绿色屋顶径流调控研究进展

绿色屋顶在屋顶径流调控方面发挥着重要作用,能够有效减少径流量、延缓产流时间、降低径流峰值和改善径流水质.本文从绿色屋顶的分类及界定、绿色屋顶对径流的调控机制、绿色屋顶对径流量和水质的调控作用及其影响因素等方面阐述了国内外的研究现状,并从绿色屋顶植物的选择、高效绿色屋顶构建模式筛选、绿色屋顶径流调控规律研究、绿色屋顶截流能力的价值评估、绿色屋顶径流污染物的源 汇解析及缓解措施等方面提出了绿色屋顶径流调控的研究趋势,以期为城市绿色屋顶的建设提供理论和方法支持.     

绿色屋面降雨径流水质及消减污染负荷研究

2011年5月至11月对12场降雨时段的屋面径流和干湿沉降进行采样监测,比较了屋面径流(绿色屋面和沥青屋面)、干湿总沉降和降雨中污染物的浓度和污染负荷,并运用多元统计方法分析了降雨特征对绿色屋面径流水质的影响。结果表明,从径流水质层面上分析,绿色屋面是总悬浮物(TSS)的汇,对p H值有较好的中和作用,对于总磷(TP)、溶解态铜(DCu)和溶解态锌(DZn)是非源非汇,是电导率(EC)、总氮(TN)、氨态氮(NH+4-N)、硝态氮(NO-3-N)、化学需氧量(COD)、5日生化需氧量(BOD5)和溶解态铅(DPb)的源;从污染负荷的角度分析,绿色屋面是NH+4-N、TSS和BOD5的汇,对于TN、DPb、DCu、DZn、TP和COD是非源非汇,是NO-3-N的源;与控制屋面相比,绿色屋面可以消减TSS、TP、BOD5、COD、NH+4-N、DZn和DPb的污染负荷,分别消减了90.53%、49.38%、41.31%、36.48%、35.45%、28.27%和14.20%;但是增加了NO-3-N和TN的污染负荷,分别增加了821.02%和275.48%;绿色屋面径流污染物的浓度与降雨量、降雨历时和降雨强度呈负相关关系,而与降雨间隔呈正相关关系。研究结果为绿色屋面的科学设计及正确评价绿色屋面对径流水质的影响提供依据。     

The role of vegetation in regulating stormwater runoff from green roofs in a winter rainfall climate

Extensive green roofs composed of a thin layer of growing medium topped with vegetation can significantly reduce both the timing and magnitude of stormwater runoff relative to a typical impervious roof. However, regional climatic conditions such as seasonality in rainfall and potential evapotranspiration could strongly alter the stormwater performance of green roofs. In this study we evaluate the stormwater performance of green roofs in the predominately winter rainfall climate of the U.S. Pacific Northwest. We also test whether the amount of irrigation used to maintain green roof vegetation in a seasonally dry climate such as the Pacific Northwest influences stormwater performance. We monitored stormwater performance over one year for sets of experimental roofs constructed using three designs: a conventional impervious design, a medium-only design, and a typical extensive green roof design that included vegetation. During the winter rainy season vegetation had no significant influence on stormwater retention; medium-only and vegetated roofs reduced stormwater runoff nearly identically relative to the impervious roofs. In contrast, during summer vegetated roofs retained significantly more rainfall than medium-only roofs, although this effect depended strongly on the size of the rain event. In addition, total relative retention for both roof types was significantly higher during summer than during winter. Irrigation significantly reduced summer retention capacity of both medium-only and planted roofs, but only during the largest dry season rain event. These results suggest that cool wet season climates such as the Pacific Northwest are challenging ones for green roof stormwater performance. In order to optimize stormwater benefits of green roofs, designers should create explicitly regional designs that include plant selections better matched to the specific environmental and management constraints.     

Runoff water quality from intensive and extensive vegetated roofs

Vegetated roofs are becoming a trend in urban design, among others as a tool for city greening, mitigating urban heat island effect, and lowering urban storm runoff. Additionally, pollutant removal within vegetated roofs is often expected; however, it is commonly not a design feature. This study investigated influence on runoff water quality from two full-scale vegetated roofs (an intensive from Japan and an extensive from Sweden). Results show that both extensive and intensive vegetated roofs are a sink of nitrate nitrogen and ammonium nitrogen with similar performance. The intensive vegetated roof is also a sink of total nitrogen in contrast to the extensive roof. Phosphorus release is observed from the extensive vegetated roof but not from the intensive vegetated roof; release of dissolved organic carbon and potassium is observed from both roofs. The vegetated roofs, if not retaining the metal pollutants, were generally not a significant source. The increase of average pH during rainwater passage through the intensive vegetated roof indicated rapid neutralization of the acid depositions.     

