Dam-break Flood Risk Management. an Integrated Project

Contemporary dam safety regulations include risk assessment at downstream flood plains and consideration of potential damages due to dam rupture, regardless of the expected probability of occurrence of such event. The aim of these kind of procedures is to increase the safety level along the valley against abnormal floods caused by dam accidents. Emergency plans for downstream flood plains, including zoning, warning and evacuation plans, are being developed as special risk mitigation procedures. In modern open societies these plans should include public information and training. All these valley actions will be justified in order that the global safety level be increased, not only in objective terms by increasing the survival probability, but also in subjective terms. In fact, public risk perception is a very important dimension in any risk management methodology. For dam and valley safety policy, public participation and perception becomes more and more a very important issue. Among the different complex aspects of this topic, the ethical questions related to risk assessment and management as well as with the risk communication need to be considered. Risk public perception is one of the variables that must to be introduced in the emergency planning. To study, develop and improve an integrated methodology for dams and valley risk management in Portugal, a special project is under development, since 1994. This project is sponsored by NATO, through its Science for Stability Program. The main objectives of the project were the following ones: − to improve the computational capacity to simulate dam-break floods (one and two-dimensional models), including validation procedures based on physical and experimental models; − to improve the portuguese dam safety legislation in what concerns downstream valleys; − to introduce the applied social sciences in risk management methodologies, specially in what concerns risk public risk perception and information and the land-use management during dam lifetime; − to develop new decision tools to aid dam and valley risk management based on advanced computer technologies (SIG and multimedia databases); − to develop a guideline for valley emergency plans and a full scale exercise. The project was organized in five sub-projects that were being working in order to reach the objectives. The work was based on a theoretical and applied works for a case study, including valley with two dams: Arade valley at Algarve, in the south of Portugal, where two dams are in operation upstream two cities. The paper will briefly describe the main concepts and developments achieved by this NATO project including the conclusions and the practical consequences and measures that are being implemented in Portugal.