Dam Solutions - Flood Management

For better or for worse?

Many dams have a function for flood control, but in some cases dams can actually make floods worse!

Many dams, by their very nature, serve contradictory aims: dam owners want them to be kept full so they can generate electricity and improve navigation, while residents of lowland areas want them kept largely empty so they can retain floods.

And often safety concerns loose out to the direct economic interest of keeping a dam full. This was painfully clear in the case of the Central Europe Floods of 2002. Dams on the Vltava River initially managed to prevent extensive flooding after heavy rains, but when within days another period of even heavier rain struck, the dams overflowed and sent flood waves downstream, causing extensive damage throughout the basin.

Dams for flood prevention also provide a sense of security that is not always justified. If a dam successfully prevents average floods, the temptation to move into the floodplains often proves too big, leading to damage and loss of life in case of extreme floods.

There are almost always alternatives to dam construction for flood control. Strategies have shifted from a focus on structural responses to introducing more non-structural responses as part of an integrated flood management strategy. Such a strategy consists of three broadly complementary approaches.

• Reducing the scale of floods through better catchment management, controlling runoff, and protection of wetlands.
• Isolation of flood threat by flood embankments, flood proofing and limiting floodplain development.
• Increasing people's coping capacity with emergency planning, forecasting, warnings, evacuation, compensation and insurance.