Dam construction allows us to make better use of our water resources, prevent flood risks, and generate clean and sustainable electricity. In today’s post, why are dams constructed along with their positive impacts and what’s against them?
If we look at the definition provided by Wikipedia, which is even more specialised if possible, we find that a dam is “a barrier built over a river or stream, the purpose of which is to impound water in the riverbed. It is built with materials such as stone or concrete, sometimes taking advantage of a gorge or ravine. The stored water can be used for supply, irrigation, or electricity production. Dams can also moderate or prevent flooding downstream from their location.”
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Let’s take it from the top.
Why are Dams Constructed?
The main purpose of dam construction is to store water and produce energy. Their benefits are numerous. For example, in times of drought, the course can be diverted to ensure irrigation for crops and human consumption.
Here’s a more detailed breakdown of the reasons for dam construction:
Water Storage
Dams create reservoirs to store water that ensures a consistent supply for various needs, including drinking water, irrigation, and industrial use.
Flood Control
Dams are constructed to control and regulate water flow. They help us prevent or mitigate the effects of devastating floods even during monsoons.
Hydropower Generation
Many dams are equipped with turbines that convert the energy of moving water into electricity, one of the major sources of renewable energy.
Development
Because the dam construction requires the relocation of villages, there is an opportunity to develop modern villages, hill stations and other tourist destinations that provide an economic boost to the locals.
Containment of Mine Tailings and Pollution Control
Some dams are used to contain mine tailings or control pollution.
The Impact of Dam Construction on Fish
Dams are used for irrigation, and more importantly, they provide extremely climate-friendly hydroelectric power – and thus contribute to the fight against climate change and the end of fossil fuels. But they often contradict the natural cycles of water. Nevertheless, more than 500 dams are currently being planned or are already under construction in protected areas worldwide.
The impacts of such large dam construction projects are diverse. Sediment accumulates in the reservoir due to the lack of flow. This “silts up” the ecologically important space at the riverbed and thus destroys the habitat for aquatic fauna. While the silt can be washed into the downstream watercourse by flushing the reservoir, this also has negative consequences for aquatic ecology. Fish, for example, suffocate when the concentration of fine sediment is too high.
Furthermore, there are hundreds of thousands of obstacles, such as barrages, weirs, and dams, in the rivers. Dams have the most significant impact on the migratory movements of certain fish species. The fact that fish can move freely within their habitat is important for another reason. It’s a way for them to adapt to climate change. Global warming affects temperature and water quality. River fish, however, cannot develop new habitats if they are hindered by dams.
Dams change the dynamics of rivers not only in their direction of flow but also in their interaction with the floodplain. And because the dams also hold back the flow of sediment into the valley, delta regions, for example, could sink in the long term. This is particularly problematic given rising sea levels caused by climate change. Experts against large dam construction say intact river systems fulfil many functions for an ecosystem. They are transport routes or habitats that provide food to humans along with aquatic animals.
Other Disadvantages of the Construction of Dams
Dams are bad because they turn parts of the land into a reservoir. However, such land often already contains houses and fields. The people who live there then have to move away. The largest structure is the Three Gorges Dam on the Yangtze River in China. Nearly two million people had to be relocated there.
Tehri Dam Construction Case
Need to mention, Tehri Dam is the largest dam in India and is also one of the tallest dams in the world. It is a major engineering feat and a lifeline for millions in northern India. However, according to an article published by IIT Roorkee, to build the Tehri dam, 109 villages (full or partial) and Tehri town (full) were affected, and the residents were to vacate their ancestral homes and agricultural fields. Houses, schools, roads, and much more are submerged in water and have to be rebuilt elsewhere. This costs a lot of money. Forests, flora and fauna are all impacted negatively by the shift in places.
Dammed Nile River
One more case is with the dammed Nile River. When the dam was constructed over the Nile near Aswan in Egypt, even the famous temple of Abu Simbel was threatened with submergence. To save this World Heritage site, the temple was dismantled and rebuilt at a higher location. Also previously, the Nile flooded the land every year. It brought with it a lot of fertile mud, which acted like fertiliser for agriculture. Since the Nile was dammed, this fertiliser has disappeared. Farmers have had to spend a lot of money on artificial fertilisers ever since.
Dam Construction and Nature Suffering
Nature also suffers from the construction of dams. Slopes can slide. When water stagnates instead of flowing, it deposits sand there. This changes life for all aquatic animals. Some animals lose their habitat, or it changes dramatically. For example, fish that try to cross the dam are often injured or even killed. Some dams have fish ladders so that animals can get from one side to the other, but not all of them manage this. Dams have therefore contributed to there being fewer fish worldwide.
Are there any other impacts of dam construction you would like to mention?