高度城市化地区屋顶绿化径流调控效益评价——以厦门岛为例

屋顶绿化的降雨径流调控效益对城市水安全与可持续发展具有重要作用,尤其是在土地资源紧缺与环境问题突出的高度城市化地区,然而目前针对城市尺度进行屋顶绿化降雨径流调控效益的研究较少。以厦门岛142 km~2的典型高度城市化地区为研究对象,采用ArcGIS与SCS-CN水文模型,研究了四种屋顶绿化实施场景在四种不同重现期(2、5、10、20年)降雨事件下各汇水区屋顶绿化的降雨径流调控效益,并依其空间分异特征制定差异化生态建设策略。结果显示,(1)平均地表径流减少率随城市屋顶绿化量的增加从0.91%增加至4.51%,随降雨强度的增加从2.86%下降到2.01%。屋顶绿化对南部城市核心区中山路商圈汇水区的地表径流削减作用最为显著,在2年重现期降雨事件和100%屋顶绿化实施场景下地表径流减少了8.84%。(2)厦门岛易积水区域主要分布在高崎机场、西北部港口、筼筜湖、五缘湾和环岛路;在四种屋顶绿化实施场景下,平均积水深度降低1.68、4.68、6.45、14.43 cm,平均积水面积减少6.11、16.89、23.29、52.06 hm~2,而随着降雨强度的增加,积水面积减少率幅度降低,屋顶绿化对中低...     

High water users can be drought tolerant: using physiological traits for green roof plant selection

Background and aims

Green roofs are often installed to reduce urban stormwater runoff. To optimally achieve this, green roof plants need to use water when available, but reduce transpiration when limited to ensure survival. Succulent species commonly planted on green roofs do not achieve this. Water availability on green roofs is analogous to natural shallow-soil habitats including rock outcrops. We aimed to determine whether granite outcrop species could improve green roof performance by evaluating water use strategies under contrasting water availability.

Methods

Physiological and morphological responses of 12 granite outcrop species with different life-forms (monocots, herbs and shrubs) and a common green roof succulent were compared in well watered (WW) and water deficit (WD) treatments.

Key results

Granite outcrop species showed a variety of water-use strategies. Unlike the green roof succulent all of the granite outcrop species showed plasticity in water use. Monocot and herb species showed high water use under WW but also high water status under WD. This was achieved by large reductions in transpiration under WD. Maintenance of water status was also related to high root mass fraction.

Conclusions

By developing a conceptual model using physiological traits we were able to select species suitable for green roofs. The ideal species for green roofs were high water users which were also drought tolerant.     

城市区域绿色屋顶普及对水量水质的影响

绿色屋顶是城市降雨径流管理的主要措施之一,为了解绿色屋顶普及对城市流域降雨径流量和径流水质的影响,本文以重庆大学虎溪流域为研究载体,评估了绿色屋顶规模化应用与流域降雨产流和径流水质的响应关系.结果表明： 在城市流域进行屋面绿化有助于消减降雨径流以及产污负荷,且屋顶绿化规模和空间分布情景影响降雨径流水质.在屋顶占城市区域总面积的比例为25%、降雨持续时间15 min、降雨强度14.8 mm·h^-1的条件下,当区域内屋顶全部绿化时,峰值降雨径流降低5.3%,降雨径流总量降低31%;总悬浮物（TSS）、总磷（TP）、总氮（TN）的污染负荷分别降低40.0%、31.6%、29.8%,峰值浓度分别降低21.0%、16.0%、-12.2%,平均浓度分别降低13.1%、0.9%、-1.7%;随屋顶绿化率的增加,TSS、TP浓度消减率有所提高,而TN浓度消减率则呈降低趋势,靠近流域总出水口进行屋面绿化,更有利于径流水质的改善.     

