Nature based solutions for fluvial flood mitigation: an integrated assessment framework

Abstract

Inland flooding along with its casualties is expected to increase. Climate change, urban expansion on floodplains, degraded ecosystems due to human interventions, lack of effective emergency flood risk management plans contribute to flood intensification and risk exposure. The heretofore flood mitigation practices seem to stop short of both mitigating flood risk and providing further economic, social, and environmental benefits. Instead, practices co-working with nature and its physical processes are constantly gaining ground. Nature-based solutions (NBS) are measures encompassing the ‘co-operation with nature’ approach; mitigating fluvial flood risk while being cost-effective, resource-efficient, and providing numerous environmental, social, and economic benefits. Current progress is working on strengthening the evidence-base of NBS projects through multiple on-going projects. Such evidence would lay the foundation for the mainstreaming and transferability of the NBS practice that will, eventually, lead to its upscaling. To this end, there is need for holistic and coherent organisation of all the NBS information and approaches acquired in practice. Therefore, several frameworks have been developed in an attempt to map the NBS design and implementation and/or evaluate them using indicators. Contribution of NBS to sustainable development has also been established since the social, economic and environmental sectors, on which NBS have an impact, constitute the so-called “triple bottom line” of the sustainability concept. Given the unequivocal link between NBS and sustainability, a growing interest recognizes the need to explore a NBS connection to the Sustainable Development Goals (SDGs), as set by the United Nations Organization. Additionally, since NBS seek to complement conventional infrastructure, their engineering characteristics should also be assessed. Therefore, this research project develops a framework for assessing the NBS performance for fluvial flood mitigation. The framework adopts an integrated approach, using indicators for evaluative and benchmarking purposes. Novel aspects of the framework are the direct link between the NBS for fluvial flood mitigation and the SDGs and the introduction of technical assessment indicators. Ultimately, the NBS framework is meant to assist experts in providing guidance for similar projects and contributing to the mainstreaming and transferability of the NBS practice. The framework was guided by a review of existing NBS assessment frameworks and methodologies, already realized NBS projects, and the UN 2030 Agenda. The assessment frameworks and methodologies worked as a starting point both for the structure and the components of the deliverable framework. Already realized NBS projects were treated as case studies calibrating the literature findings with what was applied in practice. The UN 2030 Agenda was used for developing indicators that address contribution to the SDGs. Finally, the framework was tested by applying it to an already realized NBS project, the Eddleston Water Project (different from the calibration ones), by giving the project metadata as input to the framework indicators. Overall, the framework performed well as most of its indicators are having indicative data that were found in publicly available references. Expert consultation was needed for acquiring some of the data but was kept to a limited extent as much as possible. Additionally, some overlaps between the needed data per framework indicator were observed that can probably be attributed to the scope and current state of the Eddleston project. Regarding the Eddleston project it was found that meets its initial objectives, contributes to SDGs 1, 6, 8, 9, 11, 12, 13, 15, and 17 while enhances several provisioning, regulating, cultural, and supporting ecosystem services of the Eddleston Water. To the downsides of the framework, its testing with only one case study due to the time frame of the project. Furthermore, it was developed and tested focusing on the developed world. Additionally, the link between NBS and SDGs is based on the author’s self-explanation and gained insights throughout the project. Hence, a more experienced person might create different links. In line with the aforementioned limitations, future recommendations suggest further testing with ranging, both in scale and in location, case studies. Expert judgment could also be used as another testing way by examining experts’ suggestions and willingness to use the framework. Finally, the inclusion of the SDGs in the indicators offer several opportunities: (i) re-evaluating potential NBS-SDG links and (ii) examining framework changes in case of considering the developing world.