MOST Nigerians have described the pattern of rainfall this year as unusual. What we have seen so far is a shorter period of rainfall but intensity has been quite high. Under normal weather conditions, Nigeria should have the wet and dry seasons. All parts of the country should be observing the dry season now.
However, while the core north is witnessing severe winter or dry season, the coastal states of the country are still experiencing heavy downpour with flooding as its resultant effect.
While some people attribute the change in weather pattern to climate change, others believe it is due to weather variation which has nothing to do with climate change.
A top official of the Lagos State Ministry of the Environment who prefers anonymity described climate change as the principal factor for the heavy flooding in various parts of the country.
He explained that the intensity of rainfall all over the world made water levels to go up in lagoons and oceans. As the water level rose, it caused tidal lock which implies that water which was supposed to flow down could not, causing water to over flow.
“In the case of Lagos flooding, the release of excess water from Oyan dam by Oshun River Basin Authority and Ogun River Basin Authority compounded the problem.
This was a replica of what happened in Jigawa and Sokoto floods. The three cases were caused by over flow of dams due to lack of maintenance. This is why they cannot cope with high water level during rainfalls’, he stated.
Coordinator of the Nigeria Climate Action Network, (Nigeriacan), Mr. Ewah Otu Eleri seems to share this view.
According to him, there is already some significant change in rainfall patterns in Nigeria.
“We are having shorter rainfall seasons, but the volume of rains have become heavier. The United Nations Inter-Governmental Panel on Climate Change predicts that this trend will intensify as greenhouse gas concentrations in the atmosphere increase. In other words, we have to be prepared for more flood disasters,” he said.
On what the government should do to mitigate the occurrence, Mr. Eleri said :
“We have to work with the rest of the world to reduce the emission of these harmful gases into the atmosphere. However, the damage has already been done. We need to equally plan to adapt to these more frequent disasters. Nigeria needs a climate change adaptation plan.
This will identify our areas of vulnerability, especially in agriculture and human settlements. It will also set out strategies to address both drought and flooding. The process of formulating this plan has been dragging and requires more efforts and the collaboration of several agencies of government.
The establishment of a national climate change commission will be important in developing and implementing plans to address climate change. The bill to establish the commission has recently been passed and harmonised by the National Assembly. It is now time for the President to show leadership on climate change and sign the bill into law.
This will ensure that Nigeria is prepared to meet the challenges of future climatic disasters,” he said
“We are battling with climate change, so we have to expect what is happening. For instance, the caused of the Sokoto issue is because of the increasing water levels in the dam.
The dam the has capacity of 942 million cubic meters. when the dam gets filled water flows out. It will interest you to note that we can rarely predict rain pattern because of climate change , we just have to be cautious of this kind of disaster.
Apart from the destruction, we may face food shortage. That is why government must be at its best, if we must avoid the looming danger.” Tonye Williams, an Abuja based environmentalist noted.
But Chief Acting Meteorologist at the Nigerian Meteorological Agency (NIMET), Oshodi, Mr. Abayomi Oyegoke disagreed. He stated that rains being experienced up to the end of the year have to do with weather variation while flooding is man made and not climate change related.
According to Oyegoke, activities such as drainage blockage, construction works along drainage channels and sand filling of drains to enable people build on them are the factors responsible for the flooding in Lagos and other places.
“Our annual rainfall prediction for this year was that we will have a shorter period of rainfall. Weather is dynamic in nature, that is why we are still having rainfall up to this period of the year. In the next one or two weeks, the normal rainfall will come to an end and skeletal rains will be experienced in the southern part of the country.
“The north is already experiencing dry season. The extreme north is already experiencing hot and sunny weather. But from latitude 10-11 down to the south will be experiencing at times dry thunder, at times thunder associated with rains just as we are experiencing now in Lagos.
This change in weather pattern should not be associated with climate change. It is as a result of little variation in climate. The tropical weather we are experiencing in Nigeria is not violent compared with what happens in Europe. The weather in Nigeria is very friendly’, Oyegoke explained.
We need engineering solution to solve flooding
REACTING to the flooding particularly in the Lagos area, President of the Ikeja
branch of the Nigerian Society of Engineers (NSE), Engr. Kunle Adebajo noted that the water level in Lagos is high and it is to a large extent, surrounded by water.
“The topography of the city is relatively flat and flat terrains do not give much room for the design and construction of proper functional self cleaning drains in terms of minimum allowable slopes etc.
In such a situation, very deep drain sections would normally be required and yet the high water table does not facilitate this. This is generally the reason behind having shallow drains in the Lagos environs,” he said.
The former president of the Nigerian Institution of Structural Engineers (NIStructE) stated that forces of nature are against a city like Lagos.
“Apart from the ground, majority of the water would normally be expected to be channeled towards storm water out falls.
The main out falls for storm water runoff in Lagos are the canals and the lagoons. Unfortunately, they are also characterised by high water level. In addition, the existing condition of the main storm water out falls is very poor and most of the canals are stagnant. Illegally located buildings and structures will need to be demolished and this would mean that the people will be displaced.
The drainage system will however be dramatically improved and considering the benefit to all who live in Lagos and indeed the benefits to the economy of the entire nation, this is by no means too great a sacrifice to make,” he said.
Engr. Adebajo who is the Senior Partner of Ovie Arup & Partners ( a firm of structural engineers) called for an enduring engineering solution to the problem of flooding in the country.
He canvassed the construction of more drainage structures to complement existing ones which should be kept functional. A proper storm water drainage master plan, he said, should be prepared for the city and this should be faithfully implemented.
According to him, only qualified civil/structural engineers should be involved in the design and execution of such projects.