2.6.2.1 Methods

Summary

The numerical modelling is designed to provide probabilistic estimates of the potential hydrological change due to coal resource development at receptors. Differences in spatial and temporal scale necessitated the development of a model chain of three models to assess the hydrological change in the surface weathered and fractured rock layer, the alluvial aquifer and in the stream network.

The model chain consists of a regional scale analytic element groundwater model to simulate the change in the surface weathered and fractured rock layer and provide a boundary condition for two local MODFLOW models that simulate groundwater flow in the alluvial aquifers. The change in surface water – groundwater interaction flux is propagated to the AWRA-L model that integrates this change with the interception of runoff by open pit mining to simulate the change in streamflow.

This section discusses the fitness for purpose of the model chain and modelling approach and provides an outline of the uncertainty analysis workflow.