Urban green-blue infrastructure as nature-based solutions for urban heat adaptation in Hue city, Central Vietnam – Potential impacts in contrast to citizen demands for urban greenery

Idea and Objectives: The health and well-being of urban populations are increasingly under pressure from climate change, for example, due to temperature extremes resulting in heat stress. The demand for heat mitigation is particularly high for urban areas in humid, tropical climates, as they are affected by heat stress already today, and for which a further amplification of heat stress is expected. For the case of Hue, a humid tropical Central-Vietnamese city, based on a typology of selected green-blue infrastructure elements, potential benefits for the regulation of outdoor temperature and outdoor thermal comfort are systematically virtually implemented and modelled. In order to promote acceptance of greening interventions by the public in Hue, citizen demands and preferences towards urban green elements, including potential co-benefits, are considered in this study, and in so-doing, best practices for local action shall be identified.   Background: Vietnam is a country that faces multiple challenges. Climate change is anticipated to exacerbate natural hazard risks, i.e., of flooding, storms, and prolonged periods of extreme heat, which are known to increase the risk of mortality, particularly among vulnerable groups. This is compounded by ongoing, rapid urban growth, that urgently necessitates safeguarding urban ecosystem services to facilitate climate change adaptation, and to support human health and well-being. Elements of the urban green-blue infrastructure are typically regarded as efficient nature-based interventions for the delivery of often multiple ecosystem services, including benefits for urban heat mitigation, i.e., the improvement of outdoor thermal comfort. Accordingly, such measures are increasingly being funded, politically recognised and implemented in Southeast Asian countries, including Vietnam. However, specifically for Vietnam, certain knowledge gaps remain with respect to the effectiveness of greening interventions for heat mitigation under local conditions, as well as in regard to ensuring the implementation of locally relevant and thus sustainable and resilient nature-based solutions.