2.5.1 Methods

Summary

Surface water model nodes used in water balance reporting are selected to quantify hydrological changes due to proposed coal resource development over the minimum possible area that incorporates all hydrologically connected cumulative changes.

In the Galilee subregion, changes in surface water from coal mines accumulate along a hydrologically connected stream network (Sandy Creek–Native Companion Creek–Belyando River). The cumulative changes to surface water occur primarily in the Belyando river basin, which forms part of the headwaters of the Burdekin river basin.

For the estimation of total changes, a single model node was selected on the Belyando River (node 53) that captures the cumulative changes on surface water in the Galilee subregion due to the seven coal resource developments in the coal resource development pathway (CRDP) that can be modelled.

Unlike cellular numerical groundwater models, the analytic element model is not capable of producing a water balance, therefore, a conceptual groundwater balance method was developed using an accounting approach to estimate the groundwater balance for the portion of the Burdekin river basin that occurs within the Galilee subregion. The approach taken is a modified version of the water cycle report defined for the Water Accounting Stocktake project undertaken by the inter-jurisdictional National Water Initiative Committee (SKM, 2006). While this relatively simple approach to the groundwater balance does not produce stochastic outputs, it is considered fit for purpose for this BA as it will flag if there is potential for groundwater pumping by coal mining operations to cause changes to a major component of the groundwater balance, as well as identify possible data gaps.

Many of the modelled coal resource developments include an estimate of extra water that is required from sources external to the mine area. External water required for mine sites is not included in water balance estimates presented in this product as the location of the external water offtakes and the licensed amounts are yet to be finalised.