|
|
| The
Great Rift Valley, north of Nairobi, Kenya
-
formed about 25 million years ago by the violent
separation
of two of the earth’s continental plates floating
on the molten magma of its core.
-
4,000 miles long, from the Red Sea to Mozambique,
and its sides are still moving apart, slowly
but imperceptibly.
- slow
separation brings dramatic outpourings from
the molten core which have created volcanoes,
mountains and escarpments.
-
the Rift is a long fissure in the landscape
and
water collects in depressions and has no way
out except by evaporation which leaves sediment
and salts behind. We know these depressions
as lakes and wetlands, but here they are unique
because of this geological accident. |
|
| Soda
Lakes
 |
The
accumulation of salts by evaporation can
eventually produce caustic soda water. Very
few species can live in such harsh conditions,
but those that can, do so in spectacular
abundance. Lakes Bogoria,
Nakuru and Elmenteita are
soda lakes that can be bright green when
viewed from space because of the huge density
of spirulina. Spirulina, a micro-organism,
a blue-green ‘alga’, is the main food of
the lesser flamingo, an animal highly specialized
to filter the microbes through its beak. |
| The
intense green of the lake waters often contrasts
with the vivid pink of the flamingos gathered
along the shores. Up to a million birds congregate
on a single small lake creating “one of the
top ten bird-watching spectacles in the world”.
Flamingos cannot drink soda water they
have to use the same few freshwater springs
and streams at the edge of the lake for drinking
and preening as the local people use for
their homes and their cattle. Helping to
reconcile potentially conflicting uses of
precious freshwater in the dry lands of Kenya,
is at the bottom line of this long-running
Earthwatch Institute-funded project. |
Freshwater
Lakes
 |
Nowhere
is that man-nature conflict over water
use more acute than at the two freshwater
lakes Naivasha and Baringo.
Geological accidents keep them fresh
against the odds. In a land full of
volcanoes, hot springs and faults,
water flows out of Naivasha underground
- taking dissolved salts with it.
Both
lakes have drainage from high altitude
and high rainfall areas, a considerable
distance away, give them great inflows. |
Lake
Naivasha’s fresh water supports the largest area
of horticulture (cut flowers and vegetables) in the
country and the industry is Kenya’s largest export
earner besides tourism. Amazingly, Naivasha’s ecology
still supports very high bird diversity. Lake Baringo
lies in the more arid, lower altitude part of the
Rift about 150 miles north of Naivasha, just north
of the equator. There, the soils are fragile and
easily eroded, the climate unpredictable and harsh.
The result though, is a starkly beautiful lake, bright
brown in colour (which comes from the soils) and
set against a backdrop of the Tugen Hill, which supply
its drainage. Lake Baringo’s high biological diversity
needs scientific understanding to help save it. |
|
|
|
