| Erosion


Right: Building farm dams that last relies on hard- won experience and solid science


Layered solutions that work A typical dam in Australia needs more than a single fix


– it requires a layered approach, much like insurance. Effective erosion control uses several tactics: Cut diversion drains and contour channels along the tops of embankments. They should have a gentle curve, not sharp corners, and usually measure at least 150mm deep – enough to safely guide heavy stormwater away from weak points. Lay down coir, jute, or synthetic geomats as soon as construction wraps up. Blankets lock soil in place and give seeds a fighting chance against the first rains. Bring in robust revegetation. For us, nothing beats native grass and shrub coverage, aiming for at least 70% coverage. These roots knit the soil together and create habitats too. Build rock checks, timber baffles, silt fences, and sediment traps, especially below spillways or wherever machines disturb the ground. A simple barrier can catch tons of sediment before it ever leaves the site.


Fence embankments so livestock can’t trample or expose vulnerable soil – that alone can save months of hard work and money. If the local clay isn’t up to standard, we opt for HDPE dam liners. Installing these liners isn’t a casual task; teams need to prepare the surface, weld seams, dig anchor trenches, and thoroughly leak-test every section before the dam holds water.


Why erosion control fails (and what


happens next) Erosion trouble often traces back to missed inspections or putting off repairs. Ignore those small gullies after a storm and before you know it, you’re dealing with costly fixes, lost water, and regulators stepping in. In several regions, dam slopes have collapsed unexpectedly and the cleanup was anything but cheap. Officials expect dam owners to act fast; if erosion or sediment is spotted, repairs must happen immediately.


What the weather throws at dam owners Australian weather has a mind of its own. Sudden


storms can overrun drains, and long dry spells wipe out protective grass cover. That’s why modern dam projects may need bigger drains, tougher HDPE liners, and advanced silt fences. Quick revegetation, timed to local weather forecasts, keeps bare soil to a minimum.


Erosion management: stories from


the field On a property in Tasmania, after a particularly bad flood, we were called to stabilise a battered earth slope. Rapidly installed diversion drains and geotextile mats made a difference – the next season, the embankment was fully grassed over again. Meanwhile, a new dam build in New South Wales saw straw bales and fibre rolls cut down silt in creeks below the site by 90%, allowing us to meet compliance and lower cleanup costs.


Technical tips that matter Cut contour drains no less than 150mm deep with


smooth paths.


Lay erosion control blankets right after shaping any slope steeper than 1V:3H. Hit at least 66% plant coverage on exposed soil within twelve months. Put sediment barriers in before any digging starts— never later. If clay is lacking, install HDPE liners with robust, thermal-welded seams and firmly anchored edges for waterproofing.


Wrapping up Taking erosion seriously is the foundation of smart


dam management. By combining advanced design, correct liner selection, water-control structures, and strategic revegetation, dam operators not only safeguard their investments – they protect local water, comply with regulations, and support healthy ecosystems. The Big Ditch team is proud to offer lasting solutions for anyone building earth dams or seeking professional maintenance across Australia.


Further information


After retiring as President of BHP Diamonds in 2002, Angus bought a large organic farm in the hinterland of Australia and started his second career as a water security specialist. In 2004, based on a lifelong interest in sustainable water security, permaculture and aquaculture, he created the Big Ditch Dam Building Company.


Since then, his water security construction company and corporate consultancy has also been working in such places as the US, Mexico, Canada, Dubai, UAE, China and Nigeria.


www.bigditch.com.au www.waterpowermagazine.com | November 2025 | 17


Above: The Big Ditch team works with those building earth dams or seeking professional maintenance across Australia


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