Kenya: Rift Valley Lakes Water Levels Rise Dangerously

28 August 2020

In Kampi ya Samaki, a village near the shores of Lake Baringo, a cockerel supplements its usual cereal diet with some protein, a rare delicacy straight out of the lake - a crocodile hatchling. Ordinarily, crocodiles make a meal of chickens on these shores.

But the tables have lately turned, thanks to the rising level of the lake, which has brought the hunters to the doorsteps of the hunted, with the latter savouring every bit of home advantage.

A group of tourists marvel at the spectacle of the cockerel making mincemeat of the hatchling.

The mother crocodile had moved her newly hatched babies from the nest to the shallow part of the lake, where they were learning to fend for themselves when the floods came, sending everyone - crocodiles, snakes, fish, chicken and even people scampering for safety.

The floods rearranged everything, from the food chain to the physical features.

The bed of the local seasonal river is now the old tarmac road that cuts through Kampi Samaki Health Centre, which is now halfway in the water.

Unprecedented levels

Mr Mathew Rono, a boat operator and tour guide in the area, says he has lately witnessed abnormal happenings around the lake since the flooding began.

"It is the crocodile that should feed on chicken, but the reverse is happening because the lake waters are ashore," he says.

The overflow of Lake Baringo and several others in the Rift Valley - which in 2006 were on the verge of drying up - has not only reached unprecedented levels and displaced area residents, it has also changed the ecology.

People are catching fish right behind their houses. Crocodiles bask on the rooftops of submerged houses, some watching helplessly as their hatchlings are turned into scrumptious chickenfeed.

Cases of human-wildlife conflict have spiralled and myriad dangers lurk in the neighbourhood. For one, crocodiles, hippopotamuses and snakes are not man's best friends. Many are the days villagers wake up to find hippo faeces at their doorsteps, and the numbers of victims of snakebite are rising.

The Baringo waters have spread from 176 square kilometres to 260 currently -- the highest level recorded in 60 years. This has led to the displacement of nearly 6,000 people from more than 20 villages and destruction of homes, businesses and farmland.

Access to electric power, hospitals and schools has been disrupted by damaged roads.

Of the seven islands that attract tourists to the county, three are submerged. The offices where tourists used to obtain tickets to access the famed hot springs and flamingo spots, among other exciting activities, have been marooned by water and the islands cut off from the mainland.

In Loruk, Mr Dickson Lenasolio had an orchard. It is now submerged.

Business destroyed

Mr Samuel Cheruiyot, a 73-year-old businessman, has seen his home and business destroyed.

"I have never witnessed this amount of water since the 1960s. It receded over the years, but it seems to be rising to reclaim its space," says Mr Cheruiyot.

Mr Nicholas Maitano, a warden at the nearby Ruko Conservancy, says wildlife such as giraffes, warthogs, impala and ostriches are also in danger. When the Saturday Nation visited the area last week, a giraffe was stuck on one of the islands and a team of rescuers had been called in to help save its life.

Ms Emily Ombaso, a community nurse on Chelis Island, says she no longer receives patients because they fear crossing the crocodile-infested waters.

Transport to the neighbouring Chemolingot and Tiaty and farther in West Pokot, Elgeyo-Marakwet, Samburu and Laikipia counties has been disrupted.

Baringo Governor Stanley Kiptis describes the flooding as a complex occurrence requiring a multi-agency intervention.

Baringo is a shallow freshwater lake located in a semi-arid volcanic region. It is separated from the saline Lake Bogoria by the Sandai plains. Lake 94 and vast swamps are found nearby.

Natural features

Lake Baringo lacks a surface outlet and relies on underground faults, just like Lake Bogoria. The Journal of African Earth Sciences, however, says Lake Bogoria "lies in a topographically closed basin that might also be hydrologically closed," hence maybe surviving on its high rate of evaporation to ease the volumes.

