Sunday 17th November 2019
Sunday, 17th of November 2019
Home / Human Settlement / Lagos flood: Beyond panic control, but high-tech engineering solutions

Lagos flood: Beyond panic control, but high-tech engineering solutions

We are at it again. The Lagos megacity is being overrun by flood. Like a routine phenomenon, it happens year in, year out, often with increasing devastation of the milieu coupled with human fatalities and large-scale destruction of property and damage to road infrastructure.

Lekki flood
Flooded highway in Lekki, Lagos

Penultimate week, many parts of Nigeria, most especially the southern part, was bombarded with torrents of rain which lasted for long hours and wreaked havoc everywhere while it lasted.

Reporting about the extent of and damages caused by the 10-hour-downpour, most newspapers carried screaming and heart-rending headlines as samples here: “Rain of tears…Flood sacks Lagos, 6 dead, buildings collapsed as 10-downpour wreaks havoc.” (Sunday Tribune, October 13, 2019). “Flood forces Ondo to close schools.” (Sunday Vanguard, October 13, 2019) “Lagos rains: Mother, three kids die in building collapse, flood kills 11-year old, rescuer,”(Sunday Punch, October 13), “Downpour: Gasman drowns, Lekki, Ikorodu residents, landlords flee,(The Punch, Monday, October 14, 2019).

The media reports had also unpleasant graphics of collapsed buildings caused by landslide, major city roads rendered impassable due to deluge of floodwater, uncountable vehicles and homes completely submerged in floodwater and flood victims crying uncontrollably over the colossal loss of their property in billions of naira. It was a pitiable spectacle!

Let us examine the facts behind the susceptibility of Lagos to excessive flooding. Flood is a seasonal occurrence in Lagos. It is pervasive at the peak of the rainy season (June-October) and accentuated by the ravaging incursion of the Tropical maritime air mass from the South Atlantic Ocean across the entire country from south to the north.

By its geographic location, Lagos is on the trajectory of the moisture-laden Tropical maritime air mass which brings a lot of precipitation in its wake. And as recently reported by CCN cable TV network, Lagos “geography makes (the city) prone to flooding, and the coastline has already been eroding.

As sea levels rise due to global warming, the city is increasingly at risk. Lagos is virtually below sea level and Chief Ede Dafinone, president of the Nigerian Conservation Foundation (NCF), has cautioned that “if nothing is done, Lagos will be submerged by 2050.”

Eko Atlantic City, a blessing or a curse? In a hurry to be among the league of global cities, Lagos is in a hungry for ultra-modern urban development to befit its newly acquired mega city status.

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Out of the desperation came into being the Eko Atlantic City, whose development started in 2007 by a consortium of foreign developers who already deployed huge capital outlay to realise their dream city, dubbed “Dubai of Africa.”

The Eko Atlantic City stands on reclaimed land from the waters of the Atlantic Ocean abutting the coastal shore of Victoria Island, a component part of Lagos megacity. The total area of the new city is 25 km2 (10 sq. mi) out of which 10 km2 (4 sq. mi) is made up of land, while 15 km2 (6 sq. mi) is water. (Eko Atlantic City, Wikipedia).

The new development is undoubtedly a high-end development with all the trappings of a well-planned, self-sustainable smart city with good roads, distinct commercial hub, luxury homes, uninterrupted power supply, tree-lined streets and artificial lake for water recreation.

Despite its success story, Eko Atlantic City has its environmental assessment drawbacks. Some experts and critics argued that the sand-filling of the Atlantic Ocean for the development of the city “has caused devastating changes to coastal currents”. It is believed that “the displaced currents have washed away more than 25 metres of land from the shoreline.”

The devastation of the ocean current is more visible and pronounced at the Alpha Beach along the coastline not too far from the location of the new city. The point being made here is that land reclamation on a large-scale and indiscriminately by fast-buck developers for residential purposes have aggravated flooding in the entire city because the wetlands which are supposed to be catchments for rain runoff are being aggressively depleted without the commensurate and protective arrangement for flood control. At any downpour, the Lagos is like a makeshift swimming pool showing signs of flood on major roads and residential hoods.

The grave error made during the conception of the Lekki master plan cannot be overlooked.

Formerly a vast wetland, but later reclaimed in the early 1990s, Lekki was developed without due diligence to the development of a well-planned drainage system and channels capable enough to discharge runoff water into the huge water body (the Lagos Lagoon) in the proximity of the estate whenever it rains. That inadvertent technical blunder continues to haunt the sprawling estate to-date.

