A map of lowland areas (in red) expected to be inundated when predicted sea levels rise beyond one metre in the coming years.
A map of lowland areas (in red) expected to be inundated when predicted sea levels rise beyond one metre in the coming years. Richmond River County Council

Underwater way of life

NEW computer-aided mapping tools now show that a one-metre rise in sea level, predicted by 2100, would submerge large areas of the lower Richmond River floodplain.

In the landmark study, by Southern Cross University environmental scientist Clement Akumu, it has been found that large areas of farmland would face inundation in a strip between New Italy and Lennox Head.

Ballina Nature Reserve is already home to vast tracts of wetland and mosquito breeding sites but under a predicted sea level rise that swamp would surround Ballina Island through to Ross Lane at Lennox Head and south through the Emmigrant Creek valley to Teven and Cumbalum.

East of the river between Broadwater and South Ballina there will be a series of interconnected swamps filling low lying cane paddocks around South Ballina, Keith Hall, Pimlico, Empire Vale, East Wardell, and Patchs Beach.

Tuckean Swamp will enlarge and low areas around Kilgin and Dungarubba will also face inundation.

Rocky Mouth Creek catchment, which is a huge area of low land around Swan Bay and New Italy will go under, as will low land around the Evans Head – Woodburn golf course.

Mr Akumu, from the Centre for Geoinformatics Research and Environmental Assessment Technology in the SCU School of Environmental Science and Management, is using satellite data and a range of geoinformatics software to assess the potential impacts of climate change on coastal wetlands in the study area.

Commenting on the study, floodplain co-ordinator with the Richmond River County Council, Michael Wood, said rising salt water would compound problems with acid soils.

Areas previously drained, such as Tuckean Swamp, might not respond well to rising sea levels.

As an example he cited the Broadwater on the Clarence, where salt water let back on previously drained land merely scalded the soil as it reacted with existing acid sulphate levels.

SCU’s Mr Akumu said that when assessing the possible effects of climate change, the most commonly used estimate was a one-metre sea-level rise by 2100, which was a conservative estimate.

The research originally focussed on wetland areas and did not include farmland or urban land. However, once the modelling neared completion the software started to indicate that large areas of farmland and urban land also would be affected.

Across the entire study area, urban land which now totals 95 sq km, is predicted to decrease to 78 sq km by 2025, 74 sq km by 2050 and 62 sq km by 2100.

Mangroves and salt marshes will increase from 37 sq km to about 102 sq km



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