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A dam built across a river will obviously have a major effect on the river valley upstream of the dam which will be flooded as the new storage reservoir fills. Less obvious is that the river downstream of the dam will also be significantly affected. Large dam projects are highly individual in their design, geological setting and the construction materials used to build them. They are also individual in their impact on their environment. Some large dam projects in tropical Africa have created lakes hundreds of kilometres long in areas which had large local populations. The major impacts that these projects had on the plant, animal and human population of the area have been well documented, however it would be a mistake to assume that all dam projects necessarily have similar major impacts on the environment.
Some adverse effects of building a dam are easy to mitigate during the design of the dam as the following example shows. Fifty years ago a typical dam could release water only from the bottom of the storage reservoir. This water was very different from the water that would have flowed down the river before the building of the dam. Water from the bottom of a storage is usually cold and depleted in oxygen compared to normal river water and this had adverse effects on animal life in the river downstream of the dam. Since about the 1980s dam outlet works are usually specifically designed so that the adverse effects described above do not occur when water is released from the dam. Today's dams have an intake tower with withdrawal ports at different levels so that water can be released from the top layer of the reservoir regardless of the storage level at the time.
Provision of fish ladders is another example where dam design can remove or reduce an adverse effect of dam building. Today every reasonable effort is usually made to reduce the effect of the dam project on the environment eg borrow areas for clay, sand and gravel construction materials needed to build the dam are located, if possible, in the area which will be flooded by the reservoir so that the disturbed areas will not be visible after the dam is completed.
Not all adverse effects can be so easily removed. Building a dam changes forever the flow regime in the river: floods are much reduced in frequency and size and the natural pattern of short duration floods and long periods of low flows is changed to a less variable flow regime. In fact the reduction in flooding may be one of the reasons for building the dam in the first place. Flooding is damaging to humans and their property but may be necessary in the life cycles of some species of trees, fish and birds. It may be possible to at least partially mitigate these adverse effects on the natural environment by arranging water releases from the dam at specific times of the year to mimic the natural flooding that occurred before the dam was built.
What else can I help you with?
What has the author Darrell L Cauley written?
Darrell L. Cauley has written: 'Post-construction analysis of environmental impacts' -- subject(s): Dams, Environmental aspects, Environmental aspects of Dams, Environmental aspects of Reservoirs, Reservoirs
Are dams renewable?
Dams themselves are not renewable; they are man-made structures that can last for decades or even centuries. However, the energy produced by hydropower plants associated with dams is considered renewable, as it harnesses the natural water cycle and can be replenished over time. The sustainability and environmental impact of dams can vary significantly based on their design, location, and management practices.
Are there dams in Africa?
==== ==== the total number of large dams in Africa is 1 272;
Which change is an environmental effect of building dams?
flooding
What has the author Vijay Paranjpye written?
Vijay Paranjpye has written: 'Salauli Dam' -- subject(s): Dams, Economic aspects of Irrigation, Economic aspects of Water resources development, Environmental aspects of Dams, Irrigation, Salauli Irrigation Project, Water resources development 'Evaluating the Tehri Dam' -- subject(s): Dams, Economic aspects of Dams, Environmental aspects of Dams, Social aspects of Dams, Tehri Project
Which senate committee deals with environmental policy and public works such as the creation and maintenane of bridges and dams?
which senate committee deals with environmental policy and public works such as creation and maintenance on bridges and dams
Do large rivers require large dams?
Yes,Becouse they are big.
What major hazard is created by low -head dam?
Low-head dams are dangerous because people fail to realize that these dams are just as dangerous as larger dams. The movement of the water at the base can pull people under and trap them. These low-head dams have been nicknamed 'drowning machines.'
What has the author H A Morrison written?
H. A. Morrison has written: 'The applicability of various frameworks and models for assessing the effects of hydropeaking on the productivity of aquatic ecosystems' -- subject(s): Aquatic organisms, Dams, Effect of dams on, Effect of habitat modification on, Environmental aspects, Environmental aspects of Dams, Environmental aspects of Hydroelectric power plants, Fishes, Hydroelectric power plants
What has the author S R Barber written?
S. R. Barber has written: 'Wildlife (Saskatchewan)' -- subject(s): Dams, Environmental aspects of Dams, Environmental aspects of Hydroelectric power plants, Hydroelectric power plants
What is the bad thing of dams?
Dams can bring both benefits and problems to the environment. Dams affect the land and environment over a large area. These dams are also good targets for terrorist activity.
Hydroelectric dams use the kinetic energy of water to produce electrical energy What is the environmental drawback of building hydroelectric dams?
One environmental drawback of building hydroelectric dams is the disruption of river ecosystems, including changes in water flow, sediment transport, and fish migration patterns. Dams can also lead to reduced water quality downstream and the displacement of communities and wildlife due to flooding of land for reservoirs.
