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

northwards to join the Limpopo River downstream of the Mogalakwena River (Figure 4.2). Flow patterns are
very variable as a result of the prevailing low and unpredictable rainfalls (average 375 mm) and the streams
normally only contain surface water immediately after rainfalls during the summer months. The sub-catchment
contains one water supply dam for the Vinetia Diamond Mine and a few very small farm dams that provide
water to livestock (Boroto & Görgens, 1999).
4.19.1.2 Geology
This small sub-catchment is underlain by a sequence of silicified sandstones and quartzites, accompanied by
minor carbon-rich mudstones and shales, and then basalts, of the Karoo Sequence. The sandstones are
resistant to weathering and remain as harder outcropping rock formations that stand clear of the surrounding
terrain to form small, steep-sided ranges of hills. Quaternary deposits of unconsolidated or poorly consolidated
sandy material overlie large areas of the sub-catchment. An important diamondiferous kimberlite pipe is located
in the area and is being worked (Vinetia Diamond Mine).
4.19.1.3 Pedology, agriculture and land use
Soils in the sub-catchment can be divided into two main groups:
• Moderately deep sandy soils on the sloping and undulating terrain in the upper reaches of the subcatchment;
and
• Relatively shallow, coarse-grained sandy soils and silt deposits in flat and undulating terrain in the lower
reaches of the sub-catchment, particularly along the flood terraces of streams.
The area along the banks of the Limpopo River is part of a formal irrigation area, and uses water that is pumped
either from the bed of the Limpopo River or from boreholes sunk next to the riverbed. Further away from the
main river channel, the land use consists of small-scale livestock farming and the raising of game animals. A
few small settlements are present, though population densities are very low.
4.19.1.4 Surface water users
All of the farmsteads and settlements in the sub-catchment rely on water supplied from local boreholes or runof-river
abstraction points in the bed of the Limpopo River. Most of the water used in the sub-catchment is
consumed by irrigation along the banks of the Limpopo River, though the Vinetia Diamond Mine is also an
important water user (Midgley et al., 1999).
4.19.1.5 Water management systems
The South African Department of Water Affairs and Forestry (DWAF) is responsible for the management of all
aspects of water supply and water use in the sub-catchment. Due to the absence of significant surface water
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