Analysis of flood warning and evacuation efficiency by comparing damage and life-loss estimates with real consequences related to the São Francisco tailings dam failure in Brazil

Abstract

Abstract. Economic damage and life-loss estimates provide important insights for the elaboration of more robust alerts and effective emergency planning. On the one hand, accurate damage analysis supports decision-making processes. On the other hand, the comparison of different flood alert scenarios through modeling techniques is crucial for improving the efficiency of alert and evacuation systems design. This work evaluates the use of flood damage and life-loss models in floods caused by tailings dams through the application of these models in the real case of the São Francisco dam failure, which occurred in January 2007 in the city of Miraí in Brazil. The model results showed great agreement with observed damage and loss of life. Furthermore, different simulations were done in order to measure the impact of increasing and decreasing alert system efficiency on life-loss reduction. The simulated scenarios exploring the inefficiency of flood alert and evacuation revealed that life loss could have reached the maximum rate of 8.7 % of the directly exposed population when considering the more pessimistic and uncertain scenario instead of the actual null life loss achieved. The results of this work indicate that the models could represent both the observed accident and different alert and evacuation efficiency impacts. It highlights the importance of developing and implementing robust alert and evacuation systems and regulations in order to reduce flood impacts.