Modelling the impact of irrigated vegetation on urban microclimate: A review

The repeated occurrence, intensity and frequency of urban heatwaves pose significant challenges to urban areas. This paper critically reviews the current state of modelling the impact of irrigated vegetation on urban microclimate. It synthesizes findings from recent publications on the subject, focusing on the methodologies, challenges, and advances in numerical models that describe thermal comfort and heat mitigation strategies. Emphasizing the need for a transdisciplinary approach, the review highlights the key thermal and water-related factors influencing urban microclimates, including aerodynamic, radiative and phase change (e.g. evapotranspiration) processes, in interplay with urban geometry, materials and vegetation, especially when irrigated on purpose. The paper categorizes existing models based on their applications, physical modelling capabilities, and spatial-temporal discretization, offering guidelines for model selection tailored to specific urban planning objectives. Additionally, it provides a detailed description of the most pertinent models, especially regarding vegetation modelling for urban areas. The review underscores the necessity of validating existing models and the need for a standardized validation method for urban climate models. Future research directions are proposed to enhance the integration of vegetation effects in urban climate models, optimize irrigation strategies, and improve the predictive accuracy of these models to support sustainable urban design and policy-making.