Complexity of adaptation and mitigation measures in urban canyon – microscale modeling approach

0568772 - ÚI 2024 RIV US eng A - Abstract
Geletič, Jan - Belda, M. - Bureš, Martin - Krč, Pavel - Resler, Jaroslav - Řezníček, Hynek - Krayenhoff, E. S.
Complexity of adaptation and mitigation measures in urban canyon – microscale modeling approach.
AMS 2023: 103rd Annual Meeting Program Book. Denver: AMS, 2023.
[AMS 2023: American Meteorological Society Annual Meeting /103./. 08.01.2023-12.01.2023, Denver / Online]
R&D Projects: GA TA ČR(CZ) TO01000219
Institutional support: RVO:67985807
Keywords : PALM * urban planning * biometeorology * air quality * vulnerability
OECD category: Meteorology and atmospheric sciences

ZÁKLADNÍ ÚDAJE: AMS 2023: 103rd Annual Meeting Program Book. Denver: AMS, 2023. KONFERENCE: AMS 2023: 103rd Annual Meeting Program Book. Denver: AMS, 2023. ANOTACE: Cities worldwide, specifically in times of climate change, facing increasing global temperature. Higher temperatures have a negative effect on citizens, because heat-waves episodes are still longer and more intensive. Moreover, climate change is one of the most current and probably the most difficult challenges local governments face. Although a large number of adaptation strategies and climate plans have emerged recently, many have a common result (at least in Central Europe), the simplest and economically most advantageous solution is usually represented by urban greenery, primarily planting of trees or shrubs. Very popular are the implementation of high-reflective surfaces, green roofs or green walls. Usually known prejudice is that all adaptation and mitigation measures will improve the current situation. On the other hand, modern cities are very complex - and somehow also living - (eco)systems of various relations and their interactions. As an example, greenery in urban environments is perceived as an essential element of the face of cities and its characteristics are automatically accepted by residents as positive. The negative effects of greenery in urban areas, apart from possible allergies, are practically not considered in urban planning. For example, trees negatively affect air pollution concentrations, because they significantly modify distribution of micro and local scale eddies in urban canyons. However, the impact of adaptation and mitigation measures in cities, positive and negative, should be a significant consequence of adaptation policies, as well as the associated costs of care. Many models, mostly micro-scale, analyze the potential effect of selected adaptation measures in a realistic urban environment. But the commonly used models are rarely complex enough to model air quality and thermal properties on a fine enough scale. They are typically focused on one problem only, mostly on energy-related variables (surface/air temperature, biometeorological indices or mean radiant temperature, etc.). Situation in the street canyon is more complicated, because trees change energy balance and directly affect wind velocity. Moreover, to get valid results, proper models are not a guarantee, without good quality and precise enough input data. Main purpose of this presentation is to explain and summarize the latest findings on the positive and negative effects of adaptation and mitigation measures at the street level, which were analyzed using the LES-based PALM modeling system. Selected scenarios, discussed in detail with local municipality, were considered for a typical urban environment in Dejvice, a quarter in the Czech capital, Prague, confirming the inverse effect of greenery on biometeorological versus air quality indicators (ie. improving thermal comfort may bring about an increase of air pollution concentrations). Results suggest minimal effect of green roofs or green walls on pedestrian level, despite the fact that greenery has optimal conditions. Moreover, high-reflective surfaces also significantly change the energy balance of the surface, it strongly decreases convection, which represents potential problems in streets with heavy traffic. Thanks to detailed input and output geodata it is easy to analyze all results and describe all effects of adaptation and mitigation measures in their surroundings, same as in their neighborhood. Finally, microscale modeling systems show their huge potential for evaluation of future scenarios, as could be complex developer projects and re-organization of public transport (e.g., new tunnel or highway).

Permanent Link: https://hdl.handle.net/11104/0340032