Assessment of Flood Susceptibility in Conakry, Guinea Using GIS-Based AHP Multi-Criteria Analysis

The Republic of Guinea, located in the tropical climatic zone, is one of the wettest countries in West Africa with high rainfall, which means it can be vulnerable to flooding, and is the overflow of water onto land that’s normally dry. It can happen gradually or suddenly, and its impact ranges from minor inconvenience to major disaster. Flooding is a growing environmental threat in Conakry, Guinea, exacerbated by rapid population growth, lack of proper zoning, building regulations, and poor drainage infrastructure. To assess the Flood Susceptibility in Conakry, Guinea, we use GIS-based Analytic Hierarchy Process (AHP) and use the following dataset, including ten spatial factors, including elevation, slope, LULC, NDVI (2014 & 2024), rainfall (2014 & 2024), TWI, drainage density, soil type, and proximity to rivers and roads. Pairwise comparisons yielded a consistency ratio of 0.074, confirming methodological soundness. Flood susceptibility maps for 2014 and 2024 show that high-risk areas increased from 20.5% (8,419.2 ha) to 33.3% (13,669.2 ha), while low-risk zones decreased from 15.0% to 6.1%. Built-up areas expanded by 5.9%, while vegetation declined by 20.4%, intensifying runoff and reducing infiltration. High vulnerability areas correspond with low elevation (< 14 m), dense drainage networks (> 6,082 km/km²), very high TWI (> 2.68), and poorly draining soils like Stagnosols and Fluvisols. The findings provide the first high-resolution flood susceptibility map for Conakry and highlight priority zones for urban planning, infrastructure development, and disaster risk reduction. The model is adaptable for flood-prone, data-limited cities across West Africa.