Experts have warned that these natural features could soon merge into one large water body and this news has unsettled the residents. Observing them from the scenic Kituro viewpoint on Kabarnet road, one realises that the two lakes - Baringo and Bogoria, which used to be 24km apart - are now close to merging, as experts say they have established a synchrony in the fluctuations of all the Rift Valley lakes.

Dr Silas Simiyu, a seismologist and former chief executive of the Geothermal Development Company, says lakes Naivasha, Elementaita, Nakuru, Bogoria, Baringo, and Logipi have been rising since 2011, to levels not seen in the past 50 years. Lake Simbi in the Nyanza Rift in Homa Bay County and Lake Chala in Taita-Taveta County have also been rising.

"Rising waters alter society physically and socially," Dr Simiyu wrote in an opinion column in the Daily Nation. "For instance, due to the rising of water in Rift Valley lakes, the famous hot springs and jets at Lake Bogoria have subsided. This has had a direct impact on the aesthetics of the area and visitors that fancy this iconic site."

But why are the levels of water rising?

Though factors affecting the levels of the water have commonly been attributed to increased rainfall, siltation, climate change and pressure on land, experts say there are more complex influences to do with the location of these lakes, which are crucial to understand if the ecosystem is to be balanced.

According to Prof Bernard Rop, a petroleum geology lecturer at Jomo Kenyatta University of Agriculture and Technology, the regional earth movements around the Rift Valley have resulted in the rise in the water levels.

The lakes are situated in the East African Rift System (EARS), one of the most extensive rifts on the earth's surface -- from Jordan in southwestern Asia southward through eastern Africa to Mozambique. The system is some 6,400km long and averages 48km to 64 km wide. The belt runs from Ethiopia through Kenya, Tanzania and Mozambique.

"The EARS (where the lakes lie) is still an active system where the earth's tectonic forces of uplift and warping, accompanied by volcanism and faulting of the African Metamorphic basement, are presently trying to create new plates by tearing old ones apart. As the rift continues, the Rift Valley may sink enough that the Gulf of Aden will flood it," said Prof Rop, a former commissioner of mines.

"This splitting forms a new plate (Somali plate) while the Nubian and the Somali plates continue to move from each other and also further from the Arabian plate. The Horn of Africa (sitting on the Somali plate) would become a continental island, like Madagascar or New Zealand."

Prof Rop earned his doctorate from discovering oil in Lokichar in 2003. His sentiments corroborate what Dr Simiyu shared in 2013, when he raised concerns that various government agencies had advanced different and flawed hypotheses to explain the fluctuations.

"The Meteorological Department has reported that the rainfall patterns in the Rift and its catchment areas are normal while the Ministry of Environment, Water and Natural Resources has blamed the rise in water levels to siltation of the lakes on degradation of the catchment areas... However, scientifically, the rise in the water level of the lakes in Rift Valley is due to effects of regional tectonics influenced by the movements of global earth's plate tectonics.

"This creates near-field and far-field compressional and tensional stress fields. The near-field stress regime or earth area, will respond to the far-field stress regime, but with a time lag. In our case, the near-field is the Rift Valley responding to the pull of the Indian Ocean, which is a far-field body. Near-field means a localised area affected by earth activities. Far-field means an earth area that is far away," the seismologist explained.

Tensional fracturing

The Kenya Rift sector is the eastern arm of the EARS. The stress field in this sector is, therefore, largely classified as near-field tensional and is characterised by open normal faults that have dips into the Rift graben. Effects of the near-field tensional fracturing arising from low-stress fields result in open fractures common in Naivasha and Nakuru areas. It is through these structures that water drains into the ground.

From Loruk to Marigat, all the way to Lake Baringo, the open grounds on the earth where the faultline passes are visible.

GDC, which carries out geo-hazard monitoring in the whole of Rift Valley, notes that such open grounds often cause tremors and earthquakes.

"When the water drains through them, the faults are lubricated, hence tend to slip. Any such slight movement is massive and causes the tremors normally witnessed in the area," Dr John Langat, a GDC geologist, told journalists while touring the flooded areas.