亚热带季风区城市典型绿化屋顶的径流削减效应

屋顶绿化能够削减暴雨径流,降低城市内涝发生频率,促进可持续雨洪管理。针对亚热带季风气候区典型绿化屋顶的全年径流削减效应,以南京为研究区,以简易型、花园型两类绿化屋顶为研究对象,基于1年现场观测数据及水量平衡方程,分析屋顶雨水的滞蓄、蒸发与径流量随季节变化规律及其关键影响因子,采用SCS-CN模型计算绿化屋面的径流曲线数(CN),并估算城市尺度大面积屋顶绿化的暴雨径流削减效果。结果显示,简易型、花园型绿化屋顶全年径流削减率分别为42%和60.7%;径流削减效应的四季排序为春季冬季秋季夏季,平均径流削减率依次为78.6%、47.5%、33.2%、32.9%(简易型)及98%、84.3%、49.5%、48.1%(花园型);土壤基质层对雨水截留起主导作用,分别占径流削减总量的52%和62%;雨量和雨强是影响径流削减效应的关键因子,与径流削减率均呈显著负相关关系(P0.01),初始土壤湿度与简易型绿化屋顶的径流削减率呈显著负相关(0.01P0.05),但与花园型的径流削减率无显著相关性;基于全年77次降雨事件的降雨量-径流量数据测算得到简易型和花园型绿化屋顶的CN值分别为92和88;若南京主城区所有建筑屋顶面积的60%实施两类绿化,则其全年径流量可分别削减2.8×10~7 m~3和4.2×10~7 m~3。以上研究结果可为城市雨洪管理和海绵城市建设提供科学依据。     

Performance of dryland and wetland plant species on extensive green roofs

Background and Aims

Green roofs are constructed ecosystems where plants perform valuable services, ameliorating the urban environment through roof temperature reductions and stormwater interception. Plant species differ in functional characteristics that alter ecosystem properties. Plant performance research on extensive green roofs has so far indicated that species adapted to dry conditions perform optimally. However, in moist, humid climates, species typical of wetter soils might have advantages over dryland species. In this study, survival, growth and the performance of thermal and stormwater capture functions of three pairs of dryland and wetland plant species were quantified using an extensive modular green roof system.

Methods

Seedlings of all six species were germinated in a greenhouse and planted into green roof modules with 6 cm of growing medium. There were 34 treatments consisting of each species in monoculture and all combinations of wet- and dryland species in a randomized block design. Performance measures were survival, vegetation cover and roof surface temperature recorded for each module over two growing seasons, water loss (an estimate of evapotranspiration) in 2007, and albedo and water capture in 2008.

Key Results

Over two seasons, dryland plants performed better than wetland plants, and increasing the number of dryland species in mixtures tended to improve functioning, although there was no clear effect of species or habitat group diversity. All species had survival rates >75 % after the first winter; however, dryland species had much greater cover, an important indicator of green roof performance. Sibbaldiopsis tridentata was the top performing species in monoculture, and was included in the best treatments.

Conclusions

Although dryland species outperformed wetland species, planting extensive green roofs with both groups decreased performance only slightly, while increasing diversity and possibly habitat value. This study provides further evidence that plant composition and diversity can influence green roof functions.     

Effect of using conventional and controlled release fertiliser on nutrient runoff from various vegetated roof systems

Extensive vegetated roofs are becoming popular as a way to improve the environmental quality of cities. As more vegetated roofs are installed, there is a need for knowledge pertaining to maintenance and impact vegetated roofs have on stormwater quality. Our study investigated nutrient runoff, substrate nutrient storage and plant uptake following fertilisation of vegetation mats, shoot-established vegetation systems and unvegetated substrate using three levels of fertiliser applied as either controlled release fertiliser (CRF), or as a combination of CRF and conventional fertiliser. Conventional fertilisers caused high nutrient concentrations in the runoff water. Concentrations decreased during the duration of the experiment but at the end of the experiment they were still higher than after fertilisation with CRF. Conventional fertiliser also increased the total nutrient runoff. Vegetation system type influenced nutrient runoff and fertilisation of old vegetation mats reduced the risk for nutrient leaching compared to fertilisation of newly established surfaces. This can be attributed to temporary storage in substrate and increased uptake by vegetation. The temporary storage of nutrients following fertilisation indicated that there might be a risk for prolonged leaching. Thus, addition of conventional fertilisers or nutrient-rich material during production can reduce stormwater quality.     

