Merits, limits and preposition of coupling modelling tools for blue-green elements to enhance the design of future climate-resilient cities

This paper presents a comprehensive survey of the process-based models currently available for blue-green infrastructure for the assessment of cooling potential, stormwater and pollution control, carbon sequestration, and water provision. The assessment of the modelling tools for blue-green elements (BGEs) documents that currently there is no process-based model for the simultaneous evaluation and optimisation of multiple ecosystem services of BGEs. To evaluate coupling options, this study conducted a meta-analysis on model interoperability by assessing the model scales, drivers, overlaps, gaps, and interfaces of these models for BGEs. Model meta-analysis points out the conceptual and constructual constraints preventing easy model coupling, and thus, an integrated assessment of ecosystem services. Constraints arise due to very different disciplinary approaches from different scientific communities involved in model development, differences in the simulation of transformation and transport processes at urban interfaces relevant for BGEs, and fundamental divergences in spatial and temporal scales and time steps of existing models for single ecosystem services. In particular, the lack of vegetation models tailored for BGEs hinders current model developments towards developing a process-based tool for multiple ecosystem services, which would be able to handle nonstationary climate conditions, including feedback assessments of drought and heatwave impacts on the functioning of BGEs.