Sustainable Urban Drainage Systems in Spain: Analysis of the Research on SUDS Based on Climatology

Development of a Multicriteria Scheme for the Identification of Strategic Areas for SUDS Implementation: A Case Study from Gijón, Spain

Spain has been pinpointed as one of the European countries at major risk of extreme urban events. Thus, Spanish cities pursue new urban plans to increase their resilience. In this scenario, experiences in the implementation of Sustainable Urban Drainage Systems (SUDS) have increased substantially. Nevertheless, few cities have developed a global urban strategy for SUDS, lacking, in many cases, a method to identify strategic areas to maximize their synergetic benefits. Furthermore, there is still a need for a holistic Multicriteria Decision Analysis (MCDA) framework that considers the four pillars of SUDS design. The city of Gijón, NW Spain, has been selected as a case study due to its environmental and climatic stresses. This research presents the methodology developed for this city, which aims to analyze the need for SUDS implementation throughout the identification of strategic areas. With this aim, a combination of Geographic Information System (GIS) software and the MCDA Analytical Hierarchical Process (AHP) were proposed. The results show the potential for SUDS’ implementation, according to nine criteria related to the SUDS’ design pillars. We found that the areas where the implementation of SUDS would bring the greatest functional, environmental and social benefits are mainly located in consolidated urban areas.

Low-Impact Development (LID) in Coastal Watersheds: Infiltration Swale Pollutant Transfer in Transitional Tropical/Subtropical Climates

The control of runoff pollution is one of the advantages of low-impact development (LID) or sustainable drainage systems (SUDs), such as infiltration swales. Coastal areas may have characteristics that make the implementation of drainage systems difficult, such as sandy soils, shallow aquifers and flat terrains. The presence of contaminants was investigated through sampling and analysis of runoff, soil, and groundwater from a coastal region served by an infiltration swale located in southern Brazil. The swale proved to be very efficient in controlling the site’s urban drainage volumes even under intense tropical rainfall. Contaminants of Cd, Cu, Pb, Zn, Cr, Fe, Mn and Ni were identified at concentrations above the Brazilian regulatory limit (BRL) in both runoff and groundwater. Soil concentrations were low and within the regulatory limits, except for Cd. The soil was predominantly sandy, with neutral pH and low ionic exchange capacity, characteristic of coastal regions and not very suitable for contaminant retention. Thus, this kind of structure requires improvements for its use in similar environments, such as the use of adsorbents in soil swale to increase its retention capacity.