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Case Studies 1. Kyeamba Creek 2. Liverpool Plains 3. Billabong Creek 4. Wanilla 5. Axe Creek 6. South Loddon Plains 7. Kamarooka 8. Lake Warden 9. Brymaroo Printing help |
Axe Creek Location: Central Victoria, 2 km southeast of Bendigo. Area: 380 km2. Rainfall: 550 mm. Land use 38% cropping and horticulture, 38% grazing, 24% forestry/trees. Reference: Hekmeijer and Dawes (2001b) Salinity This is expressed both as saline land and elevated stream salinity. Most of the salinity is related to processes influenced by the Whitelaw Fault, which approximately bisects the catchment. Streams and land adjacent to streams are invariably more saline downstream from where they cross the fault. General high water levels in the flatter eastern lowlands of the catchment also cause local areas of surface salinity. Local land-holders report that the saline areas have stabilised. Groundwater system Axe Creek has an intermediate-scale fractured rock aquifer. The fractures strike predominantly northwest-southeast, while topographic features, including streams, trend northeast to easterly. These features, coupled with the complex folding and fracturing of the bedrock aquifer, make definition of the catchment boundary difficult. The role of the Whitelaw Fault presents another complication because it is not clear whether this zone exports or imports salt. Management A simplified approach that focuses on a transect of the Axe Creek catchment has provided meaningful results. The pronounced change in slope at the Whitelaw Fault is capable of promoting groundwater discharge without involving additional groundwater contributions from the fault itself. Modelling indicates that high water levels on the eastern side of the fault would persist while discharge occurs at the Whitelaw Fault. Indicative modelling estimates that the aquifer took between 50 and 100 years to fill to present levels and to commence discharging, while, with even a 90% reduction in recharge, it might take as long as 500 to 1000 years for discharge at the fault to cease and water levels to return to a pre-clearing state. If saline areas have actually stabilised, then suitable management of cropping and grazing rotations to minimise recharge would be appropriate, along with living with extant salinity. Elimination of the recharge waters that discharge at the fault would seem impractical or impossible, and, unless a major external political or economic imperative is imposed, may not be warranted. |
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