Water resources

Water is a valuable resource. We use it directly to sustain ourselves, in food production, and in sanitation systems. We also use it in industrial processes that provide goods and energy. We value water’s aesthetic appeal in waterscapes and landscapes, and often recreate in or around water. Further, water is an integral part of the natural systems which support life on Earth.  

Globally, access to fresh water and sanitation systems is limited. According to the United Nations, 1.1 billion people lack access to potable water, and 2.6 billion people have inadequate access to sanitation systems. Sustainable management of water resources is burdened by increasing pollution including salts, nutrients, toxins, and sediments. Additionally, water management and urban biodiversity are intricately linked. Waterways, water-bodies, and riparian zones are affected by a loss of biodiversity and a proliferation of exotic species, and, in urban areas, waterways provide important corridors of habitat for wildlife.

BioCity@UniSA researchers are focussed on the geomorphology and hydrology of river systems and aquifers in South Australia, the associated biodiversity, and the use of spatial technologies to measure, map, and model these systems. Research is also focussed on techniques and technologies which will help to improve the management of water resources. This research can inform the conservation of natural systems and the use of water resources in developed and developing countries. The centre’s research capabilities are enhanced by linkages with the SA Water Centre for Water Management & Reuse.

Urban Water

Under natural conditions, water supplies are affected by geography and climate. In South Australia, rainfall is low and highly variable between years. Adelaide’s mean annual rainfall is around 550mm, falling mostly between May and September. Prior to European settlement a series of intermittent creeks ran from the Mount Lofty Ranges towards the coast. These waterways would flow after periods of rainfall, often flooding, but dry out during extended dry periods. The River Torrens, which now flows through the centre of Adelaide, terminated in wetlands landward of coastal dunes. These wetlands provided valuable wildlife habitat, and were an important resource for local Aboriginal people. The Adelaide area also has groundwater supplies within numerous fractured rock and sedimentary aquifers.

Anthropogenic changes to waterways, and to land use in catchments, now influence the quality and quantity of water supplies and wildlife habitats in urban areas. Waterways have been dammed, their flows controlled by locks and weirs and diverted for industrial, agricultural, and domestic use. There has been a loss of riparian and benthic habitats, with pipes, tunnels, and concreted channels replacing rivers and creeks. Wetlands have been drained to allow urban development. For example, a channel was excavated to allow the Torrens River to flow into Gulf St Vincent, thus draining the terminal wetlands and modifying the natural coastal processes which maintain local beaches and sea-grass beds. Groundwater is used heavily in peri-urban areas to support food and wine production. Overexploitation of these resources can reduce their potential for future use by increasing salinity and subsurface erosion, and reducing aquifer capacities. Surface hydrology is also affected by aquifer mismanagement.

Natural processes of infiltration, runoff, and erosion are now highly altered in urban areas. There is little infiltration of water into the soil and aquifers due to increased hard-surfaced areas such as roofs and pavements. These changes increase the volume and velocity of stormwater, damaging the waterways that carry it seaward. In upstream areas, the clearing of native vegetation for agriculture has increased erosion, with sediments being carried downstream and deposited over floodplains. In Adelaide this material, known as Post-European-Settlement Alluvium (PESA), can be metres thick. Changes to Urban water management practices are required to improve degraded natural systems and accommodate growing city populations as there are, in many cities, limited opportunities to increase the supply of water.

Water Sensitive Urban Design

Water Sensitive Urban Design (WSUD) considers the total water cycle in accommodating urban development while sustaining, and making use of, natural water flows and processes. This approach represents a shift from the industrial model, where the efficiency of delivering water and removing wastewater are paramount, with little regard for the natural processes. More efficient use and reuse of water within the city is essential, and requires water management to be directed by the characteristics of each catchment. In these ways, WSUD includes consideration of land use, the built environment, the community, and biodiversity.

WSUD can be applied to buildings, streets, and catchments. Houses and other buildings can be fitted to collect and store rainwater, reducing their need to import water. Gardens can allow infiltration through vegetated areas and permeable paving. On a street scale, vegetated biofiltration swales can slow water flow and allow infiltration, and permeable pavements can allow rainfall infiltration. At the catchment level, infiltration basins and wetlands can be constructed to filter water, allow infiltration, mitigate peak flows following storm events, and provide habitat.

In cities like Adelaide, with a pronounced dry season, water storage is also critical. According to the Waterproofing Adelaide Strategy, around 300 000 megalitres of water are used in the city each year. Depending on local rainfall, 40% to 90% of this water is piped into Adelaide reservoirs from the exotic Murray River system. Better use of existing water resources could reduce this dependence. On average, 160 000 megalitres of storm and surface waters flow into the Gulf St Vincent each year. Much of this water could be captured and filtered through wetlands, such as those at Greenfields, to avoid marine pollution. Further, using Aquifer Storage and Recovery (ASR) technologies, large volumes can be pumped underground and stored until it is required during dry periods. Improvements in ASR technologies hold global interest, with burgeoning cities like Beijing relying on groundwater for more than half of their water supply.