Tackling erosion at its source

Soil erosion across the Burdekin catchment, particularly in the Upper Burdekin and Bowen sub-catchments, remains one of the region’s most significant environmental challenges. 

It also has a direct impact on grazing profitability, reducing the productive capacity of land.

This leads to poorer pasture quality, reduced livestock performance, and ongoing, long-term maintenance costs for landholders. 

A typical rainfall event in the Burdekin catchment, particularly the Upper Burdekin and Bowen sub-catchments, results in significant erosion from areas of low groundcover.  The high runoff rates quickly generate speed, wearing away precious topsoil and eventually forming a gully, which rapidly drains two vital resources for agriculture: water and soil.  

Gullies are often directly linked to creeks and rivers, so that sediment is transported downstream where it can harm aquatic and marine environments. 

The Burdekin is the largest contributor of fine sediment to the Great Barrier Reef, delivering an average of 3.3 million tonnes each year, more than double any other catchment along the Reef.

That sediment impacts marine plants, animals and ecosystems through excess nutrients, reduced light penetration and by smothering organisms when it does settle. 

Through the Burdekin Landscape Repair project, NQ Dry Tropics is taking a strategic, science-backed approach, working alongside landholders, scientists and engineers to better understand where erosion is happening, and why.

Using high-resolution LiDAR data and Digital Elevation Models, the team is comparing changes in the landscape. This allows them to measure where soil has been lost or deposited and identify erosion ‘hotspots’ across large areas.  

This work builds on research led by Griffith University, mapping and characterising more than 22,000 gullies across the Bowen-Bogie-Broken region, showing sediment loss was not evenly spread across the landscape.

A relatively small number of gullies are responsible for a large proportion of sediment runoff.

That insight has been a game changer.

Rather than trying to fix large eyesore gullies, the focus is to target gullies that will deliver the greatest return to the landscape, and investment.

Each site is carefully assessed and ranked, from critical and highly active through to stable or healing systems.

Importantly, size isn’t everything.

Some smaller gullies can be highly active and contribute more sediment than larger ones that are slowing down or stabilising.

That’s why on-ground verification, or ground truthing, is essential. It ensures decisions are based on what’s actually happening in the landscape, not just what the data suggests.

In recent months the project team has been visiting sites across the BBB to do this ground-truthing.

However, identifying priority gullies is only one piece of the puzzle.

A key shift in the Burdekin Landscape Repair project is moving beyond treating the symptoms of erosion to addressing its root causes. Instead of focusing solely on repairing gullies or streambanks, the team is looking at the entire catchment that feeds into them.

The question becomes, why is this gully eroding?

By analysing how water flows across the landscape, the team is pinpointing where it accelerates, concentrates and begins to cause damage.  In many cases, the problem starts well upstream.

This is where landscape repair comes into play.

Rather than allowing water to rush unchecked into drainage lines and waterways, strategies are being designed to intercept and slow it down.

This includes restoring groundcover, improving vegetation, and installing structures such as interception banks. These are carefully positioned to slow water flow and spread it more evenly across gently sloping paddocks.

The goal is to manage the movement of water, reducing its energy so it doesn’t strip topsoil as it moves through the landscape. This work is backed by detailed modelling.

Analysis is helping determine where ‘interception banks’ should be placed, and how much water they need to handle and how effective they will be before any on-ground works begin.

This is to ensure investment is targeted and cost effective.

Engineers will be engaged when appropriate, for example, in areas of high flow in lower parts of catchments repairing streambank erosion along creeks.

This work takes time. The NQ Dry Tropics team has been progressing it throughout the year and expects to start on-ground works in the coming months.