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

4.21 The Nzhelele sub-catchment
4.21.1 General description
4.21.1.1 Hydrology
This sub-catchment consists of the area drained by the Nzhelele and Tshipise rivers and their small tributary
streams. These two small rivers flows almost due northwards from the northern slopes of the Soutpansberg
Mountains to the Limpopo River, downstream of the town of Messina (Figure 4.2). The flow patterns in these
rivers are highly variable as a result of the prevailing low and unpredictable rainfalls (average 350-400 mm) and
the rivers are not normally perennial. During drought periods, both rivers may remain without surface water for
periods of several consecutive months. Summer rainfalls cause a dramatic increase in flows, though the
tributary streams are episodic and only contain water after rainfalls.
The Nzhelele sub-catchment contains two large dams and over 80 smaller dams that are used to supply water
mainly for domestic use and livestock watering purposes (Boroto & Görgens, 1999). These dams are
responsible for most of the reduced and episodic flows in the lower reaches of the Nzhelele and Tshipise rivers.
A strongly flowing thermal spring is located at Tshipise and forms the centre of a resort development there.
4.21.1.2 Geology
Similar to the northern parts of the Sand River sub-catchment, the geological features of the Nzhelele subcatchment
consist of several different formations of widely differing ages. A variety of acidic, intrusive granites
and gneisses of the Sand River Formation underlie the uppermost reaches of the sub-catchment, whilst younger
consolidated and silicified sedimentary strata, predominantly sandstones and quartzites of the Soutpansberg
Group have in turn intruded these to form the spectacular, steep-sided hills and mountains of the eastern limb of
the Soutpansberg Mountains.
Further downstream, the sub-catchment is underlain by sequences of silicified sandstones and quartzites of the
Soutpansberg Group, followed by carbon-rich mudstones and shales, and then basalts, of the Karoo Sequence.
Compact sedimentary extrusive and intrusive rocks of the Beit Bridge Complex mark the position of the Limpopo
Mobile Belt, underlying the northern part of the catchment closest to the Limpopo River.
Large areas of the central and northern parts of the sub-catchment are overlain by recent (Quaternary) deposits
of poorly consolidated sandy material.
4.21.1.3 Pedology, agriculture and land use
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