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Seasonality Index (SI) is commonly used to define rainfall variability within a year for a locality, which has got significant impact on the water resources planning and management. Both the longer periods of dry and wet conditions are reflected by SI value. As SI is calculated using historical rainfall data, a historical average value is represented for a locality. However, with the emerging impacts of climate change SI values based on historical data are likely to change. This paper presents expected changes in future SI values for the largest city of Australia (Sydney) based on projected future rainfall scenarios for the city. The paper further illustrates potential water savings through rainwater tanks under projected climate change scenarios using an earlier developed daily water balance model, eTank. For the simulations of potential water savings through rainwater tanks, projected daily rainfall data was collected from Australian government data portal for four stations within Sydney. Future potential rainwater savings efficiencies were correlated with the corresponding SI values. It is found that such correlation closely matches with an earlier developed correlation using past historical data, however the future water savings efficiency will be slightly lower than the past water savings efficiency. [ABSTRACT FROM AUTHOR]

In large cities, rainwater tanks are used to save mains water, but in peri-urban and rural areas, rainwater tanks are used as a sole water supply for many households, as these regions often do not have any other means of water supply. This paper investigates the performance of a rainwater harvesting system (RWHS) in peri-urban regions of Greater Sydney, Australia. Considering the daily rainfall data over the entire period of record at ten different locations, it has been found that a 5 kL tank can meet 96% to 99% of the demand for toilet and laundry use depending on the location in Greater Sydney regions. However, in the driest year, a 5 kL tank can meet 69% to 99% of toilet and laundry demand depending on the location. Based on the results of life cycle cost analysis, it has been found that a 5 kL tank has the highest benefit-cost ratio (ranging from 0.86 to 0.97) among the eight possible tank sizes examined in this study. Interestingly, for a 5 kL tank, with a combined use (i.e., toilet, laundry and irrigation), the current water price in Sydney needs to be increased by 3% to 16% to achieve a benefit-cost ratio exceeding one. A set of regression equations are developed which can be used to estimate reliability using the average annual rainfall data at any arbitrary location in the peri-urban regions of Greater Sydney. The method presented in this paper can also be applied to other Australian states and other countries to estimate water savings and reliability of a RWHS using daily rainfall data. [ABSTRACT FROM AUTHOR]

Rainwater tanks are increasingly adopted in Australia to reduce potable water demand and are perceived to reduce the volume of stormwater discharge from developments. This paper investigates the water balance of rainwater tanks, in particular the possible impacts these tanks could have in controlling the stormwater discharge volume. The study collected water quantity data from two sites in the Hawkesbury City Council area, New South Wales, Australia and utilised the collected data in a simple water balance model to assess the effectiveness of rainwater tanks in reducing the stormwater discharge volume. The results indicate that a significant reduction in discharge volume from a lot scale development can be achieved if the rainwater tank is connected to multiple enduses, but is minimal when using irrigation alone. In addition, the commonly used volumetric runoff coefficient of 0.9 was found to over-estimate the runoff from the roof areas and to thereby underestimate the available volume within the rainwater tanks for retention or detention. Also, sole reliance on the water in the rainwater tanks can make the users aware of their water use pattern and water availability, resulting in significant reductions in water use as the supply dwindles, through self imposed water restrictions. [ABSTRACT FROM AUTHOR]

Rainwater is a traditional but under-utilized water resource that has today had a resurgence due to the worldwide water crisis. This paper demonstrates the outcomes of research on the feasibility of rainwater use in high-rise residential envelopes for four Australian cities of Melbourne, Sydney, Perth and Darwin. Different climate patterns and various levels of water demand management were established for determination of storage dimensions; annual tank water use; reduction in both imported water flow and stormwater disposal; and water spillage from tanks. High level water demand management was a profoundly effective tool for reducing potable water supply, especially in combination with rainwater use. The economic feasibility of rainwater use systems were estimated; with Sydney having the shortest payback period compared to other cities either both with 3A rated appliances (8.6 years) or 5A ones installed (10.4 years). That was due to the higher and more consistent rainfall in Sydney. An outcome of this study was that Sydney was likely most suited to rainwater use, followed by Perth, Darwin, and then Melbourne. The objective of this study was to fill in the gap in estimating feasibility of rainwater use in various Australian cities. This investigation endeavors to provide assistance to water authorities and urban planners of Australian cities with the consideration of the potential of rainwater harvesting. [Copyright &y& Elsevier]

