scholarly journals Analysis of Stormwater Retention on Green Roofs / Badania Retencji Wód Opadowych Na Dachach Zielonych

2012 ◽  
Vol 38 (4) ◽  
pp. 3-13 ◽  
Author(s):  
Ewa Burszta-Adamiak
Keyword(s):  
Life Sciences ◽  
Green Roofs ◽  
Retention Capacity ◽  
Runoff Reduction ◽  
Science And Education ◽  
Peak Runoff ◽  
The Impact ◽  
Stormwater Retention ◽  
Maximum Runoff ◽  
Sewage Systems

Abstract This study presents the results of tests conducted in 2009 and 2010 on experimental sites installed on the roof of the Science and Education Building of the Wroclaw University of Environmental and Life Sciences. The aim of the analysis was to determine the retention capacity of green roofs and the runoff delays and peak runoff reduction during rainfall recorded in Wroclaw conditions. The research shows that green roofs allow to reduce the volume of runoff stormwater in comparison to conventional roofs, that they delay the runoff in time and influence the reduction of the maximum runoff intensity, and thus may limit the impact of stormwater on the stormwater drainage and combined sewage systems.

scholarly journals Modelling the Role of SuDS Management Trains in Minimising Flood Risk, Using MicroDrainage

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2559
Author(s):  
Craig Lashford ◽  
Susanne Charlesworth ◽  
Frank Warwick ◽  
Matthew Blackett
Keyword(s):  
Green Roofs ◽  
No Net Loss ◽  
Runoff Reduction ◽  
Porous Pavement ◽  
Detention Basins ◽  
Key Barrier ◽  
The Impact ◽  
Sustainable Drainage Systems ◽  
Maximum Runoff

This novel research models the impact that commonly used sustainable drainage systems (SuDS) have on runoff, and compare this to their land take. As land take is consistently cited as a key barrier to the wider implementation of SuDS, it is essential to understand the possible runoff reduction in relation to the area they take up. SuDS management trains consisting of different combinations of detention basins, green roofs, porous pavement and swales were designed in MicroDrainage. In this study, this is modelled against the 1% Annual Exceedance Potential storm (over 30, 60, 90, 120, 360 and 720 min, under different infiltration scenarios), to determine the possible runoff reduction of each device. Detention basins were consistently the most effective regarding maximum runoff reduction for the land they take (0.419 L/s/m2), with porous pavement the second most effective, achieving 0.145 L/s/m2. As both green roofs (20.34%) and porous pavement (6.76%) account for land that would traditionally be impermeable, there is no net-loss of land compared to a traditional drainage approach. Consequently, although the modelled SuDS management train accounts for 34.86% of the total site, just 7.76% of the land is lost to SuDS, whilst managing flooding for all modelled rainfall and infiltration scenarios.

scholarly journals Analysis of the retention capacity of green roofs

2012 ◽  
Vol 16 (1) ◽  
pp. 3-9 ◽  
Author(s):  
Ewa Burszta-Adamiak
Keyword(s):  
Urban Areas ◽  
Soil Surface ◽  
Green Roofs ◽  
Retention Capacity ◽  
Local Conditions ◽  
Rainfall Events ◽  
Runoff Reduction ◽  
Education Centre ◽  
Peak Runoff ◽  
Rain Events

Abstract Green roofs are one of the modern solutions used to achieve sustainable stormwater management in urban areas. These structures are still more often designed for newly constructed buildings in Poland, based on the observations of changes in urban areas that result in the increased sealing of soil surface and thus in the limitation of natural stormwater infiltration and retention sites. In spite of a growing interest in green roofs, the data related to their retention capacity in Polish conditions is still insufficient. This study presents the results of the author’s tests, conducted in the years 2009-2010 on experimental sites located on the roof of the Science and Education Centre building of the University of Environmental and Life Sciences in Wrocław. The aim of these tests was to determine the retention capabilities of green roofs and the runoff delay and peak runoff reduction during rainfall events recorded in local conditions. The results show that green roofs can play a significant role in the reduction of total outflow volume of stormwater falling on their surface. Multi-layered structure of green roofs contribute also to a slowdown in the outflow of stormwater and to reduction in the peak runoff volume in comparison to the maximum recorded intensity of rainfall. Mean retention for 153 analysed rainfall events amounted from 82.5% to 85.7% for green roofs. In the case of rain events up to 1 mm a day, the retention for green roofs reached nearly 100%.

