Abstract
The Wallal Aquifer System (WAS) is a predominantly confined aquifer in the West Canning Basin (WCB), Western Australia. It is located 150 km east of Port Hedland and is a major water supply for the Pilbara region. There have been several water supply assessments carried out in the WCB; none however challenge the underlying hydrogeological conceptualisation that was developed in the 1970s. The aim of this investigation is to challenge the prevailing hydrogeological conceptualisation, particularly assessing recharge potential from the immediate south of the study area.
3-D geological modelling was used to create multiple realisations of the stratigraphy using a range of possible depositional and post depositional processes. Multiple methods for recharge estimation were used in the investigation due to the inherent uncertainty with each method, particularly in arid environments. Each of the geological models was discretised into groundwater flow models and calibrated. Each model differed in the degree of heterogeneity and complexity with the most simplistic model giving the lowest error under steady state simulation. However, under transient simulation the most complex model enabled the most successful simulation of the hydrodynamics following a major storm event. The modelling shows that there is potentially a significant additional volume (40 GL/a) of groundwater available from the WAS providing impacts to existing users can be managed. This study also showed the WAS does receive surficial recharge from cyclonic events in the south of the study area, but not as a widely spread diffuse flux, but rather limited to discrete recharge windows associated with likely palaeochannels.
3-D geological modelling was used to create multiple realisations of the stratigraphy using a range of possible depositional and post depositional processes. Multiple methods for recharge estimation were used in the investigation due to the inherent uncertainty with each method, particularly in arid environments. Each of the geological models was discretised into groundwater flow models and calibrated. Each model differed in the degree of heterogeneity and complexity with the most simplistic model giving the lowest error under steady state simulation. However, under transient simulation the most complex model enabled the most successful simulation of the hydrodynamics following a major storm event. The modelling shows that there is potentially a significant additional volume (40 GL/a) of groundwater available from the WAS providing impacts to existing users can be managed. This study also showed the WAS does receive surficial recharge from cyclonic events in the south of the study area, but not as a widely spread diffuse flux, but rather limited to discrete recharge windows associated with likely palaeochannels.
| Original language | English |
|---|---|
| Qualification | Masters |
| Publication status | Unpublished - Oct 2014 |