Introduction

Flooding in Osogbo City is a frequent occurrence, and over the years it has left many residents of Osogbo in devastating conditions as it affects the livelihood of people. This project demonstrates the techniques of Remote Sensing and GIS in mapping flood in Osogbo City.

Methodology

A flood hazard map based on eight (8) flood conditioning factors (Drainage Density, Slope, Rainfall, Elevation, LULC, NDVI, and Flow accumulation) was developed. These factors were reclassified and assigned relative weights since all factors do not have the same degree of influence on the hazardous areas.

Analysis

After the determination of the weights of the factors, the re-classified factors were used as an input and handled via the GIS-based weighted superposition (weighted overlay) method by utilizing the specific weights for each factor to create a flood hazard map, which shows the hazard levels: Very High, High, Moderate, Low, and Very Low Flood Hazard Levels.

Results

The result of the flood hazard mapping shows that 29.7% and 11.7% of Osogbo City have “high” and “very high” flood hazard levels respectively, these areas are flat areas located close to rivers and generally laying at low elevations, 0.8% and 31.9% have “very low” to “low” flood hazard levels, respectively, and 34.91% has “moderate” level of flood hazards.

Conclusion

In conclusion, this study provides valuable insights into the flood hazard assessment of Osogbo City. The results derived indicate that a significant proportion of Osogbo City is prone to flooding and these results can be used to inform disaster risk reduction and management strategies in the city.