Fig 1.
The green roof is located above a NYC Parks auto garage in the Bronx, NYC.
Fig 2.
Wet, medium moisture, and dry planting zones on the Ranaqua green roof.
Fig 3.
The green roof is located above the US Post Office’s Morgan Processing and Distribution Center in Manhattan, NYC.
Table 1.
Number of studied storm events at each green roof by size grouping and season, with seasons beginning June 21, September 21, December 21 and March 21.
Fig 4.
Seasonal box plots for different rainfall depths monitored from November 1, 2013 to December 31, 2017 at the green roofs (a) Ranaqua; (b) USPS. The letters represent statistically significant differences among seasons within a particular range of rainfall depth (two seasons that share a letter are not statistically different). * denotes groupings where Ranaqua is statistically greater than USPS, while** denotes groupings where USPS is greater than Ranaqua.
Fig 5.
Rainfall versus runoff depths monitored between November 1, 2013 and December 31, 2017 for all storms with non-zero runoff.
Characteristic Runoff Equations (CREs) are drawn as dotted lines for the green roofs (a) Ranaqua; (b) USPS. The black solid curves denote 1:1 agreement, representing hypothetical roofs where all rainfall becomes runoff.
Fig 6.
Estimated annual retention means ± standard error.
Fig 7.
Monthly potential evapotranspiration (PET) and monthly evapotranspiration (ET) from both green roofs.
Data are from December 2013 to November 2015, omitting July, 2015. Monthly rainfall from the Ranaqua weather station is drawn as a 6-month moving average in order to reduce noise from rainfall variability and more clearly demonstrate when PET and ET surpass average rainfall.
Fig 8.
Soil Moisture at the beginning of rainfall events.
Fig 9.
Ranaqua green roof during the (a) winter; (b) summer.
Table 2.
Confounding factors.