Nature-Based Solutions (NBS) are set to enhance the sustainability and the resilience of the urban systems, whereas their effective design and operational lifecycle planning require the employment of appropriate methods. The aim of this research is twofold. First, exploring the various NBS design methodologies, their main features and issues, as highlighted by a review of the current literature and practice. Second, proposing a novel methodological approach for the NBS modeling, which responds to the identified challenges.
NBS comprise technical, ecological, as well as social aspects and therefore, their modeling requires elements and functions with high levels of complexity. In particular, the diverse NBS models need to reflect the physical properties and processes, and simultaneously, they need to capture a required spectrum of measurable environmental, economic and societal impacts, according to the examined scenario and the expected cascading effects. To tackle this complexity, researchers tend to develop simplified NBS models that focus on specific ecosystem services, solution types, scales, hazards and impact dimensions. Therefore, there is a need to develop a commonly accepted NBS design methodology with a holistic and versatile modeling framework and a universal ontology.
To this end, this research proposes a three-dimensional agent-based modeling framework for the NBS design. In this approach, well-known key performance indicators are inserted into the model as variables that determine the agents’ performance during the examined disruptive events or the evolution scenarios. Specific resilience and sustainability metrics are introduced to assess the overall performance of the NBS, either as an individual entity or as an interconnected network.
The findings of this work shed light on the variety of the existing NBS design frameworks, while the proposed modeling approach offers a multi-objective and multi-dimensional framework for the NBS design, planning and management.