Sizing method for stormwater harvesting tanks using daily resolution rainfall and water demand data sets

Abstract

This work presents a simplified method for rainwater harvesting (RWH) tank sizing using long day-resolution rainfall time series. This method considers heterogeneous contributing catchments and water demand flow rates. For the tank sizing, we proposed to take into account the probability to supply the water demand, as well as the most needed probable time step and their respective variabilities. The method was applied to a specific case study (Pontificia Universidad Javeriana, RHW project), with 73 years of daily-resolution rainfall information (between 1936-2010). For the analysis we used different time periods from data-set and the results were: (i) for the whole data-set 76 years: 395 m3 (28 days, probability: 78%); (ii) for the last ten years: 494 m3 (35 days, probability: 89%); (iii) for the last five years: 346 m3 (25 days, probability: 84%); (iv) for the last year: 155-198 m3 (11-14 days, probability: 89-90%). These results seem to be influenced by an evolution of rainfall depth in different selected periods, which will be studied in further researches.