Influence of substrate depth and vegetation type on temperature and water runoff mitigation by extensive green roofs: shrubs versus herbaceous plants

Abstract. Green roofs are increasingly popular measures to permanently reduce or delay storm-water runoff. The main objective of the study was to examine the potential of using machine learning (ML) to simulate runoff from green roofs to estimate their hydrological performance. Four machine learning methods, artificial neural network (ANN), M5 model tree, long short-term memory (LSTM) and k nearest neighbour (kNN), were applied to simulate storm-water runoff from 16 extensive green roofs located in four Norwegian cities across different climatic zones. The potential of these ML methods for estimating green roof retention was assessed by comparing their simulations with a proven conceptual retention model. Furthermore, the transferability of ML models between the different green roofs in the study was tested to investigate the potential of using ML models as a tool for planning and design purposes. The ML models yielded low volumetric errors that were comparable with the conceptual retention models, which indicates good performance in estimating annual retention. The ML models yielded satisfactory modelling results (NSE >0.5) in most of the roofs, which indicates an ability to estimate green roof detention. The variations in ML models' performance between the cities was larger than between the different configurations, which was attributed to the different climatic characteristics between the four cities. Transferred ML models between cities with similar rainfall events characteristics (Bergen–Sandnes, Trondheim–Oslo) could yield satisfactory modelling performance (Nash–Sutcliffe efficiency NSE >0.5 and percentage bias |PBIAS| <25 %) in most cases. However, we recommend the use of the conceptual retention model over the transferred ML models, to estimate the retention of new green roofs, as it gives more accurate volume estimates. Follow-up studies are needed to explore the potential of ML models in estimating detention from higher temporal resolution datasets.

Download Full-text

EFFECT OF SUBSTRATE DEPTH AND TYPE ON PLANT GROWTH FOR EXTENSIVE GREEN ROOFS IN A MEDITERRANEAN CLIMATE

Journal of Green Building ◽

10.3992/1943-4618.14.2.29 ◽

2019 ◽

Vol 14 (2) ◽

pp. 29-44 ◽

Cited By ~ 1

Author(s):

Mert Eksi ◽

D. Bradley Rowe

Keyword(s):

Green Roof ◽

Green Roofs ◽

Municipal Compost ◽

Sedum Acre ◽

Armeria Maritima ◽

Survival And Growth ◽

Roof Design ◽

Substrate Depth ◽

Extensive Green Roofs ◽

Better Than

Although numerous examples of green roofs can be found in Turkey, limited research has been conducted on plant material and substrate type in this climate. Both plants and substrate are very important components in green roof design, it is essential to determine the proper substrates and plants in green roof systems for domestic green roof design. Two types of growing substrates: a commercial substrate consisting of crushed brick and clay (45%), pumice (45%), and organic matter (10%), and a recycled substrate including 90% coarse pumice (10–20 mm) and municipal compost (10%), were tested in three depths of 4, 7 and 10 cm. Tested plant species included Achillea millefolium , Armeria maritima , Sedum acre and Sedum album . Overall, the commercial substrate performed better than the recycled pumice. In addition, deeper substrates promoted greater survival and growth for nearly all species tested. Either A. maritima or A. millefolium survived in the recycled pumice at any depth, whereas they did survive when grown in the commercial substrate in greater than 7 cm and 10 cm, respectively. They both likely would require supplemental irrigation to be acceptable for green roofs in Istanbul or locations with a similar climate. Both Sedum species survived in all substrate types and depths. Information gained can be utilized by green roof professionals in the Istanbul region and in other parts of the world with a similar climate.

Download Full-text

Amount of water runoff from different vegetation types on extensive green roofs: Effects of plant species, diversity and plant structure

Landscape and Urban Planning ◽

10.1016/j.landurbplan.2011.11.001 ◽

2012 ◽

Vol 104 (3-4) ◽

pp. 356-363 ◽

Cited By ~ 116

Author(s):

Ayako Nagase ◽

Nigel Dunnett

Keyword(s):

Species Diversity ◽

Plant Species ◽

Green Roofs ◽

Plant Species Diversity ◽

Water Runoff ◽

Vegetation Types ◽

Plant Structure ◽

Extensive Green Roofs

Download Full-text

Effect of substrate depth on 18 non-succulent herbaceous perennials for extensive green roofs in a region with a dry spring

Ecological Engineering ◽

10.1016/j.ecoleng.2014.07.033 ◽

2014 ◽

Vol 71 ◽

pp. 490-500 ◽

Cited By ~ 8

Author(s):

Hui Zhang ◽

Shanshan Lu ◽

Jian Wu ◽

Yi Jiang ◽

Yingmin Lu ◽

...

