Oral Presentation NCGRT/IAH Australasian Groundwater Conference 2019

Groundwater availability and climate change - assessing the combined influence of reduced water availability and increasing demand on the Barwon Downs groundwater resource (394)

Louise Lennon 1 , Brian Barnett 1
  1. Jacobs, Melbourne, VIC, Australia

Climate change has the potential to reduce future groundwater and surface water availability at times when demand will be increasing. The combined influence of less water availability and increase demand was considered for the future operation of the Barwon Downs borefield in south west Victoria.  The Barwon Down’s borefield is an important drought supply for the region and supplied up to 70% of Geelong’s water during the Millenium Drought.  The aquifer is primarily recharged from infiltration of rainfall in outcrop areas. 

To support the licence renewal of the Barwon Downs borefield, the influence of climate change on demand forecasts and recharge to the aquifer were considered.  As part of the numerical modelling assessment, a number of predictive modelling scenarios were used to address future climate change.  The assessment initially involved implementation of DEWLP Guidelines on future climate change to determine appropriate changes to groundwater recharge.  A total of four climate change scenarios were considered in accordance with the Guidelines.  Initial model results suggested that the predicted impacts were not particularly sensitive to the changed recharge condition.  This reflects the fact that future groundwater extraction is sustained through changes in water stored in the aquifer and by changes in groundwater discharged at the surface. 

Subsequent simulations included the increased future groundwater extraction that would be required to sustain the increased water demand under future climate change.  The combined influence of increased demand and reduced water availability generated significantly greater impacts revealing the true impact of a drier future climate.