Hydrological performance of extensive green roofs in response to different rain events in a subtropical monsoon climate

Rapid urbanization transforms permeable land into developed areas with predominantly impervious surfaces, significantly increasing stormwater runoff and exacerbating the risk of pluvial flooding. Green roofs provide an attractive strategy for increasing surface permeability by mimicking pre-development hydrologic functions and mitigating flood risks in compact cities. However, the potential of this strategy has not been rigorously assessed, despite advances in global stormwater management. This is mainly due to insufficient scientific knowledge of hydrologic performance and a lack of experimental studies of rainwater-harvesting capacity under specific climatic conditions. This study evaluated the hydrologic performance of a real-scale extensive green roof (EGR) constructed in a subtropical monsoon climate in Nanjing, China. Overall, the EGR showed considerable ability to retain rainfall (mean retention ~?60%, accumulated retention ~?30%), although retention performance varied from 11% to 100% depending on the rainfall event considered, and decreased with increasing rainfall. Event-based rainfall–runoff comparisons demonstrated that the EGR retained rainwater efficiently during the early stages of a rainfall event and significantly attenuated peak runoff flows compared to bare roofs. Statistical analysis showed that total rainfall depth, rainfall duration, and substrate layer moisture influenced the overall retention most strongly, but also the percentage retention and runoff depth, highlighting the impact of substrate properties in addition to rainfall characteristics on EGR hydrologic performance. These findings provide new knowledge of and important insights into the hydrological performance of green roofs in subtropical monsoon climates, which could be used to guide EGR construction to increase landscape permeability, mitigate the risk of pluvial flooding, and enhance the climatic resilience of urban regions.

     

Brown/biodiverse roofs: a conservation action for threatened brownfields to support urban biodiversity

Despite the need to restore urban green spaces, there are rarely enough open spaces due to urban densification. Thus, rooftops of buildings, which had not previously been regarded as spaces for planting of vegetation, have been utilised as a type of open space, and green roofing has become one of the rapidly developing fields of urban ecological engineering. However, current green roof approaches each have negative aspects in terms of enhancing urban biodiversity: intensive roofs in urban areas cannot contribute a large amount of green area, and extensive roofs cannot create high-quality green areas. In this report, we outline brown/biodiverse roofing in the UK, which is a relatively new type of extensive roofing used to provide brownfield wildlife with mimic brownfields. Brownfield refers to land that was previously developed for housing or industry but has since been abandoned and recolonised by different ecological assemblages. Brownfields provide habitat conditions similar to more natural habitats, and they can help maintain populations of some rare species. From the 1980s to the present day, the UK government has set a target of building 60% of new dwellings on brownfields. One of the most successful strategies that has been employed by the third constituency in its efforts to campaign for urban biodiversity and brownfield conservation has been to compromise with developers of brownfields and to persuade them to install wildlife-friendly mitigation technologies on roofs. This is the origin of brown/biodiverse roofs, which benefit from techniques that offer diverse habitats under severe conditions of thin substrate layer.     

Digging the New York City Skyline: Soil Fungal Communities in Green Roofs and City Parks

In urban environments, green roofs provide a number of benefits, including decreased urban heat island effects and reduced energy costs for buildings. However, little research has been done on the non-plant biota associated with green roofs, which likely affect their functionality. For the current study, we evaluated whether or not green roofs planted with two native plant communities in New York City functioned as habitats for soil fungal communities, and compared fungal communities in green roof growing media to soil microbial composition in five city parks, including Central Park and the High Line. Ten replicate roofs were sampled one year after planting; three of these roofs were more intensively sampled and compared to nearby city parks. Using Illumina sequencing of the fungal ITS region we found that green roofs supported a diverse fungal community, with numerous taxa belonging to fungal groups capable of surviving in disturbed and polluted habitats. Across roofs, there was significant biogeographical clustering of fungal communities, indicating that community assembly of roof microbes across the greater New York City area is locally variable. Green roof fungal communities were compositionally distinct from city parks and only 54% of the green roof taxa were also found in the park soils. Phospholipid fatty acid analysis revealed that park soils had greater microbial biomass and higher bacterial to fungal ratios than green roof substrates. City park soils were also more enriched with heavy metals, had lower pH, and lower quantities of total bases (Ca, K, and Mg) compared to green roof substrates. While fungal communities were compositionally distinct across green roofs, they did not differentiate by plant community. Together, these results suggest that fungi living in the growing medium of green roofs may be an underestimated component of these biotic systems functioning to support some of the valued ecological services of green roofs.     

