Nature's Integration in Cities' Hydrologies, Ecologies and Societies (NICHES)

Combined sewer overflows (CSO) in cities are one of the major pollution sources for aquatic ecosystems and threats to freshwater and marine biodiversity in Europe and beyond. While sewage system renewals require large and long-term infrastructure investments, restorative nature-based solutions (NBS) in cities represent a promising approach to mitigate stormwater runoff in a cost-effective way while producing multiple co-benefits for city dwellers. As such, NICHES (Nature's Integration in Cities’ Hydrologies, Ecologies and Societies) applies a social-ecological-technical systems approach to develop a holistic understanding of the ecological, social and economic needs for and benefits of runoff mitigation using NBS. Focusing on five cities characterised by different challenges and experiences (Barcelona, Berlin, Boston, Sheffield, and Rotterdam), NICHES addresses four objectives: (1) examine ecological, social and economic impacts from CSO on aquatic ecosystems; (2) develop and run restorative urban NBS to estimate runoff mitigation potentials and their co-benefits; (3) develop integrated assessment frameworks and transition pathways that support the integration of restorative NBS within existing urban policy frameworks; and (4) effectively consider trade-offs between people’s needs across different parts of the urban SETS system, including the location of NBS implementation and the areas around water bodies receiving CSO.