Academic journal article Theoretical and Empirical Researches in Urban Management

The Problem of Annual Occurrences of Floods in Accra: An Integration of Hydrological, Economic and Political Perspectives

Academic journal article Theoretical and Empirical Researches in Urban Management

The Problem of Annual Occurrences of Floods in Accra: An Integration of Hydrological, Economic and Political Perspectives

Article excerpt

1. INTRODUCTION AND BACKGROUND OF THE STUDY

In the past five years or more, Ghana--a West African country of 25.3 million people (2012 estimates) and a nominal Gross Domestic Product (GDP) of about US 39,199 million dollars (2011 estimates) -has experienced several forms of natural disasters and hazards ranging from droughts in 2006 to floods in 2007, 2010 and 2012. As in most developing countries in Africa, natural disasters and hazards present serious challenges to recent gains and improvements made in terms of macroeconomic stability and economic growth and development. In other words the recent gains made on the African continent in terms of the Millennium Development Goals (MDGs) could be destroyed by one major or series of natural disasters as observed in Asia such as earthquakes, Tsunamis, floods, among others.

Some studies have linked the issues of drought and floods to climate change and variability, indicating direct correlation and causality. Therefore with continuing climate change and variability one could predict that several forms of floods and other natural disasters and hazards would be prominent in the near future. This would primarily be due to increasing intensity and erratic nature of rainfall leading to flash floods in many areas of Africa including Ghana. Further, other drivers of floods could have more or the same impact as those occurred as result of climate change and variability. The consequences of floods in Accra is further exacerbated by poor development planning of the residential areas and also inadequate (or no) information on the early warning signs. Further the success or failure of early warning signs/systems would depend on the size, slopes and degree of sealed areas of a given water/river basin. Hydrological processes occur at a wide range of scales, from unsaturated flow in a 1 metre (m) soil profile to floods in river systems of a million square kilometres (Blosch and Sivapalan, 1995). As floods or the hydrological behaviour of a catchment imply multi-scales processes, its understanding (or study) invariably involves some sort of across scales analysis. The size of the catchment (meso, macro, among others), and its shape, the topography, the geology and the soils, the land use/cover, among several other factors considerably influence the hydrological behaviour of a catchment. In addition to the characteristics of the catchment, parameters of the rainfall (amount, intensity, spatial and temporal distribution, among others) influence the hydrograph (interacting with spatial and temporal characteristics of the catchment).

Of all the different land use/cover, the urban areas are probably the one that significantly modify the hydrological behaviour of a catchment. Indeed the imperious areas created by the urbanization (roofs, roads, dams, among others) hamper infiltration and create overland flow subjecting urban areas to floods (flash floods) in case of poor drainage system. The urban areas are therefore floods driver, even if some cases studies (for example Chocat, 1997) highlight a negligible role of urbanization in the flood severity, arguing by the fact that the proximity of the urban area to the outlet of the catchment reduces its impact on the hydrology of the catchment. Many other case studies (for example Du et al., 2012) reveal a huge impact of the city on the hydrograph, especially in the reduction of the time to peak and increasing peak flow. The location of the urban areas in the catchment is then a key element in its exposure to floods. The second key element is the planning of the urban area, which determines its water drainage capacity (facilities). As a city development plan provides areas for natural water flow and creates a drainage system to convey out the surplus of water due to the urbanization.

Other issues relating to floods in Ghana are the poor, ineffective and at times belated responses by the central government and other organizations (both governmental and non-governmental) in responding to the aftermath of floods. …

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