Stormwater Management Performance of Green Roofs

Green roofs are gaining recognition in North America as effective tools for managing stormwater runoff in urban areas. A greater understanding of how green roofs perform with respect to fundamental stormwater management criteria, such as stormwater retention and peak flow attenuation is required. This study investigated the impact that changing climates have on the retention performance of three green roofs in London, Calgary, and Halifax. It was found that Calgary (67%) has significantly better retention performance then both London (48%) and Halifax (34%). However, London retained the greatest volume of stormwater (758 mm), followed by Halifax (517 mm) then Calgary (474 mm). Further monitoring of the hydrologic response for a fourth green roof in London Ontario was conducted to identify and measure the fundamental processes of peak attenuation on a green roof. It was determined that field capacity is a quantifiable point, after which peak attenuation performance significantly decreases. Before field capacity peak attenuation is governed by capillary storage (72%) and routing (7%). After field capacity, gravity storage provides peak attenuation (22%) and drainage routing plays a larger role (11%). A predictive model was developed using Richards equation to simulate the outflow hydrographs of a green roof. Model results show that there is no significant difference from observed data for the performance metrics (ie., water storage, drainage, and peak flow rate). For the first time in green roof literature the impact of climate on retention was assessed, the processes of peak attenuation were quantified, and an accurate predictive model was presented

EVALUATING THE BENEFITS, SUSTAINABILITY, AND RESILIENCE OF GREEN INFRASTRUCTURE ON A SUSTAINABLE RESIDENTIAL HOME

With global populations becoming increasingly urbanized, green infrastructure (GI) is progressively being recognized as a sustainable approach to mitigating urban environmental problems. Unlike traditional ‘hard’ engineering approaches that historically viewed problems in isolation and solutions in singular terms, implementation of GI promises some deferment from the effects of urbanization by providing a multitude of benefits such as reduced stormwater runoff and flooding, decreased heat waves, and enlivened local environments and ecological habitats. These benefits are important considering many cities are projected to be more vulnerable to the effects of urbanization with climate change, especially as the vast amount of the global population lives in coastal urban environments. However, the diversity of GI benefits has not been fully characterized, and they are increasingly applied in residential settings. Furthermore, current research has not fully explored the beneficial role of GI in achieving sustainable and resilient communities. Using an Integrated Water: Energy Monitoring System measuring meteorological, water, and energy fluxes over two years (July 2014-June 2016) on a sustainable home in Rockville, Maryland, U.S., the following objectives were explored: (1) Examined how a sloped modular extensive green roof, constructed wetland and bioretention designed in-series affected site hydrology. Furthermore, we studied the effect of season, antecedent substrate water content, storm characteristics (size, intensity, frequency), and vegetation development (green roof only) on hydrological performance. (2) Characterized the seasonal thermal performance of the green roof (to the building and surrounding environment) relative to the cool roof. Evaluated how green roof thermal performance related to evapotranspiration, solar reflectance (albedo) and thermal conductance (U-value). Additionally, the effect of substrate water content, vegetation development, and microclimate on evapotranspiration, albedo and U-values was assessed. (3) Green roof evapotranspiration was measured and compared to values predicted with the FAO-56 Penman-Monteith model. Furthermore, the effects of substrate water content, vegetation characteristics and microclimate on evapotranspiration rates was also evaluated. (4) Finally, using emergy theory, GI sustainability and resilience relative to a gray wastewater system and natural forest was explored

Environmental assessment criteria and protocols for residential developments

Master'sMASTER OF SCIENCE (BUILDING

UNDERSTANDING THE INTERACTIONS BETWEEN VEGETATION AND HYDROLOGICAL SYSTEMS IN TROPICAL URBAN AREAS FOR SUSTAINABLE WATER RESOURCES MANAGEMENT

Ph.DDOCTOR OF PHILOSOPH

Urban Runoff Control and Sponge City Construction

The rapid urbanization, sometimes lacking adequate planning and design, has led to worsening city syndrome situations, such as urban flooding, water pollution, heat island effects, and ecologic deterioration. Sponge city construction have become the new paradigm for a sustainable urban stormwater management strategy. Deviating from the traditional rapid draining approach, the new paradigm calls for the use of natural systems, such as soil and vegetation, as part of the urban runoff control strategy. It has become a widespread focus in urban water management research and practices globally. In this Special Issue reprint, there are 13 original scientific articles that address the different related urban runoff control issues. We are happy to see that all papers presented findings characterized as innovative and methodologically new. We hope that the readers can enjoy and learn deeply about urban runoff control and sponge city construction using the published material, and we hope that sharing of the researches results with the scientific community, policymakers and stakeholders can prompt the urban runoff control and sponge city construction globally