Why we need them and what happens when they fail. Levees Why we need them and what happens when they fail.

What is a levee? A levee is a natural or artificial slope or wall to regulate water levels around a river or stream Emergency levees are made from piling sandbags to contain water Can be made by individuals to protect homes and property

Types of Levees Natural Levee Artificial Levee Made from Sediment Formed by natural processes of erosion and deposition Artificial Levee Made from sediment or concrete May be made from sandbags Designed to address specific areas of concern

What is the purpose of a levee? Levees are usually built to protect areas within a floodplain from flooding and to control the flow of water

How do natural levees fail? Because natural levees are made of compacted sediment, as water pushes up against these barriers Sediment becomes saturated and weakens Levee breaks and water is allowed to flow freely

How do man made levees fail? Levee breach – when a piece of the levee breaks away leaving room for water to pour through Water spills over the top of the levee Too much water pushes agains the levee causing cracks and leakage You Tube Video – Katrina Levee Failure http://www.google.com/url?q=http://www.youtube.com/watch?v=9vKMJsfzkZg&sa=U&ei=s zX_Td-CMsO30AHqxPi1Dg&ved=0CCYQtwIwAQ&usg=AFQjCNEavbXEW

What are the consequences of levee failure? Significant property damage Loss of life and personal injury Flooding of farmland and destruction of crops