Due to its position in a Mediterranean-type climate region, rainfall is concentrated during the cool winter months, with a steep gradient from the south-eastern upper catchment (>1200mm per year) to less than 300mm per year at the north-western estuary. Summers are dry and can get very hot, particularly on the more northerly interior plains at the foot of the mountains. Cooler conditions prevail in the mountains and along the windy coastline. The area is geologically diverse and includes Table Mountain sandstone, granite and Malmesbury shale, with extensive coastal sandy areas of recent geological origin. The combination of climate and soils results in patches of high fertility, but large areas of lower potential productivity suited only to dryland farming.
This catchment is a significant water source on a regional level. The area is an integral part of the Western Cape Water Supply System (WCWSS), which focuses both on ensuring adequate water supply for the metropolitan area of Cape Town and surrounds, as well as supplying the needs of irrigators and some rural towns. Major users of the water within the catchment include irrigated agriculture (grapes and fruits, ca. 54% of water resources), processing of agricultural produce, municipalities (urban water supply, wastewater treatment), and industry (mainly around Saldanha Bay and Paarl/Wellington). Water is abstracted primarily from surface water (57% of total water resource), although groundwater (8%) is used in some towns such as Porterville and Hopefield.
A few larger dams form part of the WCWSS. They are the Berg River Dam (completed in 2007) and Wemmershoek Dam, both in the upper catchment, the Voëlvlei Dam and the Misverstand Dam. Substantial amounts of water (27% of the water resource) are transferred into the basin during the summer months from the adjacent Breede River catchment to supplement the water resource. Many hundreds of small private farm dams also provide an essential water resource for irrigated agriculture. Nevertheless, the Berg River system is under water stress and new water augmentation schemes will be required by 2022 in order to avoid deficits. New sources of water are likely to become increasingly costly.
Poor water quality has been identified as a major concern in the Berg River system, particularly further downstream. The reasons range from agro-chemical runoff from intensive farming operations, and ageing and under-capacity waste water treatment facilities for burgeoning settlements, to a natural tendency towards high levels of salinity from tributaries underlain by shales of marine origin. This pollution situation threatens the viability of export-driven agriculture and industrial processes in Saldanha Bay (e.g. steel production) which require water of a minimum quality standard. Various initiatives and projects are underway to address this, notably the Berg River Improvement Plan (BRIP).
Pollution in the Berg River. Source: Mark New
Roughly sixty percent of the Berg River catchment is agricultural, with primarily grapes and deciduous fruits being cultivated intensively in the eastern regions, and small grains (e.g. wheat, canola) and livestock (cattle and sheep) dominating the drylands to the west. Significant foreign revenue earnings flow from the export of fruits and wine/spirits, with most of the production being exported. Other products include vegetables, indigenous ‘fynbos’ flowers (Protea and others), olives, dairy products and poultry. Agriculture also drives much of the secondary economy in the form of fruit and vegetable processing, including canning, drying, juicing, and jam production.
Extensive land use change from natural fynbos and Renosterveld vegetation to agriculture and settlements has placed the rich biodiversity under threat. The area forms part of the Cape Floral Kingdom, the smallest of the six Floral Kingdoms in the world, but containing extraordinary high levels of terrestrial and aquatic biodiversity and endemism. This biodiversity ‘hotspot’ has immense intrinsic value for the healthy functioning of the ecosystems of the catchment, as well as having great economic value associated with wildflower harvesting and ecotourism. Conservation efforts have been aided by the proclamation of numerous protected areas, concentrated in the mountains and the West Coast area. The most significant threats are the encroachment of alien invasive plants and the rising risks of wildfires, as well as degraded river banks and wetlands. The Langebaan RAMSAR site serves to protect the rich biodiversity of the Lagoon and surrounding wetlands, including ca. 55,000 waterbirds in summer, many of them migrants.
The Berg River catchment imports almost all its electricity requirements from the national grid through the utility ESKOM. This energy is heavily coal-based, with a small nuclear and gas component. Electricity supply has been strained for a number of years and this has impacted on all users countrywide. Until new generation capacity up-country comes online, economic development, especially heavy usage associated with some industries envisaged for the Saldanha Bay area and elsewhere, could limit accelerated economic growth. Additional electricity is required to fully service the growing informal settlements in the area. Within the Berg catchment, a few wind farms have been constructed but with small generating capacity. Further development of this renewable resource, together with solar power, is supported by national and provincial government goals but is currently held back by lack of investment and sub-optimal economic and regulatory conditions.