Aliens Newsletter - ISSG

“Field IT for East Africa”: training young African scientists
in Lake Naivasha (Kenya)
David M. Harper, J. Robert Britton, Kenneth M. Mavuti, Nic Pacini, Elena Tricarico &
Francesca Gherardi
Lake Naivasha: gem of the Rift Valley
Lake Naivasha (0°45’S, 36°20’E; altitude 1890 m,
depth 3-6 m) is the second largest lake in Kenya after
Lake Victoria. It lies on the floor of Africa’s Eastern
Rift Valley, 80 km North-West from Nairobi, and
together with Lake Baringo, constitutes a precious
and vital freshwater resource within the Eastern Rift.
The natural fluctuation in its water level has been
in excess of 12 metres over the last 100 years, as
the result of long-term wet and dry climatic cycles
superimposed to annual variations of rainfalls
(Becht & Harper 2002).
Since the 1980s, industries of national importance
have mushroomed around the lake (geothermal pow-
er plant, intensive horticulture) opening employment
opportunities that have attracted tens of thousands of
Kenyans from all over the country. This high immigration
rate has inevitably produced a degradation of
lakeshore habitats due to: unplanned settlements, illegal
fishing, narrowing of the papyrus belt, and livestock
overgrazing (Becht et al. 2006) (Figure 1). The
proliferation of small scale agriculture throughout the
basin has led to the cultivation of river banks with
increased erosion and lake sedimentation (Harper &
Mavuti 2004). At the same time, massive water abstraction
for agricultural production and for industrial
purposes lowered the lake level by about a third
from its expected value, thus increasing the proportion
of shallow littoral areas to open water (Becht &
Harper 2002) (Figure 2).
Figure 1. The current state of Lake Naivasha, devoid of native aquatic plants because of crayfish, turbid water because of crayfish
and carp stirring up the sediment and with water hyacinth the dominant floating plant on the lake side of papyrus.
Photo: Francesca Gherardi
48 29/2010