Runoff and focused groundwater-recharge response to flooding rains in the arid zone of Australia

• Published in: Hydrogeology journal Vol. 29; no. 2; pp. 737 - 764
• Main Authors: Acworth, R. Ian, Rau, Gabriel C., Cuthbert, Mark O., Leggett, Keith, Andersen, Martin S.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-03-2021; Springer Nature B.V
• Subjects: Aquatic Pollution; Aquifers; Arid lands; Arid zones; Aridity; Borehole geophysics; Boreholes; Climate change; Climatic data; Daily precipitation; Earth and Environmental Science; Earth Sciences; Environmental monitoring; Environmental tracers; Field investigations; Flooding; Floods; Fluid dynamics; Fluid flow; Gauges; Geologic mapping; Geological mapping; Geology; Geophysics; Geophysics/Geodesy; Groundwater; Groundwater age; Groundwater recession; Groundwater recharge; Groundwater runoff; Hydraulics; Hydrogeochemistry; Hydrogeology; Hydrology/Water Resources; Pleistocene; Rain; Rain gauges; Rainfall intensity; Rainfall runoff; Rainfall-runoff relationships; Runoff; Storms; Streambeds; Surface water; Tracers; Waste Water Technology; Water flow; Water Management; Water Pollution Control; Water Quality/Water Pollution; Australia; Rainfall/runoff; Groundwater recharge/water budget; Australia; Equipment/field techniques; Geophysical methods
• ISSN: 1431-2174; 1435-0157
• DOI: 10.1007/s10040-020-02284-x

A groundwater recharge investigation in the arid zone of Australia is presented. The investigation used a wide range of hydrogeological techniques including geological mapping, surface and borehole geophysics, groundwater hydraulics, streambed temperature and pressure monitoring, and hydrogeochemical and environmental tracer sampling, and it was complemented by analysis of rainfall intensity from 18 tipping-bucked rain gauges, climate data and stream runoff measurements. Run-off and recharge from a 200-mm rainfall event in January 2015, the largest daily rainfall in the local 50-year record, were investigated in detail. While this major storm provided substantial run-off as a potential source for focused, indirect recharge, it only produced enough actual recharge to the shallow aquifer to temporarily halt a long-term groundwater recession. A series of smaller rainfall-runoff events in 2016 produced a similar recharge response. The results suggest that the total magnitude of a flood event is not the main control on indirect groundwater recharge at this location. A deeper aquifer shows no hydraulic response to surface-water flow events and is isolated from the shallow system, consistent with its Pleistocene groundwater age. This supports a growing body of evidence indicating that attributing or predicting generalised changes in recharge to changes in climate in dryland environments should not be attempted without first unravelling the dynamic processes governing groundwater recharge in the locality of interest. The results should prompt more detailed and long-term field investigation in other arid zone locations to further understand the episodic and nonlinear nature of recharge in such environments.