Assessing the role of location and scale of Nature Based Solutions for the enhancement of low flows

Jessica Hilary Fennell* (Corresponding Author), Christopher Soulsby, Mark E. Wilkinson, Ronald Daalmans, Josie Geris

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


Water resources management during drought is a significant challenge worldwide, particularly for upland areas. Additionally, variations in water availability are becoming more extreme with climate change. Nature Based Solutions (NBS) e.g. Runoff Attenuation Features (RAFs) could provide an alternative to hard-engineering. Using more natural processes, flow pathways are intercepted and attenuated in features during wet periods, increasing infiltration opportunity and thus water availability for use later. NBS research has primarily focused on flood mitigation, but little is known about low flow impacts; knowledge is required on where and at what scale to implement NBS. To explore these questions, we used a physically-based catchment model (MIKE SHE) integrated with a hydraulic river model (MIKE 11) to evaluate scenarios with varying RAF volumes and locations. We applied this to an intensively monitored upland Scottish catchment (0.9 km2) where 40 RAFs(∼2m3storage each) were installed for low flow enhancement. Model results showed installed RAFs increase recharge (∼0.1%), groundwater contribution to streamflow (∼4%) and low flows(∼1%) and reduce high (∼5%) and mean flows (∼2%), suggesting RAFs could be used to mitigate extreme flows. The scenarios revealed that RAF location (primarily soil type) and scale (total storage volume and spread of features) were both important. Doubling installed RAF volumes increased impact on low flows by∼25% and high flows by∼40%, although lower additional benefits were predicted with further storage increases. RAFs had greater impact in freely-draining soils than poorly-draining, however distributing the same storage volume across many smaller RAFs over greater areas (both soil types) provided the largest effect. Absolute changes observed were relatively small, and given model uncertainty, should be treated with caution. Nevertheless, the direction of change was clear and given ecological systems and water supply rely on small margins of change, even slight increases in low flows will likely be beneficial.
Original languageEnglish
Pages (from-to)743–758
Number of pages35
JournalInternational Journal of River Basin Management
Issue number4
Early online date13 Jul 2022
Publication statusPublished - 2023

Bibliographical note

We would like to acknowledge financial support from the UK Natural Environment Research Council (project NE/P010334/1) and Chivas Brothers via a CASE industrial studentship. Mark Wilkinson received funding from the Rural & Environment Science & Analytical Services Division of the Scottish Government programme. Dr Luca Fabris and Dr Aaron Neill are thanked for advice on modelling and David Drummond, Dr Katya Dimitrova-Petrova, Martyn Roberts and Eva Loerke are thanked for assistance with fieldwork. Trevor Buckley and staff at the Glenlivet Distillery are thanked for on-site assistance and supply of data and abstraction records. We thank Audrey Innes for her support with the laboratory analysis. Finally, many thanks to DHI for providing the software for MIKE 11/MIKE SHE used in the hydrological simulations.


  • drought management
  • low flows
  • water resources management
  • groundwater recharge
  • runoff attenuation features


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