Floods and how you can control them
By: Tom van Buuren
Dams can stop most of the water coming into the land in a flood. But not all. It can also reduce the speed of the water in a flood and can they can save many lives.
How many Dams are there in the world?
There are over 82,000 large dams in the world but it is nearly impossible to count all the dams in the world because of how many small dams there are and all the dams created by beavers and animals.
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 provide prime recreational facilities throughout the United States.
By the end of the 20th century, the dam industry had choked more than half of the Earth's major rivers with some 50,000 large dams. The consequences of this massive engineering program have been devastating. The world's large dams have wiped out species; flooded huge areas of wetlands, forests and farmlands; and displaced tens of millions of people. Dams can also break apart and that can create very big flood and problems.
Flood walls and Levees
A flood wall is a tall wall that can stop incoming floods. It can be create by many things from sand to metal bars. Sand-bag flood walls are about 91 metres high and about 1 metre long and has about 7,000 sandbags and is about 250 tons of sand.
Levees and flood walls are barriers that hold back floodwaters. A levee is constructed of compacted soil and requires more land area. Flood walls are built of manmade materials, such as concrete and masonry. These structures may completely surround the building or may tie into high ground at each end. If openings are left for the driveway and/or sidewalk, closures must be installed to seal these access points prior to a flood.
- Levees and flood walls cannot be used alone to bring substantially damaged or substantially improved structures into compliance with floodplain management ordinances and laws.
- The amount of excavation and space required for levees may make them impractical for existing sites and most building sites in urban areas. Flood walls may be applicable in these sites, but are more expensive to construct.
- The use of levees and in some cases flood walls may affect drainage in the area, potentially worsening flood damage in adjacent sites