Towards integrated national modelling with particular reference to the environmental effects of nutrients

The excess of nutrients in the Netherlands, mainly from agricultural activities, leads to widespread acidification and eutrophication, affecting biodiversity and drinking water resources. Policy measures are aimed at decreasing nutrient emission and spatial planning is directed to decreasing land use for agriculture, for the benefit of nature development and urbanisation. Decision Support Systems (DSS) are developed to evaluate, integrate and design policy scenarios with respect to social-economy, environmental protection, spatial planning and nature development. Two examples are given. STONE is a DSS for nitrate and phosphorus in agricultural areas, which integrates the predictive models and data for emission, atmospheric deposition and leaching ofN and P. The `Nature Planner', is a DSS for the multistress effects of acidification, eutrophication and desiccation on, until now, terrestrial nature. It is shown that with the Nature Planner environmental scenarios can be evaluated in terms of biodiversity indicators. Integration of STONE and the Nature Planner into one DSS will give a still more powerful policy analysis tool. With this new DSS scenarios for the conversion of agricultural land into nature can be evaluated