Abstract:
The objective of this study was to assess flood causative factors, flood hazard, and risk
spatial distribution in the Upper Awash Valley Sub-basin using a Geographic information
system and remote sensing techniques based on multicriteria decision analysis of the
analytical hierarchy process approach. Seven flood causative factors (elevation, slope,
drainage density, distance from the river, rainfall, soil type, and land use) were prepared,
prioritized, weighted, and overlaid. Accordingly, the resultant flood hazard in the Upper
Awash Valley basin revealed, 4.4% (27260.33 ha), 26.58 % (164423.9 ha), and 11.56 %
(71544.33 ha) were subjected to very high, high, and medium flooding hazard area
respectively. The developed flood risk map showed that 1.69% (10434.61 ha), 17.16%
(106129.5 ha), and 11.23% (69448.3 ha), of the study area were subjected to very high,
high, and medium flooding risk areas, respectively. The created flood risk map was
compared to actual floods using satellite images, Google Earth, and ground observations
by gathering ground truth points in places that had actually experienced flooding. The
developed risk map showed good agreement with the areas that had been damaged by
previous flood occurrences, demonstrating that the method was successful. The result
gained from this study facilitates the identification of flood risk-prone locations, helps
governmental institutions, and non-governmental organizations for flood risk
preparedness and response measures effectively. Finally, an identified flood hazard and
risk area demand integrated flooding risk management measures like strengthening
institutional framework, Terracing, Land use planning, emergency response plan, timely
and effective early warning. Moreover, it is recommended that water release from the
upper stream hydroelectric reservoirs of the Koka Dam and the Awash hydroelectric
power be regularly checked and discharged before it causes the Awash River to overflow
