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

indices of per capita agricultural production (Dalal-Clayton, 1997). In many parts of the Olifants basin,
progressive urbanization has been accompanied by the development of peripheral “informal” settlements
around the major urban areas.
In stark comparison to the Zambezi Catchment, the South African and Mozambique portions of the Olifants
Catchment are relatively densely settled (Table 5.2). Whilst the Olifants basin does not contain any very large
cities, there are numerous medium- and small-sized towns and villages. In the Mozambique portion of the
basin, the population is more evenly spread and the only sizeable groups of people are those associated with
irrigation activities near the Massingir Dam and the nearby Chokwe Irrigation Scheme (which is located just
outside the Olifants basin).
5.1.4 Hydrological characteristics, water availability and patterns of water use
The quantity and timing of rainfall received in the Olifants basin controls the quantity, timing and duration of
flows in the different tributary rivers. The uneven distribution of rainfall in the basin is reflected in the very
uneven distribution of water resources in the different sub-catchments. In turn, these influence the types of
economic activities undertaken by the residents in each area. The uneven distribution of water across the
basin, coupled with increasing competition for the available water resources, has led to tensions and occasional
disputes between individuals and communities as to what can be considered as a “fair and equitable share” of
the available water resources (Ashton, 2000).
The Olifants River and its larger tributaries all exhibit marked seasonal cyclical patterns of high and low flows
and many of the smaller tributaries are entirely seasonal or episodic. In some, drier years, surface flows cease
in several tributaries though some water continues to flow in the deeper alluvial deposits. The northern and
eastern parts of the basin that receive the lowest rainfalls have many seasonal or episodic rivers that have no
surface flow during the dry winter months.
The demand for water throughout the Olifants basin is both high and unevenly spread. In particular, water
demands by industry, mining and especially the formal (irrigation) agricultural sector account for over 75% of all
water used. Coupled with high evaporation losses from the numerous small dams and larger water supply
impoundments, flows in the lower reaches of the Olifants River are usually relatively small, unless they have
been “boosted” by the arrival of a tropical cyclone (e.g. the cyclone that arrived in 2000 and flooded large
coastal areas of Mozambique).
The escalating competition for water and the continued water shortage in the upper reaches of the Olifants
basin prompted the importation of additional water supplies from the Vaal and Komati basins to the south.
These water supplies are seen to be essential for continued operation of the many thermal (coal-fired) power
stations and their satellite collieries. The overall water supply “picture” is made even more uncertain by the very
real possibility that global climate changes will also have an adverse effect on water availability throughout
southern Africa (Ashton, 2000).
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