The Berg River Nexus
The Berg River catchment has the following nexus characteristics (summary):
- Water: Water supply and demand are tightly balanced and deficits are expected to arise by 2022 unless water is managed more efficiently or new sources of water are developed. 27% of the water is transferred into the catchment from the Breede River catchment. Around half of the available water is used for agricultural production, most of which is exported. Agro-processing is economically important and uses water, for example in canning and wine-making. Future growth in water demand will arise from population growth both within the catchment and in the City of Cape Town, and from growth in the industrial and manufacturing sectors. The ecological reserve has not yet been fully implemented and this is also a priority. A substantial proportion of water resources are used by invasive alien plants, mainly tree species, and eradication programmes hope to return this resource to the river system. Surface water is the main water source, and groundwater is used to a much lesser extent in some rural towns and on farms. Return flows from agriculture are sizeable but also contribute to pollution through the build-up of agro-chemicals. High levels of pollution are also caused by inadequate waste water treatment and sewage spillages, and solid waste. At present, no water is used for the production of biofuels and energy generation is limited to wind farms with a very low water footprint.
- Land and soil: There has been significant land use change from the natural vegetation to agriculture. Remaining land in its natural state is either very unproductive, heavily invaded by alien plants, or has been placed under conservation protection. Agricultural land around the urban edges is coming under increasing pressure from the growth of settlements and from high-end lifestyle property developments. Land degradation has occurred in places due to soil salinization. No land is currently used for biofuel production, and land use for energy infrastructure has a very low impact.
- Food and fibre (agriculture): Intensive agricultural production (mainly fruit and wine) occurs in the Upper Berg, whereas the Lower Berg is more suited to dryland production of small grains and livestock. There is almost no further scope for additional productive agricultural land and the water allocation to agriculture has been capped. Almost all fruit and wine farmers already use water-efficient drip irrigation technology, although actual irrigation scheduling and pumping could be further optimized. New crops need to be adapted to the climate and highly water use efficient. The poor water quality is cause for grave concern to export-oriented fruit and wine farmers and livestock farmers. There exists further potential for groundwater extraction although this requires more research and analysis to ensure sustainability. Groundwater quality is not suited to agriculture in some parts of the catchment due to high salinity levels. Food is readily available but not sufficiently accessible to poor households. Shortages in own supply are balanced through food imports.
- Biodiversity: The catchment has extraordinary high levels of terrestrial and aquatic biodiversity. A number of vegetation types, aquatic habitats and species are threatened. The loss and degradation of wetlands and destabilisation of river banks due to cultivation practices are of great concern. Other threats to biodiversity include the large-scale encroachment of alien invasive plants and the apparent increase in risk of wildfires. The considerable economic development planned for the Saldanha Bay area could threaten the integrity and biodiversity of the highly sensitive estuary and Langebaan Lagoon. Protection levels are, however, fairly good although further protection is sought for specific habitats and species. The fruit industry is highly dependent on pollinators – commercial Cape honey bees are mainly used, but a diverse group of other wild pollinators have been found to play a role.
- Energy: Very little energy is generated within the Berg River catchment, and is mainly limited to a few small wind farms. Energy and fuel requirements are met through imports, thus externalizing the water and carbon footprint of energy generation. However, supply is nationally constrained and sometimes subject to restrictions. Alien invasive trees are being harvested in the catchment and processed into wood chips which can be used as fuel – these are mainly exported. The energy required for water management (transfers, extraction, treatment and distribution) is small compared to other users. Agricultural energy use is linked primarily (around 70% of the carbon footprint) to electricity for irrigation pumping, packaging and processing (including wineries). Recently, solar energy is starting to be harnessed for agricultural applications such as water pumping and packhouse energy needs.
The FEWLB Nexus in the Berg River system shows that constraints are already being experienced in the availability of water, arable land and energy and the quality of the water. Ecosystems are already highly impacted and fragile.Agriculture remains stable as long as water, land and energy are available at current levels and pricing. Climate change and the transition to a green economy could alter this precarious balance significantly in future. Opportunities for economic development will need to be carefully assessed within this framework.