Development of Flood Prone Area Map for Igbokoda Township using Geospatial Technique

Abstract

Rapid urbanization has greatly increased the volume of runoff generated in many developed areas and subsequently resulting in flooding. This study evaluated the flood prone area of Igbokoda town in Ondo State and developed a flood risk map to facilitate proper planning and future flood mitigation. Scientific technique of GIS was used to identify flood risk areas within the study area. The Landsat 5 (TM), Landsat 7 (ETM+) and Landsat 8 (LC) images for 1986, 1999 and 2013 coupled with STRM 90 m DEM data of the area were used to identify three categorized risk zones. A total of 339 basins were delineated and stream network on the landscape of this area were carved. Hydrological and vegetation cover analyses were conducted using the satellite imageries obtained from United States Geological Surveys Archive online over the study area for three different epochs 1986, 1999 and 2013. There was a sharp decrease in area of vegetation cover from 1986 (19,630 ha) to 1999 (16,527.36 ha) and in 2013 (12,246.80 ha). The hydrological analysis results revealed that a major part of the residential area within the largest basin delineated was associated with low elevation and high slope angle. The combined stream network and slope of the area were used in developing flood risk zones. Three zones were specified: high, medium, and low flood risk zones. The total area covered by the high risk zone was 28.5615 km2 while the area of the medium and small risk zones were 15.94759 km2 and 31.3619 km2 respectively. It is recommended that an increased awareness on flood risk zone should be created among the populace of Igbokoda to guide them in further development.

A Design Workshop’s Contribution to Climate Adaptation in Coastal Settlements in Nigeria

“…The broad street axis in Igbokoda (see Figure 1), which was used as the context in the design workshop/charette, embodies these challenges. These impacts and implications for spatial planning, building, and urban design initiatives have been highlighted by many scholars [20,21].…”

A GIS–AHP-based approach in siting MSW landfills in Lokoja, Nigeria

“…Land use is vital to resolving public scuffle of the endorsement of unnecessary area of landfill amenities [57,58]. The land-use buffer map was prepared so as to avoid odour resulting from landfill sited within the study area.…”

Flood‐prone area mapping using GIS‐based analytical hierarchy frameworks for Ibadan city, Nigeria

“…Sudden flooding is intricate to be prognosticated and which are often accompanying by secondary occurrences including mass movements and soil erosion (Grimaldi et al, 2013). Flood is evaluated to be the second most pernicious of all meteorological perils with immense detriments to many societies in many parts of the world as a consequence of great perniciousness on both lives and properties (Adewumi et al, 2017). In the last decade, approximately 40% of the deaths resulting from natural hazards were attributed to floods, from which around 100,000 people have been killed, and existences of 1.4 billion people have been put to distress (Ezemonye & Emeribe, 2011).…”

“…Ibadan City in Oyo state is one of the recognised floods susceptible areas in the southwestern part of Nigeria. The earliest flood event experienced in Nigeria was in Ibadan in 1948 (Adewumi et al, 2017). It is almost customary that above 7.7 million hectares of agricultural land and built-up environments are damaged as a result of flooding in Nigeria annually (Jeb & Aggarwal, 2008).…”

“…It is almost customary that above 7.7 million hectares of agricultural land and built-up environments are damaged as a result of flooding in Nigeria annually (Jeb & Aggarwal, 2008). The occurrence of different forms of flood in Nigeria is predominant in those states along the rivers Niger and Benue in which Ibadan city is located (Adeoye et al, 2009;Adewumi et al, 2017;Jeb & Aggarwal, 2008).…”