Consider a levee as a flood control method, what is a levee and is it supposed to work?

A Levee is an embankment built along the sides of rivers,
streams and the sea as vertical or sloping walls. They are usually made of mud and prevent
flooding by stopping the water from flowing into areas that lie beside the water body by blocking
it.

To construct a levee a small area along the side of the water
body is cleared. Earth is deposited on this plain area as structures which taper upwards. A small
flat area is also created on top so that additional material could be piled there in case the
water level equals that of the levee. After the earth has been deposited measures have to be
implemented to prevent erosion, both on the side facing the river as well as the opposite
side.

Even if a small portion of a levee fails it is equivalent to
the whole structure failing and large areas beside the water bodies can get flooded. This
requires that the regulations which are meant for construction of a levee are strictly adhered
to.