Climate change impacts on potential water savings through household rainwater tanks in Adelaide (Australia)

Abstract

This paper presents impacts of climate change on future water savings through rainwater tanks for the city of Adelaide in South Australia. Four rainfall stations within Adelaide metropolitan were selected for the current study. The projected rainfall data was generated by the Australian government applying Statistical Downscaling Modelling (SDSM) technique using observed data for the period of 1986-2005. Projected data was downloaded from the Australian government’s climate portal for three future years (2040, 2065 and 2090) and for two climate change scenarios. Projected daily rainfall data was applied to an earlier developed daily water balance model, eTank, which was widely used for the analysis of rainwater tank outcomes. Analyses were conducted for a single demand of rainwater (300 L/day) for two roof sizes (150 m2 and 300 m2) and two tank volumes (5 kL and 10 kL). It is found that potential future water savings for all the selected future years for the three selected stations are expected to reduce; considering all the variables, ranges of potential reductions for “Adelaide Airport” is 1%∼53%, for “Kent Town” is 4%∼29% and for “Happy Valley Reservoir” is 1%∼27%. For the fourth station, Edinburgh Royal Australian Air Force (RAAF), water savings are expected to increase under all the scenarios with a roof size of 150 m2. Whereas, with a roof size of 300 m2, for the same station water savings are expected to decrease under all the scenarios. The maximum potential increase in water savings is expected to be 16% (with a roof of 150 m2), while the maximum potential decrease in water savings is expected to be 23% (with a roof of 300 m2).