2.6.2.4 Boundary and initial conditions

Summary

Analytic element modelling is grid independent and by default assumes aquifers and aquitards are of infinite extent. This offers great flexibility in generating output at any desired location and obviates the need to explicitly specify lateral boundary conditions as is the case for finite-difference or element codes. The eastern extents of the upper Permian coal measures and of the Clematis Group are, however, explicitly represented as no-flow boundaries.

The model directly simulates the change due to coal resource development. The initial conditions, the initial change, is zero in every model layer as currently no coal resource developments are active.

At the regional scale, coal resource development does not alter recharge. No change in recharge is therefore simulated.

The river network is considered ephemeral and disconnected. This implies that the surface water – groundwater flux is not dependent on the position of the watertable. As this flux will not change due to drawdown, these streams are not represented. The Belyando River, however, is considered as a regional discharge feature. The river stage in the Belyando River is dominated by runoff in the Belyando river basin. The river is, therefore, represented as a specified head boundary, where a change in groundwater level equal to zero is imposed in the Belyando River channel.