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Alignment with SDGs
AUTHOR
Ian Bredin, Jackie Dabrowski, Michelle Browne, Sue Viljoen, Freelance Ecologist, Hilton, South Africa, Confluent Environmental, George, South Africa, Freelance Economist, Howick, South Africa, 4WWF-SA, Hilton, South Africa
Water scarcity – a key driver
South Africa is a water-scarce country. Its socioeconomic development has been and will continue to be directly hampered by climate change and associated drought conditions. Water demand in South Africa has been witnessing a steep increase, with three major sectors driving the demand. The agriculture sector is the highest at around 63%, with the major water uses including the irrigation of crops and land used for water-intensive grazing of livestock. Water demand is expected to exceed supply in South Africa by 2030.
The scarcity of water is a key driver of the increasing pressure on freshwater aquatic ecosystems. Impacts include regulation of flow by impoundments, pollution, over-extraction of water, and the breakdown of natural biogeographical barriers all affecting the ecological condition of these resources. It is in this context that establishing buffer zones for rivers and wetlands can play a meaningful role in reducing impacts on freshwater aquatic ecosystems and in doing so, protect the range of ecosystem services that these resources provide to society.
Dairy farming is a water-intensive land use and one which can degrade water quality. Examples of potential impacts include:
• Nutrient enrichment into watercourses from runoff of slurry and fertilizers applied to pastures, or from slurry dam spillages;
• Sedimentation caused by soil erosion or soil disturbance during pasture rotation; and
• Bacterial contamination (e.g., E. coli) caused by cattle directly accessing wa-tercourses and defecating in the water
Background and study objectives
These impacts are compounded by high levels of water abstraction leading to reduced dilution capacity of surface waters. All of these potential impacts require management interventions and mitigation. A watercourse buffer zone is an effective option for contributing to the protection of watercourses.
The Institute of Natural Resources NPC, in partnership with Confluent Environmental and WWF-SA, was awarded a three-year research project through Milk South Africa’s (MilkSA) Research and Development programme. The objective of the project was to assist MilkSA in working towards its sustainability goals for the dairy sector in South Africa. A key activity for achieving sustainability, according to MilkSA’s focus areas is the “implementation of riparian buffer zones”.
The project will contribute to the sustainability of the dairy sector through the development of best practice guidelines for improved wetland and river management through the implementation of buffer zones on dairy farms.
Watercourse buffer zones
Definitions of buffer zones vary depending on their purpose. According to guidelines in South Africa, buffer zones have been defined as a strip of land with a use, function or zoning specifically designed to protect one area of land against impacts from another. Watercourse buffer zones are typically designed to act as a barrier between human activities and sensitive water resources in order to protect them from adverse negative impacts from diffuse surface runoff. The need to ensure that buffer zones provide adequate protection for biota and species movement is also addressed in the South African guidelines.
Buffer zones associated with watercourses have been shown to perform a wide range of functions and have, therefore, been adopted as a standard measure to protect watercourses and associated biodiversity in South Africa. Some of these key functions include:
- Maintaining basic aquatic processes (e.g., water infiltration, shading, sediment trapping)
- Reducing impacts on watercourses from upstream activities and adjoining land uses
- Providing habitat for aquatic and semi-aquatic species
- Providing habitat for terrestrial species; and
A range of ancillary societal benefits (e.g., reduced flood risk, enhanced visual quality, control of noise levels).
Despite the range of functions potentially provided by buffer zones, they are not the appropriate mitigating measure for addressing all watercourse-related problems. For example, buffer zones can do little to address impacts such as hydrological changes caused by stream flow reduction activities or changes in flow brought about by abstractions or upstream impoundments. Buffer zones are also not the appropriate tool for mitigating point-source discharges (e.g., slurry dam outflows), which can be more effectively managed by targeting these areas through specific source-directed controls (e.g., constructed wetlands). Contamination or use of groundwater is also not well addressed by buffer zones and requires complementary approaches such as controlling activities in sensitive groundwater zones.
Despite clear limitations, buffer zones are well suited to perform functions such as sediment trapping and nutrient retention, which can significantly reduce the impact of activities taking place adjacent to watercourses. Buffer zones are, therefore, proposed as a standard mitigation measure to reduce impacts linked with diffuse stormwater runoff from land uses/activities adjacent to watercourses. These must, however, be considered in conjunction with other mitigation measures which may be required to address specific impacts for which buffer zones are not well suited.
While watercourse buffer zone guidelines are available in South Africa, they do not adequately address the interconnectedness of activities that typically take place on a dairy farm. There is also a lack of practical guidance for dairy farmers and other key stakeholders in the dairy sector.
Establishing watercourse buffer zones on dairy farms has consequences for the dairy farmer, the environment and broader society. These outcomes result in both local (on-farm) and broader (societal) costs and benefits. These costs and benefits are not evenly distributed, both between the current land user and society, and between current and future generations. The costs and benefits also occur at different spatial scales, generally with the costs accruing at the local scale (to the land owner) and the benefits at a larger catchment scale. Increasingly, however, local scale benefits are being identified, particularly those related to soil moisture and soil health.
From the perspective of the dairy farmer, the main cost associated with establishing watercourse buffer zones is the income forgone from reduced pasture area in the case where pasture has been planted near to, up to, or into, the watercourse (i.e., within the buffer zone or watercourse itself). This cost is associated with the conversion of pasture area to buffer area (and/or back to unplanted watercourse) and is variable, depending on the farm context and specifically the productivity of the affected pasture. Pasture productivity within the buffer zone or watercourse area may be marginal relative to elsewhere on the farm. In addition, there are costs associated with the establishment and maintenance of buffer zones. Establishment activities include the removal of pasture crops from the buffer area and the planting of replacement vegetation, erosion control, and fencing. Maintenance activities include the management of biomass and alien plant encroachment within the buffer zone and watercourse. On the other hand, there is a growing recognition that sustainable management practices within agriculture can provide numerous on-farm benefits such as erosion control and topsoil retention, and aesthetic and cultural benefits associated with well-functioning natural habitats. Further, rehabilitated watercourses (and especially wetlands) are associated with an improvement in water quality and more water being retained, and for longer periods, in the catchment.
Best practice buffer zone guidelines for dairy farms
Watercourse buffer zones are increasingly recognised as part of a broader management approach towards sustainable agriculture. The guidelines being developed within this project will provide a framework for guiding the design of appropriate watercourse buffer zones and practical information on buffer zones, and how they should be considered in conjunction with alternative sustainable management practices for improving wetland and river management on dairy farms in South Africa.
The project concludes at the end of February 2023, after which the guidelines will be made available.
