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Mitigating agricultural water pollution requires changes in land management practices and the implementation of on-farm measures to tackle the principal reasons for water quality failure. However, a paucity of robust empirical evidence on the hydrological functioning of river catchments can be a major constraint on the design of effective pollution mitigation strategies at the catchment-scale. In this regard, in 2010 the UK government established the Demonstration Test Catchment (DTC) initiative to evaluate the extent to which on-farm mitigation measures can cost-effectively reduce the impacts of agricultural water pollution on river ecology while maintaining food production capacity. A central component of the DTC platform has been the establishment of a comprehensive network of automated, web-based sensor technologies to generate high-temporal resolution empirical datasets of surface water, soil water, groundwater and meteorological parameters. In this paper, we demonstrate how this high-resolution telemetry can be used to improve our understanding of hydrological functioning and the dynamics of pollutant mobilisation and transport under a range of hydrometerological and hydrogeological conditions. Furthermore, we demonstrate how these data can be used to develop conceptual models of catchment hydrogeological processes and consider the implications of variable hydrological functioning on the performance of land management changes aimed at reducing agricultural water pollution.

Mitigating agricultural water pollution requires changes in land management practices and the implementation of on-farm measures to tackle the principal reasons for water quality failure. However, a paucity of robust empirical evidence on the hydrological functioning of river catchments can be a major constraint on the design of effective pollution mitigation strategies at the catchment-scale. In this regard, in 2010 the UK government established the Demonstration Test Catchment (DTC) initiative to evaluate the extent to which on-farm mitigation measures can cost-effectively reduce the impacts of agricultural water pollution on river ecology while maintaining food production capacity. A central component of the DTC platform has been the establishment of a comprehensive network of automated, web-based sensor technologies to generate high-temporal resolution empirical datasets of surface water, soil water, groundwater and meteorological parameters. In this paper, we demonstrate how this high-resolution telemetry can be used to improve our understanding of hydrological functioning and the dynamics of pollutant mobilisation and transport under a range of hydrometerological and hydrogeological conditions. Furthermore, we demonstrate how these data can be used to develop conceptual models of catchment hydrogeological processes and consider the implications of variable hydrological functioning on the performance of land management changes aimed at reducing agricultural water pollution.

The Demonstration Test Catchments (DTC) project is a UK Government funded initiative to test the effectiveness of on-farm mitigation measures designed to reduce agricultural pollution without compromising farm productivity. Three distinct catchments in England have been chosen to test the efficacy of mitigation measures on working farms in small tributary sub-catchments equipped with continuous water quality monitoring stations. The Hampshire Avon in the south is a mixed livestock and arable farming catchment, the River Wensum in the east is a lowland catchment with predominantly arable farming and land use in the River Eden catchment in the north-west is predominantly livestock farming. One of the many strengths of the DTC as a national research platform is that it provides the ability to investigate catchment hydrology and biogeochemical response across different landscapes and geoclimatic characteristics, with a range of differing flow behaviours, geochemistries and nutrient chemistries. Although numerous authors present studies of individual catchment responses to storms, no studies exist of multiple catchment responses to the same rainfall event captured with in situ high-resolution nutrient monitoring at a national scale. This paper brings together findings from all three DTC research groups to compare the response of the catchments to a major storm event in April 2012. This was one of the first weather fronts to track across the country following a prolonged drought period affecting much of the UK through 2011–2012, marking an unusual meteorological transition when a rapid shift from drought to flood risk occurred. The effects of the weather front on discharge and water chemistry parameters, including nitrogen species (NO3-N and NH4-N) and phosphorus fractions (total P (TP) and total reactive P (TRP)), measured at a half-hourly time step are examined. When considered in the context of one hydrological year, flow and concentration duration curves reveal that the weather fronts resulted in extreme flow, ...