NERC Natural Flood Management Research Programme, Q-NFM project

In the second of two blogs about this research programme, Dr Barry Hankin, Head of Environmental Modelling explores the Q-NFM research project, and how natural flood management measures can reduce flooding at larger scales.

The scope of the UKRI-NERC Natural Flood Management Research Programme has been co-designed with project partners, Defra, the Environment Agency, Scottish Environmental Protection Agency, the Welsh Government and Natural Resources Wales to improve our understanding of the potential effectiveness of various NFM measures in differing catchments across a range of flood risk scenarios. We are working on two of the three NERC Natural Flood Management Research Programme projects: Q-NFM and LANDWISE-NFM. You can read our blog about the LANDWISE-NFM project here.

Q-NFM logo: NERC Natural Flood Management Research Programme

Q-NFM project

Q-NFM monitored micro-catchments
A monitored micro-catchment, Cumbria

Q-NFM is centred on Cumbria with the investigator team, led by Dr Nick Chappell, based at Lancaster University. The Q-NFM team includes JBA Consulting and the Rivers Trust, and we set out to understand how much nature-based measures have the potential to reduce flooding at larger scales. We shift the parameters of catchment-scale models based upon values derived from peer-reviewed studies, combined with our own measurements in a series of micro-catchments in Cumbria, and constrained by direct observations of flood hydrographs newly measured at the scale of local NFM interventions.

To model the flows of rainfall to streams the team developed a new, faster-running version of Professor Keith Beven’s rainfall-runoff model, Dynamic Topmodel, and made it open source[1]. Once water has entered stream channels, it is then routed downstream, engaging with floodplains in places, using either HEC-RAS 2D model or JBA’s own JFlow®[2].

In addition, we have combined Dynamic Topmodel runoff predictions with a 1d network model of leaky barriers, which has helped with Task 6 of Q-NFM, where we have assessed the whole system response of simple networks of leaky barriers. The analysis has included potential for failure of the leaky-barriers and the implications for more risk-averse spatial strategies for barriers in a network [3].

Applying the hybrid modelling approach, we have now begun modelling of the whole of the Eden Catchment (2,300km2) with the new Lancaster-developed version of Dynamic Topmodel. We fed what it predicts as surface and subsurface flows into over 20,000 river segments across the catchment, using the power of JFlow and our Warrington Office modellers, to look at the large-scale routing. We have compared results with JBA’s Flood Foresight (from our Skipton and Wallingford offices) and Sentinel Satellite image analysis (from our Edinburgh office) for Storm Ciara.

Q-NFM map: NERC natural flood management research programme

We have therefore helped to bring the power of some industrial processing tools to work alongside the experts at Lancaster University.

One problem with having such powerful modelling, is knowing when the system is too big to understand all of the components. There are huge numbers of permutations in baseline model runs and NFM scenarios needed to cover the uncertainties arising from the unknowns in the processes, errors in observations, model simplifications, and variability in the effects of even the same type of NFM measure. In addition to developing a range of technical scenarios (what intervention applied where in the Kent, Derwent or Eden catchments), we have worked with key end-user partners such as the Rivers Trusts to develop scenarios of interest to them. These include scenarios to help communities at risk from frequent flooding in small catchments where the evidence is stronger that NFM will work[4].

The first NFM scenario, once baseline modelling complete, will focus on the flood-beneficial effects of widespread afforestation via enhancement of wet canopy evaporation (or ‘interception loss’), as underpinning research by the Q-NFM team has shown this process can be significant in areas of upland UK where high winds combine with the presence of even small humidity deficits [5].

Want to know more?

You can access recordings of NERC Natural Flood Management Research Programme webinars on Q-NFM’s work via Yutube:

Dr Barry Hankin, Head of Environmental Modelling, JBA Consulting, presenting on Lessons from modelling NFM at the micro-scale and macro-scale is available here.

Dr Nick Chappell, University of Lancaster, presenting on Quantifying the likely magnitude of nature-based flood mitigation effects across large catchments is available here.

These are part of an ongoing series of monthly webinars run by the NERC Natural Flood Management Research Programme to allow NFM researchers and practitioners to share knowledge and experience and are open to all.

JBA Consulting provide services across the natural flood management work area, including: NFM Assessments, NFM Potential Mapping, NFM Hydraulic Modelling, NFM Surveys, NFM Engagement, NFM Training, NFM Barriers, NFM Design, River Restoration, Geomorphological Assessment, Ecological Assessments, Fisheries Science, Fish Pass Design, Habitat Surveys, Hydraulic Habitat Modelling, Water Framework Directive (WFD) Assessments, River Restoration Feasibility and Design Studies.

We have over 10 years’ experience in NFM and have led the consortium that delivered the Environment Agency’s Working with Natural Processes Evidence Base, published in 2017. If you would like more information, please contact Steve Maslen, Head of Environment. You can also find out more on our Natural Flood Management webpages.

References

[1] https://waternumbers.github.io/dynatop/

[2] Hankin, B.G, Metcalfe, P., Beven, K., Chappell, N., 2019. Integration of hillslope hydrology and 2D hydraulic modelling for natural flood management. Hydrology Research nh2019150, July 2019. https://doi.org/10.2166/nh.2019.150

[3] Hankin, B., Hewitt, I., Sander, G., Danieli, F., Formetta, G., Kamilova, A., Kretzschmar, A., Kiradjiev, K., Wong, C., Pegler, S., and Lamb, R.: A risk-based, network analysis of distributed in-stream leaky barriers for flood risk management. Nat. Hazards Earth Syst. Sci., 20, 2567–2584, 2020 https://doi.org/10.5194/nhess-20-2567-2020

[4] NFM Modelling: Developing collaborative end user scenarios. Rivers Trust Catchment Data & Evidence Forum. https://catchmentbasedapproach.org/learn/catchment-data-and-evidence-forum-2020/

[5] Trevor Page, Keith Beven, Nick Chappell, Ann Kretzschmar, Barry Hankin (2020). Assessing the significance of wet-canopy evaporation from forests during extreme rainfall events for flood mitigation in mountainous regions of the UK. Hydrological Processes. Aug 27, 2020. https://doi.org/10.1002/hyp.13895



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