A COMPARATIVE STUDY OF LANDSLIDES AND GEOHAZARD ...

2.1.5 Soils
There are four main soil groups, all differing markedly from each other in the
environmental conditions under which they have been developed: in the process of
formation; in a profile characteristics, and analytical properties (Agnew and Stubbs,
1972). The latosols are red to yellow, leached, acidic soils in which water movement
within the profile is predominantly downwards. They occupy freely drained sites, mainly
on the gently sloping plains, but also in some more steeply dissected areas. The
calcimorphic soils are grey to greyish-brown, with a weakly-acid to weakly-alkaline
reaction in which water movement is upward during at least part of the year. They
occur on nearly level depositional plains with imperfect site drainage. The
hydromorphic soils are black, grey or molted and water logged for all or part of the
year. The fourth group comprises lithosols, which are shallow or stony, and regosols,
which are immature, developed from sands (Agnew and Stubbs, 1972).
2.1.6 Hydrology
Twenty percent of the total area of Malawi is covered by water, comprising of Lake
Malawi, Chilwa, Malombe, and Chiuta and major rivers such as Shire, Songwe, North
and South Rukuru, Bua, Mwanza, Linthipe, and Ruo (Figure 2.1a). Lake Malawi is a
dominant feature with a surface area of about 28,760km 2 with a catchment area of
96,918km 2 . Annual rainfall over the Lake is estimated at 1549mm, with total inflow of
920m 3 /s and out flow of 395m 3 /s. The outlet of Lake Malawi is Shire River which has three
sections, namely, upper (132km with a gradient of 5.29m), middle (384m with a total fall
of 384m), and the lower section which stretches from the cataracts to the Zambezi River
over a distance 281km (Linceham, 1972; and Agnew and Stubbs, 1972).
2.1.7 Vegetation
A greater proportion of Malawi’s natural forest is dominated by Brachystegia
woodlands (Abbot, 2005). The plateau areas are vegetated by Brachystegia-
Julbernadia woodlands while the plain areas have broad-leaved deciduous
Combretum, Acacia and Piliostigma (Figure 2.4). These tree species are being replaced
by agricultural crops. Highlands like the Nyika are dominated by high altitude grassland
while Mount Mulanje has Montane vegetation. Areas receiving low (< 750mm per
annum) rainfall such as the Phalombe-Chilwa Plain are dominated by scrub vegetation.
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