Do Levees Cause Flooding Downstream?

Levees have several disadvantages including increased water speed which in turn can not only increase erosion but also reduce beneficial in-stream vegetation. Levee construction can increase flooding downstream.

Why do levees increase downstream flooding?

Levees shield farms and towns from flooding, but they also create risk. When rivers rise, they can't naturally spread out in the floodplain as they did in the pre-flood control era. Instead, they flow harder and faster and send more water downstream.

What causes downstream flooding?

Failure of natural dams or human made dams results in flooding downstream from the dam. Natural dams result from natural events that block streams, such as landslides, lava flows, or pyroclastic flows into streams. Humans build dams for flood control, water storage, and the for the generation of electricity.