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

4.5.1 General description
4.5.1.1 Hydrology
The Zimbabwe portion of this sub-catchment is Zones S1-S6, T1-T5, M and R of Area B (ZSG, 1984). The
major tributaries of the perennial Shashe (Shashi) River are the Thuli (Tuli) (Zones T1-T5 and M), Shashani
(Zones S2 and S3) Simukwe (Zones S4 and S5) and Ramakwebana (Ramaquebane) (ZSG, 1984). The
Shashani is dammed at Gulameta, the Chavezi, a tributary of the Thuli, is dammed near Silobi, and the Ingwezi,
a tributary of the Ramakwebana, is dammed near Domborefu.
In Botswana, small water supply dams on the Shashe River provide water for local communities and mining
operations, as well as small-scale irrigation farms.
4.5.1.2 Geology
See Figure 3.6 (ZGS, 1999). The Zimbabwe Craton underlies most of the sub-catchment, including the
Botswana portion. Important formations include: Gwanda Greenstone Belt, Lower Gwanda Greenstone Belt,
Mphoengs Greenstone Belt and granitic terrain. The south is underlain by Limpopo Belt gneisses, and the far
south (Thuli Village area) by Karoo basalts. In the western (Botswana) portion of the sub-catchment, Archaean
granites and gneisses are intruded by numerous Greenstone belts, with associated Karoo System rocks and
silicified sandstones.
4.5.1.3 Pedology, agriculture and land use
Soils in the sub-catchment can be divided into five groups:
• Moderately shallow, coarse-grained kaolinitic sands, derived from the granites;
• Very shallow to moderately shallow sandy loams, formed from gneisses;
• Very shallow to moderately shallow clays, formed from the Greenstone Belts;
• Shallow, clay soils with high sodium content in internally draining areas; and
• Very shallow sands, derived from the basalts (DRSS, 1979).
From Kezi northwards in Zimbabwe, the sub-catchment is in Natural Region IV, with low (under 650mm) and
unreliable rainfall, and poor soils. South of Kezi is in Region V, with poor soils, rainfall under 600mm and in
places under 450mm (ZSG, 1997). In the Botswana sector of the sub-catchment, rainfalls decline steadily
towards the west and south, reaching some 350-400 mm per annum at the Sashe-Limpopo junction.
North of Kezi, land use is commercial farming, private and resettlement land (ZSG, 1998), mainly livestock
rearing with some drought resistant crops. The south is Communal Lands, and agriculture limited mainly to
livestock, especially goats. The main settlements are Kezi and Maphisa Villages.
ccxxvi