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This £13,000 study, funded by a Flood and Coastal Erosion Risk Management Grant in Aid, was commissioned after public concern rose over widespread flooding during the winter of 2023/24.
Using intricate hydraulic computer simulations, the study explored the ramifications of supplementary dredging (beyond routine navigation-focused work by the Broads Authority) in the region known as the "Bure Loop." The analysis examined dredging to depths of 2.5 and 3 meters—nearly a meter deeper than the waterways' current navigational depth. These models scrutinised various fluvial and tidal events, alongside data amassed during the disruptive Storm Babet.
However, the findings of the report are conclusive: enhanced dredging in the Lower Bure does little to diminish the flood risks for the upper regions of the catchment. In fact, the primary outcome appears to be an amplified risk of tidal flooding downstream.
Initial estimates suggest that the cost of such dredging operations would exceed the entire annual maintenance budget allocated by the Environment Agency for the Broads system. Moreover, continuous dredging would be necessary to sustain the newly created depths, further inflating costs.
Beyond financial constraints, extensive regulatory and environmental considerations would need addressing, such as the challenge of disposing of vast quantities of dredged sediment, which would far surpass what the current Broads Authority programme generates for navigation purposes.
Given the minimal benefits and substantial financial outlay, this work is unlikely to secure central government funding.
Graham Verrier, East Anglia (East) Area Director for the Environment Agency, remarked:
“We’re pleased to present this report, assessing the potential flood risk benefits of dredging in the Broads. We are grateful to the Broads Authority for their cooperation. Where clear evidence shows that dredging reduces flood risks to properties without exacerbating flooding elsewhere, and where it aligns with government criteria and is cost-effective, we’ll pursue it. If, however, dredging is not the optimal solution or proves too costly relative to the flood risk mitigation it offers, we will collaborate with communities and partners to explore alternative flood management strategies."
John Packman, Chief Executive of the Broads Authority, added:
“I extend our thanks to the Environment Agency for expediting such a comprehensive study. Though it lies beyond the current remit of the Broadland Futures Initiative (BFI), these findings will certainly influence strategic flood risk planning for the Broads over the coming century.”
The complete "Bure Loop Dredging Scenario Report," along with a summarised document, is accessible via the Broadland Futures Initiative (broads-authority.gov.uk). Additional, independent information on dredging for flood management can be found through the Chartered Institution of Water and Environmental Management: Floods-and-Dredging-a-reality-check.pdf (ciwem.org).