Analysis of the potential direct and indirect impacts of dam failures on storage services for multiple purposes

Unprecedented natural disasters due to the climate crisis are a global issue, threatening sustainable development, mostly because they are associated with life, assets, and infrastructure losses and damages to the environment. Recent disasters, such as floods, were responsible for the death and displacement of thousands of people. A storm could subsequently trigger dam failures, reinforcing the disastrous consequences, as these could be part of an infrastructure network that would irrigate and supply surrounding cities and communities with much-needed water. This shows that natural disasters can induce an interruption in water services due to a cascade effect on existent measures. Since dams are usually employed to tackle multiple water management problems such as water supply and flood control, the collapse is an event that causes direct, intense and rapid impacts, and indirect ones in the medium and long term. According to the National Dam Safety Information System (SNISB), the dam risk degree depends on the Risk Category (CRI) and their Associated Potential Damage (DPA), these consider variables such as technical characteristics, dam safety plan, potential for human losses, among others. However, this classification is mostly associated with direct impacts,, which does not prioritize hydrodynamic modeling associated with the socioeconomic impacts resulting from the interruption of service to user sectors, this will be considered an indirect impact. This research aims to evaluate the direct and indirect effects of the impacts caused by the failure of the 10 largest volume and high-risk dams in the state of Pernambuco, a region with semi-arid characteristics in northeastern Brazil. Here, we employed a simplified model of the explicit Saint-Venant equations, the HydroHP-1D. Based on the preliminary dam break simulations, parameters such as maximum flow, depth, speed, extravasated volume, area flood wave and flood wave arrival time were estimated and used to identify the region’s vulnerability degree, which direct impacts have a significant correlation. The proposal of assessing the indirect impacts involves quantifying the storage service loss from the dam considered through a water balance of the studied area. This service interruption covered the supply of water to human activities, energy generation or even combating drought in certain regions. The expected results of the modeling associated with quantification of the interruption of the storage service of the respective dam made through a water balance of the study area, can reinforce the need to consider, in the preparation of contingency and water security plans, studies that explore the consequences of the interruption of supply to dams, in case of rupture. In general, this research promotes relevant discussions about disaster risk water resources management through the phases of prevention, reduction, preparation, response and recovery, which is enhanced when society is aware of the conditions of vulnerability, in order to prevent losses of life and property.