Flood Plain Mapping and Hazard Assessment of Muga River by Using ArcGIS and HEC-RAS Model Upper Blue Nile Ethiopia

Solomon Bogale Aynalem

doi:10.11648/j.larp.20200504.13

Abstract

Flood happens repeatedly and is a common phenomenon in Ethiopia causing a lot of losses to human lives as well as damage to property. The majority of flood disasters’ victims are people living in and nearby stretch of floodplains. It results direct or indirect loss of agricultural productivity, infrastructure, and disruption of transportation access and services. The objective of this study was to analyze flood inundation area mapping and Hazard Assessment of Muga River. Flood generating factors, i.e. slope, elevation, rainfall, drainage density, land use, and soil type were rated and combined to delineate flood hazard zones using a multi-criteria evaluation technique in an ArcGIS environment. The flooded areas along the Muga River have been mapped based on highest flows for different return periods using the HEC-RAS model, ArcGIS for spatial data processing and HEC-GeoRAS for interfacing between HEC-RAS and ArcGIS. The areas along the Muga River simulated to be inundated for 5, 10, 25, 50 and 100 years return periods. The flooded areas along the Muga River are 18 km2, 21 km2, 26 km2, 34 km2 and 43 km2 for 5, 10, 25, 50 and 100 year return periods, respectively. Proper land use management and afforestation, is significant to reduce the adverse effects of flooding particularly in the low-lying flood prone areas. The result of this study will helps the concerned bodies to formulate develop strategies according to the available flood plain mapping and hazard to the area.

Highlights

Flood defines as high flow that exceeds or over top of the capacity either the natural or the artificial bank of the stream or the river channel [1]
Floods can be explained as excess flows exceeding the transporting capacity of river channel, lakes, ponds, reservoirs, drainage system, dam and any other water bodies, whereby water inundates outside water bodies areas
Flood is a continuous natural and reoccurring event in floodplains of rainfall areas like Ethiopia, where over 80% of annual precipitation falls in the four wet months [4]

Summary

Introduction

Flood defines as high flow that exceeds or over top of the capacity either the natural or the artificial bank of the stream or the river channel [1]. Since excessive rain on the land, streams overflowing channels or unexpected high tides or tsunamis wave in a coastal area. Floods can be explained as excess flows exceeding the transporting capacity of river channel, lakes, ponds, reservoirs, drainage system, dam and any other water bodies, whereby water inundates outside water bodies areas Flood is a continuous natural and reoccurring event in floodplains of rainfall areas like Ethiopia, where over 80% of annual precipitation falls in the four wet months [4]. The flooding can be caused by, for instance, heavy rain, snow melt, land subsidence, rising of groundwater, dam failures. Since the industrial revolution, climate change has been clearly influencing many environmental and social sectors; in particular, it has been showing significant impact on water resources

Objectives

Methods

Findings

Discussion

Conclusion