Identifying groundwater recharge and discharge zones using geostatistical simulation of hydraulic head and its derivatives

• Published in: Journal of hydrology (Amsterdam) Vol. 617; p. 128993
• Main Authors: Keegan-Treloar, Robin, Irvine, Dylan J., Werner, Adrian D., Banks, Eddie W.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2023
• Subjects: basins; Galilee Basin; geostatistics; groundwater flow; groundwater recharge; Hydraulic gradient; Hydrogeology Sequential Gaussian simulation; Kriging; Queensland; Triassic period; uncertainty; water management; Queensland; Hydrogeology Sequential Gaussian simulation; Galilee Basin; Hydraulic gradient; Kriging
• ISSN: 0022-1694; 1879-2707
• DOI: 10.1016/j.jhydrol.2022.128993

•Hydraulic head and partial derivatives simulated using Sequential Gaussian simulation.•Minima/maxima in the hydraulic head surface located and mapped stochastically.•Concavity of the hydraulic head surface identified and mapped.•Method provides an objective interpretation of recharge/discharge areas. Identifying groundwater flow directions and the locations of recharge and discharge areas is critical for effective groundwater management. Groundwater flow directions, the concavity and the locations of extrema (i.e., minima and maxima) can be assessed using the first and second derivatives of the hydraulic head surface. We developed a geostatistical method to jointly simulate hydraulic head and its first and second derivatives using sequential Gaussian simulation. The derivative values were used to identify regional groundwater flow directions, and the second derivative test was used to probabilistically map the concavity and the locations of extrema in the hydraulic head surface. By comparing the mapped concavity and extrema to known features, it was possible to attribute areas of recharge and discharge to physical features of the system, such as rivers, lakes and geological outcrops. This was applied to Triassic aquifers in the Galilee Basin (Queensland, Australia) to delineate the likely recharge and discharge areas. This provided an objective assessment of likely recharge and discharge zones and their uncertainty, which is an important addition to a region where the hydrogeology has been the subject of much conjecture.