Viability of Green Roofs as a Flood Mitigation Element in the Central Region of Chile

Daniel Mora-Melià,Carlos López-Aburto,Pablo Ballesteros-Pérez,Pedro Muñoz-Velasco

doi:10.3390/su10041130

Daniel Mora-Melià, Carlos López-Aburto + Show 2 more

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https://doi.org/10.3390/su10041130

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Abstract

Population increase and urban development over the last 20 years in Chile have outgrown most rainwater drainage and evacuation systems. Many cities located in the central region suffer from frequent floods in some of their sectors during winter rainfall events. In addition, the lack of green spaces in these cities leads to biodiversity loss, increasing temperatures, greater energy demands, etc. Green roofs offer a solution that can mitigate climate change by reducing the runoff in cities with extensive, highly impermeable areas. This work analyses the installation of green roofs as a potential solution to the sectorial floods suffered by many cities in central Chile. The methodology includes the identification of conflictive sectors in the city of Curicó, hydrological modelling with the Storm Water Management Model (SWMM) software, the consideration of different distributions and types of green roof surfaces, and computational simulations to determine the feasibility of green roofs for preventing floods. The results show that, for moderate rainfall events, all studied sectors could avoid flooding if at least 50% of the surrounding area had green roofs (irrespective of the type of green roof). In contrast, in the presence of strong rainfall events, only some semi-extensive and extensive green roofs covering 60% to 95% of the surrounding area, respectively, could prevent flooding.

Highlights

The growing urbanization and lack of green spaces in cities have resulted in an increase in environmental pollution that produces negative effects, such as the formation of heat islands, loss of biodiversity, atmospheric pollution, and flooding [1,2,3]
The results show that the use of green roofs in these conflictive sectors produces a considerable reduction in the surface runoff, preventing saturation of these sectors and, floods during short but very intense rainfall events
Many studies in the literature show that the installation of green roofs has a positive effect in terms of alleviating the negative effects associated with climate change

Summary

Introduction

The growing urbanization and lack of green spaces in cities have resulted in an increase in environmental pollution that produces negative effects, such as the formation of heat islands, loss of biodiversity, atmospheric pollution, and flooding [1,2,3]. The installation of green roofs falls within the possible technological solutions that can contribute to the sustainable development of cities [8,9] This type of roof has a series of benefits from a social, economic, environmental and sustainable point of view, which is why they are considered an effective element for mitigating climate change [10]. Numerous studies have shown that the lack of green spaces increases the heat island effect in urban areas [14,15], while the installation of green roofs mitigates this negative effect by decreasing the temperature [16,17] In this regard, green roofs insulate buildings from both heat and cold, thereby reducing the consumption of energy to cool or heat homes [18]. There is some research [20,21] that has measured short-term (annual) pollution reduction associated with the use of green roofs in cities such as Chicago and Toronto

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