Africa's most populous city is battling floods and rising seas. It may soon be unlivable, experts warn

Residents wade through flooded Ige Road, in Aboru, Lagos, after a heavy downpour on July 6, 2020.

Lagos, Nigeria (CNN)Cars and houses submerged in water, commuters wading through buses knee-high in floods, and homeowners counting the cost of destroyed properties.

Welcome to Lagos during rainy season.
Residents of Nigeria, Africa's most populous nation, are used to the yearly floods that engulf the coastal city during the months of March to November. In mid-July, however, the major business district of Lagos Island experienced one of its worst floods in recent years.
    "It was very bad, and unusual," Eselebor Oseluonamhen, 32 told CNN.
      "I drove out of my house ... I didn't realize it had rained so much ... There was heavy traffic on my route because of the flood. The more we went, the higher the water level. The water kept rising until it covered the bumper of my car ... then there was water flowing inside my car," Oseluonamhen, who runs a media firm on the Lagos mainland, recalled.
      Photos and videos posted to social media showed dozens of vehicles inundated with water after torrential rain. The floods paralyze economic activity, at an estimated cost of around $4 billion per year.
      Home to more than 24 million people, Lagos, a low-lying city on Nigeria's Atlantic coast, may become uninhabitable by the end of this century as sea levels rise due to climate change, scientific projections suggest.
        The problem is exacerbated by "inadequate and poorly maintained drainage systems and uncontrolled urban growth," among others, according to a study led by the Institute of Development Studies.
        Nigeria's hydrological agency NIHSA has predicted more catastrophic flooding in September, usually the peak of the rainy season.

        Eroding coastline

        Lagos is partly built on the mainland and a string of islands.
        It is grappling with an eroding coastline that makes the city vulnerable to flooding, which Nigerian environmentalist Seyifunmi Adebote says is attributable to global warming and "human-induced action over a prolonged period."
        Sand mining for construction is a major contributor to shoreline erosion in Lagos, environmental experts have said.
        Manzo Ezekiel, a spokesman for Nigeria's emergency management agency (NEMA), told CNN that the riverbank of Lagos' Victoria Island is already being "washed away ... particularly in the V.I area of Lagos." "There's this problem of the river bank being washed away. The increase in water level is eating into the land," Ezekiel added.
        In Victoria Island, an affluent Lagos neighborhood -- an entirely new coastal city christened 'Eko Atlantic' -- is being built on land reclaimed from the Atlantic Ocean, and will be protected from rising waters by an 8-kilometer-long wall made from concrete blocks, developers say.
        A cargo ship passes along a waterway during construction at the Eko Atlantic city site in February 2016.
        While the ambitious project could contribute to reducing housing shortages in other parts of the city, Ezekiel fears that "reclaiming land from the sea will put pressure on other coastal areas."
        Other critics have argued that adjacent areas not protected by the wall will be left vulnerable to tidal surges.
        David Frame, the Managing Director of Eko Atlantic told CNN the project "isn't