Floods in Africa: what solutions to implement?

Every year, many cities in sub-Saharan Africa suffer from flooding, which is costly in terms of both material damage and human lives. A few months ago, cities such as Abidjan and Niamey were hit by these bad weather conditions. Here is an overview of some possible solutions to prevent these disasters.

It is true that the African coastal area from west to central Africa is suffering the full force of the consequences of climate change. The rainy season often arrives out of sync with unusually heavy rainfall. Last June, in Abidjan, the water level rose up to 2.50 meters in some houses.

Anarchic urbanization as an aggravating factor

The increasing urbanization along the coast makes these areas particularly vulnerable. For some countries, such as Senegal or Mauritania, these areas represent more than 40% of the population’s living space. In Togo, for example, the Zio plain has undergone such an accelerated transformation that it has become a peri-urban agglomeration in the space of a few years. It is therefore important to know how to preserve them.

We must take into account the multiplier effect of human influence on our territories: the situations are therefore aggravated. Of course, territorial planning remains very deficient (construction in flood-prone areas, non-application of urban development plans) which exposes more people and more property to exceptional flood phenomena.

Valuing nature-based services

One might be tempted to think that the responsibility lies with the climate or with the public authorities.

In reality, we ALL have a responsibility. Green spaces have disappeared from cities, both in public spaces and in private homes. Gardens have disappeared in favor of concrete: rainwater runs off the concrete. It ends up in the drains, which they make overflow. Especially since the gutters are regularly clogged with waste: plastics, household garbage, etc…

The water reservoirs that are formed also become sources of garbage and mosquito nests. Green spaces help retain rainwater and facilitate the infiltration of water into the soil. So everyone can do something about it: think about putting some green cover back on your house!

Buildings are growing at a frantic pace in large metropolises, but few if any real estate programs include green spaces. The action comes from each one, in its respect of the landscape, ecological and social heritage.

Local knowledge and ecological engineering

It also comes from local knowledge accumulated and rich in lessons in terms of observation of climatic facts. For example, in Saint-Louis in Senegal or in the ancient city of Grand-Lahou in Côte d’Ivoire, the authorities and inhabitants did not sufficiently measure the impact of the advancing ocean (from 2 to 5 meters/year on these coasts) on these old cities whose cultural heritage was then engulfed. The traditional calendars based on the observation of the daily life allowed to establish strategies of adaptation for the local communities but also to maintain its direct environment of life.

To this local cultural heritage are added new tools such as the need to describe a local urban plan, to create a movement for action (such as the West African Coastal Area Management Program WACA), to use geographic databases and to better integrate the living around us to continue to provide the ecosystem services necessary for our survival.

To finish with an example of ecological engineering, the water lagoon system was tested in Ouagadougou, Burkina Faso, as an effective alternative sanitation technique for the treatment of domestic wastewater, particularly in the Sahelian context. Its effectiveness depends mainly on social acceptability and the degree to which local socio-economic and socio-technical contexts are taken into account in the design of this system integrated into the landscape.

Learn more about the projection network.