New guidelines needed for more accurate groundwater modelling

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A lack of guidelines around groundwater modelling has led to inaccurate and unreliable results, a new paper has found.

In Australia, groundwater makes up about 17% of accessible water and accounts for more than 30% of the country’s total water consumption. This is expected to rise as surface water resources diminish because of climate change and prolonged drought.

Groundwater models are used to simulate and predict aquifer conditions, using either a single ‘consensus model’ or a comprehensive ‘multi-model’ system.

According to groundwater modeller and Flinders University PhD candidate Trine Enemark, although the multi-model method is considered superior, this approach is underused. When it is used, a lack of guidelines means wide variations exist.

In a review of 59 studies that applied a multi-model approach to groundwater, Enemark found the inherent uncertainty in groundwater modelling – which comes from having to run different greenhouse gas scenarios, climate models and groundwater abstraction scenarios, among others – compounded the time and cost involved in obtaining comprehensive data.

“Hydrogeological data is often scarce and uncertainty around how a groundwater system functions is always a challenge,” Enemark said.

“While it is impossible to make a model that perfectly describes reality, conceptual uncertainty, which relates to uncertainty in understanding how a groundwater system functions, is often ignored.”

She said a systematic approach is needed to develop, adapt and reject different models.

“Comprehensive parallel modelling is time consuming, but disregarding plausible alternative models can lead to surprises, and in the long run can result in additional costs.

“Reducing uncertainty in groundwater modelling reduces the risk of making decisions that could have a negative impact on the groundwater system, while also avoiding overly cautious decisions that could lead to missed opportunities.”

Enemark’s supervisor, Professor Okke Batelaan, said the research is particularly important due to the ongoing issue of groundwater in mining projects.

“The groundwater debates that often surround mining or other major projects highlight the need for a less subjective, more systematic approach that covers all aspects of conceptualisation relevant to the study objective,” he said.

The research was published in the Journal of Hydrology.

 

Originally published by the Australian Water Association, 11 February 2019.