Predicting rain garden performance under back-to-back rainfall conditions using stochastic life-cycle analysis

ABSTRACT

Rain garden performance is highly variable, with antecedent soil moisture playing a role in short- and long-term performance. We use a stochastic life-cycle analysis framework to evaluate how interstorm duration and back-to-back rainfall events affect the performance of a test rain garden in a clayey native soil. Our analysis uses the concept of ‘fragility’ to depict the conditional probability of failure of the rain garden under different storm magnitudes and interstorm durations. We also evaluate the probability of rain garden failure at 1–24 month intervals using a Monte Carlo-based approach. Our results show that the test rain garden is likely to fail in the case of two large (>6.5 cm) back-to-back rain events with short interstorm duration (<24 hr) in a climate representative of the U.S. Midwest. We conclude that rain gardens can function effectively in clayey native soils under a variety of storms, when designed appropriately.

KEYWORDS:

• Green infrastructure
• inter-storm duration
• stochastic life-cycle analysis

Acknowledgments

We acknowledge Mary Pat McGuire, David Grimely, and Andrew Phillips as the investigator team funded by the Illinois-Indiana Sea Grant College Program. Thanks to Gabrielle Bethke, Graduate Research Assistant at the University of Illinois at Urbana-Champaign, for her help with regression analysis and data compilation.

All data supporting our conclusions were obtained from the NOAA online data repository, or obtained by direct personal communication with W. Selbig as stated in the paper.

Author contributions

R.W. created and calibrated the SWMM model, performed the analysis, formulated the study, and wrote the manuscript. P.G. completed the formulation of the stochastic life-cycle analysis. P.G. and A.S.S. assisted with writing the manuscript. A.S.S. supervised the analysis and assisted with formulating the study.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported in part by the Illinois Water Resources Center and the Illinois-Indiana Sea Grant College Program, grant number NA18OAR4170082. Additional support for R. William was provided by a CEE Distinguished Fellowship from the University of Illinois at Urbana-Champaign and a P.E.O. Scholar Fellowship.

Notes on contributors

Reshmina William

Reshmina William was a Ph.D. student in Civil and Environmental Engineering at the University of Illinois at Urbana-Champaign; she is currently at Terra Engineering Ltd.

Paolo Gardoni

Paolo Gardoni is a Professor in Civil and Environmental Engineering at the University of Illinois at Urbana-Champaign.

Ashlynn S. Stillwell

Ashlynn S. Stillwell is an Associate Professor in Civil and Environmental Engineering at the University of Illinois at Urbana-Champaign.