Climate Change, Urban Degreening And Flooding In Nigerian Cities: Reducing Vulnerability Through Polycentric Planning And Urban Greenery Strategy (PPUGS)

ABSTRACT

This paper uses the Institutional Analysis and Development (IAD) framework to analyse the missing links in attempts to address the problems of flooding in Nigerian cities. Previous flooding and the recent ones have been attributed to heavy downpour, blockage of water channels and drainages, indiscriminate dumping of refuse and building of houses along channels. Areas that are neglected but pertinent to flood mitigation include: (1) degreening activities that remove green cover; (2) paving of open spaces with asphalt and concrete that accentuate storm water volume as percolation is reduced; and (3) unpaved surfaces that generate debris and silts that cause siltation and sedimentation of Atlantic Ocean and Lagoon with the consequence of rising sea level and coastal flooding. The paper reports the findings of longitudinal studies on causative factors of urban flooding. The studies commenced in IleIfe and Ibadan in 1997, conducted in Lagos in 1998-2000 and 2011 and in Ibadan in 2011 and 2012. The paper identified gaps between and among the stakeholders in environmentalism and ecosystemic balance at state and local levels. Indications from Ile-Ife, Lagos and Ibadan show that the three cities are experiencing degreening activities. For example, in Ile-Ife and Lagos, the green areas account for the least proportions, 24.1% and 27% of open spaces around buildings respectively, while 75.9% and 73.0% of the available open spaces are either paved or unpaved with the problem of heat radiation that demands additional energy for operating artificial cooling system and consequently increased global warming. In addition, degreening activities cause flooding. As more and more land is urbanised, and trees and grasses are replaced by asphalt and concrete, rainwater has less chance to be absorbed. Thus, storm water rushes down the streets while areas that were never flooded are now routinely under water. Other studies in Lagos show that: (i) there is an increase in the rate of sedimentation and sea level rise (ii) rainstorms in the city have become more intense and urban flooding will be more severe. Floods have devastated many parts of Lagos and Ibadan leading to loss of several lives and property and the displacement of several people. Statistics confirms that between 2011 and 2012, more than 150 billion naira (about $1 billion) was lost in Lagos, while 2,105 buildings were flooded  in Ibadan with property damaged estimated in billions of Naira. As a result, the Lagos and Oyo States‟ Governments spent several millions of Naira on relief to the victims. This paper raises some fundamental questions on the roles of stakeholders (scholars, public officials, practitioners, professionals and citizens) within the built environment in designing strategies at mitigating urban flooding. This paper considered it imperative for the adoption of pragmatic and problem-solving strategies that can help in mitigating flooding in Lagos and Ibadan. Consequently, the paper designs an African Polycentric Urban Greenery Model (APUGM) that can be applied to addressing the challenges of flooding in the two cities. The paper emphasizes, among other considerations, the use of traducture in reaching the grassroots for solution to the recurrent challenges of flooding. The paper also designs strategies that Lagos and Oyo states‟ governments could adopt for the depopulation of the two cities – Lagos and Ibadan respectively through deurbanisation, de-migration and re-migration.