Dar/Nairobi. Heavy rains that have recently pounded East Africa are, among other factors, driven by the Indian Ocean Dipole (IOD), also known as Indian Niño, which has been triggered by the irregular fluctuation of sea-surface temperatures, an expert says.
Mr Augustine Kiptum, the principal meteorologist at the Meteorological Department of Kenya (Met), says the western Indian Ocean that borders the East African shores is becoming alternately warmer and then colder than the eastern part of the ocean, leading to more storm clouds and as a result, more rainfall in the mainland East Africa.
During an interview with Nation, Mr Kiptum explained the why factor in the recent flooding that has wreaked havoc in most parts of Kenya and Tanzania, raising fears of a natural disaster in the region.
Mr Kiptum’s explanation comes at a time when Tanzania’s weather watchdog, the Tanzania Meteorological Authority (TMA) is saying, “There is a possibility for twin cyclones in the Indian Ocean and that may have impact in the country.”
TMA reissued alert over heavy rains which may have disastrous impact at the East African coast, specifically pointing out Dar es Salaam, Coast Region, Pemba Island and Tanga in which there are threats of floods.
TMA expressed fears of possible disease outbreaks, infrastructure destruction, flooding and disruption of transportation services. But, generally, the region is facing a bigger crisis.
On Thursday, the United Nations (UN) humanitarian agency said at least 280 people have been killed and more than 2.8 million others affected by unusually heavy rainfall and flooding in eastern Africa.
The UN Office for Coordination of Humanitarian Affairs (OCHA) said homes, infrastructure and livelihoods have been destroyed and damaged in the hardest-hit areas, and the risk of communicable diseases including cholera is rising.
“Primarily driven by the Indian Ocean Dipole (IOD), the heavy rains are likely to persist into December and to intensify in Kenya, Tanzania and Uganda,” OCHA said in its latest regional Flash Floods Update.
The UN agency said the annual short rains which ordinarily last from October to December have been exceptionally heavy in Kenya and affected more than 160,000 people in 31 of the country’s 47 counties.
“At least 132 people have reportedly died, including 72 who were killed by a landslide which buried their homes in West Pokot County,” said OCHA.
The storms have caused destruction and damage of key infrastructure in Kenya, including houses, health facilities and schools, displacing an unconfirmed number of people and disrupting basic services. Roads and bridges were damaged, hampering effective humanitarian response efforts in affected areas.
In Djibouti, the report says the equivalent of two years’ rainfall fell in one day, causing flash floods that have affected up to 250,000 people, including nine people killed.
“In many areas, the floods are coming on the back of consecutive droughts, while in others people impacted by the floods are also suffering from conflict and violence,” said OCHA.
“As families struggle to cope with these compounding and complex shocks, there is a high risk of their adopting negative coping mechanisms, including school drop-out and early marriage,” it warned.
According to OCHA, flooding in Somalia has affected 547,000 people, including an estimated 370,000 who have been displaced and 17 killed. In South Sudan, where 908,000 people have been affected since June, the flooding has submerged entire communities, destroyed or rendered inaccessible basic services and markets, and caused crop losses which will result in an early start of the lean season in January.
The UN agency said more than 420,000 people were affected by floods from August to October in Sudan, during which 78 people died and 49,500 homes were destroyed.
OCHA said about 570,000 people have been affected in Ethiopia, including more than 200,000 displaced, and rains have negatively affected the harvest season.
In Burundi, it said, 3,100 people were affected by torrential rains in Munyinga province, while in Uganda, flooding and landslides have impacted at least 12 districts, including Bundibugyo district, where more than 4,000 people were affected.
In Tanzania, said the UN agency, the death toll is over 50, including 10 people who were drowned by a flood-swollen river.
Mr Augustine Kiptum from Kenya’s Meteorological department, explains the changing weather patterns and what this entails for the region.
He says, “Over the past few years, we have seen a changing pattern that is moving away from the climate we used to have. For example, the frequencies of heavy rainfall as well as episodes of drought have increased and become common.”
“The long-term weather patterns are affiliated to climate change and this is not just in Kenya but also in the region as well. Countries such as Tanzania have been and will also experience heavy rainfall just as we are experiencing.”
“It is important that counties that are prone to drought, more so in northern Kenya, store the rain water at this time in case there is drought come early next year.”
Any other factor, apart from the IOD?
Apart from the Indian Ocean Dipole (IOD), Mr Kiptum says there are various atmospheric conditions that can lead to the occurrence of heavy rainfall.
These conditions, or rather climate drivers, are often caused by different pressure fronts or zones either from the north or south, he says.
“They include conditions such as air masses, for example the Congo air mass, Lake Victoria air mass, and the Indian Ocean air mass.”
“There are also occurrences of tropical winds or storms such as cyclones and depressions.”
“Over the past few days, there have been depressions over the Indian Ocean which has, in part, contributed to the rains we are experiencing.”
“Additionally, there are other climate drivers such as the El Niño/Southern Oscillation (ENSO), which is an irregularly periodic variation in winds and sea surface temperatures over the tropical eastern Pacific Ocean, affecting the climate of much of the tropics and subtropics.” “There is also the Madden-Julian Oscillation (MJO) which, although not common, is an eastward moving disturbance of clouds, rainfall, winds, and pressure that traverses in the tropics.”
“Other drivers include sub-tropical highs such as St Hellena, Arabia, Azores and Mascarine as well as the Inter Tropical Convergence Zone (ITCZ) which is a belt of low pressure which generally circles near the equator where the trade winds of the Northern and Southern Hemispheres come together,” says the Met expert.