Green roof runoff reduction under different substrate depths and vegetation covers: the effect of initial substrate moisture conditions and total rainfall depth

2017 ◽  
pp. 541-544
Author(s):  
K.X. Soulis ◽  
N. Ntoulas ◽  
P.A. Nektarios ◽  
G. Kargas
Keyword(s):  
Green Roof ◽  
Roof Runoff ◽  
Total Rainfall ◽  
Runoff Reduction ◽  
Initial Substrate ◽  
Rainfall Depth ◽  
Substrate Moisture ◽  
Moisture Conditions

scholarly journals Assessing the runoff retention of extensive green roofs using runoff coefficients and curve numbers and the impacts of substrate moisture

2020 ◽  
Vol 51 (4) ◽  
pp. 635-647
Author(s):  
Wen Liu ◽  
Qi Feng ◽  
Weiping Chen ◽  
Wei Wei
Keyword(s):  
Curve Number ◽  
Green Roofs ◽  
Runoff Coefficient ◽  
Rainfall Runoff ◽  
Initial Substrate ◽  
Linear Fit ◽  
Substrate Moisture ◽  
Structural Configurations ◽  
Semi Arid Region ◽  
Moisture Conditions

Abstract In this study, rainfall-runoff data of four green roofs with varying structural configurations under dry and wet substrates were analyzed to acquire the effective estimation for Runoff Coefficient (Cv) and Curve Number (CN) parameters. Results showed that for the dry and wet substrates, averaged runoff retention of vegetated green roofs varied from 34.7 to 48.5% and from 14.7 to 30.6%, that for bare green roofs was 64.9 and 35.1%, respectively. For dry and wet substrates, mean Cv of vegetated green roofs was 0.58 and 0.75, respectively. For vegetated green roofs under the wet substrate, average CN values ranged from 96 to 98, meanwhile for dry substrate, average CN varied from 93 to 97. For bare green roof, average CN was 93 for dry substrate and 97 for wet substrate. Predicted runoff using the SCS-CN method exhibited a good linear fit with the observed runoff of green roofs. A significantly positive relationship was found between initial substrate moisture and runoff coefficient as well as CNs. The drier initial substrate moisture conditions corresponded to the lower runoff coefficient and curve numbers. These results would facilitate the proper use of estimated Cv and CN values of green roofs for urban stormwater management in a semi-arid region.

Performance comparison between infiltration and non-infiltration type of structural stormwater treatment systems

2012 ◽  
Vol 66 (2) ◽  
pp. 363-369 ◽  
Author(s):  
Marla C. Maniquiz ◽  
Jiyeon Choi ◽  
Soyoung Lee ◽  
Lee-Hyung Kim
Keyword(s):  
Management Practice ◽  
Performance Comparison ◽  
Pollutant Removal ◽  
Stormwater Treatment ◽  
Storm Events ◽  
University Campus ◽  
Total Rainfall ◽  
Runoff Reduction ◽  
Rainfall Depth ◽  
Positive Correlations

The study was constructed to monitor representative inflow and outflow from infiltration and non-infiltration type best management practice (BMP) sites developed at a university campus, allowing the determination of overall performance efficiency in terms of runoff reduction and pollutant removal. Based on the monitored storm events, the runoff and discharged volume and flow rates exhibited high positive correlations with total rainfall depth (p<0.001). Findings revealed that as the total rainfall increases, the amount of volume reduction and pollutant removal decreases for both types of BMP. Infiltration BMP showed a higher ability in treatment performance especially during small storm events than non-infiltration type; however, the differences were not significant. Pollutant removal rates of infiltration type were in the range of 70–90% while between 35 and 80% for the non-infiltration type for storm events with less than 10 mm rainfall depth. Average volume reductions were 71 ± 33% and 32 ± 32% for the infiltration and non-infiltration type, respectively. The ratio of the discharge volume was significantly greater than the ratio of discharge pollutant load indicating a high potential for water quality improvement. Design recommendations were provided considering sizing and cost for on-site application of similar BMP designs in the future.

scholarly journals Influence of Temperature and Moisture Content on Thermal Performance of Green Roof Media

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2421
Author(s):  
Bohan Shao ◽  
Caterina Valeo ◽  
Phalguni Mukhopadhyaya ◽  
Jianxun He
Keyword(s):  
Thermal Conductivity ◽  
Moisture Content ◽  
Green Roof ◽  
Green Roofs ◽  
Power Functions ◽  
Thick Substrate ◽  
Different Temperatures ◽  
Test Cells ◽  
Substrate Moisture ◽  
Phase Transition Zone

The influence of moisture content on substrate thermal conductivity at different temperatures was investigated for four different commercially available substrates for green roofs. In the unfrozen state, as moisture content increased, thermal conductivity increased linearly. In the phase transition zone between +5 and −10 °C, as temperature decreased, thermal conductivity increased sharply during the transition from water to ice. When the substrate was frozen, thermal conductivity varied exponentially with substrate moisture content prior to freezing. Power functions were found between thermal conductivity and temperature. Two equally sized, green roof test cells were constructed and tested to compare various roof configurations including a bare roof, varying media thickness for a green roof, and vegetation. The results show that compared with the bare roof, there is a 75% reduction in the interior temperature’s amplitude for the green roof with 150 mm thick substrate. When a sedum mat was added, there was a 20% reduction in the amplitude of the inner temperature as compared with the cell without a sedum mat.

