18.3 Discharge to landscape
a. Groundwater model
The Department of Land Resource Management use the Finite Element Subsurface Flow system (FEFLOW) to estimate the natural water movement to and from the groundwater store within the Daly region.
FEFLOW estimates groundwater movement for the entire extent of the Oolloo aquifer and the Tindall aquifer, which extends beyond the Daly region boundary as shown in the figure below. The volumes reported in this account refer to the natural water movement that occurs within these aquifers within the Daly region boundary.
Map of the groundwater model area relative to the Daly region boundary
The Oolloo and Tindall aquifers are karstic and were modelled as an equivalent porous media with relatively limited storage. The groundwater model was calibrated using regional aquifer parameters to reproduce the observed groundwater levels and discharge to the rivers, as outlined in Knapton et al. (2010).
b. Supporting information
Groundwater discharge to the landscape is considered to be equivalent to evapotranspiration from the aquifers; however, evapotranspiration from the aquifers is not explicitly estimated in FEFLOW. It is assumed that most of the evapotranspiration from aquifers occurs at the groundwater/surface water interface (i.e. via rivers). This volume is included in line item 17.1 Evaporation from surface water. Any other evapotranspiration from the aquifers (i.e. to the landscape) cannot be quantified.