and provide details on the South Galilee model. The model presented in is a revision of the original model as outlined in thus model details presented here are derived from . However, contains much of the background information for the model.
Some basic parameters for the steady-state model are outlined in Table 5. The South Galilee model area includes the China First Coal Project area. It has a variable cell size of 50 m in the mining , and 1 km at the model boundaries.
The model contains seven layers. The uppermost model layer represents the Quaternary and Cenozoic material. Model layer 2 represents the Moolayember Formation, Clematis Group and the Rewan Group. Model layer 3 represents the primary coal resource. Model layers 4 to 6 represent the other coal seams, interburden and underburden. Model layer 7 represents the Joe Joe Group. Including the Moolayember Formation in model layer 2, which otherwise represents , partial aquifers, and coal resources, is likely to affect the ability of the model to predict on shallow groundwater levels in the Quaternary and Cenozoic material resulting from changes in deeper groundwater levels.
The northern, western and much of the eastern boundaries for the models were designated as general-head boundaries. An exception to this was the western boundary of the Rewan Group (model layer 3) and Joe Joe Group (model layer 8), which were designated as no-flow boundaries as they represent . Other areas, including the southern boundary were designated no-flow boundaries ().
was applied to the model only where alluvium was present at the surface, or where the Clematis Group outcropped. Alluvium was assigned a recharge rate of 2.75 mm/year (or 0.5% rainfall), Cenozoic (called Tertiary in the model) 5.5 mm/year (1% rainfall) and the Clematis Group was assigned recharge of 13.75 mm/year (2.5% rainfall).
bodies were represented with the MODFLOW River package, allowing flow both from aquifers to streams and from streams to aquifers. River stages were set at 5 m below the river bank elevation. The riverbed of Native Companion Creek was set at 1 m below the river stage. All other surface streams had the riverbed set at 0.1 m below the river stage. This arrangement allows a low level of constant leakage to occur from surface water to groundwater (), however most of the streams in the model domain are ephemeral.
Mining-induced fracturing was simulated in the transient model by allowing for changes in conductivity over time to occur as mining progresses in model cells that represent mine areas. Some parts of the China First Coal Mine areas were incorporated into the model so as to investigate from the China First and South Galilee coal projects (). The model was run for 100 years to simulate groundwater recovery post mining.
Predicted mine range from 2 to 8 GL/year, which equates to 5 to 23 ML/day () with a total cumulative inflow volume of 187 GL over life of mine. A analysis on the effects of faulting on the Rewan Group was undertaken by increasing the of the Rewan-Dunda layer to simulate the potential interconnectivity effect due to faulting and fracturing. The analysis showed that the model was not sensitive to drastic changes to hydraulic conductivity in the Rewan Group. This implied that the presence of faults in the Rewan Group would not significantly increase inflows to the mine. The cumulative model runs suggest that there will be minimal impacts to the Alpha town water supply. Cumulative in the Clematis Group aquifer during mining was in the order of 3 to 5 m, which is considered to be overly conservative as a result of the Clematis Group aquifer being lumped with the Rewan Group aquitard in the model.
Product Finalisation date
- 18.104.22.168 Methods
- 22.214.171.124 Review of existing models
- 126.96.36.199.1 Alpha and Kevin's Corner model review
- 188.8.131.52.2 Carmichael model review
- 184.108.40.206.3 China First model review
- 220.127.116.11.4 China Stone model review
- 18.104.22.168.5 South Galilee model review
- 22.214.171.124.6 Galilee Basin hydrogeological model review
- 126.96.36.199.7 Suitability of existing groundwater models
- 188.8.131.52 Model development
- 184.108.40.206 Boundary and initial conditions
- 220.127.116.11 Implementation of the coal resource development pathway
- 18.104.22.168 Parameterisation
- 22.214.171.124 Observations and predictions
- 126.96.36.199 Uncertainty analysis
- 188.8.131.52 Limitations and conclusions
- Currency of scientific results
- Contributors to the Technical Programme
- About this technical product