Impact of climate change on future water savings of rainwater tank in Adelaide, Australia

Climate change has been identified as one of the significant factors for alteration of weather conditions around the world. The changes in rainfall amount and temperature might have severe impact on reliability of conventional water supply system as it is totally depends on ground and/or surface water resources. To reduce the dependency on traditional water supply system, government authorities are promoting sustainable alternative technologies like rainwater harvesting system in various countries including Australia. So, It is imperative to analyze the future annual water saving efficiency of rainwater tank on the perspective of climate change as it is also depends on the amount of precipitation and its distribution throughout the year. The outcomes of such study will help rainwater tank user and policy makers on selection of appropriate rainwater tank size to fulfill their future water demand in the context of climate change. This paper presents the impact of the climate change on future water savings for Adelaide airport region, South Australia. The study shows that in year 2040, all models projected (except CSIRO RCP 8.5) annual savings for different combination of roof areas, demand and tank sizes are 4%-42% less than the observed annual savings. Similarly for year 2065, only SDSM generated rainfall data shows reduction in the annual savings by 18%-23% than historical annual savings for lower roof areas irrespective of tank size. But for the same period and higher roof areas all the model shows 6%-27% reduction in annual savings. Likewise in the year 2090, all the model generated rainfall data produced 11%-53% less annual savings for lower roof areas but for the higher roof areas, SDSM and CSIRO higher concentration pathways models only have shown 12%-36% reduction in annual savings. Overall, in the context of the climate change, rainwater tank’s efficiency for the future representative years was found lower than the historical average annual savings.