With the influence of global climate change, cities are facing more environmental challenges including Urban Heat Island effect and urban flooding. Urban Green Infrastructure (UGI) has been demonstrated to be a cost-effective nature-based solution that offers multiple ecosystem services to mitigate urban problems. However, few studies have explored the spatial organization of UGI on a city scale to maximize its benefits of heat mitigation in urban renewal. There is also a lack of studies that aim at quantifying and elucidating UGI benefits in runoff control for high-density subtropical cities.

This thesis is constituted by two studies that address the above gaps respectively. In the first study, we developed a spatial optimization method that combines an urban cooling model and genetic...[ Read more ]

With the influence of global climate change, cities are facing more environmental challenges including Urban Heat Island effect and urban flooding. Urban Green Infrastructure (UGI) has been demonstrated to be a cost-effective nature-based solution that offers multiple ecosystem services to mitigate urban problems. However, few studies have explored the spatial organization of UGI on a city scale to maximize its benefits of heat mitigation in urban renewal. There is also a lack of studies that aim at quantifying and elucidating UGI benefits in runoff control for high-density subtropical cities.

This thesis is constituted by two studies that address the above gaps respectively. In the first study, we developed a spatial optimization method that combines an urban cooling model and genetic algorithm to study the optimal geographical arrangement of roof greening in Kowloon, Hong Kong. It was found that with different planning objectives, the priorities of the buildings to implement green roofs vary. In the second study, we simulated different UGI implementations in a catchment of Kowloon for various rainfall events using the EPA Storm Water Management Model and compare their runoff reduction effects. The result shows that under a designed full-scale LID implementation scenario, the total runoff reduction can achieve 35%-45% and peak runoff reduction can achieve 30%-45%. The two studies help to further the understanding of UGI values and provide references for UGI planning in Hong Kong.

In the end, the thesis proposes the possible incorporation of the two studies and explores the direction to maximize the synergy benefits of UGI planning for heat and runoff mitigation.