Stochastic Assessment of Groundwater Contamination Risks From Onshore Gas Development Using Computationally Efficient Analytical and Numerical Transport Models

Frontiers in Water

J. Sreekanth¹  David Rassam¹  Trevor Pickett¹  Rebecca Doble²  Dirk Mallants²  Dennis Gonzalez² 

[1] Commonwealth Scientific and Industrial Research Organisation (CSIRO) Land and Water, Dutton Park, QLD, Australia;Commonwealth Scientific and Industrial Research Organisation (CSIRO) Land and Water, Urrbrae, SA, Australia;

关键词: risk assessment;    contaminant transport;    vadose zone modelling;    python;    MODFLOW;    MT3D;   

DOI  :  10.3389/frwa.2021.799738

来源: DOAJ

【 摘 要 】

Regulators require the gas industry to assess the risks of unintentional release of chemicals to the environment and implement measures to mitigate it. Industry standard models for contaminant transport in aquifers do not explicitly model processes in the unsaturated zone and groundwater models often require long run times to complete simulation of complex processes. We propose a stochastic numerical-analytical hybrid model to overcome these two shortcomings and demonstrate its application to assess the risks associated with onshore gas drilling in the Otway Basin, South Australia. The novel approach couples HYDRUS-1D to an analytical solution to model contaminant transport in the aquifer. Groundwater velocities and chemical trajectories were derived from a particle tracking analysis. The most influential parameters controlling solute delivery to the aquifer were the soil chemical degradation constant and the hydraulic conductivity of a throttle soil horizon. Only 18% of the flow paths intercepted environmental receptors within a 1-km radius from the source, 87% of which had concentrations of <1% of the source. The proposed methodology assesses the risk to environmental assets and informs regulators to implement measures that mitigate risk down to an acceptable level.

【 授权许可】

Unknown