Nationwide assessments of non-point source pollution with field-scale developed models: the pesticide case

The research chain consists of five steps, i.e.  problem definition, selection of model approach and model building, application of the model to a number of field-plots, scale transfer, including process aggregation and data aggregation, regional-scale model application, and analysis and presentation of results. It was shown that some of the steps of the research chain could not be completely carried out. In this particular study, regional-scale model validation and uncer- tainty analysis were hampered by lack of data. Probably the most impor- tant part of the research chain is the phase of scale transfer. It was shown that in the pesticide leaching study data aggregation was more appropriate than process aggregation (model simplification). Data were aggregated by stratifying the input-data and by setting up procedures in which specific model-inputs were derived from generally available data sources.