- 14th October 2020
- Posted by: Miranda Pont
- Category: Blog
In 2018 we were appointed to the Environment Agency’s (EA) Modelling and Forecasting Package 19 under the Water and Environmental Management framework.
Package 19 stood out from past modelling projects due to inclusion of a Natural Flood Management (NFM) element, and four flood mapping projects. Use of workshops and mini conferences allowed for the NFM project to be completed collaboratively with the EA and other stakeholders including the Yorkshire Dales Rivers Trust, North Yorkshire Moors National Park, borough councils and Leeds University, plus others.
The flood mapping projects focused on four geographical areas: the River Nidd (Lofthouse to Nun Monkton), Humber Tributaries (nine watercourses draining to the Humber Estuary), West Hull Becks (Setting Dike, near Hull) and Grace Dieu (urban watercourse in Leicestershire) flood mapping.
The NFM project focused on modelling of NFM interventions on four case study catchments across Yorkshire: Gargrave, Helmsley, Backstones Beck (Ilkley) and Whiston Brook.
Flood modelling projects
The flood modelling projects adopted industry established approaches, using a variety of software packages, demonstrating our breadth of modelling expertise. The tasks for each project varied, including rating reviews at hydrometric gauging stations, calibration to past flood events, joint probability analysis and integrated modelling. Model outputs were used to produce detailed flood risk maps and update EA Flood Warning procedures.
Natural flood management (NFM) projects
Workshops were held with the EA to gather local knowledge and discuss modelling techniques for NFM interventions across the four catchments.
Our in house JFlow® software was used, representing whole catchments, and applying rainfall profiles directly to the model grid.
Once present-day results were extracted, various scenarios were tested. In Ilkey (Backstone Beck) four scenarios were modelled:
- Peatland restoration
- Modelling of footpaths and peatland restoration
- Woodland planting
- An “all possible NFM” scenario.
The all NFM scenario saw showed substantial (76%) peak flow reductions across the catchment for a 100-year, 1-hour summer storm event.
The project included stakeholder engagement and training, delivered through a site visit and three interactive workshops held with EA Partnerships and Strategic Overview Officers and technical specialists, and other stakeholders from each of the four catchments.
Building on the evidence and research gaps of the Working with Natural Processes (WwNP) Evidence Base, the learning outcomes from this project allowed site specific consideration from the site visits and workshops. At the workshops, we presented sessions on WwNP Evidence Directory, Natural Capital, and engagement tools for NFM.
The final workshop brought together stakeholders from all four catchments, to discuss and share lessons learnt throughout the project.