Integrated Assessment of Water Framework Directive Nitrate Reduction Measures

Abstract

The paper develops a spatially explicit method for integrated assessment of alternative measures to reduce nitrate leaching into rivers and lakes from farms, a key objective of the European Union Water Framework Directive (WFD). This approach combines regression models, based on Farm Business Survey and June Agricultural Census data, for predicting the economic costs to agriculture of nitrate reduction measures with a hydrological model encompassing both diffuse and point source pollution to estimate the water quality changes arising from such instruments. A case study of the agriculturally diverse Yorkshire Derwent catchment in the north of England illustrates the overall approach. We consider three measures previously proposed to the UK Department for Environment, Food and Rural Affairs (Defra) for tackling diffuse agricultural pollution: (i) reducing inorganic fertilizer application; (ii) reducing livestock stocking rates; and (iii) converting arable land to un-grazed grassland. The results reveal marked variability in the economic impacts and nitrate leaching reductions, with the cost effectiveness of these measures varying by up to a factor of three. Furthermore, the analysis suggests that WFD implementation may entail major land use changes resulting in substantial economic impacts. The spatially explicit aspect of our approach permits assessment of the optimal targeting of policy implementation to areas of particular environmental interest.