Defra’s Water Quality Division (Catchment Sensitive Farming Group) is working towards identifying practical on-farm methods for mitigating diffuse water pollution from agriculture (DWPA). Amongst other activities, this has also involved commissioning a review by IGER and ADAS of diffuse pollution losses from different farming systems (‘Diffuse pollution inventory’: Haygarth et al., 2005). This inventory described the impacts of contaminants on water, the loss processes from land to water, the impacts of different farming sectors on losses, potential mitigation methods and any policy drivers for implementation of these measures. The report covered nitrate (NO3), ammonium (NH4), nitrite (NO2), phosphorus (P), sediment, faecal indicator organisms (FIOs) and biological oxygen demand (BOD). The inventory was essentially a synthesis of previous Defra-funded research, and it has helped to support policy development within the CSF Group.
The aim of the proposed project is now to improve on this inventory report to further assist Defra`s CSF Group in planning how to tackle DWPA, in particular: to provide information on agrochemicals (plant protection chemicals, biocides and veterinary medicines), add additional information from more recent estimates of the cost-effectiveness of measures to reduce N, P and FIO pollution and to add latest developments from the COST DP work. Additional information on cost-effectiveness would be provided by a related
proposal for a concurrent project `The cost-effectiveness of integrated diffuse pollution mitigation measures` and it would be important to incorporate this into the revised inventory. The present project would also produce recommendations for developing a modelling framework that would allow integration of measures across a wide range of diffuse pollutants (to support future iterations of the Programmes of Measures required under the Water Framework Directive).
The deliverables from the project will be (a) a revised diffuse pollution inventory taking account of the extra information on agrochemicals and extra information on N, P and FIOs and (b) a scoping study report on the potential use of diffuse pollution models at the catchment scale, defining the way ahead for future research.
The revised diffuse pollution inventory will revisit the original Haygarth et al. (2005) document and refine some of the work. In particular, it will add information on agrochemicals – these were deliberately omitted from Phase I but need to be included for completeness. By `agrochemicals’, we mean plant protection chemicals (fungicides, insecticides, etc), biocides and veterinary medicines. We will add information on these chemicals to all of the sections: loss mechanisms, losses as affected by farming sector, mitigation measures and external controls on losses (regulations, Directives, Voluntary Initiatives, etc). We will also include information on methods of controlling losses and the potential for ‘pollution swapping’. In addition, the existing sections on N, P and FIOs will be updated where more-recent information has become available. This information will be quite unique – little work to date has considered pesticides alongside nutrients – especially in terms of combined mitigation methods.
Finally, the work will be interpreted in the context of catchment scale approaches. We will review the state of catchment based modelling and recommend a strategy for Defra to work towards the development of an integrated policy support tool that will provide the scientific underpinning for the development of Programmes of Measures. The report will recommend approaches, identify what models exists, gaps in knowledge and gaps in supporting catchment-scale data.