Securing our groundwater future
All water users have a part to play in adapting groundwater use to the drying climate. We can all contribute by rethinking how we use, manage and interact with water in our homes and businesses.
To maintain groundwater as a viable resource for ongoing use and other public and environmental benefits, we need to stabilise groundwater levels and enable some key areas to recover.
There are many ways to do this. To help achieve a better balance, some local governments and businesses are already investing in water-efficient technology, investigating managed aquifer recharge and applying water-sensitive urban design.
New urban developments can also be an opportunity to promote alternative, local water supply solutions that are fit-for purpose, especially for public open space.
All water users will need to consider options like these and use water more efficiently to adjust to reduced groundwater availability.
Strategies to rebalance Gnangara in a drying climate by 2030
Groundwater will continue to be an important part of Perth’s water supplies because it is our lowest cost and most accessible water source.
Reduced abstraction is part of the solution if we are to adjust to less rainfall by 2030. In some locations, even with initiatives such as increased efficiency, reducing water licence entitlements is one of a number of measures that will be considered.
Groundwater abstraction for scheme supply – which was higher as an interim response to low inflow to dams – was reduced when the Southern Seawater Desalination Plant began production in 2013. The Water Corporation have also been taking less from environmentally sensitive areas and moving abstraction to the confined parts of the deeper Leederville and Yarragadee aquifers. As a result, water levels have started to stabilise in some areas of the Gnangara Mound.
The Department of Water and Environmental Regulation is now working with both the Water Corporation and self-supply water users to plan future changes, including reductions to abstraction, by 2030. The approach may vary locally depending on how much the area is out of balance and what is practical and achievable.
Land-use change such as urban expansion and removing some of the pines from Gnangara Mound will improve recharge to groundwater, which will reduce the effects of lower rainfall in some places. Enhancing recharge and protecting public drinking water sources will remain an important consideration of any land use changes.
Science and research play an important role in solving emerging water problems. The Department of Water and Environmental Regulation is currently analysing the latest scientific data alongside practical advice from Gnangara water users to work out where, when and how best we can bring use and recharge back into balance. Once we have agreed on a pathway forward, it will be mapped out in the next Gnangara groundwater allocation plan and staged over the next decade.
Exciting finds in science
The recently completed four-year study, including research from Curtin University and the University of Western Australia, developed a new groundwater model to help our task.
The study started with several data collection programs that covered over 7000 square kilometres of the Perth region using geophysical equipment mounted to planes and helicopters. More detailed investigative work, including seismic and electromagnetic surveys, followed.
Today, the Department of Water and Environmental Regulation and the Water Corporation are using the new model to assess the best locations for reinjecting recycled water to help recharge the system.
Water efficiency and innovation
Efficiency and innovation will be key to making Gnangara groundwater stretch further and be more sustainable as a resource.
Reducing demand through efficiency:
- increases productivity
- minimises water costs
- avoids or delays the need for new water sources.
Through the Waterwise Council Program, more local councils are becoming more water efficient, improving turf maintenance practices and adopting new irrigation and water monitoring technologies.
Some developers, schools and businesses are also succeeding through water-sensitive urban design. Good design is essential for reducing water use as well as for managing stormwater and enhancing recharge.
Households are helping save groundwater by being more waterwise in their home and gardens. Waterwise gardens include native and drought-tolerant plants, mulching, and efficient, well-maintained irrigation systems. One of the great side benefits of these practices is the simple fact that they save money.
Waterwise garden bore owners that use water efficiently not only give their garden the right amount of water it needs but they help share groundwater locally. Garden bores in urban and semi-rural areas collectively use 20 per cent of the Superficial aquifer. Staying within sprinkler restrictions and avoiding over-use helps reduce impacts on neighbours and the local area.
Some agricultural businesses have become very efficient through contemporary technologies, irrigation schedules, improved maintenance and better management. The combination of crop types, crop areas and the type of irrigation systems used can also boost water efficiency.
Leaders in water efficiency and innovation are showing that we can all adjust to a drying climate by rethinking how we use water wisely.
The Water Corporation already has two desalination plants, which can provide up to 50 per cent per cent of the metropolitan area’s scheme water needs. Desalination has given us a secure water source for part of Perth’s drinking water supply that doesn’t depend on the rain.
Boosting water supplies
Groundwater replenishment where large volumes of highly treated recycled water are recharged back into deep aquifers to augment our drinking water. Construction of Perth’s first full-scale Groundwater Replenishment Scheme at the Beenyup facility in Craigie is now completed with a capacity to recharge 14 GL of recycled water into groundwater for storage and abstraction each year. Planning is underway to double the schemes capacity to recharge 28 GL each year.
Managed aquifer recharge where water is infiltrated back into an aquifer through reinjection bores or ponds, basins and trenches for later use or to benefit the environment. Location and design should consider benefits for local water users and the environment. Well considered location and design will deliver benefits for local water users and the environment.
Stormwater harvesting where rainfall runoff is captured in tanks or other storages as a water source that can improve water supply for non-drinking purposes in households or businesses and parks and gardens. Good urban design can enhance stormwater recharge to groundwater – a natural form of stormwater harvesting
Wastewater treatment and reuse where wastewater is recycled to be used for irrigation of parks, public gardens and golf courses, and potentially other uses such as horticulture and industry.
The best alternative, non-potable supply may vary from place to place, and interested water users will need to carefully assess the range of options available and the costs and benefits of each.
Smarter solutions for recycled water
The City of Kalamunda is recycling winter drainage water, storing it through managed aquifer recharge, and using it to irrigate parks in summer.
In response to reduced groundwater availability and local salinity issues, the Western Suburbs Regional Organisation of Councils is investigating new ways of using recycled water to irrigate parks and public open space either directly from the Subiaco treatment plant or by ‘topping up’ the Superficial aquifer for reuse later.
The Department of Water and Environmental Regulation is also partnering with the Department of Communities, the City of Swan and developers to consider water supply options for the Department of Communities’ Brabham subdivision in Perth’s north-east.