Urban flood vulnerability mapping of part of the Lagos metropolis

Olusegun Adeaga,Olufemi Taiwo Oyeneye,Olutosin Akinbaloye

doi:10.5194/piahs-383-249-2020

Abstract

Abstract. Flooding is the most common of all environmental hazards with vast devastating effect due to enormous losses to lives and properties world-wide, annually. Thus, the effect of extreme flooding is dramatic, not only at the individual household level, but in the country as a whole. This study focuses on flood risk assessment based on urban and coastal flood estimation due to the physical peculiarity of the Lagos region and her urbanization characteristics. It involves creating a flood change detection using GIS approach with the aid of a Cellular Automation Framework to simulate flooding in Lagos Metropolitan area, mapping out the flood prone areas and generating a flood vulnerability map for flood management and planning purposes. At twenty minutes intervals the discharge distribution for the different flow regimes (Low, Medium and Extreme) display flow duration between 60–120 min while the time of concentration is attained at 1 h 20 min (80 min).

Highlights

Recurrence of extreme precipitation anomalies resulting in floods is a normal component of natural climate variability
Floods cause about one third of all deaths, one third of all injuries and one third of all damage from natural disasters (Askew, 1997; Jeb and Aggarwal, 2008). It is the most common of all environmental hazards which regularly claims over 20 000 lives per year and adversely affects around 75 million people world-wide (Smith, 1996)
In the study the basic data used and their characteristic are depicted in Table 1, in addition to the basic data input of the daily discharge, the Shuttle radar Topographical Mission (SRTM) data was converted to Digital elevation model on the GIS platform using the Arc Hydro tool and Raster Edit

Summary

Introduction

Recurrence of extreme precipitation anomalies resulting in floods is a normal component of natural climate variability. Flood is an overflow of an expanse of water that submerges land and a temporary covering by water of land that is not normally covered by water. Floods cause about one third of all deaths, one third of all injuries and one third of all damage from natural disasters (Askew, 1997; Jeb and Aggarwal, 2008). It is the most common of all environmental hazards which regularly claims over 20 000 lives per year and adversely affects around 75 million people world-wide (Smith, 1996). Death and destruction due to flooding continue to be all too common phenomena throughout the world, affecting millions of people annually. Flooding poses as one of the greatest natural risks to sustainable development; reduce the asset base of households, communities and societies through the destruction of standing crops, dwellings, infrastructure, machinery and buildings, quite apart from the tragic loss of life

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