Assessment of surface runoff, accelerated erosion, and diffuse pollution potential in the Potengi River Watershed, Rio Grande do Norte, Brazil

This study aimed to analyze the potential for surface runoff, accelerated erosion, and diffuse pollution in the Potengi River Basin (PRB), with a focus on identifying priority areas for conservation and restoration. An integrated Multi-Criteria Decision Analysis (MCDA) methodology was utilized within a Geographic Information System (GIS) environment. This approach incorporated various geoenvironmental attributes, including geological units, slope, thickness of unconsolidated materials, permeability, drainage density, surface water storage features, landform shapes, rainfall, land use and land cover, soil erodibility, soil texture, and concentrations of available phosphorus (P) and organic matter (OM). The results indicated that the PRB is primarily characterized by low to moderate surface runoff potential, covering 98.44 % of the area. However, approximately 60.91 % of the area is at high risk of accelerated erosion due to factors such as steep slopes and highly erodible sandy soils. Additionally, around 38.96 % of the watershed area exhibited a high to very high potential for diffuse pollution, emphasizing the vulnerability of water resources and the need for integrated management strategies, including the restoration of riparian vegetation. The analyses highlighted the importance of implementing measures to mitigate the impacts of erosion and pollution, thereby promoting environmental sustainability within the PRB. Furthermore, the methodology was applied successfully to characterize these processes and can be replicated for other watersheds, especially in semiarid regions where environmental pressures and natural vulnerabilities are significant. Methodological innovations in acquiring certain attributes, such as surface water storage features, drainage density, and soil erodibility, along with the use of sand and clay fractions to assess soil texture in map algebra operations, contributed to the quality of cartographic representation. This improvement allows for a more accurate and well-founded spatial analysis.