Riverbed deepening or "incising" will also lower groundwater tables along a river, lowering the water table accessible to plant roots and to human communities drawing water from wells. Altering the riverbed also reduces habitat for fish that spawn in river bottoms, and for invertebrates.
In aggregate, dammed rivers have also impacted processes in the broader biosphere. Recent studies on the Congo River have demonstrated that the sediment and nutrient flow from the Congo drives biological processes far into the Atlantic Ocean, including serving as a carbon sink for atmospheric greenhouse gases. Large dams have led to the extinction of many fish and other aquatic species, the disappearance of birds in floodplains, huge losses of forest, wetland and farmland, erosion of coastal deltas, and many other unmitigable impacts.
International Rivers is licensed under Creative Commons. Jump to Navigation. These days, authorities are becoming more aware of these issues. Resettlement plans have been developed to minimise the disruption and suffering caused to people in the reservoir area.
Good plans make sure that fair compensation and employment opportunities are provided for all people, and that the law protects their rights. In some cases, efforts have been made to resettle people in their communities.
Dams are often constructed across rivers to store water that would naturally find its way to the lower reaches of the river and into the sea. The presence of the dam upsets the natural balance of the river, affecting the animal and plant life in and around it.
These are some of the reasons. When the river valley is inundated with water, animals are forced to leave the area and plants and trees are killed. Sometimes, rare species can be affected. For some large reservoir projects, nature reserves have been created.
Plants and trees have been replanted in them and some of the affected animals have been moved there. However, the reserves can only be really successful when careful thought has been given to the way that the plants and animals depend on each other and their environment.
A dam across a river can form a barrier to fish that migrate, such as salmon. Fish passes can be included in the design of a dam to allow adult fish to swim upstream to spawn, and back downstream later with their young.
Fish passes usually take the form of a fish ladder or a fish lock. These fish passes have to be designed very carefully to make sure that the conditions are right for the fish to use them.
Many large reservoirs were built without a thorough or systematic evaluation of the long-term environmental, social, and economic interactions of different alternatives.
Up to the last quarter of the twentieth century, those responsible for the construction of dams and creation of reservoirs — entrepreneurs, decision makers, engineers, investors — were praised for the acknowledged benefits of their works: water supply, irrigated agriculture, flood control, improved navigation and firm hydroelectric generation considered clean and unequivocally renewable energy.
However, on the other hand, alarmist, especially environmental groups and organizations, have been exaggeratedly stating that infrastructure works, in general, and dams and reservoirs, in particular, cause serious and intolerable environmental impacts. Reservoir construction leads to a number of environmental issues, both during building and following completion.
The physical, chemical character and water quality of rivers draining into lakes and reservoirs are governed in part by the velocity and the volume of river water. In these last decades of industrialization and rapid population increase, human intervention on the balance of nature has never been so various and so extensive as it is today. This chapter reviews a large range of potential impacts linked to the exploitation of reservoirs and dams, such as: 1 Climate-changing greenhouse gases emissions; 2 Changes in the Temperature Regime 3 Reservoir sedimentation; 4 Water pollution; 5 Destruction of Eco-systems, and 6 Planning and reservoir management.
Skip to main content. This service is more advanced with JavaScript available. Advertisement Hide. Environmental Impacts of Reservoirs. Chapter First Online: 30 October Keywords Reservoirs Water resources Environmental impacts. This is a preview of subscription content, log in to check access.
And the drying out of wetlands destroys another valuable carbon sink. Dams are detrimental to carbon sinks in the ocean as well. Studies of the Congo River reveal that nutrient- and sediment-rich water from the river drives biological processes deep into the Atlantic Ocean, contributing to algae growth.
Additionally, blocking the sediments traveling downstream can have devastating effects when river deltas are deprived of the silt they need to defend against damage from the ocean. Without the shoring up of river deltas and wetlands, inland ecosystems and human communities become even more vulnerable against the storm surges and sea level rises caused by climate change.
Scientists have attributed over earthquakes around the world to dams and reservoirs, [xxi] a phenomenon known as Reservoir Induced Seismicity. The 7. Dams displace around 80 million people worldwide. Dams that displace large populations often cause human rights violations.
Authoritarian governments in Burma, China, Colombia, Ethiopia, Guatemala, Sudan and other countries have responded to dam opposition with violence, intimidation and threats. In the worst dam-related incident, more than indigenous people died in the suppression of opposition to Guatemala's Chixoy Dam in Additionally, old and failing dams generate both dangers and costs.
These are dams that could result in a high loss of life if they fail. The 58 year old Kariba dam could result in 3. The US also hosts several dams close to failure. Earlier this year, fear of the collapse of the Oroville Dam Spillway [xxxii] resulted in the evacuation of , people in northern California. And, in February, the Twentyone Mile Dam in Nevada burst, causing massive damage to private property and local infrastructure.
Growing recognition that old and eroding dams pose too high a risk have resulted in a growing number of dam removals. The United States has taken down 1, dams since , with a majority of those dams removed in the last two decades, and 72 in Preserving healthy and high functioning waterways contributes to controlling global temperatures and sustaining fresh water reserves, among countless other benefits.
Rivers are important in their own right, but also matter for their ability to maintain the health of surrounding river catchments, floodplains, and wetlands. We will be on the path to a sustainable relationship with a healthier environment when we recognize that Earth has intrinsic rights to thrive, evolve and flourish. Addressing the flaws in the traditional approach to development and acknowledging the rights and interests of waterways will enable us to better care for the planet and its resources.
This will benefit humans too. By understanding sustainable water management and implementing those principles into our industry and governmental systems, we can better address the causes of waterway degradation. Through understanding what waterways need to function properly, we can create laws and regulations that can better outline the parameters of human activity. Protecting waterway health must be one of the highest priorities when determining how water is used.
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