A quantitative evaluation of monitoring networks for region-specific nitrate reduction policies

Modern environmental policy implementation in many developed countries is i ncreasingly regionally oriented. Regional governments have undertaken measu res designed for the specific needs of the region but, so far the resulting change in environmental quality has hardly been monitored. This study deve lops a method for the quantitative evaluation of region-specific environmen tal policy. Two forms of monitoring are distinguished: monitoring of perfor mance of policy measures and monitoring of environmental quality. This stud y investigates two regions in the Netherlands where region-specific policy has been implemented. Performance monitoring focused on reduction of nitrat e leaching to groundwater. Leaching reductions were calculated with simple models or rules of thumb. Quality monitoring focused on nitrate concentrati ons under grassland and other land use. An analysis of variance showed sign ificant differences between different soil units. Stratified kriging was ap plied for spatial interpolation, showing within-unit variability. The curre nt monitoring network could be improved by using a more regular type of gri d. (C) 2001 Academic Press.