research program 3
environmental applications of regolith geoscience
Engineering Evaluation Initiative Phase II - Wheatbelt Geochemistry Risk Assessment (AG2)
Project Leaders : Paul Shand, CSIRO Land and Water and Brad Degens WA Dept of Environment and Water
Start date and duration: 01.01.06-30.12.08
Participants : CSIRO Land and Water, Dept of Agriculture & Food WA, Dept of Environment & Water WA, Conservation and Land Management WA, WA EEI, Avon Catchment Council, Yarra Yarra Catchment Council, WA Channel Management Group
Brief project description :
Drainage geochemical risk assessments will be expanded beyond their current focus in the Avon Catchment. Geochemical evaluation of risks will be assessed in regional drainage of saline areas in three WA basins. The Engineering Evaluation Initiative is a program founded, supported and largely funded by WA government agencies (principally WA Ag Dep, CALM) and relevant Catchment Authorities) to evaluate engineering options for environmental rehabilitations in agricultural areas subject to salinity risk. This project extends beyond the lifetime of LEME (December 2008).
Details of focus and outputs
New initiatives for drainage geochemistry risk assessment will focus on:
- Geochemical evaluation of risks associated with regional drainage of saline lands
- Assessment of potential trace-element risk risks in the Yarra Yarra, Blackwood, South Coast catchments
- Development of conceptual models for drain/groundwater interactions and element mobilisation/retardation
- Prediction of acidification risk to receiving environments
- Assessment of potential trace-element risk risks imposed by trace elements
- Active management of acid-trace element rich drainage waters
- Computer simulation(s) of groundwater evolution and regolith weathering during recent (up to 3 million years BP) aridity, with particular interest in the development of acidity.
Outputs
• Review of existing data on acid groundwater trace element geochemistry, soil types, regolith architecture, trace element analysis, flow regimes and, remote sensing data.
• Geochemical reconnaissance (similar to current Avon study) of existing drains, ground and surface waters
• Identification of knowledge gaps and additional data requirements needed to complete regional-scale geochemical risk assessment.
• Additional data collection: data required to fill knowledge gaps identified in Output iv, sampling and detailed geochemical analysis of ground waters and drainage waters, and mineralogical analysis of drainage material (especially Fe precipitates).
• Identification of potential geochemical hazards and risks.
• recommendations for management options during drain installation
• summary report of results, potential impacts, recommendations for management
• PHREEQC modelling in support of regional water balance assessments (part of EEI 2) using methods established for the CSIRO-EEI Avon Drainage Modelling project.
• Forecasting the impacts of engineering drainage on the transport and transformation of trace elements in undrained and drained environments
• Model output - Provide kinetic and/or thermodynamic input for further, more localised modelling. Input into understanding of groundwater geographical variation and impact
Geochemical risks of receiving environments
This project will complement assessments in receiving environments being undertaken in the Avon Drainage, as part of Stage two of the current Avon EEI/CRC LEME project. The aspect will focus on:
- playas and other natural wetlands,
- surface waters (rivers, creeks)
- engineered wetlands and disposal basins (Morowa, Bodallin)
Our project will provide assistance with site selection, and forge research partnerships with CALM and other partners, focussing on key receiving environments. Priory will be given to existing or proposed community drainage projects.
Outputs
• Determination of trace elements and heavy-metal loadings to receiving environments from drains
• Prediction of trace-element and heavy-metal behaviour in receiving environments (proportion of material that remains in solution, as distinct from precipitation and incorporation into sediments).
• Geochemical speciation of trace-element and heavy-metals in receiving environment sediments.
• Determination of scenarios where sediment-bound trace elements and heavy metals may be re-solubilised and re-enter the aqueous phase
• Determination of long-term acid buffering capacity of alkaline receiving environments, and estimation of useful life for acid drainage disposal
• Management options for minimising risks of trace elements in receiving environments
Project coordination
The implementation of this project will mirror that applied in the EEI - Acid Drainage WA project (AG1) involving:
- Stage 1: Review of existing geochemical and regolith data.
- Stage 2: Additional data collection involving strategic sampling of surface, ground and drain chemistry and mineralogy.
- Stage 3: Integration of geochemical and mineralogical data with regional drainage modelling to evaluate regional scale geochemical risks.
A project of this magnitude requires a WA-based project manager, to coordinate day-to-day activities of scientific and community partners, including fieldwork, sampling, community liaison, data management. The project will be managed by Dr Brad Degens WA Department of Environment and Water.
Outputs
EEI-2 Reporting,Research Management, Project Communication
Deliverables (outputs) and expected impacts of research (outcomes):
- Review of existing data on acid groundwater trace element geochemistry, soil types, regolith architecture, trace element analysis in existing drains, flow regimes and remote sensed data.
- Broad geochemical reconnaissance survey (similar to current Avon study) of existing drains, ground and surface waters across catchment to address spatial gaps in existing information.
- Identification of knowledge gaps and additional data requirements needed to complete regional-scaled geochemistry risk assessment.
- Strategic collection of additional geochemical and mineralogical data to fill knowledge gaps identified in Stage iii. (involving sampling and detailed geochemical analysis of ground waters and drainage waters, and focussed mineralogical analysis of drainage evaporates and precipitates)
- Geochemical modelling in support of regional water balance assessments using the methods established for the CSIRO - EEI Avon Drainage Modelling project - Geochemical modelling component.
- Identification of geochemical hazards and potential risks.
- Potential to provide new methods for testing regolith models and groundwater eveolution
Impacts include:
Allow hazards and risks from acid drainage to be assessed at local and regional scales and minimise environmental impact
• Science based improvements in management options
• Improved recommendations for management options during drain installation
Outcomes
• Evaluation of drainage through careful assessment of risk, opportunities and the determination of effective management systems.
• Enable NRM regions and stakeholder groups to develop a consistent approach to catchment and regional drainage, with minimal off site environmental impact.
Publications and Reports
1. Refereed Journals - tba
2. Reports
Analysis and interpretation of geochemical risk Yarra Yarra catchment
Regional Evaluation of Geochemical Risks for the Blackwood Catchment and a Coast Catchment and management implications based on geochemical modelling outcomes Final Report
3. Conferences-Seminars
ISF 2008 Adelaide. Provisional paper title: Acid saline drainage risk assessment and management.
Case studies to be included in the planned Thematic Volume ‘Inland Acid Sulfate Soil Systems' Fitzpatrick, R. (Ed)
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