Land clearing has amplified flood impacts
A SIGNIFICANT loss of forest around the Townsville region has amplified the impact of flooding, according to a new scientific study.
University of Queensland Earth and Environmental Sciences researcher Jaramar Villarreal Rosas spent four years studying flooding in the Brigalow Belt Bioregion – an area encompassing Townsville, through to Emerald and Rockhampton.
Comparing satellite imagery of forests around Townsville over a 13-year period, she determined that there was a 30 per cent loss in vegetation.
Using a hydrological model she developed called Invest, Dr Rosas calculated that the decreased forest was causing a 29 per cent increase in water run-off.
“The capacity for natural ecosystems to mitigate flooding has significantly decreased across the Brigalow Belt due to deforestation,” Dr Rosas said.
“Forests help mitigate floods by reducing the amount of water flowing on the soil surface soon after a rain event. It’s a combination of evaporation (by the trees) and filtration by the soil.”
She blamed land clearing for development for shrinking Townsville’s surrounding forests – significantly higher than the 16 per cent calculated for the total Brigalow Belt.
“While overall flood mitigation continues to decrease, urban residents in towns like Townsville and Charters Towers have borne the brunt,” she said.
“Specifically, we found that between 2002 and 2015, the decrease in flood protection to urban residents was double the amount we observed in any other sector, followed by rural communities and the food sector.
“This is a direct result of continued deforestation and land clearing of forests in the region, when forests are proven to reduce the intensity of flooding events.”
Noting that forests could only do so much to offset large-scale rain events like the 2019 flood, Dr Rosas said conserving natural areas and forests could help shield nearby urban regions from significant flooding.
Research senior author Professor Jonathan Rhodes said a greater focus on mitigating the impact of climate change was the best path forward.
“We have to place more emphasis on restoration and adaptation policies with a long-term focus,” Professor Rhodes said.
“This includes reforestation and land-clearing regulation, improved emergency response plans, and careful planning about where we locate infrastructure at risk of flooding.”