Multicriteria dam safety risk assessment model based on fuzzy logic
FAHP, Dam potential risk, Vulnerability, Dam safety
Dams are water structures that contribute to the socioeconomic development of a region. However, the absence of adequate safety procedures increases the risk of failures with the potential to cause significant impacts to downstream areas. This work developed a fuzzy safety risk assessment methodology for water accumulation dams located in the semi-arid region of Brazil. The fuzzy hierarchical analytical process (FAHP) was used to obtain the weight of the indicators and the aggregated scores corresponding to the vulnerability and potential harm criteria. In the fuzzy inference phase, the system was divided into two stages to obtain a more representative model. In the first step, vulnerability was estimated using conditional IF-THEN statements to estimate the combined effect of technical characteristics, conservation status, and security plan. Then, the defuzzified vulnerability values were combined with the potential harm to estimate the resulting potential risk. When comparing the results obtained by the proposed model with the CNRH classification regarding the CRI, it was observed that the studied dams were categorized into equivalent classes. As for the periodicity, deadlines and frequency based on the proposed danger scale, they were more rigorous than those of the ANA and allowed the establishment of priorities for safety procedures, such as monitoring and sensing, appropriate to the situations encountered in the field. Therefore, the proposed model allowed incorporating the uncertainties of the specialists' subjective judgments into the decision-making process and can be inserted as an improvement in the normative assessment to estimate the risk of dams with similar characteristics.