Why can cementing the stream or creating dams be more harmful than helpful ?
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Answer:
Large dams have junction rectifier to the extinction of the many fish and alternative aquatic species, huge losses of forest, the disappearance of birds in floodplains, erosion of deltas, wetland, and farmland, and many other irreversible impacts.
Benefits of Dams. Dams provide a range of economic, environmental, and social benefits, including recreation, flood control, water supply, hydroelectric power, waste management, river navigation, and wildlife habitat.
Dams change the way rivers function. They can trap sediment, burying rock riverbeds where fish spawn. Gravel, logs, and other important food and habitat features can also become trapped behind dams. This negatively affects the creation and maintenance of more complex habitat (e.g., riffles, pools) downstream.
he absence of new sediments downstream of the dam can cause erosion problems that modify the aquatic environment, undercut riverbanks, or wash away beaches. Dams are therefore a double-sided coin, with a positive side (energy, drinking water, irrigation, flood regulation, river navigation, fight against drought, etc.)