Are Biocrusts and Xerophytic Vegetation a Viable Green Roof Typology in a Mediterranean Climate? A Comparison between Differently Vegetated Green Roofs in Water Runoff and Water Quality (original) (raw)
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Wet season hydrological performance of green roofs using native species under Mediterranean climate
Ecological Engineering
Urban areas generate considerable amounts of stormwater runoff due to a high percentage of impervious surfaces. In Mediterranean climates, during winter, large volumes of rainfall over short periods of time can cause flooding. Green roofs are emerging as a tool for stormwater management under the Sustainable Urban Drainage Systems philosophy. This paper investigates the influence of rainfall patterns and types of native vegetation cover upon the rainfall-runoff relations of a green roof under a Mediterranean climate during the autumn/winter period. Test beds were installed on a rooftop in Lisbon, Portugal, incorporating a substrate layer 150 mm deep, three native vegetation covers and one non-vegetated control. Rainfall and runoff data were monitored over a 6-month autumn/winter period. Results show that the vegetated systems reduced the stormwater runoff, attenuated peak flow and delayed runoff. Overall, 69 of 184 events did not produce runoff, median retention ranged from 55 to 100% and median peak attenuation from 97 to 100%. The combination of shrubs, grasses and mosses proved to be the most effective vegetation cover. Antecedent substrate moisture and plant rainfall interception significantly influenced green roof stormwater performance for all the vegetation covers. Estimations based on the experimental green roof data, an empirical model and a detailed spatial analysis, revealed that, by greening 75% of the flat roof area of the municipality of Lisbon, approximately 166 500-224 000 m 3 of water could be retained, relieving the drainage systems and preventing floods.
Water
Different mitigation measures with vegetation have been proposed to sustainably manage rainwater, among which green roofs have demonstrated to be a valid solution in urbanized areas. Green roofs have gained interest also in Italy, but their spreading is generally based on application of ready-to-use packages, poorly tested in the specific climate conditions. A study was carried out to evaluate the green roof solution most suitable in the humid, subtropical climate context of Veneto Plain (north-eastern Italy) to reduce outflow volumes from building roofs into the urban drainage systems. Twelve different microcosm combinations of extensive green roof (three plant mixtures × two substrates × two storage/drainage layers) were tested and compared with gravel (considered as a conventional flat roof with gravel ballast). The tested drainage/storage layers were a preformed layer in recycled HDPE (PL) and an expanded perlite mineral layer (ML), and the growth medium layers were recycled bri...
Water
The capacity of green roofs to intercept rainfall, and consequently store and slow runoff resulting in a reduction in flood risk, is one of their main advantages. In this review, previous research related to the influence of green roofs on the hydrological cycle is examined with a special focus on studies for Mediterranean climate conditions (Csa and Csb according to the Köppen–Geiger climate classification). This climate is characterized by short and intense rainfall occurrences which, along with the increased area of impervious surface on Mediterranean regions, intensify the risk of flooding, particularly in the cities. The analysis covers the variables rainfall retention (R, %), runoff delay (RD, min or h), peak delay (PD, min or h), peak attenuation (PA, %), and runoff coefficient (RC, −), in relation to physical features of the green roof such as layers, substrate depth, slope, and vegetation, as well as, weather conditions, such as monthly temperature and monthly precipitation...
Urban water retention by greened roofs in temperate and tropical climate
Proceedings of the 38th …, 2001
The authors of this paper are working on the ecological effects of greened roofs. What are the ecological functions of plants growing on roofs? Are there any benefits for the inhabitants of cities? Urbanisation is increasing worldwide. As more and more urban areas are paved over, precipitation increasingly runs off directly into surface waters. This does not only change the flow of the waters but also increases the level of nutrients and contaminants led into them. By greening roofs it is possible to reduce such environmental impacts. Green roofs contribute as well to a better microclimate through evapotranspiration, filtering off dust from the air and decreasing temperatures at the rooftop and in the surrounding area. This team's aim of cooperation is to transfer knowledge of greened roofs of Central Europe to the tropics. This project is supported by DAAD (Germany) and CAPES (Brazil) since 2000. Long-term studies in Germany have pointed out water retention by greened roofs. Nowadays, water retention is one important aspect of modern ecological architecture. Retaining rainwater has a lot of further positive effects in the cities of Central Europe, i.e. to improve the urban climate. The above-mentioned scientific group pointed out some first results based on these European studies for tropical countries.
