A spatiotemporal indicator-based method to assess the drought and heat risks for urban green infrastructure

Given the significance of urban green infrastructure (UGI) and their ecosystem services (ES) towards urban climate resilience and sustainable development, a practical method to assess the drought and heat risks for UGI is needed for understanding the risks, selecting reduction alternatives and protecting the benefits of UGI. Hence, this study develops a spatiotemporal indicator-based method, based on a conceptual drought and heat risk assessment framework, which supports decision makers in analyzing and evaluating risks under changing conditions, and selecting risk-reduction alternatives. The UGI types of parks, creeks, and lakes are selected as representative UGI for this study for developing the assessment method. Subsequently, endpoints as variables of the biophysical risk system are derived considering the processes of drought and heat hazards, exposed UGI entities, ecosystem functions and ES. The biophysical endpoints such as biota, soil-water dynamics, and UGI’s cultural uses, are then translated into information with descriptors explaining their vulnerability aspects following a multi-layer approach and interpreted over three dimensions of provisioning, regulating, and cultural. The multi-layer approach states that the layers of descriptors are accompanied with layers of indicators as a mean to operationalize these characteristics. A two-stage literature review is applied to identify vulnerability indicators for the defined descriptors, whereas a lane-based approach is followed to interrelate these indicators based on their qualities we refer to as attributes. Using the attributes of the drought and heat hazards, the vulnerability indicators are linked with the hazards to derive risk indicators. By introducing these vulnerability and risk indicators, we pave the road for the analysis and evaluation of compound risks to support the decision makers in planning and managing UGI and protecting their ES under these risks.