New research by the Australian Institute of Marine Science (AIMS) will provide science-based advice on development issues impacting on major Northern Territory rivers such as the Daly, Mary and Roper estuaries.

Leading AIMS Scientist Dr Eric Wolanski FTSE will give a seminar tomorrow (noon, Sept 24) at Charles Darwin University (formerly NTU) on a new study aimed at predicting the impact on coastal ecosystems of more intensive land-use practices and freshwater usage.

The Northern Territory economic development strategy strives for economic sovereignty through use of natural resources and infrastructure. This includes the conversion of pastoral leases to agriculture, particularly in the Daly Basin.

Dr Wolanski said AIMS would provide NT resource managers with the knowledge necessary for effective management of these important watersheds.

"We will develop decision-support tools such as predictive models and visualisation technology to help gauge the likely impacts of planned development and changes in land-use practices," he said.

AIMS is already working in partnership with the NT Department of Infrastructure, Planning and Environment (DIPE) to monitor the flushing and sedimentation of the Daly estuary.

AIMS recently completed similar studies in the Ord and Fitzroy Rivers in Western Australia. Scientists concluded that a dam on the east arm of the Ord had suppressed river floods over the past 30 years, causing massive siltation at the mouth.

"In the Territory, we will look at how changes to Daly River flow rates from the proposed large-scale pumping of groundwater may alter the dynamics in the estuary and in turn, if siltation and erosion patterns will change," Dr Wolanski said.

He said strong tides in the Daly have an important role to play in controlling sediment dynamics. Huge tides at the mouth can reach up to eight metres, and the tide goes upriver for about 100 kilometres.

"This forms a tidal bore with interacts with freshwater runoff and controls the upriver tidal pumping of sand and mud. If the rate of groundwater usage changes dramatically because of increased agriculture, this will impact on the tidal dynamics. We will see changes in the rate of fine sand and mud pumped upriver which, in turn, may affect the tidal dynamics, further increasing siltation rates in the dry season – somewhat like what is happening in the Ord River estuary," Dr Wolanski said.

The team will also investigate the role of coastal oceanography in the growth of the tidal creek system on the Mary River, which now goes 80 kilometres inland from the floodplain, causing increased salinization.