Flood Control and erosion prevention

What is flooding? Flooding is when a river or lake breeches its limits (overflows) due to large amounts of rainfall

How can you prevent flooding? Flooding may be prevented by levees, which are large concrete walls that may surround lakes

But sometimes, they break….

The break in the levees

Lower French Quarter

Overlook of downtown New Orleans

Interstate in New Orleans

dams What are dams? A dam is a barrier that stops flowing water, causing the flowing water to slow, and creates a lake or a reservoir They may be built to prevent large amounts of flooding

Purposes of dams Prevent large amounts of flooding Water for irrigation (watering crops) Hydroelectric power (water energy)

Hoover Dam

Hoover Dam, Colorado

Drawbacks of dams… What are some drawbacks (negative) of dams? They stop rivers from flowing, therefore stopping deposition from the rivers If deltas stop getting sediment from deposition, the ocean will erode them

Smaller flood controls Sandbags (bags of sand) are used to prevent smaller floods. Why? Sand is very absorbent, and will absorb the flood waters, preventing the water from harming the interiors of buildings or further flooding

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Contour strip cropping Growing crops in narrow strips at right angles to prevent wind and water erosion

Contour Strip Cropping Contour Strip Cropping is a human intervention to prevent or slow down erosion by planting strips of grass (vegetation) in between the rows of crops. The vegetation helps to prevent the fertile topsoil from being eroded by the wind.

Deltas- a constructive force The place where a river meets a larger body of water such as a lake or ocean.

Deltas

deltas

Mississippi Delta

Tacoma, Washington delta

Georgia’s barrier islands

What is the purpose of barrier islands? Barrier islands are actually “erosion fighters” How? They protect or slow down the coastlines from being eroded by the rising sea levels They also protect the mainland from severe storms

Layout of a barrier island