Comparing the hydrological performance of an irrigated native vegetation green roof with a conventional Sedum spp. green roof in New York City

Nandan H Shetty; Robert M Elliott; Mark Wang; Matthew I Palmer; Patricia J Culligan

doi:10.1371/journal.pone.0266593

Comparing the hydrological performance of an irrigated native vegetation green roof with a conventional Sedum spp. green roof in New York City

PLoS One. 2022 Apr 20;17(4):e0266593. doi: 10.1371/journal.pone.0266593. eCollection 2022.

Authors

Nandan H Shetty¹, Robert M Elliott², Mark Wang², Matthew I Palmer³, Patricia J Culligan⁴

Affiliations

¹ Department of Civil and Environmental Engineering, The Citadel, Charleston, South Carolina, United States of America.
² Department of Civil Engineering and Engineering Mechanics, Columbia University, New York, New York, United States of America.
³ Department of Ecology, Evolution, and Environmental Biology, Columbia University, New York, New York, United States of America.
⁴ Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America.

Abstract

The objective of this study was to compare the hydrological performance of an irrigated, 127 mm deep green roof, planted with vegetation native to the New York City area, to a conventional, non-irrigated, 100 mm deep green roof, planted with drought-tolerant Sedum spp. Four years of climate and runoff data from both green roofs were analyzed to determine seasonal stormwater retention. Empirical relationships between rainfall and runoff were developed for both roofs, and applied to historical rainfall data in order to compare stormwater retention values for different rainfall depths. Crop coefficients for the vegetation on each green roof were estimated using the soil moisture extraction function. This function was also used to estimate monthly evapotranspiration. Despite being irrigated, the green roof with native vegetation retained more stormwater per annum (64%) than the non-irrigated green roof planted with Sedum spp. (54%). The green roof planted with native vegetation also had approximately twice the crop coefficient (1.13) than the green roof planted with Sedum spp. (0.57), indicating that the New York City native plants transpire more stormwater than the Sedum spp. plants given certain climate and substrate moisture conditions. Overall, the results of the study indicate that, for the New York City climate region, irrigated green roofs of native vegetation have the capacity to better manage stormwater than non-irrigated green roofs planted with drought-tolerant succulents.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.
Research Support, Non-U.S. Gov't

MeSH terms

Conservation of Natural Resources / methods
Hydrology
New York City
Plants
Rain
Sedum*

Grants and funding

This work was funded, in part, by the National Science Foundation grant CMMI-1325676 (PC) (https://www.nsf.gov/), Environmental Protection Agency contract EP-15-C-000016 (PC) (https://www.epa.gov/), and South Carolina Sea Grant 2004324 (NS) (https://www.scseagrant.org/). The authors wish to thank the New York City Department of Parks & Recreation for constructing and monitoring the Ranaqua green roof through a grant from the National Fish and Wildlife Foundation and the New York State Office of the Attorney General. Any opinions, findings, and conclusions expressed in this paper are those of the authors and not meant to represent the views of any supporting institution. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.