Morphological Structure and the Anthropogenic Dynamics in the Lake Naivasha Drainage Basin and its Implications to Water Flows
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Authors
Onywere, S. M.
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Summer School 2005
Abstract
Throughout its length, the Kenyan Rift Valley is characterized by
Quaternary volcanoes. At Lake Naivasha drainage basin, the Eburru
(2830m) and Olkaria (2434m) volcanic complexes and Kipipiri
(3349m), Il Kinangop (3906m) and Longonot (2777m) volcanoes
mark the terrain. Remote sensing data and field survey were used to
make morphostructural maps and to determine the structural control
and the land use impacts on the drainage systems in the basin. Lake
Naivasha is located at the southern part of the highest part of Kenya’s
Rift Valley floor in a trough marked to the south and north by
Quaternary normal faults and extensional fractures striking in a
N18°W direction. The structure of the rift floor influences the axial
geometry and the surface process. Simiyu and Keller (2001) interpret
the rift floor structure as due to thickening related to the pre-rift
crustal type and modification by magmatic processes. The rift
marginal escarpments of Sattima and Mau form the main watershed
areas. From the marginal escarpments the Rift Valley is formed by a
series of down-stepped fault scraps. These influence the nature of the
soils and the rainfall regime. The drainage is also influenced by the
fault trends. At the Malewa fault line for example the drainage is
south-easterly influenced by the trend of the Malewa fault line
(Thompson and Dodson, 1963). The morphotectonic control on the
drainage has implications on ground water recharge in the Naivasha
basin. This may also influence the spring water supply and geothermal
reservoirs. The nature of the terrain, human development processes
and their impact on the lake was visualized using Landsat TM satellite
data (path 169/Raw 060) from three dates (28/1/1986 L5, 1/3/1989 L4
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Citation
FWU, Vol. 3, Topics of Integrated Watershed Management – Proceedings