Flood Vulnerability and Risk Mapping in Tana River River County, Kenya, Using Multi-Criteria Decision Analysis and GIS


  • Alfayo Koskei Egerton University


Flood hazard mapping, flood exposure mapping, environmental vulnerability to floods, GIS, Tana River.


Flood is one of the major recurring and seasonal environmental problems in Kenya and often causes huge losses of life and economy through destruction of property. The increase in magnitude and frequency of floods and landslides are attributed to human activities in the most vulnerable areas and climate change phenomena such as Indian Ocean Dipole. Among the notable and vulnerable areas is the Tana Delta. The flood vulnerability mapping of the region is crucial for wetland management, early warning system and development of response initiatives. The purpose of this study was to develop flood vulnerability maps for flood prediction in the study area. GIS-based methodologies were used to map the distribution and extent of floods and landslides which include spatial distribution models such as Digital Surface Model (DSM), Digital Elevation Models (DEM) and Landsat Imagery. Geographical Information System (GIS)/Remote Sensing (RS)-based multi-criteria approach was used to select the flood causal factors and vulnerability assessment. Relative weight of each factor was determined using Analytical Hierarchical Process (AHP). The first step in the flood vulnerability analysis was to identify the factors. Then each factor was analyzed with satellite images in the GIS environment, weighted and overlaid to produce the flood vulnerability maps. The results show that although very highly vulnerable areas cover the smallest proportion in the study areas (6%) a sizable proportion of areas has substantial vulnerability (20%). The extremely low and minimal flood vulnerability classes cover 11.1% and 27.4%, respectively. The model predicted that a total of 217,882 hectares of land would be inundated during a rainy period. Areas that are under highly vulnerable in the study area include Garsen North, Mikindu, Chewani and Kipini West. The extremely highly vulnerable areas are: Garsen Central and Garsen South. All these areas are within high and extremely high hazard zones and are dominated by low elevation and slope degree. These vulnerability maps are critical in mapping the flood and landslide events in order to develop a clear roadmap to an early warning system.


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How to Cite

Koskei, A. (2022) “Flood Vulnerability and Risk Mapping in Tana River River County, Kenya, Using Multi-Criteria Decision Analysis and GIS ”, Egerton University International Conference. Available at: https://conferences.egerton.ac.ke/index.php/euc/article/view/41 (Accessed: 4 February 2023).



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