt habitats
Flood alleviation works have been built to move large volumes of water quickly from one area to another to protect against flooding. However, this leads to downstream flooding, causing a chain reaction that necessitates a cascade of alleviation works further downstream. These works have resulted in the destruction of riverine, riparian and floodplain habitats.
Nº 17
1) South America, Brazil, Upper Paraná Basin
2) Asia, China, Yangtzie River
3) Asia, China, Low Yellow River
4) North America, United States, Mississipi and Missouri Rivers
- N/D
- Adaptation to Environmental Degradation
- Protection Against Flooding
some attempts made
past case
Region-1
Region-2
Region-3
Region-4
ongoing case
no attempts made
None
Cascading flood alleviation works disrupt habitats
1) There are about 150 reservoirs with dams in the Paraná Basin. The construction of cascade reservoirs along the rivers of the Paraná Basin region has led to changes in fish populations and the environment. Specifically, fish populations in these reservoirs have experienced changes in abundance, biomass and diversity.
2) The Yangtze River in China has more than 50,000 dams built along its course, and the construction of these cascade dams has had an undeniable impact on the river’s environment. These include the fragmentation of habitats, an increase in water temperature, a reduction in water flow and an impact on fish populations.
3) On the lower reaches of the Yellow River in China, the Xiaolangdi Dam was officially closed in 1999 (this does not mean that the dam was closed, but that the river was actually closed) with the aim, among others, of reducing flood risks in the region. Immediately afterwards, some morphological changes were observed in the river, such as bed incision and sediment coarsening, which actually increase the “flood stage” in the downstream part of the river.
4) “Man-made changes to the Missipi and Missouri Rivers in the United States to manage flood risk, such as channelling, have actually increased flood stage in the middle Missipi and lower Missouri.
- Facilitated the efforts to address the initial problem
- Cascading (far-reaching effects following each other)
1) Ferrareze, M., Casatti, L. & Nogueira, M.G. (2014). Spatial heterogeneity affecting fish fauna in cascade reservoirs of the Upper Paraná Basin, Brazil. Hydrobiologia 738, 97–109. https://doi.org/10.1007/s10750-014-1922-5
2) Cheng, F., Li, W., Castello, L. et al. (2015). Potential effects of dam cascade on fish: lessons from the Yangtze River. Rev Fish Biol Fisheries 25, 569–585. https://doi.org/10.1007/s11160-015-9395-9
Wang, Y., Zhang, N., Wang, D., Wu, J. (2020). Impacts of cascade reservoirs on Yangtze River water temperature: Assessment and ecological implications. Journal of Hydrology, 590, 125240, ISSN 0022-1694. https://doi.org/10.1016/j.jhydrol.2020.125240.
3) Ma, H., Nittrouer, J. A., Fu, X., Parker, G., Zhang, Y., Wang, Y., . . . Wu, B. (2022). Amplification of downstream flood stage due to damming of fine-grained rivers. Nature Communications, 1-11. https://doi.org/10.1038/s41467-022-30730-9.
4) Criss, R. E., & Shock, E. L. (2001). Flood enhancement through flood control. Geology (Boulder), 29(10), 875–878. <a href="https://doi.org/10.1130/0091-7613(2001)0292.0.CO;2″ rel=”noopener noreferrer” target=”_blank”>https://doi.org/10.1130/0091-7613(2001)029<0875:FETFC>2.0.CO;2
Ferrareze, M., Casatti, L. & Nogueira, M.G. Spatial heterogeneity affecting fish fauna in cascade reservoirs of the Upper Paraná Basin, Brazil. Hydrobiologia 738, 97–109 (2014). https://doi.org/10.1007/s10750-014-1922-5
Cheng, F., Li, W., Castello, L. et al. Potential effects of dam cascade on fish: lessons from the Yangtze River. Rev Fish Biol Fisheries 25, 569–585 (2015). https://doi.org/10.1007/s11160-015-9395-9
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