Fractured bedrock and saprolite hydrogeologic controls on groundwater/surface-water interaction: a conceptual model (Australia)

• Published in: Hydrogeology journal Vol. 17; no. 8; pp. 1969 - 1989
• Main Authors: Banks, Edward W., Simmons, Craig T., Love, Andrew J., Cranswick, Roger, Werner, Adrian D., Bestland, Erick A., Wood, Martin, Wilson, Tania
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.12.2009; Springer Nature B.V
• Subjects: Active control; Aquatic Pollution; Aquifer systems; Aquifers; Bedrock; Creeks; Dynamical systems; Dynamics; Earth and Environmental Science; Earth Sciences; Geology; Geophysics/Geodesy; Groundwater; Groundwater flow; Hydraulics; Hydrogeology; Hydrologic models; Hydrology; Hydrology/Water Resources; Stream discharge; Stream flow; Surface water; Waste Water Technology; Water Management; Water Pollution Control; Water Quality/Water Pollution; Australia, South Australia; Fractured rocks; Groundwater/surface-water relations; Hydrochemistry; Australia; Saprolite
• ISSN: 1431-2174; 1435-0157
• DOI: 10.1007/s10040-009-0490-7

Hydrologic conceptual models of groundwater/surface-water interaction in a saprolite-fractured bedrock geological setting often assume that the saprolite zone is hydraulically more active than the deeper bedrock system and ignore the contribution of deeper groundwater from the fractured bedrock aquifer. A hydraulic, hydrochemical, and tracer-based study was conducted at Scott Creek, Mount Lofty Ranges, South Australia, to explore the importance of both the deeper fractured bedrock aquifer system and the shallow saprolite layer on groundwater/surface-water interaction. The results of this study suggest that groundwater flow in the deeper fractured bedrock zone is highly dynamic and is an important groundwater flow pathway along the hillslope. Deep groundwater is therefore a contributing component in streamflow generation at Scott Creek. The findings of this study suggest that hydrologic conceptual models, which treat the saprolite-fractured bedrock interface as a no-flow boundary and do not consider the deeper fractured bedrock in hydrologic analyses, may be overly simplistic and inherently misleading in some groundwater/surface-water interaction analyses. The results emphasise the need to understand the relative importance of subsurface flow activity in both of these shallow saprolite and deeper bedrock compartments as a basis for developing reliable conceptual hydrologic models of these systems.