Flood Hazard Mapping: a Case Study of Tana River Watershed, Kenya

Flooding is a recurring natural hazard with socio-economic and environmental impacts. Flooding risks are linked to areas with rapid population growth, uncontrolled urban development, unplanned land-use change, and an unregulated municipal system. These are common occurrences in the developing countries. In Kenya, areas such as the Tana River watershed is frequently flooded and require easily readable and rapidly accessible flood hazard maps to prioritize mitigation. This study aimed to classify watershed zones based on the flooding hazard vulnerability. The study used weighted overlay method in ArcGIS to integrate various flood modulating factors. The hazard maps depicted different levels of vulnerabilities ranging from low to high risks. The majority of the area lie within the moderate risk zone. This study demonstrates that GIS-oriented multi-criteria analysis technique could be used effectively and efficiently for modeling flood hazards for disaster management decision making. One of the downsides of this analysis however is that the DEM used has a coarser spatial resolution. A finer spatial resolution dataset could be used to fine-tune the results and thus improved decision-making.