Direct and indirect impacts of nature-based solutions on urban heat

14:00 Wednesday 29 May

OC157

Room S11

 

Bruno Augusto (Portugal) 1; Peter Roebeling (Portugal) 1; Sandra Rafael (Portugal) 1; Joana Ferreira (Portugal) 1; Ana Ascenso (Portugal) 1

1 - University of Aveiro

Cities are growing and becoming more densely populated. This results in changes in land use, where there is an increase in impermeable surfaces and a decrease in green spaces. These changes in the urban environment alter the ecology of the cities, which can cause effects such as urban heat islands and overall urban heating. Nature-based solutions (NBS) are considered sustainable, cost-effective and multi-purpose solutions to address these problems, although NBS may also trigger urban compaction and increase in population density. The EU Horizon 2020 project UNaLab aims to develop a robust evidence base and European framework of innovative, replicable, and locally-attuned nature-based solutions to enhance the climate and water resilience of cities.

The main objective of this study is to provide an assessment of the direct (short term) and indirect (medium to long term) impacts of nature-based solutions on urban heat fluxes, having as a case study the city of Eindhoven (The Netherlands). The aim is to provide public planners, decision makers and stakeholders with a tool to help predict the effects of implementing nature-based solutions. For this purpose, an integrated modelling approach composed of a meteorological model coupled with an urban energy balance model (WRF-SUEWS) and an hedonic pricing simulation model (SULD), was used to determine the urban cooling effect (direct impacts) and the urban compaction effect (indirect impacts), respectively.

Results show that nature-based solutions have a local cooling effect in the short term, due to an increase in green/blue spaces. In the medium to long term, nature-based solutions have an urban compaction effect due to attraction of residents from peripheral areas to attractive green/blue spaces – reducing the direct local cooling effect while resulting in an overall urban cooling effect. This study provides evidence that nature-based solutions can be used to reduce the effects of urban heating and urban sprawl, depending on the type and size of the nature-based solutions. Also, it reinforces the idea that an integrated modelling approach allows to better understand the short to long-term effects of NBS and can be used as tool for public planners and decision makers.