Changes in groundwater recharge resulting from clearance of mallee vegetation

Recharge rates under mallee in the western Murray Basin are estimated to be less than 0.1 mm yr^-1, irrespective of soil type. When the mallee vegetation is removed, recharge increases due to the shallower depths of rooting of crop and pasture species. Recharge rates under crop/pasture are spatially variable, reflecting factors such as geomorphology and soil type. They typically range between 3 and 60 mm yr^-1. Over much of the western Murray Basin, where the watertables are 30 to 50m deep, there may be a time delay of the order of tens to hundreds of years before the effects of land-clearing on water tables begin to be seen. In other areas, where the water table is relatively shallow, the effects are seen much sooner. -Authors