Research targets geochemistry of coastal river dead zones

Southern Cross University has partnered with a regional flood mitigation authority to investigate better ways to manage water quality in the Richmond River, especially during summer floods when blackwaters draining from coastal wetlands devastate the river system by causing widespread deoxygenation events and fish kills.

Southern Cross University and Richmond River County Council were successful in receiving $320,000 in funding for the project through the Australian Research Council’s Linkage Projects scheme announced recently by the Minister for Tertiary Education, Skills, Science and Research, Senator Chris Evans.

Southern Cross GeoScience Co-Director and project leader Professor Sullivan said the geochemistry of deoxygenation events in the Richmond River was poorly understood despite regular major flood events in the Northern River region.

“Deoxygenated dead zones are a rapidly growing global crisis in coastal areas. A major cause of dead zones in our estuaries is the formation and release of blackwaters from coastal wetlands,” said Professor Sullivan.

His project team is made up of Associate Professor Andrew Rose, Associate Professor Ed Burton, Associate Professor Scott Johnston, Professor Richard Bush and Monash University’s Dr Vanessa Wong.

“Our Southern Cross GeoScience research team will use cutting-edge geochemical techniques to get a better understanding of the chemical nature of the compounds being exported as blackwaters into the river during flood events and of the landscape features and management practices that influence the production of these compounds,” Professor Sullivan said.

Entitled ‘Episodic estuarine hypoxia: resolving the geochemistry of coastal floodplain blackwaters’, the project will investigate the combination of soil, land use and vegetation factors that create deoxygenated dead zones.

“We aim to bring this information together into a comprehensive model to allow local councils and state agencies to further optimise land use decisions to help minimise the intensity and duration of deoxygenation events in the Richmond,” Professor Sullivan said.

The project is the third investigation into flood aggravated impacts on the Richmond River estuary undertaken by Richmond River County Council (RRCC) in partnership with Southern Cross University.

“Richmond River County Council actively supports research to assist local and state planning authorities on possible management directions for phenomena such as blackwater events, which have major impacts on the Richmond River estuary particularly following summer flooding,” said Michael Wood, RRCC Flood Services Manager.

RRCC is contributing funds and major in-kind contributions towards the project, including a two-dimensional flood model on the floodplain, the largest of its kind for analysing flood behaviour on the NSW coastline.

“Southern Cross GeoScience will be utilising this flood model as an important resource during their investigations,” Mr Wood said.

“RRCC staff will also provide on-ground support to the project through our expertise in floodplain processes and services, and access to landholders.”
Photo: Blackwater formation in the mid Richmond river area (Credit: Richmond River County Council).