Climate change and its resultant effect on our daily lives is a reality. The effect of climate change is multi-faceted. It goes beyond increased rain, flooding, increase in temperature and drought. Climate change posses a great threat to regional economic stability, as well as food security.
Though Nigeria is known internationally as an oil producing nation, its agricultural base is as critical as its oil and gas sector. Being the largest black nation in the world, this comes with the burden of feeding a population of over 200 million people and ensuring economic development across board.
In the last decade, the most obvious effect of climate change in Nigeria comes from perennial flooding in the northern region and coastal flooding south of the country. With the northern part of Nigeria hosting the food belt of the nation, mitigating effects of climate change in the region ought to be the priority of local authorities, so as to ensure food security and economic prosperity of the nation. Asides increase in annual volumes of rain, the periodic release of water from the Lagdo Dam in the northern region of Cameroon has caused record flooding in farming communities and cities along the River Benue and its discharge point at its confluence with the River Niger, moving further towards the southern part of the country.
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The Lagdo Dam is a reservoir of water in northern Cameroon, covering an area of 586 km2. Its construction was meant to meet the electricity and irrigation needs of northern part of Cameroon. Over the years, since its completion in 1982, silt build up has considerably reduced the dam's capacity and efficiency, thereby necessitating periodic release of water at more than usual peak volumes, so as to avoid dam overflow and possible collapse. With its primary inflow and outflow being the Benue River, releases at peak volumes are made back into the Benue River, entering Nigeria from the south of the Mandara mountains along the Adamawa State axis. These releases have in the past created tension between Cameroonian and Nigerian authorities, bordering on early warning non-communication. Floods in Nigeria resulting from record release of water from the Lagdo Dam since 2012 has resulted in the flooding of communities and farmlands in Nigeria, leading to loss of lives, properties and cash crops. Recently, many more states have suffered from higher than usual annual rainfall volumes, resulting in loss of lives and properties.
The Nigerian Hydrological Services Agency (NIHAS) has set up an early warning system, by monitoring releases from the Lagdo Dam, which by itself is not enough in mitigating flooding in communities downstream of the Benue River, which spans across multiple states . The sad reality is, even if the Cameroonian authorities were to give warnings months in advance of anticipated releases, responses on the part of the Nigerian authorities would be limited to evacuations and emergency response plan activation by the National Emergency Management Agency (NEMA). On the part of affected states, the various state emergency management agencies would usually be burdened with the responsibility of setting up internally displaced persons camps and disbursement of relief materials to affected individuals, in collaboration with Non-Governmental Organisations (NGOs). The process is repeated again when the next flood hits, without plans of avoiding future recurrences. As a nation, Nigeria ought to be more focused on prevention of such disasters instead of sitting on its hands hoping for the best out of a bad situation.
With such a unique challenge, it's appropriate to construct dry reservoir dams along the Nigerian stretch of the Benue River and other major rivers with high-yield tributaries. Such a dam can be sited at the entry point of the Benue River into Nigeria. In the absence of a large enough span of land south of the Mandara mountain to site such a dam, three dry reservoir dams can be constructed in Adamawa, Tararba and Benue with a joint capacity to hold the highest possible volume of release from the Lagdo Dam or flash flooding from localised downpour. These dry reservoir dams are meant to store higher than usual volumes of water diverted into them, which are held temporarily to prevent flooding around downstream communities.
The diverted volume of water is then emptied back into the source river at a controlled rate, once the peak period of the rainy season has passed. After draw-down and complete emptying of the dam is achieved, the dam is then maintained and kept dry in preparation for the next rainy season. These dams wouldn't only prevent flooding in the host states, they would also prevent flooding in the south of the country where huge volumes of water coming from the Benue and Niger river are discharged towards.
Judging by data of loss (lives, property and cash crops/life stock) from flooding events across downstream communities of the Benue as well as the Niger rivers, an environmentally engineered solution like an off-stream dry reservoir dam would be cost-effective in preventing such huge loses. Because such an undertaking is capital intensives, there should be a cross-regional collaboration to solving this problem, as the impact zone of such floods spans across many states of the federation. The federal government can through its Ministry of Water Resources lead the initiative by collaborating with the affected states in drafting a master plan, funding modalities, and a timeline for achieving this. All other forms of infrastructural development would be counter-productive if they are left vulnerable to perennial flooding. Thus the need to prioritise climate resilience, over emergency response.
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A classic example of an approach by a government to make its major city and other downstream communities climate resilient is the construction of the Springbank Off-Stream Reservoir Dam by the government of Alberta, located west of the city of Calgary, Canada. This is a project conceptualised and funded by the government of Alberta, in response to the 2013 flooding of the city of Calgary and other communities downstream of the Elbow River. With the last flooding event being 12 years ago, plans are in advance stage to mitigate future flooding by diverting river flow off-stream, into the dry reservoir dam at Springbank. This dry reservoir would, at completion, have the capacity to hold volume of water equal to (or even more than) previous flood volumes that passed through Calgary. That's the power of data and strategic planning.
This is not one solution that is meant to fix all the climate change challenges ravaging many Nigerian cities and communities, but it will mitigate perennial flooding and its resultant effects to a considerable extent. This would empower local communities with the right conditions needed to cultivate the land, feed their families and make some income; which all adds up to bolstering Nigeria's food security and overall economic growth.
Bwala, an Environmental Geologist, wrote from Calgary, Alberta, Canada
