Riparian erosion causes substantial environmental damage and economic costs, both in Australia and internationally. To stabilise banks, traditional hard engineering solutions based on concrete and steel are often undesirable because they are costly and environmentally harmful; in many cases, they are not permitted.
Here, we present an alternative method of slope stabilisation for riparian and coastal environments. This nature-based approach uses bamboo poles to construct biodegradable retaining structures. These structures enable revegetation by temporarily stabilising the slope, after which they biodegrade. The newly established vegetation, through its root systems, ensures long-term slope stabilisation.
We trialled this method on the Richmond River (Kyogle, NSW) at a site affected by a deep-seated rotational landslide that continues to move due to toe erosion. To stabilise the site, we designed and built a 12 m-long, two-steps retaining wall using 3 m-long bamboo poles. The retaining wall comprises driven piles and sleepers made of bamboo pole bundles; it also includes back-ties and underground drainage constructed with bamboo. Revegetation involved planting a mix of long-rooted grasses and trees both below and above the wall.
We present the lessons learned from this pilot test in terms of effectiveness and ease of installation and further discuss the potential of this nature-based solution to mitigate erosion in a variety of riparian and coastal environments.