Oil spill on Lake Malawi can take 700 years to recover
The Department of Fisheries under the Ministry of Agriculture and Food Security has for the first time spoken on the effects of a potential oil spill on Lake Malawi and the prospects of drilling oil.
Principal Fisheries Research officer who is also Officer-in-Charge of the Senga Bay Fisheries Research Centre, Maxon Ngochera, explained that because Lake Malawi can be described as a closed lake it has an estimated 8,000 cubic km volume of water but only discharges 11 cubic km of water through the Shire River although some water is also lost through evaporation.
“Because of this, the lake has a long ‘flushing time’ of approximately 700 years,” explained Ngochera, “
“This means that if the lake was polluted with a chemical that can only be removed in the dissolved form [and not gaseous form], it would take over 700 years for the lake to recover naturally to its original state.”
He said the amount of water leaving Lake Malawi annually through the Shire River is approximately 0.1 percent of the total volume in the lake while approximately 0.3 percent leaves the lake through evaporation.
“This will take decades to millennia for the lake to flush out naturally should any pollutants enter the lake,” he said.
He said this might be disastrous and therefore prevention is the only realistic and affordable policy for maintaining Lake Malawi in a healthy condition and ensuring its continued beneficial uses by its riparian people.
He explained that Lake Malawi is not unique because it is Rift Valley Lake, but because it was formed approximately 5 million years ago through tectonic activities which is the process of falling of the earth’s crust.
He also pointed out that the lake is the second deepest in Africa [estimated at 700m deep around Usisya area in the north] with a mean depth of 290m.
“It is estimated that Lake Malawi has accumulated more than 4km of sediments over the years,” said Ngochera who said it makes the best place for archaeologists to go and study the life on earth over the 5 million years….
By GREGORY GONDWE
Originally published by The DailyTimes.