scholarly journals Soil and Water Conservation in Rainfed Vineyards with Common Sainfoin and Spontaneous Vegetation under Different Ground Conditions

Water ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 1058 ◽  
Author(s):  
Nahed Ben-Salem ◽  
Sara Álvarez ◽  
Manuel López-Vicente
Keyword(s):  
Water Conservation ◽  
Cover Crop ◽  
Sediment Traps ◽  
Sediment Yields ◽  
Rainfall Depth ◽  
Ephemeral Gullies ◽  
Ground Conditions ◽  
Spontaneous Vegetation ◽  
The Mean ◽  
Moisture Conditions

Soil erosion seriously affects vineyards. In this study, the influence of two vegetation covers on topsoil moisture and the effect of different physiographic conditions on runoff and sediment yields were evaluated in a rainfed vineyard formed by four fields (NE Spain) during 15 months. One field had spontaneous vegetation in the inter-row areas, and three fields had a cover crop of common sainfoin. Moisture conditions were dry and stable in the vineyards’ rows, wet and very variable in the inter-row areas and wet and very stable in the corridors. Topsoil moisture in the areas with common sainfoin was much higher than in the rows (62–70%), whereas this difference was lower with spontaneous vegetation (40%). Two runoff and sediment traps (STs) were installed in two ephemeral gullies, and 26 time-integrated surveys (TIS) were done. The mean runoff yields were 9.8 and 13.5 L TIS−1 in ST2 and ST3. Rainfall depth (12 mm) and erosivity (5.2 MJ mm ha−1 h−1) thresholds for runoff initiation were assessed. The mean turbidity was 333 (ST2) and 19 (ST3) g L−1. Changes in the canopy covers (grapevines and vegetation covers), topography and rainfall parameters explained the runoff and sediment dynamics.

scholarly journals A modelling study of the event-based retention performance of green roof under the hot-humid tropical climate in Kuching

2017 ◽  
Vol 76 (11) ◽  
pp. 2988-2999 ◽  
Author(s):  
C. T. Chai ◽  
F. J. Putuhena ◽  
O. S. Selaman
Keyword(s):  
Flash Flood ◽  
Retention Rate ◽  
Meteorological Data ◽  
Green Roof ◽  
Tropical Climate ◽  
Climatic Conditions ◽  
Retention Performance ◽  
Strong Negative Correlation ◽  
Rainfall Depth ◽  
Event Based

Abstract The influences of climate on the retention capability of green roof have been widely discussed in existing literature. However, knowledge on how the retention capability of green roof is affected by the tropical climate is limited. This paper highlights the retention performance of the green roof situated in Kuching under hot-humid tropical climatic conditions. Using the green roof water balance modelling approach, this study simulated the hourly runoff generated from a virtual green roof from November 2012 to October 2013 based on past meteorological data. The result showed that the overall retention performance was satisfactory with a mean retention rate of 72.5% from 380 analysed rainfall events but reduced to 12.0% only for the events that potentially trigger the occurrence of flash flood. By performing the Spearman rank's correlation analysis, it was found that the rainfall depth and mean rainfall intensity, individually, had a strong negative correlation with event retention rate, suggesting that the retention rate increases with decreased rainfall depth. The expected direct relationship between retention rate and antecedent dry weather period was found to be event size dependent.

scholarly journals The influence of concrete substrate moisture condition on the tensile pull-off strength of protective coatings

2018 ◽  
Vol 199 ◽  
pp. 07016
Author(s):  
Sean Kay ◽  
Hans Beushausen
Keyword(s):  
Bond Strength ◽  
Protective Coatings ◽  
Surface Coatings ◽  
Moisture Condition ◽  
Coating Application ◽  
Substrate Saturation ◽  
Coating Durability ◽  
Substrate Moisture ◽  
Moisture Conditions

A range of different surface coatings are available for the protection of concrete surfaces, typically aimed at reducing the ingress of deleterious substances into the concrete and providing adequate aesthetic appeal on patch-repaired elements. The coating systems are usually of high material quality and perform well when applied and maintained correctly. The long-term success of protective surface coatings is largely a function of application procedures. In particular, coating durability with regards to bond strength and crack resistance is dependent on the preparation of the concrete substrate prior to coating application. This research gives insight into the effects a sound, clean and profiled concrete substrate that is subjected to different moisture conditions has on coating bond strength. The influence of three different methods to precondition concrete substrates on the tensile pull-off strength of two commercial coatings, applied to substrate concrete with various strengths was investigated. The moisture condition was found to have a significant influence on the pull-off strength of the coatings, higher degrees of substrate saturation typically resulting in higher strengths. Similarly, with increasing substrate moisture content, the failure mode increasingly shifted towards substrate cohesion failure.

