Levee breach

Some engineers think that boils lead to a form of internal erosion called piping which undermines the levee, but others consider them a symptom of generalized instability of the foundation.

When the tree falls the root system will likely take a chunk of the saturated soil out of the levee.

Overtopping can lead to significant landside erosion of the levee or even be the mechanism for complete breach.

This is a crater-like depression just behind the breach where soil and other material has been violently scoured out by the rushing water.

Again during record-breaking flooding in 2011, the US Army Corps of Engineers blew up a section of a Mississippi River levee with dynamite to open the New Madrid Floodway.

In some areas reclaimed land is given back to nature by breaching and removing dikes to allow flooding to occur (again).

The sudden breaching released water at a high velocity that moved houses off their foundations and tossed cars into trees.

In New Orleans, the United States Army Corps of Engineers is the Federal agency responsible for levee design and construction as defined in the Flood Control Act of 1965 and subject to local participation requirements, some of which were later waived.

[2] The St. Elizabeth's flood of 1421 was caused by a surge of seawater being forced upriver during a storm, overflowing the river dikes and submerging approximately 300 square kilometres (100 sq mi) of land in the Netherlands.

A further 307 people were killed by dike breaches in the United Kingdom, in the counties of Lincolnshire, Norfolk, Suffolk and Essex.

In the Netherlands this flood was a main reason for the construction of the Delta Works, probably the most innovative and extensive levee system in the world.