In 2023, the Horn of Africa experienced an unprecedented natural catastrophe, as torrential rains followed a historic period of drought. This deluge, which defied early climate forecasts, resulted in extensive flooding across the region, leading to the displacement of hundreds of thousands and causing substantial damage.
The heavy rainfall, occurring in October and November 2023, had a profound impact on Somalia, Ethiopia, and Kenya. This calamity unfolded on the heels of a record-breaking drought spanning from 2020 to 2023, which had left millions of people grappling with food insecurity. According to the United Nations Office for the Coordination of Humanitarian Affairs, since October 1, the flooding has claimed the lives of over 100 individuals and forced more than 700,000 people from their homes.
Countries within the Horn of Africa typically experience two distinct rainy seasons: the “short rains” from October to December (OND) and the “long rains” from March to May (MAM). In the OND season of 2023, rainfall levels were exceptionally higher than usual, with precipitation totals from October 1 onwards ranging from double to quadruple the average for southern and western Ethiopia, Somalia, and Kenya, as reported by the Famine Early Warning Systems Network (FEWS NET).
The excess rainfall in the highlands of Ethiopia and Somalia in late October and early November caused the Shebelle River to rise significantly, eventually overflowing on November 11. Subsequent rainfall further exacerbated the situation, leading to the river breaching its banks in central Somalia and inundating the surrounding areas, including the town of Beledweyne (Belet Weyne). This catastrophe compelled an estimated 250,000 people, constituting 90 percent of the population, to flee their homes.
Comparing satellite images, the devastation in Beledweyne is evident when juxtaposed with a snapshot from September 12, 2023. The images, acquired by the Operational Land Imager (OLI) on Landsat 8, utilize false color to highlight water presence, represented in shades of blue.
The relentless heavy rain also caused the Juba River, situated in western Somalia, to overflow, resulting in the inundation of croplands and roads in the town of Luuq. In Bardheere, a bridge was swept away, severing access to the town.
In July 2023, researchers at the Climate Hazards Center at the University of California, Santa Barbara, employed climate models to issue early warnings regarding rainfall and flooding in the Horn of Africa during the OND “short rains” season. The Climate Hazards Center provides rainfall data and forecasts to FEWS NET, a program supported by the U.S. Agency for International Development (USAID) in collaboration with various other agencies, including NASA.
At that time, climate models indicated that sea surface temperature patterns in the Indian and Pacific Oceans would lead to abnormally high rainfall in East Africa. A positive Indian Ocean Dipole (IOD), characterized by warmer-than-normal sea surface temperatures in the western Indian Ocean and cooler-than-normal temperatures in the eastern equatorial Indian Ocean, typically favors a wet OND in eastern Africa. El Niño conditions, characterized by warmer-than-normal sea surface temperatures in the central and eastern tropical Pacific Ocean, further enhance the influence of a positive IOD. Both these factors are associated with flooding in East Africa and drought and wildfires in Australia.
Chris Funk, director of the Climate Hazards Center, noted the evolving concern regarding the situation. In July, they predicted a threat to East Africa due to a strong El Niño and IOD. In September, their forecasts grew more alarming, and by October, a significant strengthening of the IOD, marked by rapid cooling over the eastern Indian Ocean, pointed to an extremely wet season.
While the excessive rainfall since October has alleviated the prolonged drought in the Horn of Africa, it has also raised the risk of cholera outbreaks, crop and livestock pests, and diseases. This, in addition to the loss of life that has already occurred, underscores the multifaceted impact of this natural disaster.
Researchers at the Climate Hazards Center have drawn parallels between the strength of this year’s IOD and conditions observed in late 2019 when a positive IOD event contributed to exceptional rains, flooding, and displacement in the Horn of Africa. Moreover, unusually wet soils in that year contributed to a desert locust outbreak in early 2020, which infested and devastated crops across at least 70,000 hectares (173,000 acres) of land in Kenya.
Funk highlighted the center’s efforts to use advanced climate modeling to predict these droughts and deluges months in advance, aiming to inform risk management, agriculture, and livestock practices for the benefit of the affected regions.
Frequently Asked Questions (FAQs) about Horn of Africa Flooding
What caused the catastrophic flooding in the Horn of Africa in 2023?
The catastrophic flooding in the Horn of Africa in 2023 was primarily caused by heavy and prolonged rainfall following a historic period of drought. This excessive rainfall led to the overflowing of rivers and inundation of towns and croplands.
How did the flooding impact the region?
The flooding had devastating effects on the region, displacing hundreds of thousands of people and causing extensive damage to infrastructure and livelihoods. It also raised the risk of cholera outbreaks and the spread of crop and livestock pests and diseases.
Were there any early warnings about the flooding?
Yes, researchers at the Climate Hazards Center at the University of California, Santa Barbara, issued early warnings about the rainfall and flooding in the Horn of Africa during the OND “short rains” season. They used climate models to predict the increased risk of flooding.
What were the factors contributing to the heavy rainfall?
The heavy rainfall was influenced by a positive Indian Ocean Dipole (IOD) and El Niño conditions. These climate phenomena led to warmer-than-normal sea surface temperatures in the western Indian Ocean and the central and eastern tropical Pacific Ocean, favoring wet conditions in eastern Africa.
How has the Climate Hazards Center been working to address these issues?
The Climate Hazards Center is using advanced climate modeling to predict droughts and heavy rainfall months in advance. Their aim is to provide early warnings and inform risk management, agriculture, and livestock practices in the affected regions.
More about Horn of Africa Flooding
- UN Office for the Coordination of Humanitarian Affairs
- Famine Early Warning Systems Network (FEWS NET)
- Climate Hazards Center at the University of California, Santa Barbara
- U.S. Agency for International Development (USAID)
- NASA Earth Observatory
- Indian Ocean Dipole (IOD)
- El Niño
- Desert Locust Outbreak