A Multicriteria Assessment of Vulnerability to Extreme Rainfall Events on the Pacific Coast of Mexico

The likely increase in extreme rainfall events (ERE) due to climate change, particularly associated with tropical storms and hurricanes, threatens coastal communities worldwide. A model based on socioeconomic and environmental indicators was used to assess and categorize vulnerability to ERE at the municipal level, in Sinaloa, a coastal state of northwest Mexico. Coastal vulnerability was assessed based on a system of indicators, integrated into five criteria within two higher categories: response capacity (Economic conditions, Social development, and Living standards), and severity (Geographic exposure and Risk intensifiers). From a preliminary set of 25 indicators, three of them were selected by criterion using the Delphi method, and their values were later standardized from 0 (low) to 1 (high) on a vulnerability scale. Both criteria and indicators were weighted following an analytical hierarchical process (AHP), resulting in the main determinants of vulnerability being Geographic exposure (0.43) and Economic conditions (0.34). This first approach to a vulnerability assessment using standardized values showed that Guasave (to the north) and Escuinapa (to the south) are the most vulnerable municipalities, scoring >9.0 (with 15 being the maximum score). In contrast, Culiacan and San Ignacio, both central municipalities, ranked as the least vulnerable (<5.5). A further analysis using the integral vulnerability index (IVI) corroborated Guasave (3.73) and Escuinapa (3.15) as the most vulnerable, discarding latitudinal changes as a possible promotor of vulnerability. Although the coastal population was the main determinant of vulnerability (median = 0.57), other indicators associated with severity as well as response capacity were responsible for the increase in IVI scores. This study highlights the need for an integrated vulnerability analysis to support public policies and the decision-making process to protect coastal communities from environmental climate change.