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

4.12.1.3 Pedology, agriculture and land use
Soils in the sub-catchment can be divided into four groups:
• Relatively deep, unconsolidated sands of marine origin covering much of the Chagane sub-catchment;
• Moderately shallow, coarse-grained sands derived from the Rhyolites of the Lebombo Mountains;
• Moderately shallow to moderately deep, medium-grained loamy sands and silty sands along river channels
and flood terraces; and
• Shallow, coarse-grained sandy soils derived from Karoo Series basalts.
Soils in the Chokwe Irrigation Scheme located downstream of the Limpopo-Olifants confluence consist
predominantly of silty or loamy sands derived from earlier flood events. Crops produced consist of Cotton,
Sorghum and Maize, with some cultivation of fruit trees (Mangoes and Cashew Nuts).
Land use outside of the Chokwe Irrigation Scheme consists predominantly of subsistence agriculture and minor
livestock rearing, with small-scale tourism activities along the coastline at Xai-Xai.
4.12.1.4 Surface water users
The largest water users in this sub-catchment are the Chokwe Irrigation Scheme (Boroto & Görgens, 1999) and
the town of Xai-Xai. The Chokwe Irrigation Scheme covers a potential area of 29,000 hectares (290 km 2 ) and
its water demand has been estimated at over 500 million cubic metres per year (Boroto & Görgens, 1999). It
can be anticipated that some of this water will return to the Limpopo River as seepage contaminated by
whatever agro-chemicals are used in these sandy soils.
Elsewhere in the sub-catchment, water users consist of a large number of small settlements along the Limpopo
River and in the Chagane sub-catchment. Where perennial surface water is absent, these users rely on handdug
wells for all their water requirements.
4.12.1.5 Water management systems
The Mozambique Department of Water Affairs is responsible for the management of all water resources within
this sub-catchment and monitors flows irregularly at three points along the Limpopo River. These data are
apparently insufficient for accurate modelling purposes (Boroto & Görgens, 1999).
4.12.1.6 Human impacts on water resources (excluding mining)
Impacts on water resources in this sub-catchment are expected to consist of:
• Contaminated return flows seeping from the Chokwe Irrigation Scheme;
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