Three factors contribute to the risk posed by increasing water abstraction and interception:
- the demands of a growing population
- increases in per-person water consumption for this population
- the requirement for extracting more water from an increasingly water-scarce environment to meet consumption, growth and production needs.
The potentially costly approaches to augmenting water supplies through climate-resilient sources, as well as the proven effects of good water demand management, can offset the factors contributing to risk.
A policy for developing up to 100 dams in Australia, particularly focusing on northern Australia, was released in 2013. Such development risks interrupting natural flow regimes, waterscape connectivity and operation of aquatic ecosystem processes that require the run of the river. Additionally, further development of northern Australia will require a significant difference in both the nature and magnitude of groundwater use, because groundwater provides a potential water resource to support tropical agricultural development, as well as being a primary contributor to dry-season surface flows in some rivers in the north. Changes in groundwater levels arising from abstraction or other pressures also raise risks for groundwater-dependent ecosystems (Box WAT6).
Investigations of the vulnerability of 2 fish species —barramundi (Lates calcarifer) and sooty grunter (Hephaestus fuliginosus)—in the Daly River in the Northern Territory (Chan et al. 2012) identified that full use of current extraction entitlements would have significant impacts on the fish populations; this situation is at risk of exacerbation as pressure mounts to allocate more water to meet agricultural development needs. Risks also extend to impacts on fished species, such as barramundi, where river discharge reductions were found to be likely to affect characteristics that included exploitable biomass, annual catch, maximum sustainable yield and spawning stock size (Tanimoto et al. 2012).