Risk Assessment

During the last three years severe flood events affected a bigger part of West and Central Europe. Those flood events brought a number of fatalities, destroyed businesses, homes and public facilities and caused losses on agricultural and forestal used areas.

Flood damage does not exist per se; Losses only occur if human beings and assets are affected. Beside the loss of life, flood can cause damage to tangible assets and consequently causes economic damage of several millions of Euros. This is particularly true for vulnerable areas like cities. 

The following trends are noticed, pointing up the importance of  flood protection in flood affected areas:

• Increase in potential damage
• Increasing economic value in consequence of changes in land use
• Increase in number of extreme flood events
• Increasing discharge because of river training or climate changes

As consequence of recent large-area flooding the public interest increased. But, if flood events do not occur for a long period of time, the risk of flooding as well as the damage caused by flood events are forgotten. Residents are often not prepared sufficiently in case of further flood events.

To avoid or reduce the impact of floods is a task of Integrated Flood management (IFM). IFM comprises flood probability assessment and flood impact assessment as well as all forms of structural and non-structural mitigation measures and the decision making process.

Risk assessment is an essential part of flood impact assessment. To get a better idea of the possible amount of damages in case of a flood event diverse strategies of risk assessment have been developed.

The results of risk assessment can become visualised on a map, showing the levels of expected losses which can be anticipated in specific areas, during a particular time period and as a result of a particular flood event. These maps are called risk maps. Risk maps are an important medium of communication in sustainable flood management. They may help to transfer the risk information to the residents as they depict flood risk in a colourful and easy understandable way.