scholarly journals Wind drives drought responses of green roof vegetation in two substrates

2018 ◽  
Author(s):  
Arkadiusz Przybysz ◽  
Konstantin Sonkin ◽  
Arne Sæbø ◽  
Hans Martin Hanslin ◽  
Keyword(s):  
Biological Diversity ◽  
Green Roof ◽  
Green Roofs ◽  
Plant Performance ◽  
Succulent Plant ◽  
Hieracium Pilosella ◽  
Key Factor ◽  
Substrate Moisture ◽  
Species Specific ◽  
Functional And Phylogenetic Diversity

The multifunctionality and delivery of ecosystem services from green roofs is improved by biological diversity of the roof vegetation. However, the frequency and intensity of drought episodes on extensive green roofs may limit the use of non-succulent species and the potential functional and phylogenetic diversity of the vegetation. Wind accelerates water use by plants and desiccation of the green roof substrate, and may be a key factor in selection of non-succulent plant species for green roofs. In this study, we tested wind interactions with green roof substrate composition and the effects on plant and substrate water balance, overall plant performance, and wilting and survival of three non-succulent species (Plantago maritima L., Hieracium pilosella L., and Festuca rubra L.) under realistic prolonged water deficit conditions. We found that, regardless of species or substrate tested, wind accelerated drought response. Drought-stressed plants exposed to wind wilted and died earlier, mostly due to more rapid desiccation of the growth substrate (critical substrate moisture content was 6-8%). The moderate wind levels applied did not affect plant performance when not combined with drought. Species with contrasting growth forms showed similar responses to treatments, but there were some species-specific responses. This highlights the importance of including wind to increase realism when evaluating drought exposure in non-succulent green roof vegetation.

scholarly journals The influence of a green roof drainage layer on retention capacity and leakage quality

2018 ◽  
Vol 77 (12) ◽  
pp. 2886-2895 ◽  
Author(s):  
Anna Baryła ◽  
Agnieszka Karczmarczyk ◽  
Andrzej Brandyk ◽  
Agnieszka Bus
Keyword(s):  
Water Quality ◽  
Green Roof ◽  
Life Sciences ◽  
Meteorological Station ◽  
Runoff Water ◽  
Retention Capacity ◽  
Drainage Layer ◽  
Second Year ◽  
Substrate Moisture ◽  
Leachate Quality

Abstract The aim of the research was to determine the influence of the substrate and different drainage materials on retention capacity and runoff water quality from three green roof containers. Phosphates were chosen as the water quality indicator based on their potential adverse impact on water quality in urban rainwater collectors. The field experiment was conducted at the Warsaw University of Life Sciences Water Center meteorological station in years 2013–2015. In terms of precipitation, the monitoring period covered a wet (+147.1 mm), average (+42.7 mm) and dry (− 66.3 mm) year. Leakage from the containers was recorded when the substrate moisture exceeded 20% and precipitation exceeded 3.5 mm/d for washed gravel, or 5.0 mm/d for a polypropylene mat and expanded clay. Phosphates were observed in leachates from all containers, with higher values observed in the second year of monitoring. As the result of this study, it can be concluded that the polypropylene mat and aggregates create different conditions for the formation of the leachate, in both volumes and its chemistry. The drainage layer made from a polypropylene mat is the most effective in terms of rainwater retention capacity and the resulting leachate quality.

scholarly journals Hydrological Effects of Urban Green Space on Stormwater Runoff Reduction in Luohe, China

2020 ◽  
Vol 12 (16) ◽  
pp. 6599
Author(s):  
Peihao Song ◽  
Jianhui Guo ◽  
Enkai Xu ◽  
Audrey L. Mayer ◽  
Chang Liu ◽  
...  
Keyword(s):  
Green Space ◽  
Urban Green Space ◽  
Canopy Interception ◽  
Canopy Layer ◽  
Total Rainfall ◽  
Area Index ◽  
Urban Green ◽  
Runoff Reduction ◽  
Runoff Regulation ◽  
Rain Events

This paper reveals the role of urban green space (UGS) in regulating runoff and hence on urban hydrological balance. The modeling software i-Tree Hydro was used to quantify the effects of UGS on surface runoff regulation and canopy interception capacity in four simulated land-cover scenarios. The results showed that the existing UGS could mitigate 15,871,900 m3 volume of runoff (accounting for 9.85% of total runoff) and intercept approximately 9.69% of total rainfall by the vegetation canopy. UGS in midterm goal and final goal scenarios could retain about 10.74% and 10.89% of total rainfall that falls onto the canopy layer, respectively. The existing UGS in the Luohe urban area had a positive but limited contribution in runoff regulation, with similar responses in future scenarios with increased UGS coverage. UGS rainfall interception volume changed seasonally along with changing leaf area index (LAI) and precipitation, and the interception efficiency was distinctly different under various rain intensities and durations. The UGS had a relatively high interception performance under light and long duration rain events but performed poorly under heavy and short rain events due to limited surface storage capacities. Our study will assist urban planners and policy-makers regarding UGS size and functionality in future planning in Luohe, particularly regarding future runoff management and Sponge City projects.

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