Uganda Today: Large dams in Africa, like in many other regions, can have both positive and negative impacts on the ecological system. While dams contribute to economic development, water supply, and energy production, they also pose significant challenges to the environment. Here are some ways in which large dams can affect the ecological system in Africa:
- Alteration of River Flow: Dams regulate river flow, leading to changes in the natural flow patterns. This alteration can affect the downstream ecosystems, leading to erosion, sedimentation, and changes in water temperature, which can impact aquatic habitats and species.
- Loss of Biodiversity: The creation of reservoirs behind dams can result in the submersion of large areas of land, including forests and wetlands. This can lead to habitat loss and fragmentation, threatening the biodiversity of both terrestrial and aquatic ecosystems. Many species, especially those adapted to specific river-line conditions, may struggle to survive or migrate.
- Water Quality Changes: The impediment of water behind dams can alter water quality by affecting nutrient levels and sediment transport. These changes can have cascading effects on the aquatic ecosystem, affecting the health of fish, invertebrates, and other aquatic organisms.
- Displacement of Communities: Large dams often require the resettlement of local communities living in the dam’s inundation zone. This displacement can disrupt traditional livelihoods, lead to loss of access to natural resources, and result in social and economic challenges for affected communities.
- Methane Emissions: Reservoirs created by dams can be significant sources of methane emissions, a potent greenhouse gas. Decomposition of organic matter in submerged areas can lead to the production and release of methane, contributing to climate change.
- Sediment Trapping: Dams trap sediment, preventing it from flowing downstream. This sediment is essential for maintaining downstream ecosystems, and its retention behind dams can lead to erosion downstream, impacting riverbeds, aquatic habitats, and the health of riverbanks.
- Altered Flood Regimes: Dams can modify natural flood regimes, reducing the frequency and intensity of floods. While this may protect downstream areas from flooding, it can also disrupt ecosystems that depend on periodic flooding for nutrient replenishment and the maintenance of habitat diversity.
It’s important to note that the ecological impacts of dams can vary depending on factors such as dam size, location, and management practices. Some mitigation measures, such as fish ladders and environmental flow releases, can help alleviate some of the negative effects, but the overall impact depends on careful planning and sustainable management practices.
Can Huge Dams Solve Our Economic Problems?
2nd January 2, 2024.
Long ago as an anti-large dam crusader bewildered and unimpressed by the choice of African governments in general and that of Uganda in particular to populate the Continent’s large rivers with large dams, ostensibly to power Africa into the industrial revolution, I wrote an article to commemorate the International Day of Action against Dams for Rivers, Water and Life marked on 14 March 2000. Most Africans and Ugandans now of age were not yet born and many were very young people perhaps unbothered by global challenges, problems and issues bedeviling the environment and the energy sectors of African economies. Governments were convinced there was no alternative to hydropower although today, especially in Uganda, they are devout supporters of solar energy. The article is on the Website of International Rivers, https://archives.internationalrivers.org
Despite the wisdom in these articles governments in Africa collectively decided to seek Chines loans to construct some 52 or so dams on our large rivers. Uganda government went on to construct Owen Falls Extension Dam, Bujagali Dam, Isimba and not long ago had embarked on constructing Karuma dam at excessive ecological, environmental, cultural, spiritual, and financial, human and climate costs.
I am recasting the said article for Africans in general and Ugandans in particular, to know and perhaps appreciate that while we could some of us tried within our powers to save our huge rivers from strangulation with huge dams for hydro power at the expense of ecology, environment, culture, spirituality, humanity, climate and futurity. I hope the various Media, which were not there then will capture the article for all humanity.’