Estimation of groundwater recharge and discharge across northern Australia

Russell S. Crosbie, James L. McCallum, Glenn A. Harrington

Research output: Chapter in Book/Conference paperConference paper

4 Citations (Scopus)

Abstract

Groundwater recharge is one of the more difficult components of the hydrological cycle to estimate but one that is becoming increasingly important as Australia turns to groundwater resources for future economic development. Also of concern is groundwater discharge. The extraction of groundwater by pumping inevitably reduces groundwater discharge to rivers where the two are connected. Knowledge of both groundwater recharge and discharge is required for effective management of groundwater resources. Across northern Australia there are few detailed studies investigating groundwater recharge and discharge and none that have applied three independent estimates across 1.2 million km 2. In this study, groundwater recharge has been estimated by upscaling the results from a 1-D soil-vegetation-atmosphere-transfer (SVAT) model (WAVES) and a chloride mass balance. Groundwater discharge to surface water has been estimated through baseflow separation of gauged stream flow data. The SVAT model was used at a point scale to develop relationships between rainfall and recharge for different combinations of soil and vegetation types. These relationships were used to upscale recharge across northern Australia on a 0.05° grid using maps of soil, vegetation and annual average rainfall as co-variates. A chloride mass balance requires measurements of chloride deposition and concentration of chloride in groundwater. A review of field studies over the last few decades has provided a relationship between chloride deposition and distance from the coast; this has enabled a raster layer to be developed of chloride deposition across northern Australia. The chloride concentrations in groundwater have been assessed from data collected by the WA, NT and Qld state agencies. The baseflow analysis was conducted on gauged data collected by the WA, NT and Qld state agencies using the Eckhardt (2005) filter and converted to a depth using the catchment area as determined using a digital elevation model. At a point scale both estimates of recharge and the estimate of discharge showed a range of over three orders of magnitude, from less than 1 mm/yr to over 1000 mm/yr. As a gross generalisation, the relative magnitudes between the three methods were as expected from a conceptual point of view: the upscaling of the SVAT model had the greatest recharge; the chloride mass balance method gave less recharge than the upscaling of the SVAT model; and, the groundwater discharge was the lowest of the three estimates. The upscaling of the SVAT model is an estimate of gross recharge (water added to the saturated zone), the chloride mass balance is an estimate of net recharge (gross recharge - ET from GW) and the baseflow is groundwater discharge to surface water which should be less than recharge due to groundwater extraction and ET from the riparian zone. Each technique therefore provides complementary information to assist future groundwater resource planning in northern Australia.

Original languageEnglish
Title of host publication18th World IMACS Congress and MODSIM09 International Congress on Modelling and Simulation
Subtitle of host publicationInterfacing Modelling and Simulation with Mathematical and Computational Sciences, Proceedings
Pages3053-3059
Number of pages7
Publication statusPublished - 1 Dec 2009
Externally publishedYes
Event18th World IMACS Congress and International Congress on Modelling and Simulation: Interfacing Modelling and Simulation with Mathematical and Computational Sciences, MODSIM09 - Cairns, QLD, Australia
Duration: 13 Jul 200917 Jul 2009

Conference

Conference18th World IMACS Congress and International Congress on Modelling and Simulation: Interfacing Modelling and Simulation with Mathematical and Computational Sciences, MODSIM09
CountryAustralia
CityCairns, QLD
Period13/07/0917/07/09

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Crosbie, R. S., McCallum, J. L., & Harrington, G. A. (2009). Estimation of groundwater recharge and discharge across northern Australia. In 18th World IMACS Congress and MODSIM09 International Congress on Modelling and Simulation: Interfacing Modelling and Simulation with Mathematical and Computational Sciences, Proceedings (pp. 3053-3059)