Understanding localised recharge mechanisms in the Pilbara

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Ali, Riasat; Dawes, Warrick; Barron, Olga; McFarlane, Don; Hodgson, Geoff


2013-12-31


Conference Material


IAH 2013 Perth Australia, Perth Convention and Exhibition Centre, 15-20 September, 2013


online in press


1


Mining and urban populations in the Pilbara region is likely to increase substantially over current levels. This will further increase pressure on water resources because of expected increased demand for drinking and process water, dewatering as mining goes below the watertable and its disposal into surface environments, and a warmer, if not drier, climate. There are many types of aquifers in the Pilbara region which are replenished by diffuse recharge via rainfall infiltration or by localised recharge via leakage from creeks, streams and rivers when they flow following significant rainfall events. Alluvial aquifers are the main aquifer systems which are mainly replenished by the localised recharge mechanisms. Understanding, characterising and quantifying surface water – groundwater interactions in the alluvial systems is critical to determine the nature and extent of interactions, the frequency and magnitude of aquifer storage recovery, and the rate and volume of flux exchange. Such analyses are also important as surface and groundwater integration has significant ecological values, as they define the river pools dynamics. This study is aimed to understand surface water – groundwater interactions in the alluvial aquifers, addressing the recharge mechanisms including the type of connectivity with groundwater which appears to change during the flow event and the effect of previous recharge event on the aquifer storage recovery. Rainfall, surface water flow, groundwater monitoring and groundwater abstraction data were used to analyse the impact of rainfall, streamflow and groundwater abstraction on groundwater levels in the alluvial systems. The impact of other potential localised recharge control parameters on localised recharge was also assessed. The study found that localised recharge occurs only during the streamflow events, with or without rainfall or diffuse recharge in the immediate area. The localised recharge occurs in response to runoff from significant rainfall events only. The main localised recharge control parameter in the alluvial systems of the Pilbara is streamflow. Both frequency and duration of streamflows influence localised recharge rates with duration having a dominated effect on localised recharge.


IAH


Localised recharge, Pilbara, alluvial aquifers, groundwater hydrology


Hydrogeology


Link to Publisher's Version


EP133157


Conference Abstract


English


Ali, Riasat; Dawes, Warrick; Barron, Olga; McFarlane, Don; Hodgson, Geoff. Understanding localised recharge mechanisms in the Pilbara. In: IAH 2013 Perth Australia; 15-20 September, 2013; Perth Convention and Exhibition Centre. IAH; 2013. 1.http://hdl.handle.net/102.100.100/95711?index=1



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