Lagos Flooding: What Government Can, And Cannot Do

As written by Kelechi Deca

Do they still teach Geography in our secondary schools? Or they sacrificed the subject for Arabic Studies, CRK and Islamic Religious Studies?

In our Physical Geography class in secondary school, we were taught that flash flooding usually takes place when the volume of rainfall over a given area exceeds its normal range within a certain period of time. That is, if a volume of rainfall that should fall in two weeks fell in two days or even a day. Irrespective of existing infrastructure, there must be flooding, and when the catchment area is a coastal city, the case is worsened due to inundation and  rising sea level.

Also, when it rains rapidly on an already saturated soil or dry soil that has poor absorption ability, the water goes nowhere because the earth cant absorb more, instead it will start releasing ground water to add to the surface water. In this case, there must be flooding, if topography is unfavorable.

Add to the above, is when the natural or artificial watercourses or networks do not have the capacity to convey the huge volumes of excess water. There must be flooding.

Sometimes, existing capacity to adequately convey water runoff can be overwhelmed by the volume of rainfall.

 Have you ever tried to pour so much liquid through a funnel before? If the volume you are pouring in is so much and at a very fast rate, the funnel will overflow. That is what happens when existing water courses are overwhelmed. That overflow is flooding.

Then there is inundation, especially in coastal areas due to storm surge.Add to inundation is topography. Water naturally flow via difference in pressure, if the topography is flat, the pressure will be very low, and speed of runoff very slow.And if speed of runoff is slow it means that the more the volume, the higher the water will rise with nowhere to go....

This is where we can blame the government, especially if the canal network and underground watercourses are poorly constructed or inadequate.

Also, we have attitude problem. Many of those blaming Ambode still have this belief that the gutters are where wastes and garbage should be deposited into. They throw things out from their car windows, they do not dispose wastes properly, they throw even recyclable cans into gutters, all these go down to clog  the  canals and waterways blocking passages of rainwater.

Who takes responsibility?

But in all these, adequate physical planning is essential. At least it will mitigate the impact. Proper regulation is of great importance. The unregulated exploitation of underground water in a place like Lagos will lead to subsidence. The city is sinking little by little without anybody observing it, while the sea is rising at alarming rate.

It does not matter whether you believe in Climate Change or not. And it does not matter whether there was adequate physical planning or not. In this war with nature, the ingenuity of engineering is getting limited by the day. Check out New Orleans, Venice, Bangkok, Shanghai, Amsterdam, Brugge, Maldives, some of these have world class physical planning but the fear of going under is real....


As ice from the poles melts, the water flows towards the equator and forms a bulge there due to the forces created by the Earth's rotation, according to a study published in Geophysical Research Letters.This causes the sea level to rise more in the tropics than in the north.

The south will bear the brunt of Climate Change more...