Intl. J. River Basin Management Vol. 1, No. 2 (2003), pp. 165–171 © 2003 IAHR & INBO Implementation of the water framework directive – can we use models as a tool in integrated river basin management? JESPER DØRGE, DHI – Water & Environment, Agern Allé 11, DK-2970 Hørsholm, Denmark E-mail: jed@dhi.dk JØRGEN WINDOLF, County of Funen, Amtsgården, Ørbaekvej 100, DK-5220 Odense SØ, Denmark E-mail: jwn@anv.fyns-amt.dk ABSTRACT The implementation of the Water Framework Directive requires adjustment of the administrative structure for the water management in each of the Member States. Modifications of the procedures for river basin management are also foreseen.Today, river basin management in Denmark is for the most part carried out at regional levels (in 14 counties) and the environmental problems for freshwater systems in Denmark are mainly associated with diffuse pollution sources (primarily originating from agriculture) and pollution with pesticides and other xeno-biotics. Viewed in the context of the Directive river basin models may play an important role for a successful water administration – being tools in the technical solutions for how to achieve “good status” for groundwater and surface waters. In Denmark integrated river basin modelling is used in connection with restoration projects, also empirical models are widely used. The benefits from applying river basin models are manifold. Besides being able to evaluate “good status” for freshwater bodies based on hydrology, land-use, agricultural practices and ecology of individual river stretches (including lakes and wetlands), modelling can also identify solutions for flood/drought problems in combination with defining protection measures for the aquatic environment. Keywords:Water management; water framework directive; model; water quality. Introduction In 1995 the European institutions agreed that a fundamental review and restructuring process was needed for Community water policies and in February 1997 the Proposal for a Water Framework Directive was adopted. Its purpose is to establish a framework in order to achieve the following four main objectives of a sustainable water policy: • sufficient provision of drinking water • sufficient provision of water for other economic requirements • protection of the aquatic environment • alleviation of the adverse impact of floods and droughts The environmental objective of the Directive is to obtain “good status” for all ground-waters and surface waters within the European Union. To achieve this, river basin management basin should be established based on an assessment of the character- istics of the river; the monitoring of the status of its surface and ground-waters; the definition of quality objectives; and establish- ing programmes for measures to realise the defined objective. However, the administrative procedure to implement this river basin management is left to the discretion of Member States. Mathematical models serve as tools for water management of river basins and modelling could be an important element of the practical implementation of the Directive. Received and accepted on June 2, 2003. Open for discussion until September 30, 2003. 165 In Denmark today, models are widely used by the water authorities ranging from very simple empirical (static) models for lakes (eutrophication, yearly mean values), monthly-based diffuse nutrient discharge models and up to fully dynamic mod- els for rivers, lakes, groundwater and marine waters. The use of models, so far, has mainly dealt with specific environmental problems for selected river stretches, sub-catchment etc. Conse- quently, truly integrated models for the hydrological cycle of a given river basin simulating both surface water and groundwa- ter compartments, impacts on river water quality from land-uses, point sources etc., as well as the influence on the final marine recipient, are not applied. This paper addresses technical and administrative aspects of current Danish river basin management practices, the linkage to the implementation of theWater Framework Directive and the use of models as a tool for integrated water planning. For practical reasons the paper comprises freshwater systems only. Water management in Denmark Administrative structure The management of the aquatic environment in Denmark is organised at three levels: • National authorities, national aims and measures