Performance of rainwater tanks for runoff reduction under climate change scenarios: a case study in Brazil

ABSTRACT

Rainwater tanks or cisterns are a low impact development infrastructure used to control stormwater runoff and reduce water demand. However, climate change may affect its performance due to increased rainfall intensities. This study evaluates the uncertainty on the effectiveness of cisterns to reduce peak runoff under climate change in an urban watershed in Brazil. Twelve updated intensity-duration-frequency curves, based on six Global Circulation Models and two Representative Concentration Pathways (RCP 4.5 and RCP 8.5) from the Coupled Model Inter-comparison Project 5, were used to yield hyetographs for 2 h-storm events with different recurrence intervals. Peak runoff reduction ranged between 0.4% and 5.5% for RCP 4.5 and 0.4% and 6.3% for RCP 8.5. Under climate change, a reasonable runoff control could be reached if at least 20% of the buildings installed a 5 m³ cistern. Uncertainty in future climate should be addressed in rainfall-runoff modelling to guide stormwater management decisions.

KEYWORDS:

• Rainwater harvesting
• climate change
• urban runoff management
• low impact development

Acknowledgements

This work was supported by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior under Grant number 88882.344015/2019-01, the Conselho Nacional de Desenvolvimento Científico e Tecnológico and the Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico.

Disclosure statement

The authors declare no conflicts of interest.

Data availability

The data that support the findings of this study are available from the corresponding author, T.M.N.C., upon reasonable request

Additional information

Funding

This work was supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico [441457/2017-7]; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior [88887.123932/2015-00]; Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico.