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Lakes are the new battlegrounds in Africa. They are impacted by climate change, face massive degradation, and increased pressure from rising population growth.
Mathew Herrnegger, a senior scientist at the Institute of Hydrology and Water Management (HyWa), University of Natural Resources and Life Sciences, Vienna, recently studied the Kenyan lakes in the East African Rift Valley on why water levels were rising. “The Kenyan lakes in the Rift have witnessed significant water level increases. Recent increases in lake areas range from 21 per cent for Lake Naivasha to 123 per cent for Solai," Mathew observed.
"Homes, schools and hospitals have been flooded," he added. "A Kenyan government report estimates that about 80,000 households — 400,000 people — have been affected by the floods since 2010.”
The study brought out how the lake ecosystem is undergoing changes and impacting local livelihoods. It said, “Human activity and changes in underground permeability have been advanced before to explain the lake level rises. The results of our study illustrate that surprisingly minor changes in the water balance are enough to explain the lake level rises. An increase of only 0.4-2 per cent of mean annual effective rainfall leads to the observed phenomena.”
Mathew and co-researchers found that lakes are changing fundamentally. Kenyan lakes showed low fluctuations and smaller water areas between 1984 and 2010, which have increased dramatically since 2010, the study concluded. For instance, Lake Baringo had a water area of 118 square kilometres in 1995, the lowest value from 1984-2020.
The water area expanded by over 52 per cent in the years 2014 and 2020 to reach 195 km. The water area of Lake Solai, a smaller and less-known lake south of Lake Bogoria, increased from 3km in 1984 to nearly 12 km in 2014 and 2020, a four-fold increase.
The Eastern Africa region has witnessed intermittent spells of drought as well as wetter periods in the past. Mathew’s study said fluctuations in lake water levels were not unusual.
In June 2023, another evaluation of lakes in East Africa warned that heavy rains, wind storms, and floods threaten the survival and water access of the communities living in the Lake Victoria Basin (LVB). The scientific report, published in the journal Nature, showed significant precipitation changes and increasing extreme climate events in the near future of the already sensitive region, affecting both its large human populations as well as endemic biodiversity.
One of the largest freshwater lakes and fisheries in the world, LVB’s 40 million inhabitants are strongly affected by extreme weather events such as regular flooding. In late 2019 and early 2020, Lake Victoria’s water levels were observed at an unprecedented high. The massive flooding that followed in lake-adjacent areas displaced over 200,000 people in Kenya, Uganda and Tanzania. These are three of the five countries that the LVB covers, also including Burundi and Rwanda.
In 2021, the United Nations Environment Programme (UNEP) warned that lakes were in fact staring at a wetter future which threatens livelihoods and also can trigger migration. For instance, consider Lake Turkana, the world’s largest desert lake in the arid northern region of Kenya. This lake has been predicted to be 'dead' in near future as its river inflows have been drastically curtailed due to a large number of dams being built upstream.
Since 1988, Ethiopia has built a series of hydroelectric dams on its main tributary, the Omo River, leading to predictions of Lake Turkana’s demise. The new UNEP study has predicted that in the next two decades climate change would result in more intense rain over Lake Turkana thus raising its levels and also causing severe flooding. This could impact the 15 million people who live on the lake shores.
UNEP warned governments in Kenya and Ethiopia (both share a border with the lake) that rare floods like the ones that hit the region in 2019 and 2020 would be regular occurrences.
Africa is known for its lakes, a major source of freshwater. According to the WORLDLAKE database, there are 677 lakes in the continent out of which 88 are listed as principal lakes. Three of the 10 largest freshwater lakes on Earth, in terms of area and volume, are located in Africa — Victoria, Tanganyika and Malawi lakes.
Many lakes are transboundary. According to UNEP, 15 principal lakes cross the political boundaries of two or more countries.
Some estimates say that these lakes hold about 30,000 cubic kilometers of water, the largest volume in the world. Lakes in Africa are following the global trajectory. Lakes cover 3 per cent of global land area and a critical part of the planet’s hydrology. Lake ecosystems store around 87 per cent of the planet’s liquid surface freshwater and offer a variety of ecosystem services, including fisheries and water supply. Besides, lakes support local livelihoods, fishery being the most important of the many economic benefits being reaped from these waterbodies.
Lakes, rivers and wetlands hold 20–30 per cent of global soil carbon despite occupying only 5–8 per cent of its land surface.
"Lakes are in trouble globally, and it has implications far and wide," Balaji Rajagopalan, a professor at the University of Colorado Boulder and co-author of a research study that lakes across the world and its findings were published in the journal Science. Balaji, along with other researchers, analysed satellite observations and climate data of over 30 years covering 1972 largest global lakes. Their finding was alarming: they found “significant storage declines for 53 per cent of these water bodies over the period 1992–2020”. The study concluded, “The net volume loss in natural lakes is largely attributable to climate warming, increasing evaporative demand, and human water consumption, whereas sedimentation dominates storage losses in reservoirs.”
"It really caught our attention that 25 per cent of the world's population is living in a lake basin that is on a declining trend," he said. The study found significant loss of lake water storage in southern Africa, besides in western Central Asia, the Middle East, western India, eastern China, northern and eastern Europe, Oceania, the conterminous United States, northern Canada and most of South America. However, the study pointed out the rise in lake water levels in many regions including in Africa compensating for the losses in other regions.
The rise in lake water levels as mentioned above has been attributed to climatic changes leading to high rainfall. The study said, “Approximately one-third of the total decline in all drying lakes is offset by lake storage increases elsewhere, largely in remote or sparsely populated areas such as the Inner Tibetan Plateau, Northern Great Plains, and Great Rift Valley.”
This article is excerpted from the State of Africa’s Environment 2024 report.