A green roof experimental site in the Mediterranean climate: the storm water quality issue
Water Science and Technology, 2013
INTRODUCTION (I) 9 th International Conference on Urban Drainage Modelling Green roofs are used to beneficially contribute to storm water management problems since they retain (volume reduction), detain (peak reduction) and slowly release storm water; Problem OVERVIEW The quality of green roof outflow depends on several factors: the building technique, the maintenance operations, the land use characteristics, etc. The behaviour of green roofs as a source or sink for pollutants is still a debated issue among researchers. The positive impact of green roof in term of water quantity issue is widely recognised and documented in the literature; 9 th International Conference on Urban Drainage Modelling
Innovative Green Roofs for Southern Europe: Biocrusts and Native Species With Low Water Use
In regions of Europe with dry hot summers, the cost of watering green roofs can outweigh the benefits. A low-water use solution is under development in the frame of the project NativeScapeGR, by associating native plant species and biocrusts to build a new type of green roof. The use of these species aims at creating valued and valuable landscape urban areas, lowering water requirements to a minimum level, without compromising aesthetic value, enhancing biodiversity and sustainability, whilst facilitating a tool for climate change adaptation.
2015
Professora Maria do Rosário Cameira agradeço a orientação permanente, inesgotável disponibilidade, amizade e todo o tempo que dedicou à minha tese de mestrado. Agradeçolhe também por tudo o que me ensinou nos últimos meses, por ter acreditado no meu empenho e capacidades e ainda pela oportunidade de desenvolver um trabalho inovador numa área do meu interesse. Agradeço à Professora Fernanda Valente, minha coorientadora, por todo o seu acompanhamento, amizade e disponibilidade e principalmente por nunca ter desistido de me transmitir todos os conhecimentos de estatística necessários para a realização do trabalho. À Professora Teresa Afonso do Paço agradeço a prontidão e simpatia com que sempre me ajudou, contribuindo para a articulação da minha tese com outras componentes do projecto NativeScapeGR, assim como pelo material fotográfico de grande qualidade que me disponibilizou. Pela disponibilidade em reunir comigo, transmitir-me a sua experiência e conhecimentos e pelo interesse demonstrado pelo meu trabalho, gostaria de agradecer à Arquitecta Paisagista Maria Matos Silva (FA-UL), à Arquitecta Sara Godinho (CML), ao Professor Pedro Arsénio (ISA) e ao Professor Miguel Águas (Lisboa E-Nova). Agradeço ainda a todos os colegas e amigos que em diversas alturas me apoiaram e se interessaram pelo trabalho que eu estava a desenvolver. Em particular agradeço à minha grande amiga Mariana Coelho por me ter ajudado a rever o trabalho. Agradeço à minha irmã, Maria do Mar, pelas vezes em que prescindiu dos seus tempos livres para me ajudar em tarefas exaustivas de inserção e análise de dados. Por último e acima de tudo agradeço aos pais, ao meu irmão, ao Pedro e a todos os familiares que me apoiaram em todos os momentos, mesmo naqueles em que a minha impaciência, cansaço e ansiedade puseram a sua tolerância à prova.
2017
Green infrastructure and in particular green roofs are crucial to meet the challenge of sustainable urbanisation fostered by the current European Research and Innovation agenda. Several guidelines were issued in the last decades in Europe for regulating design, construction and up-keep of roof greening. In particular, the actual German guidelines (FLL 2008) have been widely adopted as reference basis for green roof design and regulation worldwide, because of its exhaustiveness and proven buildingand landscaping tradition. With the aim to assess the effectiveness of green roof norms in supporting plant and soil biodiversity of different ecoregions, and particularly of the Mediterranean one, the German, the Swiss and Italian regulations are screened and discussed in this paper. The German guidelines were chosen for its traditional referential role, the Swiss norm for its peculiar biodiversity approach, the Italian one for its application on a territory with remarkably heterogeneous en...
Sustainability
Green roofs are increasingly being implemented in cities for their multiple environmental benefits. Their optimal design requires an appropriate selection of components, including substrates and plant species, to ensure local sustainability in the long term. The present study seeks to assess the runoff quality and quantity of extensive green roofs located in Bogotá (Colombia). The assessment consists of testing different substrates, designed using locally available constituents and a selection of native species. The best performing substrate mixtures, in terms of runoff volume reduction and plant establishment, were jointly evaluated with three native species (i.e., Paepalanthus alpinus, Achryrocline bogotensis and Echeveria ballsii). On average, engineered substrates presented significantly lower concentrations in several water quality parameters (electric conductivity, total phosphorus, phosphates, Total Kjeldahl Nitrogen, nitrates, nitrites, color, biological oxygen demand and ch...
Water, 2019
Green roofs can provide various benefits to urban areas, including stormwater retention. However, semi-arid regions are a challenging environment for green roofs as long dry weather periods are met with short but intense rainfall events. This requires green roofs to retain maximum volumes of stormwater, while being tolerant to minimal irrigation supplies. The objectives of this study are (i) to quantify the stormwater retention of two substrate mixtures with two plant species under natural rainfall; (ii) to assess the performance of two plant species under two levels of deficit irrigation; and (iii) to compute stormwater runoff reduction and reuse by green roofs and rooftop water harvesting systems for three standard residential plot types in urban Nicosia, Cyprus. A rooftop experiment was carried out between February 2016 and April 2017 and results were used to compute long-term performance. Average stormwater retention of the 16 test beds was 77% of the 371-mm rainfall. A survival...