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 Genevieve Larsen
Faculty of Science, Quaternary Earth and Water Systems
Thesis Title: Understanding coastal groundwater processes by modelling hydrology, hydrochemistry and stable isotopes, Fraser Coast, southeast Queensland
Project Objectives:
This study is part of an integrated project funded by an ARC Linkage grant with Forest Plantations Queensland (FPQ) as industry partner. The project is entitled Hydrological Controls over Distribution of Fe within a Forested Coastal Catchment and was developed in response to concerns regarding the potential impact of forestry practices on estuarine and marine environments.
This component of the project focuses on the coastal zone as an interface between the fresh water catchments and the marine environment. The investigation involves modelling of hydrological and hydrochemical processes, in order to determine hydrological links between surface and sub-surface water bodies and the potential transport mechanisms for dissolved metals and nutrients to the ocean. This study provides a groundwater overview of the Fraser Coast region and then focuses on the mouth of Poona Creek and its shoreline. In order to obtain a more regional picture of water chemistry and transport processes in the region, data collection sites in other catchments of the coastal zone adjacent to Poona have been included in this study. Extensive hydrochemical and isotope data (dO18, dD, dS34, dN15 and dC13) has already been obtained for all sites in addition to ground and surface water level data adjacent to and within the Poona Creek estuary.
The main objective of this study is to understand the hydrological processes of the near-shore coastal setting and establish if catchment derived solutes could pass through this zone to the ocean. This will be achieved through the development of the following linked sub-studies.
- The chemical and isotopic character of coastal waters, combined with inverse modelling of hydrochemical reactions, will be used to determine hydrological links between surface and sub-surface systems, as well as potential solute sources, in a regional context
- A 2-D, transient, fresh-saline groundwater modelling will be used to determine whether coastal zone unconsolidated Quaternary deposits are pathways for solutes from adjacent agricultural land to estuarine waters
- Artificial neural networks and spectral analysis of water level variations in tidally-influenced, unconfined aquifers and adjacent surface-water bodies will be used to quantify and predict the effect of tidal forcing on the saline-fresh mixing zone in a subterranean estuarine environment
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