De consequenties van de Kaderrichtlijn Water (KRW) op de Nederlandse economie en

Summary There is a need to gain more insight into the consequences of the implementation of the Water Framework Directive (WFD) on the national economy and water quality. To fulfill this need, within the context of the project ‘Water Economic Modeling for Policy Analysis (WEMPA)’ an instrument has been developed which provides insight in both the consequences on the national economy and water quality. The instrument consists of a link between the economic model DEAN-W and the national substance flow model WFD Explorer. With the economic model the direct and indirect economic consequences of implementation of several policy alternatives can be evaluated. The policy alternatives describe a certain level of emission reduction at the national scale. For each policy alternative, the most cost effective set of measures is determined as well as the effect of the implementation of these measures on the national economy and on specific economic sectors (agriculture, industry, households). The national substance flow water quality model allows estimation of the sectoral emission reductions on water quality in the main water bodies in the Netherlands. The combination of results from both exercises gives an impression of the overall effect and feasibility of the different policy alternatives. The results show that in order to reach a substantial improvement in water quality, it is necessary to reduce domestic emission levels by at least 50% compared to their baseline level in 2000. This results in a decline of Gross Domestic Production (GDP) by 2015 with almost one percent. An emission reduction of 20% has no significant negative impact on the national economy but does not affect the water quality in a significantly positive way either. For the selection of measures priority should be given to the so-called ‘problematic substances’. No specific measures should be taken to improve the water quality for those substances which already show a reasonable quality. For certain substances the inflow from abroad (especially via the Rhine) will need to be reduced as well to be able to reach an acceptable water quality level. The study shows the usefulness of considering both the economic as well as the water quality effects of WFD implementation, especially in the context of articles 11 (selection of cost-effective programs of measures) and 4 (exemptions based on technical feasibility and disproportionate costs) in the WFD. The current simple combination of models to predict the effects of WFD implementation on the economy and water quality can easily be extended and adapted to allow for a more sophisticated cost-effectiveness and welfare analysis. The integrated modeling approach provides insight in the total direct and indirect economic costs of WFD implementation, the effectiveness of the programs of measures in terms of water quality improvement and the feasibility of policy alternatives, hence supporting national policy and decision-making regarding the exemptions provided in article 4 in the WFD.