Uncertainty analysis in sizing rainwater harvesting tanks in an isolated island with limited water resources

This research work focuses on the analysis of the involved uncertainty and the corresponding reliability in the sizing of rainwater harvesting systems. For this reason, an uncertainty analysis was carried out, based on 23 years of historic daily record of a station in Kimolos Island (Aegean, Greece). In order to produce the synthetic daily timeseries, a disaggregation procedure was followed. The resulting dataset was used in a rainwater harvesting tank balance model for the optimal sizing of the system. Three representative timeseries, as well as the historic one, were selected for further investigation, concerning two different scenarios. The results show that a rainwater harvesting system in the island of Kimolos does not show great reliability for small collection surface areas. For high reliability, relatively large water collection areas and lower daily water consumptions are required. A cost-benefit analysis was also conducted, which shows that a rainwater harvesting system is advantageous considering the state’s expenses for water transportation, but it is profitless for households, based on current pricing of water.