Palaeovalleys are geologically ancient, buried river valleys which no longer function as active surface water systems. Palaeovalleys in arid and semi-arid regions of Australia were originally formed when climatic conditions were different, and wetter, than they are today.
Although surface water no longer flows in most of the palaeovalleys, the sediment which has filled the river channels commonly forms good quality aquifers which are capable of storing significant quantities of groundwater. In many desert areas of Australia, the groundwater resources contained in palaeovalley aquifers may be the only reliable supply of potable water available to remote water users such as aboriginal communities and pastoral stations.
Palaeovalley aquifers typically have a higher storage capacity and hydraulic conductivity than adjacent and more extensive weathered and fractured basement aquifers. Bores can yield relatively significant amounts of water. Palaeovalley aquifers are limited by their shallow depth (typically <50m) and narrow width, but they can extend for great distances longitudinally down-valley (typically tens to hundreds of kilometres), with good aquifer connectivity along the length of the palaeovalley.