Water in the region
Water supports the life of the region. Water sites are sacred to the people of the Alinytjara Wilurara region and are critical for the communities to survive in this area. Historically, trade routes were linked to access to water supplies and as such many important Aboriginal story lines are also linked to water.
Though there are a number of water sources in the Alinytjara Wilurara region but fresh water is very scarce. It is scarcest in the Maralinga Tjarutja, Yalata areas and Mamungari National Park. Rainfall is higher in the APY Lands, where ranges along the northern border act as a rain trap and direct relatively fresh water through shallow aquifers down into much of the APY region. There is older, salty water under the Maralinga Tjarutja and Yellabinna areas which may be millions of years old.
The region contains a number of water dependent ecosystems. The limestone caves of the Nullarbor Plains provide refuge for many animals that require caves for part or all of their life cycle including crustaceans, centipedes, cockroaches, carabid beetles, grasshoppers, locusts, pseudo-scorpions and spiders. Some of these species occur nowhere else in the world. Two vertebrate species that are also known to use the caves are the bat, Chalinolobus morio, and the Nullarbor population of the masked owl, Tyto novaehollandiae. Maintaining the current aquatic environment of the caves is a priority for the region’s Management Plan.
The lack of surface water has played a significant role in the history and movement of people in this region. Before European arrival, Aboriginal people moved across the landscape depending on where the water was. Rockholes and soaks played a very important role in providing reliable water sources, governing where family groups clustered and travelled. Many of these sources have significance to the Aboriginal people as ceremonial, social and trading locations.
Since European arrival, a number of Aboriginal settlements and missions have started, then closed down due to lack of water. Important permanent water supplies have been destroyed, forcing settlement patterns of the people of this region to change. The testing of nuclear weapons at Maralinga resulted in an immediate and widespread change to settlement patterns across the whole region.
Surface water features include:
- claypans that may hold water in a wet season or after significant rainfall
- small soaks, rockholes and springs scattered through dunes and in the ranges
- ephemeral watercourses due to the irregular rainfall
- a large number of temporary waterholes in the deeper/wider reaches of the water courses which can hold water from a few months up to a few years
- rockholes or ‘gnammas’ in isolated granite outcrops (or inselbergs) may dry out during a hot summer or prolonged drought.
Many water features are highly significant for Aboriginal groups.
Ground water is extracted using wells and bores. The salinity of ground water in the region varies considerably. Water flows are generally low, from 0.0001 L/s to 34 L/s. Groundwater recharge in the arid climate of the region occurs only after periods of extreme local rainfall, typically greater than 100–200 mm/month. In some cases the water is hundreds of years old and replenishment may be very slow or in some cases not at all.
Shallow freshwater aquifers exist in fractured rock or deep river ancient aquifers. Artesian aquifer systems extend across and beyond the region. Taking water from these aquifers must be well planned to ensure there are no detrimental effects on other users or established ecosystems.
Threats to water in the region
Feral camels, donkeys and horses invading the region has resulted in significant disturbance of rockhole environments. Rotting carcasses, urine, and faeces pollute the water, and trampling destroys native vegetation in the surrounding area. They also drink copious amounts of water significantly reducing the scarce supplies captured in rockholes. This threatens eradication of native species dependent on rockhole environments. The presence of feral animals also presents major health issues for Anangu visiting these rockholes.
The Alinytjara WIlurara team continues to work with the region's Traditional Owners to protect rockholes from damage by large herbivores. Although cattle also impact on surface water when it's available they generally drink from bore-fed troughs.
Understanding the full extent of ground water supplies and the interaction of underground water flows across such a vast system is complex. Located mainly between fractured rock, the water in some cases is hundreds of years old with very slow to no replenishment capability. The main threat to fresh water supply is over extraction through a lack of knowledge about the replenishment rates and rainfall being intermittent.
The use of non-potable water for activities such as mining or the development of infrastructure also needs close consideration before being approved particularly in relation to its effect on the water table.