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

3.16.1 General description
3.16.1.1 Hydrology
This area comprises a series of small sub-catchments, whose rivers flow in a southerly direction towards the
Luano Rift valley, where they swing westwards to join the Luangwa River. The two main rivers, the Mulungushi
and the Lusemfwa, are both perennial and have incised relatively deep channels through the edge of the
escarpment where they drop into the Luano Rift Valley. Both of these rivers have been dammed for
hydroelectric power, at the Mulungushi and Mita Hills dams, respectively. Smaller, non-perennial and perennial
tributaries that drain the higher rainfall region to the north of the sub-catchment feed both of these rivers. There
are several small wetland areas and seeps in the upper reaches of the rivers.
3.16.1.2 Geology
The plateau is composed of quartzites, sandstones, arenites and associated rocks, underlain by sedimentary
rocks and some basalt to the south. These rock formations are intruded by small Greenstone formations that
are normally associated with gold and copper mineralization. The Kabwe lead-zinc-vanadium deposit is
associated with a dolomite and limestone outcrop. The mobile belt marking the rim of the Luano Rift Valley
hosts several pegmatite deposits with high quality mica and other pegmatite minerals, as well as small
quantities of gold.
3.16.1.3 Pedology, agriculture and land use
Soils in the sub-catchment can be divided into four groups:
• Moderately deep, well-leached ferralitic soils in the wetter northern parts;
• Moderately deep sandy soils derived from quartzites and sandstones associated with the Luano Rift Valley;
• Moderately deep kaolinitic sandy to loamy sand soils derived from quartzites and associated rocks along the
floor of the rift valley;
• Moderately deep, sandy loams on areas underlain by limestone deposits.
Much of the sub-catchment experiences annual rainfalls in excess of 1,000 mm, whilst areas in the Luano Rift
Valley receive lower rainfalls of around 850 mm.
Land use comprises a mixture of sparsely populated communal lands with subsistence agriculture, densely
populated urban areas of Kabwe and Kapiri Mposhi, with commercial stock farming (beef cattle and goats) and
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