Challenges of improving river water quality in diverse settings with changing drivers

Intensified food production together with ongoing climate change will exacerbate the transfer of agro-chemicals from land to water resulting in freshwater body quality degradation. Planning for future mitigation strategies requires an understanding of the process’s driving pollutant loss, including changing climate, agronomy and policy. Knowledge on the influence of complex catchment characteristics, such as hydrology, soil chemistry and biological transformation processes is essential. Within the Irish Agricultural Catchments Programme (ACP), sub-hourly hydro-chemo-metric data is gathered since 2009 together with other environmental, agronomic and socioeconomic data, in five intensively farmed headwater river catchments, and one karst spring contribution zone. The catchments cover a range of soils, landscapes and farming systems. This paper reflects on key findings from the ACP in the light of informing and supporting targeted strategies for improving river water quality for different catchment typologies. For example, the holistic approach has provided insights to critical areas, critical times and critical pathways of nutrient loss. The long term and high-frequency monitoring of water quality has facilitated the development of new analytical methods. These methods enable the identification of nutrient delivery pathways and quantifying the catchment risk for P mobilisation and delivery. Dominating controls within an inherently complex catchment can be identified and targeted measures selected. Such methods are useful for inter-catchment comparison, assessing the influences of climate change and for scaling up processes to model larger areas. It further allows to assess inter-seasonal water quality trends that may be hidden in inter-annual trends, and trends in specific pathways that may be counteracted elsewhere. While this has contributed to a better understanding of the underlying processes of pollutant loss to water, it is clear that a sustainable agriculture also need to include social, economic and innovative aspects. To maximise farmers’ uptake of environmental measures it is necessary to bring all these aspects together. It will also be useful to bring disparate datasets, disciplines, and human diversity together as these can spark creativity and interventions, which can direct science and policy into new productive spaces. Integrated knowledge transfer is key to implement catchment management of the agricultural landscape.