The influence of large-scale climate patterns on sediment loss from agricultural land – exploration using an instrumented field and catchment scale platform

Accelerated soil erosion and sediment delivery are threats to water quality. In western Europe, weather patterns are strongly influenced by large scale climate systems such as the North Atlantic Oscillation (NAOi). Recently, however, a new climate index has been developed, called the West Europe Pressure Anomaly (WEPAi), which may be more relevant for weather in northwestern Europe. Recent attempts have tried to link variability in weather patterns as described by hydro-climatic indices and amplifications in the degradation of water quality. However, to our knowledge, no previous work has been undertaken on investigating their effects on suspended sediment concentrations.
A study was conducted in southwest England using long-term meteorological, monthly NAOi and WEPAi, and 15-min discharge and turbidity datasets collected from an instrumented field and catchment scale monitoring platform. Monthly winter precipitation totals, and air temperature were both found to be significantly positively related to NAOi, but not in the summer. Both variables were significant and more strongly related with the WEPAi for both seasons. Flow weighted mean suspended sediment concentrations calculated for both seasons over a 4-year period were compared to monthly NAOi and WEPAi. In winter months, no significant relationships were found at any scale for NAOi. However, significant positive relationships with the WEPAi were present regardless of catchment size. In the summer months there were no significant relationships with either climate indices.
Large-scale climate drivers are important in the sediment responses of agricultural landscapes. An ability to forecast monthly climate scale drivers could enable farmers to better plan for those periods when hydro-sedimentological responses are likely to be elevated. More work is needed across a range of landscape typologies to confirm that the relationships observed hold true more widely.