As researchers, we need a range of expertise to fully understand complex water supply systems. In this article I demonstrate what this means in the real world. Read on to find out how multi-disciplinary teams can be so important.
Water supply systems are complex. As we begin using more alternative sources of water, such as harvested stormwater and groundwater, these systems only become more complex. In a traditional water supply system, we rely on surface water from less developed or natural catchments. Climate change, population growth and overuse of these sources have put stress on our water resources. To ease the pressure, water utilities, local councils, developers and other water system managers have turned to alternative water supplies.
Analysing systems that use alternative sources from a hydraulic engineering background does not provide all the answers. We need different expertise to fully understand these systems.
How the hydraulic analysis approach works, in a traditional water supply system
A hydraulic analysis of a water supply/distribution system typically considers the system all the way from a supply reservoir to the consumers. It includes the pumps, tanks, pipes and valves along the way (Fig. 1). When we design and analyse such a system from a hydraulic perspective, our main considerations are:
- Sizing of tanks: Taking into account the amount of water required by consumers and supplying water in emergencies (such as fires or pump outages).
- Sizing of gravity pipelines: To provide adequate pressure for consumers, but also avoid high velocities that may damage pipelines.
- Sizing of pumps and pressure pipelines together: Considering pressure and velocity constraints on the pipe and energy losses due to friction
- Adding valves where required: To sustain pressure, reduce pressure, or isolate sections of the network.
- Determining operating rules for the system that ensure tanks always have enough water to supply demands, and, where possible, defer pumping to off-peak (cheaper) electricity tariff periods.
This approach assumes that water is always available in the water supply reservoir at the start of the system. We may need some assistance from hydrologists to ensure that this is a reasonable assumption.
This diagram shows the path of supply and distribution. The model runs left to right, as follows: Reservoir, pump, through a pressure pipeline and up to a tank, then through a gravity pipeline downwards to consumers.
Figure 1: A simple example of a traditional water supply system
Harvested stormwater systems need additional expertise
Harvested stormwater is run-off collected from urban areas. It is often used for non-potable supplies such as irrigation of open green spaces.
The Ridge Park Managed Aquifer Recharge Project in the City of Unley, South Australia, which is at the edge of Adelaide (Fig. 2) is a harvested stormwater system. In winter, this system:
- collects water from Glen Osmond Creek (run-off comes from urbanised areas around the bottom of the South Eastern Freeway)
- treats the water through biofiltration and a small treatment plant
- injects the water into an aquifer for storage.
In summer, water is extracted from the aquifer and used to irrigate parks and reserves in the City of Unley area (Fig. 3).
Ridge Park Managed Aquifer Recharge Project in the City of Unley, South Australia
This is a diagram of the Ridge Park Stormwater Harvesting and Aquifer Recharge System. It shows why additional expertise is needed. This diagram has a harvest pond that Glen Osmond Creek flows into. Water is pumped from the pond into a bioretention basin, and from there up into a storage tank via a treatment plant. Water is also pumped into the tank from the aquifer, but that water does not go via the treatment plant. From the tank water is then distributed.
Figure 3: The Ridge Park Stormwater Harvesting and Aquifer Recharge System
Additional information needed to analyse the system
We need to consider the hydrology of Glen Osmond Creek and its catchment to know how much water is available to be harvested. This is in addition to a typical hydraulic understanding of the pumps, pipes and valves.
When analysing this system in our research, we have come across several problems that require expertise of other disciplines. Of note is the expertise provided by hydrogeologists and electrical engineers.
- How much pressure is required to pump water into and out of the aquifer?
- How do the aquifer properties affect the flow rates that can be achieved?
- How much energy does it take to pump water through the treatment plant?
- How much water can be held by the biofiltration basin and how long does it take to filter through?
In order to solve these problems, we reached out to people in our networks that have different expertise.
Non-technical expertise can be important
Input from non-technical areas, for example economic and social aspects, may be important.
The economic analysis of a system is particularly important in the concept or proposal phase. It can help to justify the benefits of going ahead with a project.
A social analysis of a system is also important. It helps us consider how alternative water source systems affect people’s use of water and public land. It also helps in considering the amenity of the land used for the system’s infrastructure. For example, building a dam on a creek to harvest stormwater may take land away from public use. But, if the water is used to irrigate other open green spaces, the project may be beneficial overall.
Networks and co-operative research centres improve research
Researchers, particularly PhD students, often work on very specific topics. They have very deep but not necessarily broad knowledge in their respective technical areas. In order to solve the problems identified above, we need to talk to people with different technical backgrounds and learn from them.
PhD students do not often have a broad network of people that they can go to for help on issues outside their fields. Our academic supervisors can be great resources in this respect. They help us to expand our networks, and show us where to start looking for answers.
I have found that being part of a Cooperative Research Centre (CRC) for Water Sensitive Cities has also proved useful. This CRC is a group of researchers from several different universities, from different disciplines. We collaborate with industry and government partners. Our outcomes are urban water management solutions, education and industry engagement. The goal is to make towns and cities more water sensitive. This large group of researchers and industry partners help me to better understand my research. It also improves the final results of my work.
This research is part of the CRC for Water Sensitive Cities Project C5.1 (Intelligent Urban Water Networks). It is supported by funding for post-doctoral research and a PhD top-up scholarship. The support of the Commonwealth of Australia through the Cooperative Research Centre program is acknowledged.