Reports indicate the Rift Valley in Kenya is opening at an average rate of 2mm-3mm per year, varying from periods of fast extension to those of low extension.

Dr Simiyu says the change in the rate of extension is controlled by the far-field plate tectonic processes occurring in the mid Indian ridge in the East and the Mediterranean Sea in the North.

"Under normal stress regime and with normal rainfall, the lake levels would be expected to maintain near constant levels, that is equilibrium when the rate of drainage and that of input are at par. However, during high near-field tensional stress regime and normal rainfall, ground water seepage would be reduced due to decreased porosity associated with closing of pores and fractures. Then we will experience cases of drying up lakes," said the earth expert.

The Eastern Africa section of the Rift is said to be under increased near-field stress related to changes in global stress patterns due to a decreased far-field extensional process.

Seismologists say that in an environment of increased stress, the lake levels rise and would remain high even with normal rainfall until a new steady state is reached. When the stress differential is negative, lake levels rise and when positive, they go down and sometimes dry as it happened in 2006.

"This is more of a geophysical phenomenon that we have to live with than rainfall, forests and siltation," said Dr Simiyu.

Climate change

A study titled Assessing Socio-Ecological Change Dynamics using Local knowledge in the semi-arid lowlands of Baringo District by Oliver Wasinga of the University of Nairobi shows that there are established longitudinal relationships between land cover, land use, rainfall variability, human and livestock population and therefore ecological changes, hydrological trends and earth movements.

"The rapid ecological changes world over are most profoundly influenced by human land-use. Most affected particularly are the arid and semi-arid ecosystems owing to their inherent climatic variability that renders them more susceptible to land-use pressure than other ecosystems."

In 2017, the chief executive officer of the World Wide Fund-Kenya, Mr Mohammed Awer, said the fact that the rising had gone on for years meant that there was some bigger cause than just climate change.

"Whereas the easy explanation for us would have been climate change, when this is sustained for three years, then there must be something beyond this. We think that there might be certain tectonic movements considering the lakes were formed by the fact that the earth moved apart. The lakes are actually on the floor of the Rift Valley," he said.

Prof Rop says hydrological developments cannot be ignored as a contributing factor for the flooding.

"Whenever it rains, water has to percolate the soil to the ground reservoirs. If that does not happen, it could mean that the aquifers can't contain any more, and the runoff is now high and ends up in the lakes," says the geologist.

Interestingly, a team of researchers led by Dr Judith Nyunja of the Kenya Wildlife Service have a reason to believe that there exists a mystery source of groundwater feeding the lakes in the region and are doing research in Lake Nakuru to establish that.

Lake Baringo is fed by rivers Molo, Perkerra and Ol Arabel while hot springs and geysers discharge water into Lake Bogoria from about 200 spring vents located along the lakeshore.

Permanent inlet

The only known permanent inlet to Lake Nakuru is the Baharini spring on its eastern shoreline, contributing only about 0.6 cubic metres of water per second.

That the salinity of the lake has been diluted speaks to the presence of a larger source of fresh water to the lake, leading to the migration of the flamingos.

The Lake Nakuru National Park has reported that due to the reduced salinity, flamingos have flown in their thousands to Lake Bogoria. The birds feed on algae, which thrive in alkaline water. But Nakuru waters are now too deep, and not salty enough to support the growth of the phytoplankton.

Other than the migration of the flamingos, another proof of freshening of Nakuru water is the ability of fresh-water fish to thrive in the area where only cichlid tilapia could survive initially.

With the rising water levels, the lake has turned into a breeding ground for four different species of tilapia.

Lake Bogoria almost reached its spill point into the Baringo basin around 1900 and attained a similar level during the 2013 and 2016 rise.

In the event the merger happens, the salty waters of Bogoria will contaminate Baringo and harm fish, planktons and other aquatic life. On the reverse, flamingos would also suffer the dilution of the concentrated salts of Bogoria waters.

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