Hydrological modelling of green and grey roofs in cold climate with the SWMM model

Modelling runoff reduction through implementation of green and grey roofs in urban catchments using PCSWMM

“…The first field station serves as a full-scale testing facility for rooftop stormwater management solutions at Høvringen (Figure 1, 63°26ʹ47.5"N 10°20ʹ11"E) equipped with a meteorological station, including a highresolution precipitation gauge and ultrasonic wind sensors. Data from this field station were used as input to the roof configurations, this data originates from previously published studies (Hamouz et al 2018;Hamouz and Muthanna 2019;Johannessen et al 2019). The second site is an urban hydrological research catchment at Risvollan (Figure 2, catchment outlet 63°23ʹ55.1"N 10°25ʹ22"E) established by the Norwegian University of Science and Technology (NTNU) together with the city of Trondheim and Norwegian Water Resources and Energy Directorate (NVE), used for long-term monitoring and data collection of hydraulic and hydrological processes in the urban area (Matheussen 2004;Hailegeorgis and Alfredsen 2018).…”

“…The parameters related to the Green-Ampt infiltration model (Suction head -soil capillary suction head, Conductivity -Soil saturated hydraulic conductivity and Initial deficit -initial soil moisture deficit) were adopted from a study focused on infiltration estimation using MDP infiltrometer (Becker 2016). The parameters related to the green and grey roofs were adopted from the study focusing on modelling of runoff from the green and grey roofs using the EPA's SWMM model (Hamouz and Muthanna 2019).…”

“…The vegetated green and nonvegetated grey roofs were calibrated using the EPA SWMM Green roof LID module. More information can be found in Hamouz and Muthanna (2019). It was tested how the green and grey roof implementation impacts runoff in the catchment in terms of peak flows, volume reduction, and exceedance of three thresholds (100, 50, and 25 L/s).…”

Urban stormwater characterization, control, and treatment

“…The collection of full‐scale performance data of green roofs has allowed for several research to explore modeling the long‐term behavior of full‐scale green roofs, many utilizing SWMM 5.1 (Hamouz & Muthanna, 2019; Johannessen, Hamouz, Gragne, & Muthanna, 2019; Liu & Chui, 2019). Liu and Chui (2019) utilized SWMM to compare the response of green roofs in Hong Kong, China, Beltsville MD, USA, and Sidney, NY, USA, to storms of increasing return periods.…”

“…Although the values varied between locations, average runoff reduction increased with storm return period but plateaued at storms with longer return periods (i.e., 5–10 years). SWMM was also used to model green and gray roofs in Germany (Hamouz & Muthanna, 2019). The green roof model performed well under calibration, NSE of 0.94 and volume error of 3%, but deteriorated during the validation stage which utilized long‐term continuous datasets.…”