Abstract

Urbanization exacerbates interconnected environmental challenges, most critically the Urban Heat Island (UHI) effect and increased flood risk. The Montreal region, with its urban island geography, is particularly vulnerable to the cumulative effects of climate change. Therefore, there is a requirement for integrated assessments that can analyze and synthesize the cumulative benefits of nature-based solutions. The current thesis fills this literature gap by quantifying the cumulative effects of large-scale green roof implementation for mitigating UHI and urban flood risk simultaneously.
The methodology integrates two analytical approaches. First, a flood risk map of the Montreal area was generated on a Geographic Information System (GIS) platform, which incorporates the Analytic Hierarchy Process (AHP) procedure, which systematically weigh the following hydrologic factors: drainage density, elevation, stream distances, and precipitation. Second, the ENVI-MET microclimate simulation software was used to calculate the microclimate effect of green roofs on a dense urban study area under normal and extreme heat conditions.
The results state significant climate resilience benefits. The microclimate model conclude that the use of green roofs can contribute to lowering pedestrian level air temperatures by up to 2.16°C on the peak summer day. Furthermore, the hydrological analysis concludes that the installation of green roofs across the whole region could yield significant changes in the levels of flood risk, with over 55% of the region showing decreased levels of flood risk. Therefore, the integration of data on projected microclimate changes and risk analysis provides clear, data-driven information for the urban planners, policymakers that green infrastructure is an essential component in making a city more resilient and sustainable.