Australian scientists may have come up with a way to protect the Great Barrier Reef from the dangerous run-off into rivers that is degrading water quality and putting coral and other marine life at risk.
The team from Griffith University identified a key driver of the problem – thousands of hectares of rapidly eroding gullies in the rivers that feed fine sediment into the waters of the ailing reef.
“These giant alluvial gullies can be up to tens of hectares in area, each producing tens of thousands of tonnes of sediment to the reef each year,” said Dr Andrew Brooks, from Griffith’s Australian Rivers Institute.
After expensive field work over six years, Brooks and his team have developed a strategy that could reduce erosion rates by 75% in just two years, but it is a big job involving grading the sodic soils in the highly erodible gullies to recreate a protective surface soil that can support dense grass cover.
The team have tried it in some gullies in Cape York.
“The experiment showed that using the optimal treatment we can reduce erosion rates by 75% in two years,” said Dr Brooks.
“The trials also show that regrading with no soil treatments actually increases the erosion rate compared to doing nothing. So, if not done properly by people who understand these soils, it will make the situation worse.”
The key to cost effectively targeting the erosion hot spots is through precision mapping to see which gullies contribute the highest sediment load, Brooks said.
Bill Condie is a science journalist based in Adelaide, Australia.
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