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Lekki is busting at the seams with a high inflow of population. Poor and or near absence of drainage is responsible for the seasonal flooding in Lekki, plus the fact that it is currently overdeveloped beyond its holding capacity as originally planned. The paved surface is ubiquitous making the land impervious, while stagnant rainwater remains on the tarred roads for days after the rains.

Lagos has long been prone to frequent flooding, but preventive measure to protect the environment is feeble and unsustainable. The fire brigade approach by successive administrations in Lagos State has been less effective. Indiscipline, official mendacity, corrupt practices, and governmental lethargy are responsible for the failure to minimise flood in Lagos.

The LASG is not oblivious to the massive development of the city’s wetlands without consideration for their environmental value in mitigating flood. The lack of professionalism which has almost become a  norm (?) among the officials of the Ministry of Physical Planning and Urban Development who grant approvals, pardon me, to some of the crazy/questionable developments in every nook and cranny of the city, are aspects the LASG is too lethargic to curb, despite public outcry against such unethical practice.

What you allow is what will continue. Lagos is not the only coastal city in the world plagued by flood, but the only difference is the type of strategy being applied to curtail flood overrun. In more developed climes, governments have moved away from “old school” tactics such as the construction of barriers, canals, and levees. Most of the coastal cities are now introducing High-Tech Flood control solutions which have proved very effective.

In Lagos, flood control is often reactionary… a spur-of-the-moment remedial action. No proactive plan and the strategy if any, have been repetitive with no application of modern engineering technics common among coastal cities in other parts of the world.

For example, the city of Venice, Italy has its engineering feat called the MOSE project with which it controls flood perennially being a city inside water. The equipment is used to prevent overflowing waters from the nearby Adriatic Sea.

The lessons of the destructions caused by hurricane Katrina in 2005 brought out the latent ingenuity among the city engineers in New Orleans, Louisiana, USA. They were able to come up with a better-coordinated system of flood control having realised that the construction of levees and floodwalls is not sufficient to solve the problems of flood occasioned by the hurricane.

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In Amsterdam, The Netherland 60% of the population lives below sea level. Despite this watery environment, engineering innovations have been applied to wage unrelenting war against incessant flood year-round. A few of the mechanisms and High-Tech engineering solutions to contain a high volume of water when flood occurs are “Deltawerken (the Delta Works) – a complex combination of dikes, dams sluices to control storm surge.

They also have a system known as Hagestein Weirs which many city engineers around the world come to Amsterdam to understudy and replicate in their cities or countries to solve flood problems.

Governor Sanwo-Olu cannot afford to be indifferent to flood problems in Lagos. A city is worth living only when there is an assurance of security of lives and property, investment-friendly environment and adequate protection from the elements… rain, flood, storm and other natural disasters.

This writer once wrote in times past about the innovative approach that must be implemented to curtail Lagos flood to the barest minimum, most especially about the change of tactics, application of High-Tech solutions and citizens’ attitudinal change. I rehash excerpts from the article:

“Change of tactics must be experimented by the LASG. Instead of sticking to the structural method of flood control, which gives a false impression of security, the time is ripe to use non-structural methods of flood protection, especially cost-effective floodplain management techniques in vogue around the world. Such methods are made possible through land-use zoning regulation which must be religiously enforced. The simplistic idea of floodplain management is to reduce the effects of flooding by keeping people away from floodwater, instead of the herculean task of trying to keep floodwater away from the people!

“Again, I want to stress that this would entail attitudinal change among the citizenry who must comply with the law and upright government officials who must enforce the law. Development in the flood fringe must be guided by floodplain construction standards as stipulated by subsisting regulations. The government should consider the preparation of flood hazard boundary maps for the state and also develop a Floodplain Management Programme intended to reduce to the barest minimum, the adverse effects of flood.

“A holistic scientific study of the many causes of flooding in Lagos and its environs is highly recommended. The collections of data for urban planning, rainfall, and the cycle of flood occurrence must be resuscitated. There are best practices about flood control in some coastal cities like Lagos around the world which the LASG officials can understudy.

“Copenhagen in Denmark, Venice in Italy, Helsinki in Finland, Perth in Australia and New Orleans in Louisiana State, USA are examples of coastal cities where engineering innovation has helped to conquer the ravaging effects of coastal erosion and ocean tide flooding.”

By Yacoob Abiodun (Urban Planner/Planning Advocate, Parkview Estate, Ikoyi, Lagos)

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