People, Places, Flood and Flood Risk in the Greater Lagos Metropolitan Area, Nigeria (PAP014986)

Código

PAP014986

Autores

FASONA, MAYOWA JOHNSON, Ibidun Adelekan, BOLANLE WAHAB

Tema

Flood risk management in mega cities

Resumo

The Lagos megacity - a conurbation that encompassed several previously standalone towns (now locally referred to as 'new Lagos') in the north of Lagos State- is expected to reach some 25million people by the year 2015. A significant proportion of population and economic activities in the Lagos Megacity is concentrated in the greater Lagos metropolitan area - a group of barrier islands less than a thousand square kilometer, almost surrounded by creeks, lagoons and estuaries, and bordered in the south by the Gulf of Guinea. This natural location makes the greater Lagos metropolitan area naturally vulnerable to flooding even without the additional stressor posed by climate change. The greater Lagos metropolitan has over 40 Development Areas and 15 of the 20 Local Government Areas in Lagos State. Thousands of families are temporarily dislocated and vehiclular traffic almost grounded annually during the rainy peaks of July and September. Lagos Megacity generally exhibits a critical human-environmental conditions including poor physical planning, unsustainable sanitation and waste disposal methods, poverty, infrastructure deficits, landuse pressure, housing deficits and overcrowding and emergence of slums, ghettos and shanties in delicate low-lying beaches, levees and floodplains. The relationship between physical and social vulnerabilities and weak governance and capacities is complex and its concomitant effect often dislocates the city subsystems and exacerbates flooding impacts. Through the Lagos Coastal Cities at Risk Project, we generated spatial data and associated metrics on the indices of physical vulnerability including terrain, location and structure exposure, land-use pattern, critical infrastructure, present and future rainfall projections, and historical flooding episodes in the greater Lagos metropolitan area. Spatial data and associated metrics were also generated for indices of social vulnerability including population characteristics and distribution, poverty profiles, housing conditions, access to communication, social networks, as well as governance and emergency support services from several sources including government statistics and field survey. The data were processed and integrated within GIS. Spatial analyses were carried out to decipher flooding and flood risk pattern across the city. Physical and social vulnerability patterns were also cross correlated across space. Expectedly, the results suggest strong positive relationships between the pattern of physical and social vulnerabilities to flood. The more socially disadvantaged population tend to cluster in areas of higher risk of flooding. This result provides the first city-wide integrated risk and vulneraility maps for the greater Lagos metropolitan area.