Climate risks in cities – how flooding and heat prevention can be tackled holistically.

Human-made climate change is increasingly impacting our living conditions, destroying infrastructure and threatening lives. The recent years and months have led to unprecedented events and record-breaking temperatures, with March being the tenth month in a row being the hottest so far (Copernicus).  

Not only rising temperatures but also altered precipitation patterns pose a challenge to the existing urban environments and thus to 2/3 of the human population (REF). Cities are especially affected since they consist of mainly sealed surfaces, which enhance climate change impacts such as increased heat or intensified precipitation events due to their different characteristics as natural areas (e.g. albedo, heat capacity, infiltration). 

Within KNOWING two climate impacts are investigated comprehensively – flooding (fluvial, pluvial) and its impact on infrastructure as well as heat and its impact on health. Therefore, two urban areas (Granollers, Spain and Tallinn, Estonia) are considered. To quantify possible interventions to adapt to current and future climate change impacts, two different models are applied: PALM-4U [1] and ICM-Infoworks. PALM-4U is an urban climate model used for quantifying the impact of greening on urban heat load. ICM-infoworks is used for assessing adaptation measures to lessen pluvial flooding. As both models rely on land use, the changes planned to adapt to heat (e.g. greening and unsealing) and those for reducing flooding (retention areas, unsealing) coincide.  

Within PALM-4U interventions such as increased tree cover, implementation of recreational parks, renaturalization of rivers and building-related measures (e.g. green roofs, retrofitting) are considered. All interventions leading to increased unsealing of areas and thus infiltration, also lessen the risk of flooding and can thus be implemented within ICM-Infoworks, quantifying the impact of the same interventions on flood risk. By assessing the impact of the same interventions within two models and concerning two different climate risks (heat and flooding) the double effectiveness is accounted for, thus allowing the holistic approach of adaptation to climate change.