Most West African coastal cities have grown into the economic hotspot of their countries because of the past history of colonialism and their closeness to the ocean. However, the ocean and the associated wetlands also bring some risks. Repeated flooding occurs mainly due to the minimal coping capacities of these countries; leading to huge damage and loss of lives together with associated threats like erosion, epidemic diseases, land subsidence and salt water intrusion in fresh water. With the current rapid urban growth, climate change and sea level rise, flooding will be exacerbated and will become a public issue.
During the past four decades, in the data base of the Centre for Research on the Epidemiology of Disasters, the number of disaster flood events in West Africa, evolved from 4 to 19, 42 and 105. Accordingly the number of fatalities also, evolved from 0 to 252, 586 and 1155 respectively. But during the ongoing decade, from 2010 to 2015, 57 disastrous flood events were already recorded with 1169 fatalities.
To cope with floods, some strategies and policies are implemented at regional, national, community or household level. The present trend of flood frequency and the huge magnitude of the damage induced testify that the measures applicable for managing floods are not adequate and efficient. This paper tries to point out the gaps and the challenges that need to be tackled for a proper flood risk management.
To do this, a case study approach is used. Four coastal cities were selected: Accra, Cotonou, Dakar and Lagos. The data used for the analysis is mainly secondary data.
Flood risk management has roughly two parts: flood risk assessement and flood risk reduction. In general, the simple way of determining flood risk as at now, in West Africa, is by flood prone areas mapping and this done by observation and interview. This method is used by local authorities, particularly after flooding. Damage is estimated roughly after flood event mainly to know the number of affected people and organise the relief services. In West Africa, structural measures are insufficent and even the existing ones are not well maintained. Emphasis is put mainly on non-structural measures especially emergency measures.
Adequate data, assessment tools and methodologies are needed to support the choice of measures. But they do not exist due to lack of fund and skilled personnel. They must be developed. Flood risk must be assessed in a holistic manner taking into account at the same time all possible flood types and all possible scenarios of climate and land use changes and sea level rise. long term planning is necessary. Another path that can help is to learn from other countries and screen the local knowledge. Measures should be selected in a way that they safeguard the environment while minimizing the flood damages.
Funding and political will are needed to support the risk assessment and the implementation of measures. A strong legal framework is necessary but scientific research should precede regulations and laws.