Capture of more recharge and discharge is the only means of increasing the sustainable yield of the Gnangara Mound, Western Australia

摘要

The Gnangara Mound is a major source of water for market gardens, private and metropolitan water supply, as well as sustaining major pine plantations, native Banksia woodland and numerous wetlands and lakes. With a reduction in annual rainfall and increasing consumption by multiple users, groundwater levels are currently declining and anticipated to continue to decline unless measures are taken to enhance recharge or capture groundwater discharge that currently flows to the ocean. The three largest water losses from the Gnangara Mound are: pine forest plantations, modified remnant native vegetation and market gardens (1-2 MM~3d~(-1)). Removing the pine plantations and proper management of the Banksia areas and capture of fresh groundwater discharging to the sea will increase the sustainable yield by about 500,000 m~3day~(-1). Applying all these measures will only reduce the environmental impacts and not eliminate them. It is very difficult to achieve an acceptable balance, especially with changing weather patterns, increasing water demands and the relatively low infrastructure cost of groundwater abstraction. It is also essential that the environmental criteria, which control sustainable yield of the aquifers, be sensibly based.