OVERVIEW OF THE IMPACT OF MINING ON THE ... - IIED pubs

This portion of the Zambezi Valley lies in a relatively dry zone with annual rainfalls averaging between 650 and
750 mm. Below the Cahora Bassa dam, the Zambezi River flows through the deeply incised Cebrasbassa
Gorge before emerging onto a broad, flat-bottomed river valley where the river meanders between high flood
levees.
The smaller, perennial and non-perennial streams that drain the escarpments from the north and south all have
steep gradients and only contain significant quantities of water after rainfalls.
3.18.1.2 Geology
The plateaux on both sides of the Luangwa Rift Valley are composed of quartzites, sandstones, granites and
gneisses, underlain by Karoo Supergroup sedimentary rocks with extensive coal measures running from west to
east. These rock formations are intruded by numerous small pegmatites and Greenstone formations that are
host to a variety of semi-precious stone deposits and gold.
The intrusions of Greenstone formations and the coal measures mark the position of the Zambezi Mobile Belt
and its associated mineralization. A significant deposit of uranium is also located in this zone.
3.18.1.3 Pedology, agriculture and land use
Soils in the sub-catchment can be divided into two main groups:
• Moderately deep, well-leached soils in the wetter northern and eastern parts of the sub-catchment; and
• Moderately deep sandy soils derived from quartzites and sandstones and associated alluvial material along
the floor of the Zambezi Valley.
Land use comprises a mixture of sparsely populated communal lands with subsistence agriculture, the densely
populated urban area of Tete, and the small communities associated with the various mining ventures in this
sub-catchment. Livestock consists almost entirely of goats and most families rely on fish caught from the
Zambezi River. Several small communities are located along the major roads between Zimbabwe and Blantyre
in Malawi and between Tete and the Cahora Bassa Dam. Large areas of vegetation have been removed to
make charcoal for fuel.
3.18.1.4 Surface water users
There is some consumption of water for small-scale agriculture, whilst water used for domestic purposes in the
larger towns is obtained from the Zambezi River.
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