scholarly journals Impact of Urbanization on Stormwater Runoff from a Small Urban Catchment: Gdańsk Małomiejska Basin Case Study

2014 ◽  
Vol 61 (3-4) ◽  
pp. 141-162 ◽  
Author(s):  
Borys Olechnowicz ◽  
Katarzyna Weinerowska-Bords
Keyword(s):  
Stormwater Management ◽  
Overland Flow ◽  
System Development ◽  
Drainage System ◽  
Wave Model ◽  
Green Roofs ◽  
Army Corps ◽  
Peak Time ◽  
Runoff Reduction ◽  
The Impact

AbstractThis paper deals with the impact of different forms of urbanization on the basin outflow. The influence of changes in land cover/use, drainage system development, reservoirs, and alternative ways of stormwater management (green roofs, permeable pavements) on basin runoff was presented in the case of a small urban basin in Gdansk (Poland). Seven variants of area development (in the period of 2000-2012) - three historical and four hypothetical - were analyzed. In each case, runoff calculations for three rainfall scenarios were carried out by means of the Hydrologic Modeling System designed by Hydrologic Engineering Center of the U.S. Army Corps of Engineers (HEC-HMS). The Soil Conservation Service (SCS) Curve Number (CN) method was used for calculations of effective rainfall, the kinematic wave model for those of overland flow, and the Muskingum-Cunge model for those of channel routing. The calculations indicated that urban development had resulted in increased peak discharge and runoff volume and in decreased peak time. On the other hand, a significant reduction in peak values was observed for a relatively small decrease in the normal storage level (NSL) in reservoirs or when green roofs on commercial centers were present. The study confirmed a significant increase in runoff as a result of urbanization and a considerable runoff reduction by simple alternative ways of stormwater management.

scholarly journals Can the implementation of Low Impact Development reduce basin runoff?

2021 ◽  
Author(s):  
Xinxin Sui ◽  
Frans van de Ven
Keyword(s):  
Urban Development ◽  
Development Strategy ◽  
Regional Scale ◽  
Low Impact Development ◽  
Green Roofs ◽  
Distributed Model ◽  
Model Framework ◽  
Permeable Pavements ◽  
Peak Runoff ◽  
The Impact

Abstract. Low impact development (LID) was promoted as an alternative to conventional urban drainage methods. The effects of LID at site or urban scales have been widely evaluated. This project aims to investigate the impact of LID implementation on basin runoff at regional scale in a half urbanized catchment; especially the overlap of urban and rural sub-flows at peak times is concerned. A SUPERFLEX conceptual model framework was adapted as a semi-distributed model to simulate the rainfall-runoff relationship in the catchment for San Antonio, Texas as a case study. Scenario analyses of both urban development and LID implementation were conducted. Results show that (1) the infill urban development strategy benefits more from runoff control than the sprawl urban development strategy; (2) in non-flood season permeable pavements, bioretention cells, and vegetated swales decrease peak runoff forcefully and permeable pavements, bioretention cells, and green roofs are good at runoff volume retention; (3) contrary to the general opinion about the peak reduction effect of LID, for partly urbanized, partly rural basins and extremely wet conditions, the implementation of LID practices delays urban peak runoff and may cause stacking of rural and urban sub-flows, leading to larger basin peaks.

