A Vanishing Lake?

Hello – I’ve been meaning to run a number of posts on the changing environment in East Africa. As pretty much everyone is aware, there are a lot of changes taking place globally, with shifting weather patterns having serious effects on many different habitats. In Kenya, and much of East Africa, drylands are very sensitive to change and without annual rains that renew and refresh, they slowly turn to deserts. Even though much of the Eastern Great Rift Valley and it’s extensions are hot and arid, there are many lakes in it that area fed from streams and rivers that originate in forests in the surrounding highlands. These highlands are also home to millions of people and the ‘bread-basket’ of the country as this is where all of the food is grown. However, much of the agricultural land is expanding and many rural populations rely on firewood for fuel which places a lot of pressure on forests.Many local watersheds (areas that drain into a single lake/river system) are impacted by human activities both close by, and far away. Kenya’s lakes are in deep trouble, and this message is being screamed out by one small lake in the Northern Rift, Lake Kamnarok, a blue canary in the coal-mine, if you will, but is anyone listening? The Kerio Valley is one of my favourite places in the world. Many of the more exciting posts on this blog have been about the insects and other inhabitants of this special place…In the central floor of the valley is Lake Kamnarok, which has been until recently, a permanent freshwater lake fed by the Kerio River from the surrounding highland forest. These forests have been relatively undisturbed until recently and are especially lovely when the Cape Chestnut trees flower, dotting the green mosaic with pink.Lake Kamnarok, like many of the lakes in this region does undergo seasonal fluctuation.Here is a picture of the lake from a few years ago:July is just after the ‘long rains’, and the lake was pretty full at the time. Even in the dry season that same year, there was still water in the lake from the ‘short rains’….   Over the last few years, Lake Kamnarok has been getting shallower, and large beds of rooted weeds have appeared in the lake. You can see this in the picture below taken in August last year… So what’s going on here?Well – two separate things, but both having the same result.Firstly, there is severe soil erosion taking place locally. The pastoralist peoples of the valley floor are increasingly sedentary. More and more people are keeping more and more goats who are busy eating anything they can find. Here is a picture of some serious erosion on the valley floor near the lake…The result of this erosion is hundred of tons of silt and soil washing into the lake. This raises the lake bed and makes it easier for invasive plants to take hold. It also makes the rate of evaporation go up.Of course, as this is a remote part of Kenya, with only a poor, rural subsistence economy, it never received much attention. Through 2007, more and more silt was washed in by the rains. And, simultaneously, water began to be diverted upstream in the highlands. Of course this had very serious implications. If you put in less water than is being lost to evaporation, well even a pre-school child can figure out that the lake will shrink: if you put in less and take out more, sooner or later you will run out! Not only did it shrink, but it dried up completely! This happened some time at the end of 2007/beginning of 2008.Despite the rains (you can see the green fields in the highlands above the valley in the bottom of the picture), the lake did NOT fill up. The local community cannot remember when the lake last dried up, and many of the plants now appearing in the drying mud-flats are also ‘new’ to them – i.e. recent invasive species. Here is a picture of the lake entirely dry earlier this year: In case you can’t tell where the lake is, this picture highlights the dry lake bed: The lake was home to an estimated 20,000 crocodiles. They retreated to a series of tiny pools trapped in hollows towards the Kerio River. Then in August some very heavy rains did bring water back to the lake. But not much, as you can see from these pictures taken from the lake-bed itself…(Above photo by J. Mamlin) The lake is currently rapidly drying up once more. While this dramatic event has not made any headlines in Kenya or elsewhere, Lake Kamnarok, as fragile as she is, is still crying out a warning to us – stop deforestation and soil erosion or soon there will be no freshwater! The people most affected by this will be those in the valley first – as many thousands of households rely entirely on the lake and surrounding pools/ponds for all their livestock and human daily water needs. This girl has to walk even further
when the lake dries up in order to fetch water for her family (Photo by J. Mamlin)…  When I last looked at the lake, before travelling, it was rapidly drying up again…Hopefully this time someone will listen to her…