An ADAS team led by Professor Adrian Collins has been using innovative dual-signature tracer technology to assess the efficacy of riparian buffers for mitigating sediment losses to neighbouring watercourses.
This work forms part of a national research project working in all three Defra Demonstration Test Catchments (DTCs); namely the Hampshire Avon, Wensum and Eden catchments.
Riparian buffer strips function by slowing surface runoff and promoting deposition which can prevent some sediment size fractions and sediment-bound pollutants (e.g. phosphorus) transported in surface flow from entering neighbouring watercourses. More detailed collaborative work is looking at phosphorus retention in the riparian buffers. A range of riparian buffer widths (e.g. 2, 4 and 6 m) is currently offered by agri-environment schemes and policy teams require improved evidence on the efficacy of fixed width options to ensure that best practices are promoted.
Unlike previous studies on buffer efficacy which have relied on traditional bounded plot experiments and, in many cases, simulated rainfall, this project is being undertaken at unbounded field scale and under natural rainfall conditions. The work relies on a novel dual-signature sediment tracking technique. Tracer grains have been developed to match the hydraulic properties of the target soils at the experimental sites, ensuring that the movement of the artificial tracer mimics the natural soil redistribution during erosion events. The ten experimental sites selected across the Hampshire Avon, Wensum and Eden catchments represent a range of different soil types, slopes and rainfall conditions. The results of the tracking work are currently being processed and will be disseminated soon.
For more information on this national DTC project, please contact the project lead Professor Adrian Collins at adrian.collins@adas.co.uk on 01902 693404 or Leasa Williams at leasa.williams@adas.co.uk on 01249 758213.