TY - JOUR

T1 - Impact of structural factors on green roof runoff – A field investigation and statistical analysis

AU - Xie, Haowen

AU - Liu, Jun

AU - Randall, Mark

N1 - Publisher Copyright: © 2022 Elsevier B.V.

PY - 2022

Y1 - 2022

N2 - Green Roofs (GRs) are a type of Blue Green Infrastructure, growing in popularity due to their ability to provide numerous benefits. Designers and modelers of GRs typically make the assumption that GRs are homogeneous, which means that for different roof areas and the same structural factors such as substrate depth and composition, they have the same runoff per unit area. Based on this assumption, the measured data from small scale GRs in the laboratory can be applied to large GRs in the field. However, this assumption of homogeneity has not been sufficiently verified. To investigate this gap, an outdoor experiment was carried out from April 25 to December 1, 2021. Thirty-six GRs were constructed following an orthogonal experimental design with four primary structural factors investigated (i.e., substrate type (ST), substrate depth (SD), plant richness (PR), and roof area (RA)). Rain and runoff data were recorded and N-way ANOVA was used to evaluate the impact of the structural factors. Results showed that there were no statistically significant interactions between the structural factors that affected the GR runoff. The order of influence of the individual parameters, determined by the F value statistical metric was: SD > RA > ST > PR. However, substrate depth was the only structural factor which significantly affected the runoff per unit area of GR. Plant richness and substrate types showed no statistically significant effect on the GR runoff. The results of this study indicate that the implicit assumption: GRs are homogeneous, is acceptable.

AB - Green Roofs (GRs) are a type of Blue Green Infrastructure, growing in popularity due to their ability to provide numerous benefits. Designers and modelers of GRs typically make the assumption that GRs are homogeneous, which means that for different roof areas and the same structural factors such as substrate depth and composition, they have the same runoff per unit area. Based on this assumption, the measured data from small scale GRs in the laboratory can be applied to large GRs in the field. However, this assumption of homogeneity has not been sufficiently verified. To investigate this gap, an outdoor experiment was carried out from April 25 to December 1, 2021. Thirty-six GRs were constructed following an orthogonal experimental design with four primary structural factors investigated (i.e., substrate type (ST), substrate depth (SD), plant richness (PR), and roof area (RA)). Rain and runoff data were recorded and N-way ANOVA was used to evaluate the impact of the structural factors. Results showed that there were no statistically significant interactions between the structural factors that affected the GR runoff. The order of influence of the individual parameters, determined by the F value statistical metric was: SD > RA > ST > PR. However, substrate depth was the only structural factor which significantly affected the runoff per unit area of GR. Plant richness and substrate types showed no statistically significant effect on the GR runoff. The results of this study indicate that the implicit assumption: GRs are homogeneous, is acceptable.

KW - Field monitoring

KW - Green Roof

KW - N-way ANOVA

KW - Roof Area

U2 - 10.1016/j.jhydrol.2022.128345

DO - 10.1016/j.jhydrol.2022.128345

M3 - Journal article

AN - SCOPUS:85138444100

VL - 613

JO - Journal of Hydrology

JF - Journal of Hydrology

SN - 0022-1694

M1 - 128345

ER -