Niches D2.1_Module-on-ES-Provisioning.pdf

NICHES advances scientific knowledge on restorative NBS through the application and testing of impact assessments, models and transitional governance models for improved urban drainage in five cases within and beyond Europe. The project hypothesizes and aims to demonstrate that sustainable transformations of cities based on restorative NBS which enhance water retention capacities in urban areas could widely mitigate impacts from combined sewers on aquatic ecosystems. As the urban catchment is part of a multi-owner landscape with associated stakeholder conflicts linked through teleconnections and multi-scale governance structures, the involvement of diverse stakeholders and their values from the NICHES core cities is vital to co-design the impact assessment and ES module design and to ensure maximal applicability. This deliverable describes the development of an aquatic ecosystem services module for the Rotterdam case study. In short, we build on an existing framework (Seelen et al., 2021) where ecosystem service delivery is determined based on threshold values of water quality and ecological variables. Rather than determining these variables from field-based measurements we retrieve them from an ecosystem model, PCLake+, which is widely used within the Netherlands by water management. In doing so, the ecosystem service provisioning may be estimated not only under the current conditions but also under scenarios of future conditions. We validated and exemplify its use by applying it to the waterscape of Rotterdam where we test the impact of increasingly intense rainfall events. In conclusion, the model is well suited to model changes in ES delivery due to increasing CSO events. By taking a quantitative approach to we lay the groundwork for a risk-based assessment of CSO impacts on ecosystem.