Towards a generic rainfall-runoff model for green roofs

2010 ◽  
Vol 62 (4) ◽  
pp. 898-905 ◽  
Author(s):  
H. Kasmin ◽  
V. R. Stovin ◽  
E. A. Hathway
Keyword(s):  
Green Roofs ◽  
Storm Event ◽  
Rainfall Runoff ◽  
Retention Capacity ◽  
Continuous Simulation ◽  
Moisture Storage ◽  
Substrate Moisture ◽  
Rainfall Runoff Model ◽  
Stormwater Retention ◽  
Runoff Model

A simple conceptual model for green roof hydrological processes is shown to reproduce monitored data, both during a storm event, and over a longer continuous simulation period. The model comprises a substrate moisture storage component and a transient storage component. Storage within the substrate represents the roof's overall stormwater retention capacity (or initial losses). Following a storm event the retention capacity is restored by evapotranspiration (ET). However, standard methods for quantifying ET do not exist. Monthly ET values are identified using four different approaches: analysis of storm event antecedent dry weather period and initial losses data; calibration of the ET parameter in a continuous simulation model; use of the Thornthwaite ET formula; and direct laboratory measurement of evaporation. There appears to be potential to adapt the Thornthwaite ET formula to provide monthly ET estimates from local temperature data. The development of a standardized laboratory test for ET will enable differences resulting from substrate characteristics to be quantified.

scholarly journals Rainwater retention effect of extensive green roofs monitored under natural rainfall events – a case study in Beijing

2018 ◽  
Vol 49 (6) ◽  
pp. 1773-1787 ◽  
Author(s):  
Yongwei Gong ◽  
Dingkun Yin ◽  
Xing Fang ◽  
Dandan Zhai ◽  
Junqi Li
Keyword(s):  
Green Roofs ◽  
Northern China ◽  
Regression Equations ◽  
Peak Reduction ◽  
Retention Capacity ◽  
Rainfall Events ◽  
Natural Rainfall ◽  
Rainfall Depth ◽  
Reduction Effect ◽  
Peak Runoff

Abstract The rainwater retention and peak flow reduction effect of seven extensive green roof (EGR) modules were studied in Beijing under natural rainfall events from May to September 2015. Monitored EGR modules had a layer of vegetation widely planted in northern China and a substrate layer with a thickness of 20 or 50 or 100 mm. The EGRs effectively retained rainwater, and regression equations of the potential retention capacity as a function of rainfall depth were developed for five EGR modules, which show that generally the capacity decreased as rainfall depth increased. The EGR with Sedum lineare Thunb and 100 mm improved soil had relatively higher average retention capacity (61.8%) than others, but all EGR modules had similar retention for an extraordinary rainfall event of 114.4 mm. For rainfall events less than 15 mm, EGR modules had 100% rainfall retention most of the time. The reduction in peak runoff rate ranged from 30.8% to 85.4%. The EGRs with Sedum lineare Thunb using 20 mm improved soil and 50 mm either pastoral soil or ultra-low weight substrates have similar peak reduction (51.3–58.2%). The EGRs with Sedum lineare Thunb have better rainfall retention and peak reduction than EGRs with Angiospermae or Sedum aizoon L.

scholarly journals Hydrological performance of dual-substrate-layer green roofs using porous inert substrates with high sorption capacities

2017 ◽  
Vol 75 (12) ◽  
pp. 2829-2840 ◽  
Author(s):  
Xiaoou Wang ◽  
Yimei Tian ◽  
Xinhua Zhao ◽  
Chenrui Peng
Keyword(s):  
Activated Charcoal ◽  
Green Roofs ◽  
Water Retention Capacity ◽  
Expanded Perlite ◽  
Retention Capacity ◽  
Substrate Layer ◽  
Rainfall Depth ◽  
Extensive Green Roofs ◽  
Stormwater Retention ◽  
Dual Substrate

Given that the common medium in existing green roofs is a single layer composed of organic and inorganic substrates, seven pilot-scale dual-substrate-layer extensive green roofs (G1–G7), which include nutrition and adsorption substrate layers, were constructed in this study. The effectiveness of porous inert substrates (activated charcoal, zeolite, pumice, lava, vermiculite and expanded perlite) used as the adsorption substrate for stormwater retention was investigated. A single-substrate-layer green roof (G8) was built for comparison with G1–G7. Despite the larger total rainfall depth (mm) of six types of simulated rains (43.2, 54.6, 76.2, 87.0, 85.2 and 86.4, respectively), the total percent retention of G1–G7 varied between 14% and 82% with an average of 43%, exhibiting better runoff-retaining capacity than G8 based on the maximum potential rainfall storage depth per unit height of adsorption substrate. Regression analysis showed that there was a logarithmic relationship between cumulative rainfall depth with non-zero runoff and stormwater retention for G1–G4 and a linear relationship for G5–G8. To enhance the water retention capacity and extend the service life of dual-substrate-layer extensive green roofs, the mixture of activated charcoal and/or pumice with expanded perlite and/or vermiculite is more suitable as the adsorption substrate than the mixture containing lava and/or zeolite.