Plant Species and Functional Group Combinations Affect Green Roof Ecosystem Functions

Background

Green roofs perform ecosystem services such as summer roof temperature reduction and stormwater capture that directly contribute to lower building energy use and potential economic savings. These services are in turn related to ecosystem functions performed by the vegetation layer such as radiation reflection and transpiration, but little work has examined the role of plant species composition and diversity in improving these functions.

Methodology/Principal Findings

We used a replicated modular extensive (shallow growing- medium) green roof system planted with monocultures or mixtures containing one, three or five life-forms, to quantify two ecosystem services: summer roof cooling and water capture. We also measured the related ecosystem properties/processes of albedo, evapotranspiration, and the mean and temporal variability of aboveground biomass over four months. Mixtures containing three or five life-form groups, simultaneously optimized several green roof ecosystem functions, outperforming monocultures and single life-form groups, but there was much variation in performance depending on which life-forms were present in the three life-form mixtures. Some mixtures outperformed the best monocultures for water capture, evapotranspiration, and an index combining both water capture and temperature reductions. Combinations of tall forbs, grasses and succulents simultaneously optimized a range of ecosystem performance measures, thus the main benefit of including all three groups was not to maximize any single process but to perform a variety of functions well.

Conclusions/Significance

Ecosystem services from green roofs can be improved by planting certain life-form groups in combination, directly contributing to climate change mitigation and adaptation strategies. The strong performance by certain mixtures of life-forms, especially tall forbs, grasses and succulents, warrants further investigation into niche complementarity or facilitation as mechanisms governing biodiversity-ecosystem functioning relationships in green roof ecosystems.     

醴陵市绿色屋顶生态系统服务潜力评估及规划

近年来, 生态系统服务评估逐渐地被运用到城市绿色基础设施的规划建设当中, 发掘能提供高生态效益的绿色屋顶潜力区域是增加城市生态空间有效途径。以提供城市空气净化、雨水截留、生物栖息地、热环境调节四个方面的生态服务为目标, 借助GIS平台确定醴陵市绿色屋顶生态空间潜力区域并提出规划策略, 为醴陵市以绿色屋顶形式完善城市生态空间结构提供参考。研究表明: (1)醴陵市潜在绿色屋顶生态系统服务评估中, 有20.3 km2的区域被划分为高效益服务区域, 约占研究区域面积的63.8%。(2)建筑年龄、结构和资金是小城市建设绿色屋顶的主要限制因素, 现状建筑中, 不适宜改建的建筑约占总建筑面积46.25%, 低限制改建的建筑占15.86%。 (3)通过叠加分析, 提取了高效益区域内的低限制改建建筑, 作为醴陵市绿色屋顶生态空间潜力区域, 面积为0.53 km2。 (4) 结合醴陵市绿地系统规划, 以“生态源地-廊道-节点”为结构, 以“分期规划, 重点建设”、“空间互补, 全域网络”两大原则, 形成“五重要节点、四优先区域、五主要廊道、全域网络”的醴陵市绿色屋顶生态空间格局。所提出的潜力评估和规划策略, 不仅可以为醴陵市建设绿色屋顶、优化城市空间构架提供依据, 还可为其他小城市以绿色屋顶形式增加生态空间的规划建设提供参考。     

Portulaca grandiflora as green roof vegetation: Plant growth and phytoremediation experiments

Finding appropriate rooftop vegetation may improve the quality of runoff from green roofs. Portulaca grandiflora was examined as possible vegetation for green roofs. Green roof substrate was found to have low bulk density (360.7 kg/m³) and high water-holding capacity (49.4%), air-filled porosity (21.1%), and hydraulic conductivity (5270 mm/hour). The optimal substrate also supported the growth of P. grandiflora with biomass multiplication of 450.3% and relative growth rate of 0.038. Phytoextraction potential of P. grandiflora was evaluated using metal-spiked green roof substrate as a function of time and spiked substrate metal concentration. It was identified that P. grandiflora accumulated all metals (Al, Cd, Cr, Cu, Fe, Ni, Pb, and Zn) from metal-spiked green roof substrate. At the end of 40 days, P. grandiflora accumulated 811 ± 26.7, 87.2 ± 3.59, 416 ± 15.8, 459 ± 15.6, 746 ± 20.9, 357 ± 18.5, 565 ± 6.8, and 596 ± 24.4 mg/kg of Al, Cd, Cr, Cu, Fe, Ni, Pb and Zn, respectively. Results also indicated that spiked substrate metal concentration strongly influenced metal accumulation property of P. grandiflora with metal uptake increased and accumulation factor decreased with increase in substrate metal concentration. P. grandiflora also showed potential to translocate all the examined metals with translocation factor greater than 1 for Al, Cu, Fe, and Zn, indicating hyperaccumulation property.     

