Diagnóstico da micro e macrodrenagem e mapeamento das áreas de inundação do município do Cabo de Santo Agostinho/PE

Abstract

In Brazil, flood-related issues in urban environments are present in many municipalities, resulting in damage to society. Therefore, this study aims to diagnose the Urban Drainage and Stormwater Management System (SDMAP) and map the flood-prone areas of the municipality of Cabo de Santo Agostinho/PE. Initially, secondary data collection was conducted using databases from the Brazilian Institute of Geography and Statistics (IBGE) and the National Sanitation Information System (SNIS) to obtain socioeconomic information and drainage indicators. The microdrainage diagnosis was performed using Google Earth Pro, with Street View images, to locate, identify, and classify drainage system structures, considering type, conservation status, and number of inlets. The macrodrainage diagnosis was based on image analysis, evaluating waste accumulation, slope stability, bottlenecks, and channel bed types. Subsequently, the municipality’s drainage problems were prioritized using control checklists from Environmental Impact Assessment, classifying them in order of priority. The drainage performance assessment was conducted using the Drainage and Stormwater Performance Index (IDAP), with indicator data collected from SNIS and scores ranging from 0 to 5 assigned to each indicator, which were then summed to generate the IDAP. The assessment of flood-prone areas considered four variables: Land Use, Hypsometry, Slope, and Pedology. The variables were reclassified according to their vulnerability level, categorizing them as "very weak," "weak," "moderate," "strong," and "very strong." Through the research results, 3,391 storm drains were identified in the municipality, with over 60% of the structures classified as well-maintained, and more than 70% categorized as curb inlets with a single entrance. Additionally, 919 inspection chambers were identified. Regarding macrodrainage, the most frequent problem was the number of bottleneck points and the frequent presence of sediments in the channels, especially those located in highly urbanized areas. The flood area mapping revealed that the most flood-prone neighborhoods are those situated in areas with less pronounced relief within the basin. This reality exposed the presence of households in these risk areas, as confirmed by historical flood records in the municipality. Overall, it is evident that the municipality requires better planning and management of risk areas and improved drainage system efficiency to serve the population during extreme events. Therefore, future studies simulating heavy rainfall scenarios are essential to assess how different areas of the city respond to stormwater runoff, particularly considering the drainage system’s capacity to manage stormwater and identifying critical points that require urgent intervention.