Aquatic Ecodynamics


Caboolture River Estuary

Unravelling the cycling of nitrogen along a subtropical freshwater-marine continuum using a multi-isotope, multi-tracer and modelling approach

This is an ARC Linkage project between MBRC, SCU and UWA based around the Caboolture catchment-river-estuary in Queensland, Australia. The aim to use a combination of state-of-the-art multi-isotopic and multi-tracer techniques, process measurements and modeling to unravel the complex sources, delivery pathways and cycling of nitrogen along a sub-tropical freshwater-marine continuum.

The project utilises innovative combination of stable carbon, nitrogen, oxygen (12C, 15N, 18O) and radioactive radon (222Rn) isotopes, process measurements and coupling 3-D hydrodynamic and isotope-enabled biogeochemical model for performing nutrients accounting of Caboolture Estuary. This will resolve the sources, delivery pathways and cycling of nitrogen along a sub-tropical freshwater to marine continuum, including contribution from groundwater input. The use of stable isotopes will enable us to distinguish a number of nitrogen sources through mixing and fractionation processes. The use of radioactive 222Rn isotope will unravel the contribution of submarine groundwater discharge (SGD) in the nutrient budget of the Caboolture Estuary, as the signal of 222Rn concentration measured in the groundwater is in higher order of the magnitude than in estuary and tributaries. Adding to the uniqueness of the project is that we develop a framework that can be applied to undertake an uncertainty assessment on the biogeochemical parameters using a Markov chain Monte Carlo (MCMC) which falls within a Bayesian Hierarchical Formulation (BHF). This assessment is necessary for solving spatiotemporal problems due to the complexity of the study area.

The image below is a created Mesh grid of Caboolture Estuary for 3-D modelling, from River (left) to Ocean (right).

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Regional Centre for Coastal Biogeochemistry, Southern Cross University, Lismore, NSW 2480, Australia

Moreton Bay Regional Council (MBRC), Queensland

eWater, ACT, Australia


Adiyanti, S. & Hipsey, M.R. (2013). Unravelling sources of nutrients to an estuary using an isotope-enabled model. Presentation at the Institute of Australian Geographers Conference, Perth, Western Australia 1-4 July 2013.

Adiyanti, S., Hipsey, M.R. , Haase, R., Santos, I., Maher, D. & Eyre, B. (2013). A coupling between a 3-D Carbon Isotope Deterministic Model and a 1-D Non-Conservative Mixing Statistical Model. Presentation at MODSIM2013 - 20th International Congress on Modelling and Simulation. Modelling and Simulation Society of Australia and New Zealand, December 2013, Adelaide, Australia.

Bruce, L.C., S. Adiyanti, A.L. Ruibal & Hipsey, M.R. (2013). Modelling the effect of hydrological change on estuarine health: An Australian Perspective. Presentation at AGU - American Geophysical Union Annual Meeting, December 2013, San Francisco.

Adiyanti, S., M. Hipsey, L. Golsby-Smith, D. Maher, I Santos & B. Eyre - in prep. A Carbon Isotope-enabled Model for Validating Carbon Flux Pathways in a Salt-Wedge Estuary. Draft manuscript to be submitted to Environmental Modelling & Software.