湿热地区简单式屋顶绿化的截流雨水效应

城市内涝是困扰各大城市的环境问题,其主观原因是来自迅速增加的城市不透水面.国外运用屋顶绿化作为截留雨水的措施得到广泛实践,而屋顶绿化滞留雨水能力随气候条件的变化而变化.湿热气候区具有气温高、湿度高、雨量大的气候特点,在此气候条件下探讨屋顶绿化截留雨水的效能具有重要意义.本研究以在夏季雨热同期的广州市为例,搭建3个简单式屋顶绿化测试平台,通过13个月试验期的气象观测和数据测定推算其截留雨水的效能.结果表明: 基质厚度30、50和70 mm简单式屋顶绿化的降雨滞留率分别为27.2%、30.9%和32.1%,平均峰值减少量为18.9%、26.2%和27.7%.广州市建成区面积1035.01 km²,屋顶面积约占37.3%,假设在此区域推行30 mm厚度基质的屋顶绿化,小、中、大雨的总迟滞比率分别为72.8%、22.6%和17.4%,以此推算得出可滞留雨水体积达14317×10⁴ m³,说明简单式屋顶绿化的截留雨水效应具有巨大潜力.本研究结果可为湿热气候区城市缓解城市内涝、建设海绵城市的构想提供参考.     

Dandelion diaspore dispersal: frictional anisotropy of cypselae of Taraxacum officinale enhances their interlocking with the soil

Plant and Soil - Green roofs are important novel urban ecosystems, but their shallow substrates can create plant water deficits in dry climates. Physiological approaches can improve green roof...     

Heavy metals in leachate from simulated green roof systems

The contribution of green roofs to urban water quality, either as sinks or sources of pollutants, is an open question. This study examined leaching of Cd, Fe, Ni, Pb, and Zn from simulated green roof systems that had been deployed under field conditions and naturally leached for 22 months. The objectives were to determine if Arkalyte (an expanded clay), when mixed with pine bark as a substrate, leached metals and if so, whether leaching was influenced by the depth of substrate, structural components of the green roof system, or wet/dry deposition. Leachate was collected from each system after wet deposition events in June 2007, October 2007, February 2008, and April 2008 and analyzed. The concentration of four elements routinely exceeded USEPA water quality criteria for chronic and/or acute toxicity and were therefore of possible relevance to water quality, particularly for Pb. The frequency and intensity of local wet deposition influenced the volume of leachate recovered from the systems and in some instances the corresponding metal concentration in the leachate. There were no consistent trends with respect to depth and metal concentration in the leachate, due perhaps to the confounding effects caused by leaching of metals from materials used to construct the built-in-place systems and from inputs from deposition. Further evaluation of this substrate and the structural materials is needed to determine if their use in green roof systems will improve or degrade urban water quality.     

不同气候区绿色屋顶蒸散发模拟研究

蒸散发过程决定绿色屋顶雨水滞留能力的恢复,进而影响绿色屋顶径流调控功能。基于水量平衡原理和Penman-Monteith公式,利用北京市实验绿色屋顶气象和蒸散发连续监测数据,构建并验证绿色屋顶水文过程模型,模拟分析不同气候区城市绿色屋顶蒸散发变化规律。结果表明：(1)该模型能较准确模拟绿色屋顶蒸散发量,率定和检验期的Nash-Sutcliffe效率系数分别为0.6385和0.6014,决定系数(R²)分别为0.7191和0.6168;(2)基质厚度相同的情况下,从半干旱区(兰州)、半湿润区(北京)到湿润区(武汉和广州),绿色屋顶日平均实际蒸散发量呈增加趋势;(3)增加基质厚度可提升绿色屋顶最大雨水滞留能力,进而增加绿色屋顶实际蒸散发量,但基质厚度对绿色屋顶蒸散发量的影响存在阈值,在兰州、北京、武汉和广州,当基质厚度分别超过10 cm、17 cm、24 cm和25 cm时,绿色屋顶的日平均实际蒸散发量变化不再明显。此外,不同气候区城市绿色屋顶的日平均实际蒸散发量也存在阈值,广州绿色屋顶日平均实际蒸散发量的阈值依次高于武汉、北京和兰州。本研究有望为我国不同气候区绿色屋...