Residents of Thornton-le-Dale in North Yorkshire were growing concerned about the impacts increased sedimentation at Thornton Beck might have on channel capacity, flood risks, environmental impacts and aesthetics for this ‘picture postcard’ tourist hotspot.
Working with the Environment Agency, we researched the sources and causes of sedimentation at Thornton Beck which had not previously been monitored, but this is the case for most UK rivers.
We used geomorphological fluvial audit and sediment budget techniques, including remote sensing data and sediment transport theory, to produce catchment sediment data, map sediment source and transfer zones, predict river sedimentation risks at the village, and identify appropriate management options. The sediment load in Thornton Beck channel was estimated at around 40,000 tonnes, most of which is stored and immobile.
The annual mobile sediment yield at Thornton-le-Dale is estimated as 15-60 tonnes per annum and considered low in comparison with monitored catchments of similar character. Our approach provided a measurable basis of costs and benefits along with justification for catchment management decisions. A range of management and mitigation options were recommended with ‘sediment savings’ and flood risk benefits.