AfroMont Independent

Water forms the key ecosystem value from mountains in South Africa

For humankind, mountains are essential for life as they provide water for much of the global population (Viviroli et al., 2007).  South Africa is no different. We often hear that South Africa is a water-stressed country, and that the finite water resources will be a constraint on further economic growth. In 1998, the IPCC noted that water availability in African upland countries (including South Africa) would decline – in the case of South Africa to below the 1000 cubic metres per capita per annum threshold deemed to be a standard for ‘well-being’ (Beniston, 2003). This decline will be driven by both population growth and predicted modified precipitation patterns.

Fresh water stream in the Drakensberg Mountains foothills. Photograph SJ Taylor

Climate  change  is  only  one  of  several  drivers  currently  informing  water  resource planning  and  decisions  in  South  Africa.  Most  critically,  surface  water  resources  were already  over-allocated  and  experiencing  water  stress  by  the  year  2000  in  five  of  19 Water Management Areas (WMAs). Demand is expected to increase with economic  growth,  increased  urbanisation, higher  standards  of  living  and  population growth.  Surface-and  groundwater  are  also  exposed  to  contamination  and  pollution from  diffuse  urban,  industrial,  and  agricultural  sources,  as  well  as  point  sources  at water treatment works, land-fills and mines. All of these changes will have significant impacts on the future availability of water resources (SNC, 2011: 71).

 For this reason, South Africa should work harder to ensure that mountain catchments, the source of most of South Africa’s water, remain in as near pristine condition as possible.  An ambitious data gathering programme is needed, along with high altitude observatories (weather stations, river flow monitoring equipment and biodiversity study sites). The  net  impacts  are  speculative,  but  increased  tree  cover  driven  by  rising  CO2 and  climatic  changes  could  have  adverse impacts  on  surface  water  flows  in  the  currently  grassland-dominated  catchments  of the  Drakensberg  – a  major  source  region  for South  Africa’s water    supply;    while    appropriate    control    of    tree   establishment    through    fire  management could offset this change (SNC, 2011: 86).

Gauteng province, the economic heartland of South aFrica, and now the most populous province, receives water from the Vaal River catchment, and water from the Lesotho Highlands Water project augments the Vaal system,  ensuring the livelihoods of around 11 million persons in Gauteng and supporting the entire economy of Gauteng – industry, mining, power generation and agriculture. The Gauteng GDP is R897 553  million (2010), almost none of which would be secure without the water from the Drakensberg/Maloti highlands catchment.

The principal dams that supply the Cape Town Metropolitan area in the Western Cape province are all located in the Cape Fold Mountains to the east of Cape Town. They are the Theewaterskloof Dam, Wemmershoek Dam,  the Steenbras Dams (Upper and lower), the Voëlvlei Dam and the  Berg River Dam. As we know, these dams have been empty in the last few years, creating a water crisis in Cape Town. Cape Town was said to be the first big city in the world to actually run out of water.

The Senqu-Orange Basin, which also originates from the Lesotho Highlands, supports around 18 million persons, plus irrigation and mining projects worth many millions. A significant amount of water from the Orange River is transferred from the Gariep dam into the Fish River catchment in the Eastern Cape to supply irrigation requirements for about 51 500 ha in this province as well a part of the requirements of the city of Port Elizabeth. When released from the Gariep and Vanderkloof dams the water is used for hydropower generation and forms part of Escom’s (the national electricity supplier) capacity to meet peak electricity demands.

The Senqu Orange  River relies completely on Lesotho’s mountain catchments which are now very degraded through poor land management and over-grazing. Viviroli et al. (2003) place this river in their “Group 1” which is a category indicating that these mountain catchments and their streams have immense hydrological significance for downstream lowlands. The maintenance of ecosystem functioning and ecosystem services of this and other smaller rivers with mountain catchments depends entirely on the biodiversity in the mountain catchment areas (Korner, 2004). The Intergovernmental Panel on Climate Change (IPCC) stated in 2007 that mountain regions will be particularly affected by climate change, and that hydrological changes could already be observed.

In light of South Africa’s energy constraints, the ‘health’ of mountain catchments and continued flow of good quality water through pumped storage schemes are worth mentioning as they rely on altitude to function.

Early warning systems for tracking global change in mountains

As mountain catchments and their health are so vital to the continued economic growth and human wellbeing in  South Africa, we  do not want to see mountain catchments ‘change’ without early warning of such adverse changes. We thus need an early warning system to alert decision makers and scientists when ‘thresholds of concern’ have been reached in high altitude mountain catchments.  For this reason, long term data collecting, through an array of weather stations and other monitoring technologies, is now necessary to give us the data needed to predict, create scenarios and take early action when negative trends are noted.

We also need to understand, through biodiversity monitoring, what sort of species declines (or increases) lead to ecosystem change and/or reduced ecosystem functioning.

Gazanias and insect pollinators, Drakensberg foothills near Monk’s Cowl. Photograph by SJ Taylor

Also, as a consequence of the steep topographic and climatic gradients in mountains, understanding the genetic diversity (and hence demographic history) of montane taxa will provide information not only on a species’ past, but also illuminate the potential responses of a species to future changes from a genetic perspective, as demographic changes may have occurred over comparatively short distances in relatively short time frames. However, actually demonstrating that climate change has resulted in changes in selection pressures on an organism is difficult, and many studies use phenotypic data to show a response, but cannot link this to directional selection at the genetic level (Holt, 1990; Gienapp et a., 2008).

Recommendations

While there is already formal monitoring of river quality and quantity in South Africa, through Integrated Water Management initiatives, but there are no high altitude mountain observatories tracking change to precipitation and temperatures at this level. Weather stations in the Drakensberg and Malutis do exist, but there are too few of them. There are no long-term monitoring programmes to track key indicator species of the montane biota of South Africa. This research needs to be geared towards multiple agendas, notably assisting water managers towards achieving water security for South Africa;  conservation unique montane biodiversity and ecosystem features; and preparing for climate change and a future where water may be much more constrained than presently.

Selected information sources

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