The occurrence of flood events is a **stochastic process**. As logical consequence the potential damage can not be exactly determined. The calculation is based on available statistical data and is expressed as annual flood damage potential. Therefore the damage is weighted by the frequency of returning.

Assumption: The maximal damage is set as the upper limit of integration (recurrence interval T_{¥} = T_{max}); the expected damage can only be calculated for events which probability of occurrence is more frequently than T_{max}. The corresponding probability for this design event is P_{max} As consequence the remaining risk cant be considered.

The **flood damage potential** is a function of flooded area, land use and water depth. It is summarized in the following formula: