Flood vulnerability assessment and disaster risk reduction in Kubwa, Federal Capital Territory, Nigeria (original) (raw)
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This study attempted to assess the spatial impact of river Kaduna flooding of Kaduna South LGA on the surrounding areas using High Resolution Satellite Imagery. A Digital Elevation Model (DEM) was developed with Arc. GIS.10 version to identify flood prone areas along the middle course of the river. A flow accumulation model was created using the DEM and was reclassified into very high risk, high risk, moderate risk, low risk and very low risk zones using equal interval of separation based on elevation. This was overlaid on the map of the settlement extracted from land use/land cover classification of 1990, 2006 and 2010 landsat ETM+ images using ENVI version 4.7 to produce a vulnerability map of the area. The result of the analysis shows that about 30% equivalent to 17.76km 2 of 59.03km 2 is at very high risk to flood and the remaining 70% is either moderate or at low risk. It was shown that a flood map can be effectively used in public enlightenment, disaster response planning and flood risk management. This study demonstrated the contribution of geospatial methods in mitigating and monitoring the effects of flooding along river Kaduna and environs.
Journal of Geography, Environment and Earth Science International
A flood is an overflow of water that submerges land that is usually dry. Flooding may occur as an overflow of water from water bodies, such as river, lake or ocean, in which the water overtops or breaks levees, resulting in some of that water escaping its usual boundaries, or it may occur due to an accumulation of rain water on saturated ground in an area. To find out the most vulnerable communities, the Digital Elevation Model (DEM) and location data of selected communities were used. The Image Re-class and Map Overlay were performed on QGIS software to identify communities that are most affected. The result shows that the region has no river channel that discharge excess water easily. It also shows that four, out of twelve settlements were located at the high risk zone. The settlements are Uniport, Omuoda, Omuahunwo and Okparagwa. It was recommended that the high risk zone in the area should be provided with artificial water channel that will contain and convey surface sun-off to ...
International Journal of Society Systems Science, 2011
Spatial information technologies are changing the way in which decisions are taken in relation to the environment. Geographic information system (GIS) is one of such technologies that help to generate products useful in terrain analysis. In Nigeria, especially in the study area, floodplains and river corridors have been misused resulting in severe environmental hazards. Up-to-date information is required to assist decision makers in tackling the problems arising from the misuse of our floodplains. To this end, the capability of remote sensing (RS) and geographic information systems have been explored to generate products such as digital elevation models (DEM), slope maps and risk analysis maps which give useful information about the terrain. In our opinion, the information provided by these technologies can significantly improve strategic decision-making processes in floodplains and river corridors worldwide.
Geo-Mapping of Areas Vulnerable to Ala-River Basin Flood Disaster Risk in Akure, Ondo State, Nigeria
Flood is identified as one of the major disasters in the world; it destroys both human and properties across the world, where lives are lost, properties, public infrastructure, farmlands and agricultural produce with farm crops carted away as a result of flood disaster. Studies revealed that the flood in itself is not the danger, but the level of human vulnerability to flooding disaster risk, which enhances its destructive capabilities. However, based on the challenges poses by flood disaster risk, this research identifies Ala river in Akure as a potential cause of flood, considering its location and other human activities around the river. Therefore, the research used Ala-river a case study to identify and mapped out areas susceptible to flood disaster risk. The research made use of both literature review and conducted goe-data gathering with the application GIS-computer database to retrieve georeferencing relevant data from the fieldwork in the study area of Ala-river basin to mapped out locations vulnerable to achieve the research aim. The research adopted a Geo-mapping of the vulnerable area to Ala-River basin using arc-GIS tool in combination with other software such as IKONAS and OLI (Operation Land Imager) for the production of the study area imagery, ER-ITERIM was used for the collection of rainfall data and FAO was applied for digital soil mapping. These applications produced; the land use/land cover map, digital elevation map, buffer map using 30 meters setback, annual rainfall map, soil types map, vulnerability map and soil textural table for the study area. Analysis of the produced and generated maps shows 316 buildings vulnerability to flood disaster risk; the soil texture and types, and alternative use to which the soil types can be useful. The research recommends that demolition of the identified 316 buildings prone to flood disaster and compliance of building construction to 30 meters setback by developers. Others are the conversion of the future land setback for urban agricultural purposes and preservation of water retention areas for agricultural activities during the dry season among others. The study concludes that relevant government agencies in the State and in particular in Akure South Local Government should ensure prompt compliance and implementation of the recommendations to avoid potential flood disaster risks.
This study makes use of the integrated approach of Remote Sensing and GIS techniques in flood management with the goal of identifying areas vulnerable to flood hazard in Ibadan Metropolis. Ibadan is the largest indigenous city in the continent of Africa and had experienced a lot of various severities of flood occurrences in the last fifty years. Topographic Map and Landsat TM image of 1993 and 2000 respectively were processed, scanned, digitized, interpolated, classified and overlaid using ILWIS 3.3 academic and ARC GIS 9.2 software modules to generate classified land cover map, Digital Terrain Map (DTM), Triangulated Irregular Network (TIN) and flood vulnerability map of the study area respectively. The results obtained shows that, areas lying along the banks of River Ona and River Ogunpa are most vulnerable to flood hazards with the vulnerability decreasing towards the northern part of the city, much of the area is built up with improper planning and this gives rise to high vulnerability to flash flood hazards. The Odo Ona, Idi Isin, Eleyele, Olopometa and Molete areas are the most vulnerable to flood threat. The incessant violation of land use plan, unchecked population growth, old nature of the structures and poor materials used in the construction of the houses make the areas vulnerable to flood hazard. In reducing the vulnerability of these areas from flood there is need for improved land use planning, removal of structures from River Ona and Ogunpa flood plains around the city, intensify environmental education to the residents and enhance the active participation of government agencies in the continual generation of flood vulnerability maps of urban centres. 1. Introduction Flooding is the commonest natural hazard that can happen any time in wide variety of locations within rainy season due to high intensity of rainfall events. The projections of climate change trends indicate increase of the occurrence of the intense rainfall events both in terms of the intensity as well as their frequency (IPCC, 2007). The projected high intensity rainfall events coupled with the changes in the land use patterns are expected to have implications on the intensity of river flooding and local flash flooding in a flood plain region and can significantly alter the spatial extent of future flood risk. A flood is an overflow of expanse of water that submerges the land. Floods are among the most destructive acts of nature. Over the past thirty years, floods have been the most catastrophic natural disaster affecting, on average, about 80 million people per year or half of the total population affected by any natural disaster, causing economic damage worth over US$11 million annually around the world (IFRCRCS,1998). As human activities downstream of rivers increases, it results to increase in greater flood damage, floods are also increasing in size and frequency due to human activities in the upstream section of the river system (Dutta et al., 2006). Worldwide , flood damages to agriculture, properties and public utilities amount to billions of dollars each year in addition to the loss of precious human and animal lives. In most cases, flooding is caused by a river over-spilling its banks. This can be due to excessive precipitation, combined with inadequate channel capacity. Over-spilling can also occur due to obstruction in the river bed. Flooding can also occur at confluences of streams when the main river is in high stage and backs up into the tributaries and areas there about. The role of Geographic Information Systems (GIS) in disasters analysis and management is typically important in critical life saving measures and has been using in developed countries in the last two decades. Advancements in remote sensing (RS) technology and GIS the help in real time monitoring, early warning system and quick damage assessment of flood and drought disasters (Ishaya et al., 2008a. A Geographic Information System is a tool that can assist floodplain managers in identifying flood prone areas in their community. With a GIS, geographical information is stored in a database that can be queried and graphically displayed for analysis. By overlaying or intersecting different geographical layers, flood prone areas can be identified and targeted for mitigation or stricter floodplain management practices. Remote Sensing can be very effective for flood management in two ways; firstly by detailed mapping that is required for the production of hazard assessment maps, hence for input to various types of hydrological models, and secondly by developing a larger scale view of the general flood situation within a river basin with the aim of identifying areas at greatest risk and in the need of
The study aimed at assessing flood prone areas in Uyo Capital City with a view to suggesting control measures. It used 2008 NigerSat imagery, soil texture, rainfall, and road network data of Uyo. With Multi-criteria evaluation technique, the use of Geographic Information Systems (GIS), Global Positioning System (GPS), Digital Elevation Model (DEM) and single output map algebra were employed to generate flood hazard map of Uyo. The DEM was used to generate contours, terrain elevation, slope, and aspect surfaces, where aspect provided the direction of slope that contributed to flood inundation. Flood mapping was done to determine flood locations based on a 3D terrain assessment while flood hazard assessment formed the basis for flood control in the area. From the result of the study, flood hazard areas in Uyo Capital City were identified and classified into high, moderate, and low hazard zones. Based on this classification however, flood control measures have also been rated as critical, less critical, and non-critical respectively. Out of the 25 flood locations captured during the 2012 flash flood event, twelve locations were found on the critical control zones while thirteen were found on the less critical control zones. Based on the findings from this study, it was however suggested that town planners, construction companies and individuals should work in consultation with Geographers, Hydrologists and other stakeholders in the field who have adequate knowledge of the terrain and the technical ability in flood hazard modeling. Additionally, non-structural flood control measures have also been strongly advocated for implementation in the capital city of Uyo.
An Assessment of Flood Vulnerability Areas in ETI-OSA Local Government Area, Lagos State, Nigeria
There has been a significant increase in flood occurrence with their devastating impacts leaving lasting imprints in the coastal areas especially. To this end, the study assessed flood vulnerability areas in the Eti-Osa area of Lagos. The application of Geographical Information System (GIS) and remote sensing are used in preprocessing and processing acquired spatial information. Five flood vulnerable zones are identified from the analysis. They are very highly vulnerable zone (23.59%), highly vulnerable zone (12.23%), moderately vulnerable zone (10.04%), less vulnerable zone (9.52%), and none-vulnerable zone (44.62). The residential area is vulnerable to socioeconomic development because of loss and damages to the properties of residents. The study concludes with the recommended management strategies to mitigate the adverse effects in the study area
European Journal of Environment and Earth Sciences
Flood remains one of the most common natural disasters. Its rate of occurrence and the associated destructive tendency are on a rising scale across the globe. Flood risk may increase due to human activities. It could also decrease by appropriate flood management and planning. However, this requires upgraded and newly generated reliable and up to date floodplain and flood vulnerability maps. Hence, this study analysed the Niger-Benue river flood risk and vulnerability of 256 communities in Kogi State. The aim is to generate reliable up to date flood vulnerability maps that categorises the communities into different vulnerability zones and identify likely locations for erecting flood shelter/refugee camps during flood events in the State. Shuttle Radar Topography Mission (STRM) Digital Elevation Datasets, the spatial location of 256 communities, shapefiles of Kogi State’s administrative boundaries and Niger-Benue river basin were among the datasets acquired for the study. The Digital ...
The world's population is rapidly becoming more urbanized as the world seen a swift urban population increase. Gombe Metropolis is among the urban areas of Nigeria affected by the consequence of frequent seasonal floods leading to a unpropitious effect on the flood communities in many parts of the metropolis. These urbanization dynamics has caused a rapid urban growth through the transformation of many different land uses into the built-up environment. As a result flood risk in the metropolis has been rising in recent years and efforts by the people and government to mitigate the flood risk have not been entirely successful. Thus, this paper attempts to examine the nature of flood risk on the major downstream areas of Gombe metropolis. Fundamentally, this study applied Geographic Information System and Remote Sensing as a tool for integration of spatiotemporal data for modeling and comparison of urban development scenarios and its consequential effect in creating flood risk on the downstream areas of Gombe Metropolis. Therefore, GIS and Remote Sensing have been applied to detect land use/land cover changes, by looking at the trend in Land use/Land Cover Change from 2003 to 2014 in the Gombe Metropolis. In addition, the study identified Land use/Land cover types in different residential areas of the metropolis with more emphasis on the building density in each area. Finally, Gombe Metropolis Flood Risk Zones were detected and developed into Gombe Metropolis Flood Risk Map. The paper was able to reveal a significant growth of built-up environment and the occupation of floodplains in the downstream areas as the main factors for flood risk in Gombe Metropolis. However, the flood risk index established that the residential areas found on the very high to high flood risk zones include Barunde, Government Residential Areas/Gabuka, Pantami, Dawaki, and Tudun Wada. It was further reveal that the residential areas in the moderate flood risk zone are, Jankai, Jekadafari, Herwagana, Bolari/Madaki and MUAK.