The role of monitoring sustainable drainage systems for promoting transition towards regenerative urban built environments: a case study in the Valencian region, Spain

- Sustainable drainage systems are innovative solutions in the Mediterranean.
- Pilot sites and monitoring are needed to show their feasibility in the Mediterranean.
- Engagement contributes to smarter governance in the field of stormwater management.
- Pilot sites are drivers of transition to a new stormwater paradigm in Spain.

Sustainable drainage systems are an alternative and holistic approach to conventional urban stormwater management that use and enhance natural processes to mimic pre-development hydrology, adding a number of well-recognized, although not so often quantified benefits. However, transitions towards regenerative urban built environments that widely incorporate sustainable drainage systems are “per se” innovative journeys that encounter barriers which include the limited evidence on the performance of these systems which, in many countries, are still unknown to professionals and decision makers. A further important barrier is the frequently poor interaction among stakeholders; key items such as sustainable drainage systems provide collective benefits which also demand collective efforts. With the aim of overcoming such innovation-driven barriers, six showcase projects (including rain gardens acting as infiltration basins, swales and a green roof) to demonstrate the feasibility and suitability of sustainable drainage systems were developed and/or retrofitted in two cities of the Valencian region of Spain as a part of an European project, and their performance was monitored for a year. The data acquired, after being fully analyzed and presented to a group of key regional stakeholders, is proving to be a valuable promoter of the desired transition (for instance in influencing the support to SuDS in recent regional legislation). This paper presents detailed data on how these urban ecological drainage infrastructure elements reduce runoff (peak flows and volumes) and improve its quality, contributing to the goal of healthier and livable cities. The data show that the pilots have good hydraulic performance under a typical Mediterranean climate and also provided water quality benefits. Furthermore, it shows how engagement can contribute to smarter governance in the sense of smoothing the difficulties faced by innovation when being presented, understood, and endorsed by professionals and decision-makers in the field of stormwater management. Finally, activities undertaken in the demonstration sites monitored, show how they have been drivers of innovation and transition towards a new stormwater paradigm in Spain, serving as a reference to other urban areas in the Mediterranean.