MAPPING OF EROSION RISKS IN URBAN AND PERI-URBAN ENVIRONMENTS USING GEOGRAPHIC INFORMATION SYSTEMS: THE CASE OF LUBANGO, HUÍLA

Abstract

Water erosion in rapidly growing cities results from the interaction of rainfall, terrain, soil properties, vegetation cover, drainage and land-use patterns. This theoretical and analytical article examines erosion-risk mapping in urban and peri-urban environments, using Lubango municipality, Huíla Province, Angola, as a case study. The approach combines a critical review of recent literature, an assessment of the geospatial sources used in a previously prepared QGIS risk map, and spatial interpretation of the five represented risk classes. Data from the Angolan Institute of Geographic and Cadastral Information, ESA WorldCover, OpenStreetMap, SRTM/NASA/USGS digital elevation models and WorldClim climate surfaces were considered. The cartographic reading indicates a greater concentration of high and very high risk in the northern/northwestern sector, particularly Mapunda, as well as localized occurrences along drainage lines and urban expansion fronts. The discussion shows that GIS makes it possible to integrate biophysical and anthropogenic factors in a spatially explicit framework, but it does not replace field validation or quantitative model calibration. It is concluded that erosion-risk mapping should be incorporated into municipal land-use planning, drainage management, vegetation protection and multitemporal monitoring of urban expansion.