| dc.description.abstract | Ewaso Narok swamp is a papyrus riverine wetland located in the semi-arid Laikipia
District, in eco-climatic zone four. It is located at the confluence of the Engare Narok
and Pesi rivers. The surrounding area is dominated by Acacia trees, Themeda
triandra and Chloris grasses forming wooded grassland. The wetland is a center of
farming activities, which poses a major threat to wetland biodiversity. The aim of this
study was to assess the prevailing ecological status, utilization and human impact in
the wetland. .This was done through a biological inventory, sampling of soil and
water to analyze a wide range of attributes. Temporal variation in wetland conditions
was assessed, by considering both wet and dry seasons.
The results showed high ion concentration during the dry season in both water and
soil. Significant difference in water quality was only exhibited in pH, sulphate,
Sodium Adsorption Ratio (SAR) and nitrogen due to the canalized nature of the
swamp water flow. Some ions namely potassium, sodium and magnesium showed a
pattern of low concentration in the swamp, 5.9-37.8, 7.6-3l.2 mg/l and 3.9-6.4 mg/l
respectively. Others ions with low concentration include chloride and sulphate 62.9-
l.6.5 mg/l and 1.9-5.25 mg/l respectively. Both bicarbonates and nitrogen had high
concentration range (15.3-36.7) and (0.5-l.3) mg/l respectively. A general rise in ion
concentration during the dry season was noted due to the evaporative effect.
Ewaso Narok swamp soils were notably acidic with pH range between 5.4-6.2 with
subsequent low conductivity of 0.25-0.4 mmhos/cm. Ecological factor had a stronger
influence on soil fertility.zhan seasonality. Only sodium and nitrogen exhibited
significant temporal variations with nitrogen recording highest concentration during
the wet season while sodium had low concentration during the dry season. Significant
difference in soil fertility was also recorded between the natural swamp and the
cultivated zone. Human impact in the swamp appeared to be felt more in soil the than
in the water subsystem. Water quality and nutrient level in the wetland are influenced
more by watershed geology than by human activities.
The swamp exhibited high plant diversity, especially along the edges of papyrus zone,
which provides a rich bird's habitat. The rest of the vegetation formations like
papyrus and grasslands have extensive but less varied vegetation association. The
drawdown areas also offer good habitats for both birds and grazers. Although the
edge habitat has more specialist birds, the drawdown area is composed more of
generalist species. Human impact is more evident through habitat loss than alterations
in water and soil sub-systems.
The swamp offers a number of useful resources to the local community, which
include thatching and mat making materials. The ecosystem is an important farming
and grazing area. Although land allocation is temporary, the swamp forms an
important lifeline for the local community as a source of food. The major
occupational hazard in the swamp is extensive flooding which results in great loss of
both material and life. Although dry periods allow extensive re-settlement, farming
.and grazing, the seasonal flooding facilitates swamp recovery from disturbance.
However, the continued drainage may result in total loss of this useful resource as it is
converted into a single use. Hence, the need for a sustainable use, solution. From the
results of this study, it is po-ssible to conclude that the water s slightly alkaline mainly due to upstream geology effect, while the soil are acidic to neutral due to organic
material decomposition and reduction process in the swamp. The swamp exhibit high
biodiversity, which should be conserved and utilized sustainably, since human
activities have not had major negative impact in the wetland. It is a source of
livelihood both for pastoral and agrarian communities. However, it is important that
future development be based on existing swamp resources and that further research be
carried out to establish the nutrient budget and effect of human activities in catchment
on the swamp. This study recommends the protection of the wetland ecosystem as an
important biodiversity area. | en |