Keyword(s):

Green Roofs ◽

Herbaceous Perennials ◽

Substrate Depth ◽

Extensive Green Roofs

Download Full-text

Runoff reduction from extensive green roofs having different substrate depth and plant cover

Ecological Engineering ◽

10.1016/j.ecoleng.2017.01.031 ◽

2017 ◽

Vol 102 ◽

pp. 80-89 ◽

Cited By ~ 43

Author(s):

Konstantinos X. Soulis ◽

Nikolaos Ntoulas ◽

Panayiotis A. Nektarios ◽

George Kargas

Keyword(s):

Plant Cover ◽

Green Roofs ◽

Runoff Reduction ◽

Substrate Depth ◽

Extensive Green Roofs

Download Full-text

Investigating the Plant Species and Rainfall Factors on Stormwater Retention Performance of Extensive Green Roofs in Malaysia

International Journal of Engineering & Technology ◽

10.14419/ijet.v7i3.9.15279 ◽

2018 ◽

Vol 7 (3.9) ◽

pp. 71

Author(s):

Chow Ming Fai ◽

Muhammad Fadhlullah Abu Bakar ◽

Lariyah Mohd Sidek1 Wong Jee Khai

Keyword(s):

Plant Species ◽

Green Roofs ◽

Water Runoff ◽

Storm Events ◽

Native Plant ◽

Retention Performance ◽

Rainfall Characteristics ◽

Native Plant Species ◽

Extensive Green Roofs ◽

Stormwater Retention

Information on the influences of native plant species and rainfall characteristics on the stormwater retention performance of extensive green roofs in Malaysia is still scarce. More local data is still required because rainfall and runoff generation processes in tropical environment are very different from the temperate regions. This study is aimed to investigate the stormwater retention performance of native plant species in extensive green roofs with respect to different rainfall characteristics in Malaysia. Two test beds consist of pro-mixing potting soil were vegetated each with different native plant species (Axonopus Compressus (cow grass), Portulaca Grandiflora (sedum) and one test bed with no vegetation (bare ground) was prepared as a control. A total of 22 significant storm events were collected over a 3-month period from March 2016 to May 2016. The rainfall depths for monitored storm events were ranged from 4.5 mm to 63.2 mm and rainfall intensities ranged from 0.5mm/hr to 58.5 mm/hr. The results showed that sedum exhibited higher mean runoff retention percentage than grass which is 75.8% and 70.9%, respectively. Bare soil was the least effective for reducing water runoff with retention percentage of 62.6%. Overall, sedum and grass species provided 90.6% and 88.2% of cumulative rainfall retention in this study. The rainfall depth and intensity are correlated negatively with stormwater retention performance of green roofs. Meanwhile, longer dry weather period are likely to increase the water retention capacity of green roof.

Download Full-text

Green Roof Plant Responses to Different Substrate Types and Depths under Various Drought Conditions

HortTechnology ◽

10.21273/horttech.20.2.395 ◽

2010 ◽

Vol 20 (2) ◽

pp. 395-401 ◽

Cited By ~ 73

Author(s):

Christine E. Thuring ◽

Robert D. Berghage ◽

David J. Beattie

Keyword(s):

Green Roof ◽

Green Roofs ◽

Plant Responses ◽

Ice Plant ◽

Herbaceous Perennials ◽

Central Pennsylvania ◽

Drought Conditions ◽

Expanded Shale ◽

Influence Of Substrate ◽

Substrate Depth

Plants suitable for extensive green roofs must tolerate extreme rooftop conditions, and the substrates in which they grow must fulfill horticultural and structural requirements. Deeper substrates may retain more water for plants during dry periods, but will also weigh more, especially when near saturation. A study in central Pennsylvania was conducted to evaluate the influence of substrate type and depth on establishment of five green roof plants. Two stonecrops [white stonecrop (Sedum album) and tasteless stonecrop (Sedum sexangulare)], one ice plant (Delosperma nubigenum), and two herbaceous perennials [maiden pink (Dianthus deltoides) and saxifrage pink (Petrorhagia saxifraga)] were planted in three depths (30, 60, and 120 mm) of two commercially available green roof substrates (expanded shale and expanded clay). Study flats inside a plasticulture tunnel received three drought treatments (no drought, 2 weeks early drought, and 2 weeks late drought). The two stonecrops performed well under most conditions, although tasteless stonecrop was stunted by early drought. Ice plant only grew well when provided with water. When subjected to any drought, the herbaceous perennials had the fewest survivors in the expanded shale. Saxifrage pink flowered profusely wherever it survived. The study plants were most affected by substrate depth, except for maiden pink, which responded solely to drought. When subjected to early drought conditions, the herbaceous perennials did not survive in 30 mm of either substrate, or in 60 mm of expanded shale. Although the stonecrops performed well in 60 mm of substrate when subjected to drought, their performance was superior in the expanded clay compared with shale.

