Crafting Flood Risk Maps and Intensifying Social Vulnerability Studies for Heightened Awareness and Damage Mitigation: Villahermosa, Mexico case

In recent decades, the state of Tabasco, particularly its capital, Villahermosa, has faced recurrent flooding due to a combination of natural and human-induced factors. Situated in the southeast region of Mexico, the convergence of the powerful Usumacinta and Grijalva rivers, coupled with clayey soil and a semi-confined aquifer inhibiting water infiltration, has made the region susceptible to saturation and subsequent flooding. Deforestation in the river basins since the 1970s, transforming land use from forest to agriculture, has exacerbated runoff, contributing to increased flood risk.

The intensification of tropical cyclones and extreme weather events, indicative of global climate change, further heightens the vulnerability of the region. Despite experiencing significant economic losses and ecological degradation in the past two decades, Tabasco's flood prevention policies have proven ineffective. Recognizing the need for a more proactive approach, this study emphasizes the importance of long-term flood risk assessment, incorporating both the probability of occurrence and potential impact.

In Mexico, guidelines for flood risk maps were established in 2014, resulting in the National Atlas of Flood Risk. However, these maps predominantly focus on flood rates and historical occurrences, lacking a comprehensive approach to long-term forecasting. This study addresses this gap by constructing the first risk maps for Villahermosa. Following National Water Commission guidelines, the methodology considers hydrological studies, hydraulic simulations, and social vulnerability indexes.

The vulnerability maps incorporate socio-economic factors like employment, education, and housing composition, while hazard maps determine the severity index and impact on residential structures. Through GIS-based intersection, risk maps are generated, revealing that even areas exposed to flooding during high-return period scenarios exhibit a medium risk index. Nevertheless, limitations arise from incomplete socio-economic and demographic data, hindering accurate vulnerability assessments.

Despite challenges, the study estimates annual damages, projecting over 33,000 affected individuals and economic losses exceeding MXN 250 million (USD 14 million). The creation of risk maps for Villahermosa, albeit challenging with current data constraints, serves as an essential initial step. It calls for further research to develop comprehensive databases, fostering public awareness and informed territorial policies to address flood risks in Villahermosa and other flood-prone areas in Mexico.

The methodology employed in this study lays a robust foundation for flood risk management, community safety, and sustainable development. It not only aids in precise identification of flood-prone areas but also serves as a crucial tool for the scientific community to address hydrological hazards. Furthermore, it supports the evaluation of existing public policies and the formulation of more effective strategies for reducing losses and enhancing resilience.