When to Turn the Tap Off
Abstract
The climate operating over the south-west of Western Australia is changing, notably with reduction in rainfall. Concomitant with this, there is increased pressure of land-use, some of it showing remarkably little ecological wisdom. One of the major regional aquifers is the Gnangara Mound between the Swan and Moore rivers. The Mound reached an elevation of about 70 m asl and, on its western slope, assisted in the formation of caves in the area of Yanchep National Park with cave streams lined by tuart (Eucalyptus gomphocephala) tree root mats. This reliable food supply supported a diverse, abundant and zoologically important groundwater fauna.
In the summer of 2000/2001, the streams dried, and the government response has been to remediate the situation – by restoring local mounds within selected caves. I will review briefly the fauna, the history of the remediation, and suggest that it is all futile given that it is not possible to predict reliably future climate of the region.