Flood Impact Analysis and Mitigation Measures, A Case of Basaka Lake

Abstract

Floods are the most frequent and destructive natural disasters in both developed and developing countries from the ancient up to now. Awash River basin is a major river basin that has serious flood problems in Ethiopia. Basaka Lake is situated in the tectonically active main Ethiopian rift in middle Awash River basin. As lake level increased it causes problems on traffic routes from Addis Ababa Djibouti railway and road networks. Land use such as grazing area, farmland and area in the sugarcane plantation are flooded. Because of lack of mitigation measures; loss of lives, abandoned of cultivated field and destruction of social infrastructures are becoming increasing from time to time. The purpose of this study was to analyze flood impact using GIS and find mitigation measures a case of Basaka Lake. The required input data for this study were, DEM (30*30), Land use, soil data, road network data, Rainfall, Satellite image and topographic map. After the data was collected, an analysis of all the collected data was made. Flood impact analysis was done to identify impact of flood prone areas on land use, road and soil with help of the GIS system. It was found that land use, road and soil was affected up to some extent when the areas along Basaka Lake are flooded. This information can be used for planning an effective flood emergency response in flood-inundated area using GIS.. The procedures that can be performed using the system are Property data linking, Emergency planning and Sharing risk data with public. Thus response based on GIS are effective tools for reducing flood damage. Flood causative factors such as rainfall, slope, elevation and drainage density were analyzed in the GIS environment. The result indicates that the area around Basaka Lake is highly susceptible for flood due increase of water level. The results of the image analysis for the considered periods indicate that the Lake expansion is very fast and has negative impact. The recent expansion towards south and north-east directions affected productivity of the Abadir Extension farms and dangerous for the sustainability of MSE and Metehara town in particular. From impact analysis land use such as semi-desert grassland with bush land, Acacia bush land/thicket were affected. The total land use affected in primary risk area is 17.781 sq. km and in 30 years risk area for flood is 16.369 sq. km. This would influence the livelihood of local people because their life depends on live stocks and camel production which needs sufficient grassland. Valuable infrastructures such as road and railway were also affected in the impact area due to inundation. From study finding the total road networks that would be affected were 12.5 km. The widespread flood impact on people’s crop production, livestocks and camel causes a great economic loss, because they are the most source of income for local community. In doing so, this thesis help and become an input in implementation of mitigation measures to alleviate risk due to inundation. It benefit the study area community directly where as any others can be benefited indirectly.