Nature-based solutions hierarchy (Scottish Water)

This paper outlines the implementation of a new standardised hierarchy for nature-based solutions (NbS) and non-ecosystem-based solutions (NebS) within Scottish Water. Drawing on industry guidance and global definitions from organisations such as the International Union for Conservation of Nature and European Commission, the framework addresses the need for consistent terminology and understanding across the organisation, its supply chain and its partners. The hierarchy classifies solutions into three levels: categories (e.g. surface water, wastewater), sub-disciplines (e.g. blue–green infrastructure, intelligent NbS (i-NbS)) and assets, systems and technologies (e.g. sustainable urban drainage systems, living machines, peatlands). Key contributions of the hierarchy include the integration of innovative approaches such as i-NbS, which harness artificial intelligence and robotics for adaptive system optimisation, and hybrid solutions that combine natural and engineered processes for wastewater management. Furthermore, the paper distinguishes NebS, which, while not strictly aligned with NbS definitions, provide complementary applications such as algal and mycelium technologies. The hierarchy ensures alignment across projects and stakeholders by providing clarity in definitions and terminology, improving communication and driving innovation.