Flood vulnerability assessment using GIS at Fetam watershed, upper Abbay basin, Ethiopia

Flood is a danger to human beings and their properties because less consideration is given for risk analysis and assessment of risk areas. The main aim of this study was to assess the flood vulnerability areas of Fetam watershed. For analyzing this issue, flood generating factors: slope, elevation, land use/land cover, drainage density, rainfall, and soil types were rated and collected to mark out flood vulnerability zones using a multi-criteria evaluation technique within the Geographic Information System (GIS). Maps were constructed using past data on river banks and discharge of earlier floods along with topographic data to illustrate areas susceptible to flood for various discharges. The influences of all overflow distribution factors were calculated using pair-wise evaluation techniques for decisive weighted-overlay investigation of each factor in flood vulnerability assessment. The flood vulnerability valuation map showed that 67.54, 634.11, 280.89, 121.28, and 2.81 km(2) areas correspond to very high, high, moderate, low, and very low flood vulnerabilities respectively. Residential areas and farming fields are located along with the flood hazard areas, which are susceptible to flooding. Hence, these areas are vulnerable to social and economic development due to loss of life and damage to properties of resident people. The main result of this study showed that the upstream and center part of Fetam watershed is highly sighted than the downstream part.