Professor of Engineering Geology, Tamunoene Kingdom Simeon Abam
Written By Kunle Awosiyan
Barely three years that a research by Climate Central, a science organisation based in New Jersey predicted that Lagos among 12 others may sink due to climate change and human activities, not much has been done by successive administrations in the state to prevent the impending doom.
The study published in the journal, Nature Communications mentioned New York City, Mexico City, Venice, Italy, Mumbai, India, Houston, Texas, Miami with Lagos city ranked seven on the list of the world’s sinking cities that might not even make it to the next century.
Apart from the fact that climate change is a big threat to the world with the rising sea level due to melting of the glacier, human activities like drilling of boreholes and illegal dredging and sand fillings have become major threats to the survival of coastal towns in Lagos State.
Even though Climate Central research emphasised on climate change as the real threat, a few other studies and experts opinions observed that the rate at which people sink boreholes and engage in sand dredging may sink part of Lagos earlier than as predicted.
The coastal areas in Lagos include Lekki, Victoria Island, Ikoyi and Lagos Island. While almost all the buildings in these areas were built on sand-filled foundation, Echonews observed that most of them had borehole sunk in the premises.
According to a renowned Engineering Geologist, Professor Tamunoene Kingdom Simeon Abam, much of the dredging that is done in Lagos is done in the coastal area. He said, “These are areas we have a lot of compressible material. The land is not usable at its primary condition but they elevate it above the natural level by placing sands over it.”
To him, when one places sand on compressible materials, it creates consolidation settlement. “With this, it reduces the level and make it more vulnerable to flooding. With climate change, ice melts, contributes to rise in sea level. The coastal area receives constant flooding. With some places already above sea level, it will increase their vulnerability to flooding. And those places that had been reclaimed may suffer increased flooding. In other word, water level that should not ordinarily constitute a flooding will begin to do so.”
Abam explained that there were places where borehole drilling had created excessive abstraction. He stated that in the hope of extracting water or oil, human activities had created what he called ground subsidence.
As he put it, Land subsidence occurs when large amounts of groundwater have been withdrawn from certain types of rocks, such as fine-grained sediments. The rock compacts because the water is partly responsible for holding the ground up. When the water is withdrawn, the rocks fall in on itself.
He stated that over extraction of groundwater due to the activities of borehole drillers will lead to the sinking of the ground itself. “In Lagos where you have heavy industry that utilizes large amount of water, it will induce subsidence that increases vulnerability to flooding. It can also lead to saline water infusion into the body of freshwater.
Abam noted that over-extraction of water would distort the balance between the fresh and saline water, leading to interface and salinization of the fresh water.
Recall that a former president of the Nigerian Mining and Geosciences Society Chief Alabo Charles had called the attention of government to indiscriminate drilling of boreholes due to lack of pipe-borne water. At a conference by the society, Charles said that unregulated access to water reservoirs on the ground is dangerous to the existence of the cities. “We are even lucky in Nigeria that the underground water reservoirs do not have sinkholes”, he said.
To him, unregulated sinking of boreholes has become an all-comers game, adding that “there is need for government to rise up to the challenge of regulating the system.
“Indiscriminate sinking of boreholes is a failure of government to provide potable drinking water for members of the public”.
However, Abam said that sinkhole can collapse to cause a bigger disaster that can sink a whole city. He describes sinkhole as limestone formation, an underground cavity which can collapse and lead to subsidence. Sinkhole is an aquiver that releases the water and when water is over-extracted from it, the aquiver can collapse.
Speaking, a Water Engineer and Production Director, Lagos State Water Corporation, Engr. Olufemi Ewumi said that borehole drilling will definitely affect the aquiver and dredging will remove the wall of the aquiver. “As time goes on, there will be no enough water underground,” he said. However, he noted that government is in control of borehole drilling and dredging and that no company or home can just drill the ground for water without approval by Lagos government.
Lagos government has since criminalised drilling boreholes without permit. The Environmental law stipulates a prison term or fine for residents who drill boreholes without government authorisation.
The legislation also criminalises sale or distribution of water by container, tanker, or any other method without a valid license issued by the Department of Water Resources.
However, six years after the state House of Assembly passed the bill, it has not been signed into law. Investigation revealed that the current administration of Governor Babajide Sanwo-Olu could now sign it into law because of the same reason by his predecessor, Akinwunmi Ambode that unless the state government can provide potable water, it will harsh to introduce such law.
Reacting, Lagos Commissioner for Waterfront, Dayo Bush-Alebiosu said that efforts to control illegal dredging are being put in place and that the government had been engaging dredgers over this.
He said that the Lagos state government would not tolerate such criminality, saying he had since conveyed the message to the dredgers that it would not be business as usual.
“We have a meeting with Dredgers’ Association of Nigeria, Lagos State chapter. The meeting was called to seek the cooperation of the association in enforcing guidelines regulating dredging activities and to declare Governor Babajide Sanwo-Olu’s administration’s zero tolerance for illegal dredging operations.
The commissioner said though the meeting was a familiarisation forum to interact with members of the association and get first-hand information on how dredging activities can be improved upon with the view to maintaining the state’s waterfronts and prevent environmental degradation.
While soliciting their support in sanitising dredging activities in the state, Dayo Bush-Alebiosu disclosed that the state would not condone the spate of illegal dredging activities being carried out in every nook and cranny of the state.
Alebiosu also expressed the readiness of government officials to begin enforcement activities soon, saying that anybody caught violating dredging laws and regulations of the state will be prosecuted.
In his response, the President of the association, Mr Bature Akpomejero, pledged his support and cooperation to the state government in getting rid of illegal dredgers in the state.
Dredging In Lagos