Flood inundation modeling using HEC-RAS: the case of downstream Gumara river, Lake Tana sub basin, Ethiopia

Abstract

This study presents the preparation of floodwater depth, the velocity of the flood, and water surface elevation profile with the application of unsteady flow 2D Hydrodynamic models and GIS. Flood frequency analysis is used for the prediction of peak flow. The water depth up to 1 m inundated a large amount of area of 52.5134 km², 52.4756 km² and 52.4403 km² for a 10-, 100-, and 1000 years return period respectively. Much amount of inundated area covered with a velocity value up to 0.15 m/s in all flood events, which is 53.207, 52.656, and 52.064 km² for flood events of 10, 100, and 1000-year respectively. The highest water surface elevation in the 10, 100, and 1000-year flood events was observed between 1785 and 1787 m with an inundated area of 58.806, 58.843, and 58.827 km² respectively. Finally, the result of this study is useful for early warnings, municipal planning purposes, emergency action plans, flood insurance rates, and ecological studies in the research area.

Keywords:

• Flood inundation modeling
• HEC-RAS
• flood map
• 2D hydrodynamic models
• Lake Tana sub-basin
• Gumara river

Data availability

The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

Disclosure statement

Authors have declare that they have no known personal relationships that could have appeared to influence the work reported in this paper.

Ethical statement

The authors state that the research was conducted according to ethical standards and we declare that this manuscript is original, has not been published before, and is not currently being considered for publication elsewhere. We confirm that the manuscript has been read and approved by all named authors. We further confirm and understand that the Corresponding Author is the sole contact for the Editorial process.