Transcript Namibia Soils - Nova Scotia Department of Education

Namibia may be divided into
three physical regions. The
first is the western coastal
plain of the Namib desert
which occupies 12% of the
total, the second is the
central plateau stretching
form the southern to the
northern border covering half
of the country , and the third
is the semi-arid Kalahari zone
lying along most of the
eastern portion of the
country.
On the east, the central plateau rises
abruptly at the Great Escarpment. The
plateau averages about 1100 m in
elevation, but climbs to elevations of
more than 1800 m in several
mountainous areas.
Granite mountains stand isolated
like steep islands on the plains of
the inner Namib, one of them - the
Brandberg massif - the highest in
Namibia at a height of 2579m. This
granite pluton rises 1900 m above
the surrounding desert plains and
covers an area of 650 square
kilometers.
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The Kalahari zone is covered by
sand of varying thickness.
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The unsaturated zone plays an
important role in the terrestrial
water balance; it is a controlling
factor of plant growth as well as
for the quantity and quality of the
recharge waters and of the
resultant groundwater.
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in the arid zone 95% of what
goes on there hydrologically is
governed by processes in the
unsaturated zone.
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It is the dominance of the arid
regions by the unsaturated zone
that make them special
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The western coastal plains are
largely composed of mobile
dunes,gravel and sandy plains
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approximately 250 km north west
of Windhoek a broad belt of large
igneous complexes, extend from
the coast north east to central
northern Namibia.
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these complexes are silica
undersaturated and alkaline, and
therefore have unusual
mineralogy
extensive plains, are barren near
the west coast, colonized by low
grasses and scrub further inland
and thornbush becomes
predominant in central northern
In the Etosha National Park an elephant
on its way to a water hole. These springs
are fed by water reserves in porous
bedrock. Groundwater and pedogenic
regolith carbonates, and evaporative
chemical sediments dominate the
regolith materials.
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Situated in Namibia’s central
highlands, Windhoek,the capital is an
attractive city surrounded by clusters
of hills and the impressive Auas and
Eros mountains.
The central plateau comprises
mountains, highland areas and
the Great Western Escarpment.
The semi-arid southern region
consists of sunbaked savanna
with its yellowish-brown tints and
characteristic euphorbia and aloe
plant species
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The central plateau, which runs
from north to south, has an
average altitude of between 1000
and 2000m
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This plateau gradually falls away
towards the east where a sandy
strip of land merges into the level
expanse of the Kalahari desert
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The countries soils have 97% clay content of less than 5% and
thus have a very low water holding capacity
they are generally deficient in most of the major nutrients, and
also deficient in micro-nutrients such as manganese, iron and zinc
unconsolidated sand and shallow, weakly developed soils on
bedrock characterize the main groups of soils in this semi-arid to
arid country
soil types include acrisols, alkaline soils, alluvial soils, arenosols,
arid soils, calcareous soils, cambisols, clay soils,
ferralsols,gleysols, lateritic soils, luvisols, regosols, saline soils,
sandy soils, vertisols
soil drainage is free, impeded, seasonally waterclogged
This picture shows the erosion of the Fish
River Canyon. The base rocks of the Fish
River Canyon, now at the bottom nearest
the river, are shales, sandstones and
lavas which were deposited about 1,800
million years ago.
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The Namib Desert covers some
15% of Namibia with dune seas,
gravel plains and deeply eroded
canyons such as the Fish River
Canyon which is 160km in length,
up to 27km wide and reaches a
depth of 550 meters
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A period of erosion occurred,
removing the overlying rocks and
leveling this complex to be the
floor of a vast shallow sea,
covering most of what is now
southern Namibia.
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about 650 - 500 million years ago
various sediments, were
deposited by the sea to the floor,
building up into what is now
called the Nama Group of rocks.
Effects on the Namibian Environment
 In a dry environment such as that
of Rossing radioactive dust from
mining operations and mill
tailings can present a special
problem, despite the practice of
sprinkling the tailings to keep
dust levels down. A second
environmental problem is water
borne radioactivity from the
tailings reservoir. The tailings
area is about 250 meters higher
than the Khan River, only about 6
kilo meters away
 A third environmental problem is
the high demand for water at
many stages of the operations
and the possible lowering of the
water table and rivers in a large
area around the mine as a result.
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