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Gabions can help Africa mitigate flooding

gabions - climateaction

Gabions can help Africa mitigate flooding

Climate change is a big concern and a serious threat in Africa as the continent is among the most vulnerable to climate change which is exacerbating floods and droughts.

Figure 1. Natural disasters affecting the most people across sub-Saharan African countries, 2000-19 (World Bank)Source: World Bank Group, Africa’s Pulse, October 2021 Edition.

According to the figure above, of all the climate-related natural disasters, flooding incidents are the second to have affected most people on the continent after drought.

There has been a significant increase in major storms on the continent, resulting in heavier rainfall and causing stormwater runoff which is constituting a big problem in some communities.

As is the practice in many urban areas, most of the stormwater is collected through drainage systems which end up in main waterbodies, such as creeks and rivers.

However, during intense rainfall, the water rises and causes flooding which in turn results in property damage. In hilly and mountainous areas, flooding can also cause major damage to roadways, other public infrastructure, and pose a great risk to human lives.

To control flooding and help people in vulnerable communities better adapt, the installation of gabions can be considered as they are a better alternative, especially for areas of fast water flow.

Essentially, gabions are welded mesh wire cages or boxes that are filled with natural materials like soil, concrete, stones, or local boulders. They are placed upon each other and tied securely in order to form a monolithic massive structure for low-height gravity walls.

Gabions are great for flood control as they can control water pressure and resist any differential settlement and movement. They can be installed as retaining walls, and are particularly beneficial along riverbanks, creeks, and road rehabilitation in hilly areas.

This is because the malleability of their wire mesh makes them versatile and they create a continuous, flexible, and permeable structure that has a much higher chance of staying intact — features that are important in areas where landslides are a risk, and there are chances of abrasion causing slippage into a river or along roadsides.

Gabions come in different varieties and the type of gabion dictates its use. The common types are gabion walls, gabion mattresses, gabion baskets, gabion sacks, and gabion wire mesh.

They are cost-effective, can be installed relatively quickly, are environmentally friendly because they allow for vegetation growth, and are perfect for all soil types and climate conditions.

Already, some communities in Africa are using gabions to control floods. For example, an organization like Komb Green Solutions launched an emergency flood protection and climate mitigation campaign in Korogocho, Kenya.

They built robust gabion walls in order to control flooding from the Nairobi River in the event of heavy rains into Korogocho and the people’s park green space they made while rehabilitating the Nairobi River.

Even though there was an overflow when heavy rains fell in 2021, the flood on the sides where the gabions were raised was quite minimal.

This initiative is a good solution that other African communities can emulate and replicate across borders and reduce the continent’s vulnerability to the effects of flooding.

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