Climate change: Geographer examines the shrinking African lagoon

Written by Staff Writer

The stories told by the lagoon north of Abuja, the Nigerian capital, told in satellite images, would shock the adventurous.

The result of people living on tiny islands connected to a shrinking natural channel, the disaster was once thought to be under control.

Now scientists warn erosion is becoming the main problem facing Nigeria’s capital and threatening local hydrological stability.

Erosion could make the large island of Gurara the most vulnerable part of Abuja — and a permanent obstacle to nearby rail stations, roads and the inner suburbs of northern Nigeria.

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“The vast majority of coastal areas and islands in Nigeria are flat lakes carved out by river dredging during the colonial era,” said Michael Grant of the University of Leeds.

“Our preliminary results show that erosion has reduced sand availability on the north bank. Increased subsidence from the subsidence caused by over-shore cargo ships may have been exacerbated by transport planning.”

The evidence is provided by satellite images of Lagos, on the coastal north of the country, which Grant has used to illustrate climate change’s effect on erosion.

The UK-based geographer is one of a team of researchers to be commissioned by the Nigerian government and the local Nigeria Inland Waterways Authority (NIWA) to assess existing and future issues with the islands and the marshy delta around them.

Dredging and dam-building by cities such as London, New York and Mumbai had led to an increase in global glacial water runoff, resulting in earlier snowmelt in the Northern Hemisphere, he said.

In conjunction with their mandate, Grant’s team plans to use satellite imagery to track changes over time.

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“Very rapidly, there have been several major changes to the water level in the Lagos lagoon due to the glacial runoff from the Alps,” he said.

“In just the last two decades, Lagos delta has gone from being between two to five meters above sea level to below.

“With lagoon level decreasing, frequent flooding in the city has been reported. A lot of infrastructure is on the island — it’s a huge problem.”

The northern fringes of Gurara, Nigeria, where people live on islands connected to a shrinking natural channel.

While Grant believes that climate change may exacerbate the erosion, the rapid urbanization of the northern fringes of Abuja may also play a role.

“The already rapid acceleration of the area’s development over the last 50 years is likely to be a factor in the growth of nearby areas which are vulnerable to erosion,” he said.

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