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

4.17 The Theuniskloof sub-catchment
4.17.1 General description
4.17.1.1 Hydrology
This sub-catchment consists of the area drained by two small seasonal – episodic streams, and is located
between the Laphalala and Mogalakwena sub-catchments (Figures 4.2 and 4.3). These two stream systems
flow northwards to join the Limpopo River downstream of the Laphalala River (Figure 4.2). Flow patterns are
very variable as a result of the prevailing low and unpredictable rainfalls (average 380 mm) and the streams
normally only contain surface water immediately after rainfalls during the summer months. The sub-catchment
contains a few very small farm dams that provide water to livestock (Boroto & Görgens, 1999).
4.17.1.2 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 ranges of hills. Quaternary deposits of unconsolidated or poorly consolidated sandy
material overlie large areas of the sub-catchment. A few intrusive, diamondiferous kimberlite pipes have been
discovered in the area.
4.17.1.3 Pedology, agriculture and land use
Soils in the sub-catchment can be divided into two main groups:
• Moderately deep sandy loam soils on the sloping and undulating terrain in the upper reaches of the subcatchment;
and
• Relatively shallow sandy soils in flat and undulating terrain in the lower reaches of the sub-catchment.
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 in the sub-catchment, though population densities are very low.
4.17.1.4 Surface water users
All of the settlements in the sub-catchment rely on water supplied from local boreholes or run-of-river
abstraction points in the bed of the Limpopo River. Most of the water used in the sub-catchment is consumed
cclxiii