Extreme rainfall events, flooding, and severe storms are becoming increasingly common across South Africa. For farmers and agricultural stakeholders, these events can cause significant operational and financial damage. However, one of the most overlooked consequences of extreme weather is the environmental risk posed by uncontrollable stormwater and runoff.
Risks of poor stormwater management:
-
Soil erosion and sedimentation
Heavy stormwater runoff can rapidly erode exposed and unstable soils, moving sediment into rivers, wetlands, and drainage lines. This can destabilise riverbanks, reduce water quality, and damage ecosystems. In severe cases, this type of erosion and sedimentation may trigger regulatory interventions or rehabilitation requirements if not addressed adequately. -
Agrochemical exposure
An often-overlooked risk of heavy rainfall is the impact of stormwater on chemical filling points. Stormwater entering evaporation pits, tank systems, and other chemical wastewater collection systems risks overflows of chemical wastewater into the environment. This poses significant risks to soil quality, biodiversity, and any nearby watercourses.
A compliance approach to stormwater management:
Farmers and other agricultural stakeholders should adopt a compliance-based approach to managing stormwater risks to mitigate adverse weather impacts. In addition, using a compliance-based approach supports the long-term sustainability of the farms that align with market and assurance expectations.
- Soil Erosion
Practical measures include: -
- Maintaining soil coverage via cover crops, mulch, or natural vegetation to maintain soil colloid structure and stability, and reduce erosion risks.
- Establish and maintain vegetated buffer zones to maintain soil coverage and stability.
- Ensure that cultivated areas are located at least 30 meters from a watercourse.
- Managing stormwater flow paths to reduce concentrated runoff and prevent gully formation.
- Agrochemical exposure
Practical measures include:
-
- Locate chemical filling points well away from watercourses and flood-prone areas, ideally above the 1:20 or 1:100 year flood line (the higher, the better).
- Ensure that any drain connecting the chemical filling point floor to an evaporation pit/tank system is closed with a valve or plug when not in use to prevent unnecessary stormwater entry.
- Where evaporation pits are used, consider installing covers or protective structures to minimise direct rainwater entry.
- Regularly inspecting containment infrastructure before and during the rainy season to identify leaks, blockages, or overflow risks.
Key takeaways
Climate volatility is becoming an increasingly important operational reality for South African agriculture. Preparing for extreme weather events should therefore form part of broader environmental and risk management planning on farms.
By proactively considering stormwater management, the design and location of chemical filling points, soil protection measures, and buffer zone maintenance, agricultural stakeholders can significantly reduce environmental risks, improve compliance, and minimise losses during severe weather events.
