Flood risk zone mapping using rational model in a highly weathered Nitisols of Abakaliki Local Government Area, South-eastern Nigeria

Abstract

The lack of spatially explicit flood hazard mapping has hampered the development of appropriate flood interventions at community levels in Nigeria. This paper reports on a work conducted to develop a local government level flood hazard map to delineation flood vulnerable areas. Flood vulnerability mapping in this work was addressed from a perspective of administrative unit as the unit of investigation. The study is anchored on the Modeling Flow based on Relational Rule for flood assessment using ArcGIS in combination with modified rational model. The output of the modified rational model was integrated into the Geographic Information Systems environment by the arithmetic overlay operation methods. The results show that the delineated areas/sub-catchments however experienced the same rainfall intensity of 414.2 mm/h but the flood extents in the areas are different. For instance, the very high flood risk zone covers about 22.8% of the study area while the low risk zone covers about 44.3% and the possible areas likely to experience seasonal floods with a given rainfall input are mostly below 40 m elevation. The results of this study will be helpful to prioritize development efforts at grassroot in the study location and to formulate flood adaptation strategies.

GIS-based evaluation of shallow aquifer vulnerability to pollution using DRASTIC model: a case study on Abakaliki, southeastern, Nigeria

“…1). Geographically, Abakaliki is stationed between latitudes 6° 5′ N to 6° 20′ N and longitude 8° 5′ E to 8° 20′ E. Abakaliki covers eastern part of Ebonyi State, occupying a total landmass of about 584 sq.km (Aja et al 2019). The study area reveals two prevalent topography which comprises of a vast lowland and undulating hills.…”

Flood forecasting using quantitative precipitation forecasts and hydrological modeling in the Sebeya catchment, Rwanda

“…In most cases, urban areas are mostly affected because industries and cities are usually situated in flood-prone areas (Löschner et al 2017). Accordingly, risks by severe flood events increase on account of the increase in population and economic development (Padi et al 2011;Aja et al 2019). There have been different episodes of recurring hazardous flooding around the world and it is pertinent to reflect on the impact on countries with least resilience to such natural hazards.…”

Application of an Index-Based Approach in Geospatial Techniques for the Mapping of Flood Hazard Areas: A Case of Cape Coast Metropolis in Ghana

“…When authorities correctly map flood hazard areas, it facilitates not only the timely rescue of potential victims from the flood-related crisis but also prevents post-crisis difficulties, such as issues related to insurance claims [11,12]. Several studies, including the works of Aja et al, Asare-Kyei et al, Baishya and Sahariah,Danumah et al,and Elkhrachy [7,11,[13][14][15] have argued for the use of geospatial techniques in mapping areas of flood hazards. The Sendai UN Conference on Disaster Risk Reduction in 2015 also highlights the importance of using geospatial techniques by states/local actors to implement programs designed to prevent and reduce disasters and their consequences [16,17].…”

“…Many sub-Saharan African countries are highly susceptible to floods [18]. Ghana, Nigeria, Burkina Faso, Cote d'Ivoire, and Senegal continue to experience flood problems annually [13,14,19]. In 2012, for instance, three million homes in Nigeria were inundated by floodwaters, and an estimated 1.4 million people were displaced [20].…”