By Joan Whetzel

Rivers throughout history have overflowed their banks from time to time, causing flooding of communities along their banks. Many countries, including the US, have taken to building levees in order to reduce the occurrences of flooding along rivers like the Mississippi and Missouri Rivers.

What Are Levees?

Levees are often called flood banks, stop banks, dikes or artificial embankments. They are built up as earthen levees where dirt is piled up and packed down hard along river banks which have previously been cleared. Earthen levees are usually broad at the bottom, then taper upward and are flat and level along the top. The flattened top allows for the temporary stacking of sandbags during extreme rain events.

The Purpose of Levees

Levees are artificially raised earthen, river embankments, created by humans to prevent flooding of cities and farms. They are meant to keep rivers within their banks during seasonal rainy periods and following seasonal snow melts which generally tend to raise the rivers’ water levels above the normal levels of the river banks. By raising the embankments, and thereby reducing localized flooding, the extra water is guided more quickly toward the sea.

Problems that Interfere with Effect Use of Levees

Over the years, the rivers carry silt with them as they flow down their channels. This silt gets deposited along the bottom of the river channels, raising the level of the river beds, and making the embankments seem shallower. This in turn increases flooding to the nearby cities and farming communities. The levees themselves, by restricting the rivers’ flow, increases the speed and intensity of the water flow which increases the probability that the levees will break during heavy rain events.

Flood prevention and levee maintenance are constant concerns for communities along the banks of medium and large sized rivers. Maintaining the levees and preventing floods require a number of measures including: river channel widening, river dredging, systems of multiple levees, updated rescue plans, rescue and sandbagging practice runs, road closures during heavy rain events, and clean ups after flooding and following levee breaks.