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Raising NbS to the level of conventional drainage solutions and beyond

Yesterday we celebrated the World Environment Day. This year’s theme focused on “Ecosystem Restoration,” highlighting the urgent need to revive our natural environments. Ecosystem restoration involves repairing and renewing ecosystems that have been degraded or destroyed, ensuring that they can once again provide the vital services on which humans and wildlife depend. This theme underscores the critical importance of reversing the damage done to our forests, wetlands, oceans, and urban green spaces. 

 Nature-based solutions are at the heart of ecosystem restoration efforts. These solutions leverage natural processes and ecosystem services to tackle environmental challenges.  Moreover, NbS are key for the re-naturing of cities contributing to sustainable urban regeneration.

Let’s discover together the importance of the NbS and the contribution of our project.

Nature-based what…?

Nature-Based Solutions (NbS) are techniques that mimic and use the processes of the natural environment to mitigate the consequences of climate change like intense droughts, water scarcity, flooding, the heat island effect (urbanised areas that experience higher temperatures than outlying zones due to the presence of grey infrastructures and the absence of green areas), and even the decline of the biodiversity by providing ecosystem services in urban areas. In particular, NBS for rainwater management, also called Sustainable Urban Drainage Systems (SUDS) or Water Sensitive Urban Design (WSUD) techniques, can contribute to solve also flooding and diffuse pollution by reducing the peak flow of the urban runoff and providing pollutants reduction, mainly by retention and degradation mechanisms.

In recent years, increasing attention has been given to the application of NbS also to increase the sustainability and resilience indicators of our cities worldwide.

OK, but do they work?

Despite the existence of many users’ catalogues, to date there was not a simplified parametric design methodology of NbS for rainwater management that helps practitioners’ technicians, utilities and decision makers to apply these techniques with the same confidence than conventional drainage techniques. To address this gap, the University of Cantabria in the framework of the D4RUNOFF project has developed a complete catalogue of urban drainage techniques and several tools to help decision makers to select the most appropriate technique or group of techniques according to the required functionality and the limiting factors and constrains at the specific location site.  Also considering their contribution to the achievement of Sustainable Development Goals (SDGs).

That´s all?

No, there is more to support the use of the NbS. This library is only the starting point of a more ambitious work, where the information summarized in the factsheets is linked with parametric design, Multi-Criteria Decision Analysis (MCDA) and Geographical Information Systems (GIS) in order to provide a prioritisation of solutions according to any specific situation that can arise in urban areas, offering a complete tool for decision makers.  From the synthesis of the information summarised in this library it can be stated that NbS provide alternative ways for dealing with stormwater management in urban areas. These techniques, apart from providing the necessary treatment in terms of water quality and quantity for runoff waters of most urban areas, also provide alternative benefits in terms of ecosystem services that are difficult to quantify, but that need to be considered in stormwater management plans.

Real impact until now

The D4RUNOFF project involves three utilities: Aqualia (Spain), VSC (Denmark) and Acque (Italy). The utilities collaborate with local, regional or national authorities that know the problems and possible solutions; together, hand in hand in this project, we will reach many communities thanks to the success of our case studies and replication experiences. For example, 18 months into the project, Acque is working to build a new NBS, SSF Wetlands (Sub-Surface Flow) in the framework of the project, resulting in an enhanced hybrid system for urban water management. This is a small step that we are sure will be a catalyst for extending the influence of the work done in D4RUNOFF in relation to stormwater management.

Authors: Sara García Argüelles & Jorge Rodriguez Hernandez (UCA)

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