Transient approximations in queueing networks

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Numerical hydrodynamic modelling of the Fitzroy estuary

The combination of anthropogenic pressure, the presence of natural habitats and the community desire to appreciate the natural and recreational benefits of the Fitzroy Estuary and Keppel Bay region while sustaining agricultural demands in the catchment, make the management of the Fitzroy Estuary a challenge. The Fitzroy Contaminants project aims to provide support for the assessment of the impacts of various developments and management approaches

Contaminant pathways in Port Curtis : final report

The Port Curtis Estuary has a well-developed and expanding industry within its catchment. It is also one of Australia's leading ports and is located adjacent to the World Heritage-listed Great Barrier Reef Marine Park. As a consequence of increasing population and industrial activities, the Port Curtis Estuary is expected to receive increasing quantities of contaminant inputs from diffuse sources (e.g. urban runoff) and point source discharges (e.g. industrial effluents). Sources of chemical stressors are many, and multiple contaminants are likely to be transported to the estuary by air and/or water. The challenge for coastal management within the region is the long-term sustainable anagement of further port and industrial development, related population growth, and the management of potentially significant impacts on coastal resources. The release, fate and impacts of contaminants generated within the region by industrial and urban activities are issues of obvious concern. When the Cooperative Research Centre for Coastal Zone, Estuary and Waterway Management (Coastal CRC) first started its activities in Port Curtis in 1998, there were few published studies describing contaminant distributions in Port Curtis. During the first phase of its activities, the CRC undertook the Port Curtis screening level risk assessment (SLRA) (Apte et al. 2005) which employed a rigorous, riskbased approach to identify and prioritise contaminant issues of potential concern. While there were no issues of regulatory concern, the SLRA identified some contaminant-related issues worthy of further investigation which included tributyltin (TBT) in waters, the anomalous bioaccumulation of metals by biota from Port Curtis and slightly elevated concentrations of arsenic, TBT and naphthalene in sediments. Recommendations were made for future investigations. A separate CRC project developed a pilot-scale hydrodynamic model of Port Curtis which enabled water movement to be predicted. The model has clear applications to the prediction of contaminant movement, especially point source discharges associated with industrial activities. Contaminant Pathways in Port Curtis was part of Phase 2 of the CRCs activities in Port Curtis and focused on some of the key issues that were identified in the SLRA

CSIRO Environmental Modelling Suite (EMS): Scientific description of the optical and biogeochemical models (vB3p0)

Since the mid-1990s, Australia's Commonwealth Science Industry and Research Organisation (CSIRO) has been developing a biogeochemical (BGC) model for coupling with a hydrodynamic and sediment model for application in estuaries, coastal waters and shelf seas. The suite of coupled models is referred to as the CSIRO Environmental Modelling Suite (EMS) and has been applied at tens of locations around the Australian continent. At a mature point in the BGC model's development, this paper presents a full mathematical description, as well as links to the freely available code and user guide. The mathematical description is structured into processes so that the details of new parameterisations can be easily identified, along with their derivation. In EMS, the underwater light field is simulated by a spectrally resolved optical model that calculates vertical light attenuation from the scattering and absorption of 20+ optically active constituents. The BGC model itself cycles carbon, nitrogen, phosphorous and oxygen through multiple phytoplankton, zooplankton, detritus and dissolved organic and inorganic forms in multiple water column and sediment layers. The water column is dynamically coupled to the sediment to resolve deposition, resuspension and benthic-pelagic biogeochemical fluxes. With a focus on shallow waters, the model also includes detailed representations of benthic plants such as seagrass, macroalgae and coral polyps. A second focus has been on, where possible, the use of geometric derivations of physical limits to constrain ecological rates. This geometric approach generally requires population-based rates to be derived from initially considering the size and shape of individuals. For example, zooplankton grazing considers encounter rates of one predator on a prey field based on summing relative motion of the predator with the prey individuals and the search area; chlorophyll synthesis includes a geometrically derived self-shading term; and the bottom coverage of benthic plants is calculated from their biomass using an exponential form derived from geometric arguments. This geometric approach has led to a more algebraically complicated set of equations when compared to empirical biogeochemical model formulations based on populations. But while being algebraically complicated, the model has fewer unconstrained parameters and is therefore simpler to move between applications than it would otherwise be. The version of EMS described here is implemented in the eReefs project that delivers a near-real-time coupled hydrodynamic, sediment and biogeochemical simulation of the Great Barrier Reef, northeast Australia, and its formulation provides an example of the application of geometric reasoning in the formulation of aquatic ecological processes. </p

CSIRO Environmental Modelling Suite (EMS): Scientific description of the optical and biogeochemical models (vB3p0)

Since the mid 1990s, Australia's Commonwealth Science Industry and Research Organisation (CSIRO) has developed a biogeochemical (BGC) model for coupling with a hydrodynamic and sediment model for application in estuaries, coastal waters and shelf seas. The suite of coupled models is referred to as the CSIRO Environmental Modelling Suite (EMS) and has been applied at tens of locations around the Australian continent. At a mature point in the BGC model's development, this paper presents a full mathematical description, as well as links to the freely available code and User Guide. The mathematical description is structured into processes so that the details of new parameterisations can be easily identified, along with their derivation. The EMS BGC model cycles carbon, nitrogen, phosphorous and oxygen through multiple phytoplankton, zooplankton, detritus and dissolved organic and inorganic forms in multiple water column and sediment layers. The underwater light field is simulated by a spectrally-resolved optical model that includes the calculation of water-leaving reflectance for validation with remote sensing. The water column is dynamically coupled to the sediment to resolve deposition, resuspension and benthic-pelagic biogeochemical fluxes. With a focus on shallow waters, the model also includes particularly-detailed representations of benthic plants such as seagrass, macroalgae and coral polyps. A second focus has been on, where possible, the use of geometric derivations of physical limits to constrain ecological rates, which generally requires population-based rates to be derived from initially considering the size and shape of individuals. For example, zooplankton grazing considers encounter rates of one predator on a prey field based on summing relative motion of the predator with the prey individuals and the search area, chlorophyll synthesis includes a geometrically-derived self-shading term, and the bottom coverage of benthic plants is generically-related to their biomass using an exponential form derived from geometric arguments. This geometric approach has led to a more algebraically-complicated set of equations when compared to more empirical biogeochemical model formulations. But while being algebraically-complicated, the model has fewer unconstrained parameters and is therefore simpler to move between applications than it would otherwise be. The version of the biogeochemistry described here is implemented in the eReefs project that is delivering a near real time coupled hydrodynamic, sediment and biogeochemical simulation of the Great Barrier Reef, northeast Australia, and its formulation provides an example of the application of geometric reasoning in the formulation of aquatic ecological processes