Characterisation, biophysical modelling and monetary valuation of urban nature-based solutions as a support tool for urban planning and landscape design

The recognition of nature in the resolution of societal challenges has been growing in relevance. This has been associated with the development of new concepts from science and policy such as natural capital, ecosystem services, green infrastructure, and more recently Nature-Based Solutions (NBS). NBS intends to address societal challenges in an effective and adaptive form providing economic, social, and environmental benefits. The overall aim of this PhD thesis is to develop an environmental and economic assessment of NBS for highly urbanised territories based on rationales and models underpinning system dynamics, urban/landscape ecology, and life cycle thinking approaches. This combined evaluation approach would help to better understand if NBS are intrinsically cost-effective or not. The aim is developed according to four specific objectives.The first objective corresponds to the characterisation of NBS in relation to urban contexts and the problematics that they can help to address or mitigate. To achieve this objective a critical review on the study of the relationship between NBS, ecosystem services (ES) and urban challenges (UC) was developed. As a main output, a graph of plausible cause-effect relationships between NBS, ES and UC is obtained. The graph represents a firs step to support sustainable urban planning, moving from problems (i.e. urban challenges) to actions (i.e. NBS) to resolutions (i.e. ES).The second objective corresponds to the definition of an adequate set of biophysical and monetary assessment methods to evaluate the value of NBS, especially in urban areas. To achieve this objective, a review of existing methods on ecosystem services valuation, life-cycle assessment, and environmental monetisation are developed. The review takes into account specific constraints such as easiness to use and availability of data. At the end, specific methods and indicators were considered and selected based on their robustness, easiness to use and data requirements.The third objective corresponds to the design of a combined evaluation framework integrating methods from life cycle assessment, system dynamics and ecosystem services that quantifies the value of NBS in biophysical and monetary units informing about the cost-effectiveness of its entire life-cycle. To achieve this objective, a conceptual framework is developed, building on the Multiscale Integrated Model of Ecosystem Services. From it, a system dynamics model of ecosystem (dis)services is developed and coupled with a life cycle assessment method. The combined evaluation is tested with a relevant NBS type (i.e. urban forest) in a case study in the metropolitan area of Madrid.The fourth objective is the development of a decision support (DDS) tool that integrates the evaluation framework as part of iterative design processes in urban planning and landscape design. The DSS intends to enhance the interrelation between science, policy and planning/design. To achieve this objective a user friendly web-based prototype DSS on NBS, called NBenefit®, is developed. The prototype DSS provides the user a simple form of quantifying the provision of multiple ES and costs over the entire life cycle (implementation, operational life, and end-of-life) of NBS.This thesis contributed to the characterisation of NBS and its environmental and economic evaluation to inform urban planning and landscape design processes, allowing decision that are more informed.