A comparative study between formal guidelines and resident-led practices for mitigating flood impacts on residential buildings: A case study in Santo Amaro do Maranhão, Brazil

Flooding is one of Brazil’s most frequent and destructive natural hazards. In Santo Amaro do Maranhão, northeastern Brazil, due to the lack of formal effective government interventions, residents have developed their own architectural strategies to reduce flood risks. This study investigates these resident-led adaptations shaped by socio-economic conditions, as well as construction process and perceived effectiveness of these strategies. In this context, a comparative study can be useful to understand the differences between formal guidelines and resident practices. Fieldwork was conducted over three months in the communities of Vila Nova, Alto Formoso, and Atim, including interviews with 29 households, architectural documentation, geospatial mapping, photography, and observation. The strategies were coded as elevation, wet floodproofing, floodwalls, and levees derived mainly from Federal Emergency Management Agency framework. The findings indicate that elevation on fill was the most prevalent strategy (35%) and was generally evaluated positively by residents, followed by wet floodproofing (24%), which received predominantly negative evaluations, while floodwalls (3%) and mixed strategies (24%) showed mixed results. The comparative analysis revealed potential issues in the implementation of these local strategies, including lack of accessibility, slippery surfaces, inadequate drainage, and unsuitable material selection. Therefore, the study highlights that implementing formal guideline recommendations to address each identified potential issue by translating and integrating them into municipal planning tools could enhance these resident-led practices.