Heavy rainfall events increasingly overload combined sewage systems, resulting in an overflow of contaminated water into the nearby environment and threats to aquatic biodiversity. There is thus an urgent need to identify new, more sustainable solutions which are resilient in the face of climate change. Nature-based solutions (NBS) are recognised in this context as cost-effective tools to alleviate pressure during high rainfall events while producing wider societal and environmental benefits, but uptake is limited in practice due to lacking evidence. The NICHES project – Nature's Integration in Cities' Hydrologies, Ecologies and Societies – aims to fill this gap by adopting a holistic social-ecological-technical systems (SETS) approach to explore the potential of urban NBS as an alternative to the costly renewal of grey wastewater systems. Five global cities – Barcelona, Berlin, Boston, Sheffield, and Rotterdam – will be utilized to co-create knowledge and develop a shared understanding of restorative NBS that can be applied to avoid storm-water run-off and negative impacts for aquatic biodiversity.

Project objectives and activities

NICHES will demonstrate that nature-based solutions can be utilized to sustainably transform cities, both by enhancing water retention capacities in and by mitigating negative impacts from combined sewer overflow events on aquatic ecosystems.

To achieve this aim, the project concentrates on four key tasks:

1. co-create knowledge and develop a shared understanding of restorative nature-based solutions that can be applied to avoid storm-water run-off
2. examine ecological, social and economic impacts on aquatic ecosystems from combined sewage overflows and estimate mitigation potentials and co-benefits of nature-based solutions
3. develop an integrated assessment framework to consider trade-offs and synergies between people's needs across different parts of the urban SETS system
4. co-create transition pathways to integrate restorative nature-based solutions within existing policy frameworks

In doing so, NICHES will contribute to increased urban resilience to climate change and to the ambitious targets of the EU Biodiversity Strategy for 2030 and forthcoming EU Restoration Law, which are crucial to halt the ongoing decline of biodiversity in Europe.

The role of Ecologic Institute

Ecologic Institute coordinates NICHES, which is funded under BiodivERsA and Water JPI. Moreover, Ecologic Institute is leading the work package on decision-making and transitions, including a task on governance and institutional frameworks.