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. Many story lines and trade routes are linked to water supplies so they have been important for a long time.
Though there are a number of water sources in the Alinytjara Wilurara region, fresh water is very scarce. It is scarcest in the Maralinga Tjarutja, Yalata and Mamangari National Parks and these locations are important to the local communities. 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 dependant 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, pseudoscorpions 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.
There are a number of water sources in the 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 hold water from a few months to up to a few years
- rockholes or ‘gnammas’ in isolated granite outcrops (or inselbergs) that may dry out during a hot summer or prolonged drought.
Many water features are highly significant for Aboriginal groups.
Groundwater is extracted using wells and bores. The salinity of groundwater 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.
The systems are fractured rock or deep river ancient aquifers and much of the freshwater appear to be in shallow aquifers. Artesian aquifer systems extend across and beyond the region, and so taking water from these aquifers unless well planned may have a detrimental effect on other users, particularly where the artesian heads above ground surface are already low.
Threats to water in the region
Feral camels, donkeys and horses invading the region has resulted in significant disturbance of rock hole environments. Dead animals rotting, urine, trampling the area and drinking water from the rockholes can result in terminal threats to the species that used to live in and use rockhole environments. There are also major health issues for young Anangu who play in these rockholes so it’s a broader issue than just the environment. The AW team works with Aboriginal people in the region to protect important rockholes from damage by large herbivores. Cattle also impact on the surface waters but use the bores in the area more than surface waters.
The main issue with ground water is the lack of knowledge about the resource and how the different parts of the region underground water flows interact. The location is mainly fractured rock In some cases the water is hundreds of years old and replenishment may be very slow or in some cases not at all. The main threats are over use of the fresh water through a lack of knowledge about the replenishment rates and supplies being intermittent. For the other water in the region use by mining and petroleum programs in the future may affect the water tables and this is an area that Natural Resources Alinytjara Wilurara is working closely with other government agencies to support sustainable development that the communities are aware of the impacts of the development on the water supplies.