Flood Handling and Emergency Action Planning for Dams

Even though dams are designed to bypass floods of significant magnitudes, floods less severe than the design flood may pose a threat to dams. Ongoing research into climate change also shows an increasing trend towards severe floods, that is an increased probability of floods exceeding the present design floods. Therefore, acquiring understanding of floods and risk reduction measures to mitigate any of their undesired effects is of great importance. Dam safety management in Norway has moved towards active use of risk analyses. At the same time, emergency planning and exercises are emphasized as necessary tools for handling abnormal situations such as severer floods. Few dam safety experts or dam owners have experienced large floods, which makes it difficult to assess the complexity of floods. Floods may also be difficult to assess fully by means of traditional risk analyses, as these normally focus on single dams. Floods have a certain geographical extent and must be expected to occur simultaneously in a system of dams and reservoirs. This thesis hopes to extend knowledge of floods and dam safety. The main conclusion of a literature review of risk analysis and emergency planning is that human factors must be a focus. This is further supported by findings from the case studies of hazard floods. Emergency planning and exercises are believed to be of major importance to successful flood handling, but a survey of status for these issues in Norway shows that there is still work to be done. Many dam owners have not managed to start developing emergency action plans nor carry out emergency exercises. Not surprisingly, most of these are municipalities and private citizens, typical owners of smaller dams. Further revision of the emergency planning guidelines should take these findings into consideration. The authorities should bear in mind the need for alternative approaches to encourage these dam owners to develop emergency action plans. Possible problems related to development trends in our society also deserve attention, such as increased focus on cost-effective organizations at the expense of safety and the need for robust organizations and technical systems to handle future emergencies