Download Full-text

Carabid and spider population dynamics on urban green roofs

Zoosymposia ◽

10.11646/zoosymposia.12.1.8 ◽

2018 ◽

Vol 12 (1) ◽

pp. 69-89 ◽

Cited By ~ 1

Author(s):

J. A. COLIN BERGERON ◽

JAIME PINZON ◽

JOHN R. SPENCE

Keyword(s):

Native Species ◽

Green Roofs ◽

Seasonal Distribution ◽

Dispersal Ability ◽

Urban Landscapes ◽

Pitfall Traps ◽

Native Grasslands ◽

Northern Alberta ◽

Substrate Depth ◽

Extensive Green Roofs

Green roofs are valuable ecosystems that enhance the biodiversity value of urban landscapes in northern Alberta. Using pitfall traps on green roofs and adjacent ground sites, we show that roof arthropods are characteristic of native grasslands that are threatened in Alberta. Although we found lower abundance of spiders and carabids on roofs, species richness as assessed by rarefaction did not differ between roof and nearby ground sites. Thus, arthropod communities of these extensive green roofs do not seem to be impoverished compared to ground habitats, despite differences in local environmental variables (e.g. substrate depth, surface, vertical isolation). Seasonal distribution of larval and adult captures in pitfall traps, and observation of egg sacs in spiders suggest that a number of species have established reproducing populations on these green roofs. Interestingly, carabid assemblages differed markedly in species composition between roofs and ground sites, but spider assemblages were much more similar. We explain this in relation to differences in dispersal ability between these taxa. Green roofs are likely valuable for urban conservation allowing native species characteristic of native grasslands to permeate through urban landscapes.

Download Full-text

Green Roof Substrate Type and Depth Affect the Growth of the Native Species Dianthus fruticosus Under Reduced Irrigation Regimens

HortScience ◽

10.21273/hortsci.46.8.1208 ◽

2011 ◽

Vol 46 (8) ◽

pp. 1208-1216 ◽

Cited By ~ 49

Author(s):

Panayiotis A. Nektarios ◽

Ioannis Amountzias ◽

Iro Kokkinou ◽

Nikolaos Ntoulas

Keyword(s):

Drought Stress ◽

Native Species ◽

Dry Weight ◽

Green Roofs ◽

Substrate Type ◽

Drought Period ◽

Substrate Moisture ◽

Soilless Substrate ◽

Substrate Depth ◽

Extensive Green Roofs

Extensive green roofs are a promising technology for reintroducing lost flora in degraded urban environments, but further research is needed for their application in semiarid regions. Therefore, research was undertaken to determine the effects of substrate type and depth and the amount of irrigation during a drought period on the establishment, growth, and physiology of the native species Dianthus fruticosus sub. fruticosus. Treatments included two substrate types [a soilless substrate (Pum50:Per20:C20:Z10) or a substrate with soil (S15:Pum40:Per20:C20:Z5), in which Pum = pumice; Per = perlite; C = compost; Z = clinoptinolite zeolite; and S = sandy loam soil, mixed in a volumetric proportion indicated by their subscripts], two substrate depths (7.5 cm or 15.0 cm), and two irrigation regimens during drought [15% or 30% of pan evaporation (Epan)]. Measurements included substrate characteristics such as particle size distribution, dry and saturated bulk density, water characteristic curves, and in situ determination of substrate moisture during drought stress. Plant growth was determined based on biometric measurements such as growth index (GI) and dry weight and physiological indicators such as SPAD, chlorophylla+b, and carotenoid contents. It was found that substrate moisture during drought was increased in the soil substrate compared with the soilless substrate as a result of its better water retention capacity in low tensions. Dianthus fruticosus sub. fruticosus growth was promoted by the deep substrate (15 cm) throughout the entire study, whereas substrate type and irrigation during the drought period did not have an effect. Similarly, leaf dry weight was increased in the deeper substrates, whereas shoot and root dry weights were similar in all treatments. SPAD was found to be a more sensitive method than chlorophyll and carotenoid analysis and revealed an interesting sequence of treatment influences on D. fruticosus sub. fruticosus physiology that depended on the climatic conditions and stress imposition. More specifically, during establishment, both substrate type and depth affected growth with the soil substrate and deep profiles yielding higher SPAD measurements. Soon after the initiation of drought, the deep profiles had higher SPAD values than the shallow ones, whereas in high-irrigation regimens and, to a less extent, deeper profiles provided increased SPAD values after the middle of drought imposition. Chlorophyll and carotenoid levels reduced during the drought stress period, but very limited differences were detected between treatments. It was concluded that D. fruticosus sub. fruticosus is a very promising native plant for use on extensive green roofs in the Mediterranean region, and its growth was better in a substrate depth of 15 cm. However, its growth was sufficient even with a 7.5-cm substrate depth and irrigation of 15% Epan.

Download Full-text