scholarly journals Water Resilience by Centipedegrass Green Roof: A Case Study

Buildings ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 141 ◽  
Author(s):  
Shuai Hu ◽  
Lijiao Liu ◽  
Junjun Cao ◽  
Nan Chen ◽  
Zhaolong Wang
Keyword(s):  
Soil Moisture ◽  
Green Roof ◽  
Green Roofs ◽  
Saturated Soil ◽  
Water Retention Capacity ◽  
Water Runoff ◽  
Retention Capacity ◽  
Runoff Reduction ◽  
Eremochloa Ophiuroides ◽  
Rain Events

Centipedegrass (Eremochloa ophiuroides) is a low-maintenance turfgrass. The first extensive green roof of centipedegrass was established in TongZhou Civil Squares in 2014. However, storm-water-runoff reduction, water-retention capacity, and plant-water requirements by a centipedegrass green roof has not yet been defined. The soil moisture dynamics, rainwater-retention capacity, runoff reduction, and plant evapotranspiration were investigated by simulated centipedegrass green roof plots, which were constructed in the same manner as the green roofs in TongZhou Civil Squares in 2018. The results showed that the centipedegrass green roof retained 705.54 mm of rainwater, which consisted 47.4% of runoff reduction. The saturated soil moisture was 33.4 ± 0.6%; the excess rainfall over the saturated soil moisture resulted in runoff. The capacity of rainwater retention was negatively related to the soil moisture before rain events and was driven by plant evapotranspiration. Drought symptoms only occurred three times over the course of a year when the soil moisture dropped down to 10.97%. Our results indicate that the rainwater retained in the soil almost met the needs of plant consumption; a further increase of rainwater retention capacity might achieve an irrigation-free design in a centipedegrass green roof.

scholarly journals Experimental study on the selection of common adsorption substrates for extensive green roofs (EGRs)

2021 ◽  
Vol 83 (4) ◽  
pp. 961-974
Author(s):  
Chen Xu ◽  
Zaohong Liu ◽  
Guanjun Cai ◽  
Jian Zhan
Keyword(s):  
Synergistic Effects ◽  
Low Cost ◽  
Reduction Rate ◽  
Green Roofs ◽  
High Porosity ◽  
Retention Capacity ◽  
Factors Affecting ◽  
Runoff Reduction ◽  
Practical Engineering ◽  
Selection Of

Abstract Adsorption substrate in the substrate layer of an extensive green roof (EGR) is one of the most important factors affecting rainwater retention and pollution interception capacity. However, the contact time between runoff and adsorption substrate is extremely short in actual rainfall, and adsorption substrate cannot show fully rainwater retention and pollution interception capacity. So, selection of adsorption substrate based on its physical properties and theoretical adsorption capacity is unreliable. In this study, eight commonly-used adsorption substrate experimental devices are constructed with the same configuration. The delayed outflow time and runoff reduction rate of each device, along with event measurement concentration (EMC), average EMC, and cumulative pollutant quantity of SS, ammonium (NH4+), nitrate (NO3−), total nitrogen (TN), and total phosphorus (TP) in each device outflow under nine simulated rainfall events are measured and evaluated. The results indicate that vermiculite has a significant interception effect on NH4+ and TP with the advantages of low bulk density, high porosity, low cost, and a good rainfall runoff retention capacity under torrential rain and downpour events. In future practical engineering and related studies of EGR, attention should be paid to ameliorating the deficiencies of the adsorption substrates and optimizing their synergistic effects when combined with nutrient substrates.

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