Evaluating flood damages: guidance and recommendations on principles and methods

Recent events like the 15 extreme floods that occurred 2002 in various parts of Europe showed that floods continue to pose serious risks in many EU countries. Indeed there is evidence that flooding is getting more serious over time, in terms of the number of floods occurring as well as the damage and the loss of life being caused. The social purpose of flood risk management is to reduce flood damages. Since flood risk management strategies can require a significant diversion of resources from other purposes, it is desirable to determine whether the reduction in flood damages justifies the resources so expended. Equally, only if we are in a position to evaluate alternative intervention strategies in terms of their relative benefits and costs we are able to make ‘better’ choices and introduce more effective flood risk management strategies. As a consequence, the quantification and evaluation of flood damage is practised in a growing number of EU countries as an important factor to be considered in the decision process about particular flood risk management measures. Unfortunately, the methods used are quite diverse and they sometimes do not reflect the state-of-the-art in flood damage evaluation. The major purpose of these guidelines is, therefore, to give guidance for practitioners of governmental authorities and executing bodies dealing with ex-ante flood damage evaluation in order to appropriately appraise public flood defence projects or strategies on different spatial scales.