Flash flood risk assessment using geospatial technology in Shewa Robit town, Ethiopia
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ORIGINAL ARTICLE
Flash flood risk assessment using geospatial technology in Shewa Robit town, Ethiopia Awlachew Dejen1 · Sandeep Soni1 Received: 21 July 2020 / Accepted: 17 October 2020 © Springer Nature Switzerland AG 2020
Abstract Flash flood is an extreme flooding event which is quick, short-lived, hazardous phenomena having negative environmental and socio-economic impacts. Flood risk management is essential to reduce the effects of flood on human lives and livelihoods. The main goals of this research were flash flood risk analysis and risk quantification in terms of land use land cover using geo-spatial technology in Shewa Robit town. In the present study, elevation, slope, drainage density, distance from river, NDVI, land use land cover, topographic wetness index and curvature were used as parameters determining flash flood risk. To realize these research objectives, all these data were reclassified in to five classes and different weights for each of them was assigned using analytic hierarchy process. Weighted Sum Overlay (WSO) analyses of ARC GIS software was employed to produce flood vulnerability map. Then, the accuracy of generated flood risk map was validated using historical flood data. According to the result, about 3.08%, 14.62% and 20.66% of Shewa Robit town are at a very high, high and moderate flash flood risk, respectively. In addition to this, flood risk was also quantified in terms of land use land cover. The result indicates that the settlement land use is the most vulnerable with an estimated area of 12.01 ha, 99.57 ha and 174.16 ha in very high, high and moderate risk classes. The outcome of the study will be applicable in flood hazard management and mitigation strategies. Keywords Shewa robit · Geospatial technology · Flash flood · Risk assessment
Introduction Flood in any area is natural phenomenon which is occurring because of heavy rainfall and runoff. The more severe type of flooding is flash flood that is extreme event which is quick, short-lived and hazardous. These two events are supported by natural and geographical features and that they cause socio-economic and environmental problems like loss of life, destruction of properties and natural environment (Watson and Haeberli 2004). Flash floods are usually caused by high amount of rainfall for a short period (Murray and Ebi 2012). It is very challenging to predict because runoff is generated rapidly and intensively, water level rises quickly and discharge reaches the peak within an immediate time * Awlachew Dejen [email protected] Sandeep Soni [email protected] 1
Department of Geography and Environmental Studies, Debre Berhan University, Debre Berhan, Ethiopia
(Borga et al. 2011). As a result of global warming and climate change, unpredictable weather events like flash floods are increasing (Groisman et al. 2005). According to Mason et al. (1999), climate change in most part of the world causes decrement in annual rainfall and it is a cause of increment in the occurrence of extreme rain events such as flash flo
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