Author(s): George Heritage, Neil Entwistle
Linked Author(s): Neil S. Entwistle
Keywords: Floodplains, flooding, land management, natural flood risk management
Abstract: A review of floodplain functioning in the north of England following the winter storms of 2015 is conducted using high resolution aerial imagery of the events captured using drone and helicopter survey during and immediately after the flooding. This reveals that for the most part, 100% of the floodplain area is inundated. Sediment left across floodplains from the 2015 flood events areas suggests high floodplain velocities (> 1. 5 m/s). GIS analysis of land use mapping for valley bottom areas across England reveals part of the cause for these unnaturally high velocities is the near complete loss of natural rough floodplain surfaces, having been replaced by a hydraulically smoother managed arable/grassland mix. The review has revealed extensive and severe degradation of floodplain systems in England and it is highly likely that similar results would be found for floodplains across the rest of the UK, both upland and lowland areas are equally impacted and the result is an almost complete loss of natural floodplain functioning. River restoration remains concentrated on in-channel activity, however, the push for natural flood management offers an opportunity to restore our floodplains with an associated improvement in ecological value and flood driven functionality. The research presented here suggests that it is not lack of floodplain storage space in the upper catchment, rather the decreased efficiency of floodplain areas to retard flow which is leading to increased downstream flood risk. Floodplain reconnection, vegetative naturalization and selective grazing reduction are required to begin to restore upstream floodplain flood function to alleviate flooding pressure downstream
Year: 2017