- There are a total of 800,000 dams operating worldwide; most were built after World War II.
- Dams control flooding and some serve as navigation, by stabilizing flow. Their reservoirs provide a supply of water for drinking, irrigation, and recreation.
- Dams ruin vistas, trap sediments (needed for deltas, riverbanks and beaches), hinder migratory fish, destroy ecosystems in and around waterways, and displace people.
- The rate of dam removal has exceeded the rate of dam construction for the past decade.
- Researchers expect dams to be taken down, especially small ones. Canada, Australia, U.S., France and Japan have removed or are planning to remove dams.
- In 1999 the Edwards Dam on the Kennebec was taken down; soon after, many of the river’s native fish returned and their populations grew dramatically
- In places where dams have been removed, water clarity and oxygen levels increase as flow comes back and fish and aquatic insects thrive.
- If the sediments contain high levels of pollutants, the cost of removing them—especially from remote locations—has to be weighed against the ability of the waterway to wash them away
- Dams blocked invasive species and protected threatened species.
- However, the downsides of dam removal can cause the release of sediments trapped behind a dam’s walls which can choke waterways, muddying the environment and wiping out insects and algae, which are important food for fish. Sometimes the mud trapped by the structures is contaminated.
- Sediments that aren't washed downstream may provide rich soil for invasive species as they dry out.
- Dam removal can create dangers for people living nearby, especially in places with threats of high flooding.
- Before removal of dams, researchers carefully plan on what to do with the accumulated sediments, whether to manage the fishery as a native one, and how to protect the reservoir-resident frogs.
- The biggest issue with removing dams is how to control what can be a huge accumulation of dirt and debris caused by sediments stuck behind the dam. The amount of sediment is weighed against the ability of the waterway to wash them away.
Summary:
Dams are being built because they usually control flooding and some serve as navigation, by stabilizing flow. Their reservoirs provide a supply of water for drinking, irrigation, and recreation and hydro power. Also, they blocked invasive species and protected threatened species. After the World War II, Dams have a total of 800,000 dams operating worldwide. The bad side of having dams are that they ruin vistas, trap sediments (needed for deltas, riverbanks and beaches), hinder migratory fish, destroy ecosystems in and around waterways, and displace people. Countries like Canada, Australia, U.S., France and Japan have removed or are planning to remove dams. If dams were to be removed, which it's very successful, water clarity and oxygen levels increase as flow comes back and fish and aquatic insects thrive. However, dams causes the release of sediments trapped behind a dam’s walls which can choke waterways, muddying the environment and wiping out insects and algae, which are important food for fish. Sometimes the mud trapped by the structures is contaminated. Dam removal can create dangers for people living nearby, especially in places with threats of high flooding.
My Reflection:
I only thought that dams have only pros, because of how big and useful they are for us. But now, realizing that there is always a cons to the environment. If I didn't know this, then many people probably didn't know about this problem also. If we can share this information to everyone the they would likely to solve this problem. The cons are mostly useful for us, and the cons are mostly impacting our environment. I will agree that destroying the dams are one step towards helping to our environment and also for our planet.