Flood Vulnerability Modeling Using GIS and Remote Sensing: The Case of Shashogo District, Hadiya Zone, Southern Ethiopia

Abstract

River flood is one of the natural hazards that have negative impacts on population and property. It occurs in the lower course of a river when excessive rainfall occurs in upper course of adjacent highlands. Since flood is unavoidable natural phenomena, adopting mitigation measures are crucial. This study was conducted in Shashogo district of Southern Ethiopia with the objective of identifying and mapping flood vulnerable areas. For this purpose the following data mentioned below wereused. Ground Control Points (GCP)were collected from Google earth, Digital Elevation Model (DEM) and Landsat 8 down loaded. Besides, data such as, soil data, rainfall, and population data were collected from different institutions. Flood vulnerability factors namely slope, distance to rivers, elevation, rainfall, drainage density, land use/ cover and soil type were generated. In order to map flood vulnerable area, Geographic Information System (GIS), Remote Sensing and Analytical Hierarchy Process (AHP) were used. AHP was used for computing weight for the parameters by comparing seven factors. The weight derived for slope, drainage density, distance to river, land use land cover, rainfall, elevation, and soil type, are: 21%, 18%, 15 %, 13%, 12%, 11% and 10%, respectively. The consistency ratio was less than 0.1(CR -0.6) which is acceptable weight to compute weighted overlay analysis in GIS environment. The result shows that a different degree of flood vulnerability at different locations in Shashogo district was found. The map indicated that the degree of flood vulnerability scale varies from very low vulnerable to very high vulnerable. From the total area of 358.1 Km² 0.28 % and 47.98% of the study area was found in very high and high vulnerable to flood respectively. Especially the central parts of the study area surrounding Lake Boyo were highly vulnerable for flooding. Since flood cannot be avoided totally, it is better to take mitigation measure in order to reduce the flood vulnerability of the society. It can be generalized that to reduce flood vulnerability using nonstructural method like early warning and flood vulnerability map to development of protection structure is important with integrated watershed management method to reduce flood vulnerability effectively.

Keywords: Flood vulnerability, GIS, Remote Sensing, Multi-Criteria Evaluation, and Analytical Hierarchy Process.

DOI: 10.7176/JEES/12-10-01

Publication date:October 31^st 2022