Kenya's Rift Valley boasts beautiful lakes which provide havens for wildlife, and are also vital to people and the economy. In the past decade or so, the water level in these lakes has been rising, causing the displacement of hundreds of thousands of people. An article in The Guardian explores this phenomenon and explains the efforts to find the causes of the flooding.
There are eight lakes in the Kenyan Rift Valley, where tectonic plates are moving apart. Some of them – Turkana, Baringo and Naivasha – are freshwater lakes and semi-saline lakes, and support about 1 million people living close to them, as well as most of Kenya’s flower industry. Others are salt lakes and sustain wildlife as well as local industries, such as Lake Magasi, an alkaline sodium carbonate lake, where this mineral is extracted for different industrial uses.
The lakes rose gradually throughout the 2010s, then faster after heavy rains in early 2020. The rising waters have caused large-scale displacements, inundating farmland and residential areas. They have also brought crocodiles and hippos close to dwellings, resulting in more attacks. The ecosystem balance has also been affected; Lake Turkana, the world’s largest alkaline lake, is rich in blue-green algae that provide food for lesser flamingos. But the algae cannot thrive in the diluted water, so the number of flamingos in the lake has declined.
In 2021 a report by UNEP studied Lake Turkana, between Ethiopia and Kenya, concluding that the exceptional flooding such as that occurred in 2020 is “likely to become more regular in the future without any adaptation measures”, as climate change would likely lead to heavier rains. The reports called for measures such as improved international cooperation, as well as reforestation, agroforestry and avoiding construction in areas at risk of flooding. “There is still a mindset in Kenya that lake water levels are constantly falling, which makes planning difficult,” said Tito Ochieng, Director of Water in Kenya’s Turkana County.
Lake Victoria, to the west, also experienced exceptional flooding in 2020. George William Omony, a senior meteorologist at the Uganda National Meteorological Authority, said that above-average rainfall plays a major role in causing the lake’s backflow – when the lake spills over onto its shores – but the phenomenon has been amplified by human activities. Land clearance for farming and human settlements increases erosion and the amount of silt that ends up in rivers, which then hold less water and overflow. He also noted extreme flooding follows a cycle of drought and heavy rainfall that happens every 50 years in Lake Victoria. Dams have a significant role in regulating the amount of water that flows in and out of the lake. Uganda’s Nalubaale dam controls the flow of water out of Lake Victoria into the Nile, while the Kenyan government is planning major dams to regulate the amount of water that flows into the lake from the Nyando, Nzoia and Yala rivers, in an effort to reduce flooding.
The cyclical rise of the lakes explains in part the current lakes’ rising. Hydrologist Sean Avery has noted that the lakes have been even higher in the past, and the trend towards higher rainfall means higher lake levels can be expected in the future. He also points to environmental degradation and changes in land use as contributing factors to the extreme flooding, as they cause the runoff in the catchment – both water and sediment – to increase. He explains that human pressures vary in the different lakes, including land clearing, excessive water withdrawal to feed growing development, pollution, flow regulation, excessive river inflows, etc.
Others have linked the rising lakes to tectonic activity, with a theory saying that as the Rift valley separates, groundwater from an unknown aquifer is feeding the lakes. But it would not explain the rise in Lake Victoria, which is not on either branch of the Rift Valley.
After the UNEP’s report on Lake Turkana, in 2021 the Government of Kenya and the UNDP also released a report looking at rising water levels in the Rift Valley lakes and Lake Victoria. It concluded that the main reason for the rising water levels is climate change, noting also that changes in land use practices have increased runoff into the lakes. It also mentions a possible role of geological factors, and noted that there was a significant rise in lake levels previously in 1901 and in 1963.
The last decade has seen above-average rainfall in Kenya’s lake catchments and the trend is expected to continue, driven by climate change. Although the high lake water levels are not unprecedented, they are a cause for concern as development pressures (land clearing, degradation of wetland and riparian areas) will aggravate the impact of climate change. Maintaining vegetation cover and controlling land uses that damage the environment are key to adapting and limiting damages to ecosystems, people and property.
