Mapeamento de áreas agrícolas em risco de inundações na bacia hidrográfica do Rio Búzi, usando a ferramenta GIS Flood Tool

Abstract

Floods are phenomena that occur worldwide and have been increasing in frequency and intensity in Mozambique's river basins, causing significant losses of agricultural areas and damage to infrastructure that supports the local economy. In this context, the present study aimed, as its general objective, to map agricultural areas at risk of flooding in the Búzi River Basin. To achieve this objective, geoprocessing techniques were employed using Geographic Information System (GIS) software (ArcGIS and QGIS). Data from a Digital Elevation Model (DEM) with a spatial resolution of 12.5 m and Land Use and Land Cover data with 10 m resolution were integrated in ArcGIS 10.8. Using the GIS Flood Tool, three flood extent scenarios were generated: Level 1 (5.5 – 6 m), Level 2 (6–12 m), and Level 3 (12–18 m). Spatial analysis revealed that for Level 1, the flooded area is approximately 10%; for Level 2, it increases to 16%; and for Level 3, it reaches about 22% of the basin's total territory. These flood maps were validated using historical flood data from the Dartmouth Flood Observatory (DFO). Validation indicated Kappa index performances of 66%, 78%, and 82%, respectively, demonstrating good agreement with the reference flood map. From the Land Use and Land Cover map, the agricultural class was extracted and overlaid onto the three flood levels. Spatial analysis allowed the conclusion that approximately 19% of the agricultural area lies in Level 1 flood risk zones, 23% in Level 2, and 26% in Level 3. Supporting agricultural infrastructures such as roads, settlements, water sources, and markets were also identified in Level 1, 2, and 3 flood risk zones, highlighting vulnerabilities in the functioning of the agricultural system. Therefore, the present study provides results that serve as a solid basis for decision-making when developing response and adaptation plans, promoting more effective risk management focused on the resilience of vulnerable communities in the Búzi River Basin