The production and distribution of a sufficient quantity of food and water of satisfactory quality is at the heart of sustainable development. At the small domestic scale, roof-harvested rainwater can make a significant contribution to food supply and distribution systems (production, handling, storage, and transportation). In this paper, we compare the potential crop production of a small garden plot using three methods of watering: (1) rainfed only with no irrigation; (2) irrigated with the ideal amount of water; and (3) rainwater tanks of various sizes installed and used to irrigate the plot. Yield was determined on the basis of the yield calculation method presented in FAO 33. It was found that yields can be increased considerably by installing a correctly managed rainwater storage system (RSS). A 3 kL RSS connected to a 120 m2 roof can increase yields in Nairobi from 40 kg to 96 kg. In Sydney, a larger roof of 200 m2 can increase yields from 66 kg to 143 kg. This study makes an important contribution to water and food security-related sustainable development goals. [ABSTRACT FROM AUTHOR]

Among the alternative water sources, rainwater harvesting is the most popular and readily useable. However, studies related to the knowledge of future sustainability of this resource and its usage are limited. In this paper, projected future rainfall data for two distinct future set of periods (2020–39 and 2080–99) are used to calculate future water savings potentials using an earlier developed daily water balance model for five different regions in Sydney, the largest city in Australia. The rainfall data is collected from four different projection tools provided by the Australian government's climate data portal. With the assumptions of average household water demand as 400 L/day, a tank size of 5000 L and a roof catchment area of 200 m2, water savings and reliabilities of water availability are calculated for future scenarios for five different locations within a broader region of Sydney. Water savings and reliabilities are then compared with the same for current average rainfall condition based on historical data for the same locations. It is found that for most of the studied cases, both in the near (2020–39) and distant (2080–99) future, water savings as well as reliabilities are expected to be decreased compared to the current average scenario. However, in the distant future, both water savings and reliabilities are expected to be increased compared to the near future scenario. Also, it is predicted that spatial variability of water savings within the selected region will increase compared to the current scenario. [ABSTRACT FROM AUTHOR]

Rainwater harvesting (RWH) has become a popular water saving and conservation means across the globe. In many cities, a pre-determined rainwater tank size is generally selected without a detail water balance modelling at the location on interest. However, to achieve maximum benefit from a RWH system at a given location, it is desirable to design the system based on the site specific conditions (e.g. local rainfall and loss characteristics) and other relevant design parameters. There have been limited studies on regionalization of RWH system, which can account for the spatial variability in rainfall, loss and water demand characteristics over a given region to provide site-specific design of RWH system. This paper presents a RWH regionalization approach to develop a set of design curves, which assist in the selection of an adequate RWH system at a given location. We use rainfall data from 159 rain gauges across the Greater Sydney region in Australia to develop and test the proposed regionalization approach. It has been found that there is a significant variation in rainfall characteristics across Greater Sydney region and that a common tank size across this region does not present an adequate solution. It has been found that a 5 kL tank can achieve a reliability (i.e. percentage of days the RWH can meet the given demand) of 31–93% for four people depending on the location in the Greater Sydney region and the types of water use. The developed regional design curves could result in increased water savings across Greater Sydney. The proposed regionalization approach can be adapted to other cities across Australia and the world which present a high rainfall gradient. • Water savings by rainwater harvesting at 159 locations in Sydney are evaluated. • Reliability of a rainwater tank is moderately correlated with mean annual rainfall. • A set of design curves is developed for Sydney to enhance rainwater harvesting. [ABSTRACT FROM AUTHOR]

Biomonitoring has been used internationally from as early as the 1970s to monitor environmental change associated with the transport of metals within airborne particulate matter. The low cost methods have allowed early detection of environmental change enabling regulatory adjustment of emissions limits and supporting emissions reductions, and the ability to monitor over large distances. However, without standardised methodology in Australia, the approach has largely been over-looked nationally as a screening tool for environment change. Media releases in Australia highlight the national significance of long-range metal migration in air. The health relevance includes South Australian regulators imposing bans on eating locally caught seafood and guidance against using rainwater tanks in Port Pirie due to contamination by atmospheric lead. The environmental relevance includes atmospheric metals from historic mining having contaminated the Tasmanian Wilderness World Heritage Area and significantly altering the natural geochemical signal of lakes. The cultural relevance includes the 2009 dust storm which made international news that ‘radioactive laced’ dust from inland mines was being deposited on Sydney. This poster reviews current international approaches to the use of lichen and moss for biomonitoring and considers limitations and benefits of the implementation of techniques in Australia. [ABSTRACT FROM AUTHOR]