Arid zone surface runoff – a significant resource in Australia

Abstract

The Australian arid zone has quite large resources of surface water. For example in western New South Wales an average of 7 runoff events are observed each year and in these the median depth of runoff is about 0.4mm, or 400m3/km2, providing at least 2.8 ML/km2/yr of surface water. The key to utilisation of this water is to catch it where it is, when it occurs. Simple earthworks, constructed with a blade mounted on a tractor, can be used to direct water from natural small channels to a point of concentration where it can be protected from evaporation and seepage losses, say in an excavated hole or “tank”. Even with 90% loss of the stored water a constant supply of at least 700 litres/km2/day would be available, enough to provide an adequate supply for the average Australian household.