Forecasting urban residential water demand
Creators: name: Gato-Trinidad, Shirley
Publisher: name: RMIT University
Year: 2024

description: The city of Melbourne in Victoria, Australia has been recognised as having high quality drinking water, but like other urban cities in the world, its growing population means increasing water demand. Melbourne is also already on its eight year of dry climatic conditions and is currently experiencing a drought that forced water authorities to impose water restrictions after 20 years of unrestricted supply. The current drought, dwindling supplies and possible impact of climate change highlight the importance of making better use of this precious resource. <br><br>The Water Resources Strategy has been developed for Melbourne, which serve as the basis for the Victorian Government to set per capita consumption reduction targets of 15%, 25% and 30% by 2010, 2015 and 2020 respectively. The strategy was developed to ensure a continuation of a safe, reliable and cost effective water supply that is environmentally sustainable in the long term. This is in recognition that population growth and water consumption will eventually require additional supplies of water (Water Resources Strategy Committee for the Melbourne Area 2002). <br><br>One of the key findings of the National Land and Water Resources Audit's Australian Water Resources Assessment 2000 is the lack of detailed knowledge about the end use (Australian Water Association 2001). The 'end use' of water is a breakdown of the total household water usage in a single-family home such as toilets, showers, washing machines, taps, garden watering, etc. Water use efficiency, recycling, trading and pricing are increasingly becoming priorities and provide opportunities for development. To support and foster this shift in development emphasis, improved information on water use is essential. <br><br>Recognising the lack of understanding on end use of water and the need for improved demand forecasting models as well as the development and evaluation of conservation strategies, this research adopted a detailed investigation of water use known as end use analysis. It will improve understanding on water use particularly at end use level and develop models to forecast urban residential water demand by using the available relevant data collected by Yarra Valley Water (YVW), a retail water company in Melbourne, Australia. <br><br>This research involves the analysis of end uses of water from a number of single-family homes in Greater Melbourne, Australia which included water demand data at 1-minute and 5-second intervals from logged households collected by YVW in 2001 and 2004 respectively. The research results show how much water is being used for outdoor and indoor purposes in a residential home in Melbourne and compares the water usage before and after water restrictions as well as between winter and summer water usage. <br><br>End use models for toilet, shower, laundry, tap and cooler in the form of regression equations were developed from logging data and household survey during the February 2004 monitoring. These end use models were validated using Aug 2004 and Feb 2001 monitoring data. Based on these end use models a Residential Indoor Water Use Estimation computer program (Java Applet) and a GIS-based Residential Indoor Water Use model which are designed to run within a Web-browser either on-line or off-line were developed. The estimation computer program calculates the average total water use per household for total indoor and its major components such as shower, toilet, laundry, dishwasher and cooler. The GIS-based model estimates the average daily indoor water use for each suburb in Greater Melbourne, Australia. <br><br>A new daily time series model for East Doncaster, Melbourne, Australia was also evaluated. The daily urban residential water model depends on the postulate that total water use is made up of base use and seasonal use, where base use is characterised by the water use during winter months and seasonal use on seasonal, climatic and persistence components. Using the daily data collected by YVW for East Doncaster water supply distribution zone and the corresponding rainfall and temperature data from the Bureau of Meteorology (BOM) from 1990-2000, the base values were calculated based on lowest months of water usage in a year and were correlated with the day of the week, temperature and rainfall. Results revealed these three factors to be statistically significant and therefore, base use to be climate dependent. The seasonal water use was modelled by a series of three equations. The separation of the random component from the climatic variable resulted in a better R2 value of 86%. The model was validated using different sets of data from 2000-2001 yielding a R2 value of 88%. The 'threshold' or 'reference' temperature and rainfall were also identified. The 'threshold' or 'reference' temperature is defined as the temperature below which water use is independent of temperature and the 'threshold' or 'reference' rainfall is the rainfall above which it would no longer contribute to the reduction of daily residential water use.