Levees can either be natural or man made. Man made levees are embarkments that are built to keep water in. They are built by rivers to keep them from overflowing there banks.. They are made from less impermeable soils such as clay and are narrow at the top but wider at the base. They can range in height because there is no set height on how tall they can be.
There are many advantages to levees. They allow people to live by rivers or oceans without the fear of flooding, unless the levee breaks. They also provide protection. In the Netherlands, the advantage to using a levee is that it has stopped the ocean waters from flowing onto the land. This has allowed the land to be occupied by people. Levees also keep lakes at bay and rivers from overflowing there banks.
Levees comes with many disadvantages. While providing protection from flooding in one place levees can divert the water elsewhere causing flooding in another place.Crops can drown and be killed in the flood causing problems for farmers. Levees can also fail. They can fail by overtopping, underflow, slumping, or erosion. Overtopping is when the water rises above the levee. Underflow is when water permeates the sand deposits underneath the levee and water rises up on the other side. When the weight of the water is too heavy for the levee, it can push over the sides. This is called slumping. Erosion is when the sides and top of the levee slowly start to wear down due to the waves of the water.