Second International Workshop on Implementing Economic Analysis in the Water Framework Directive

The evaluation of water bodies “at risk” of not achieving the Water Framework Directives goal of “good status” begs the question of how big a risk is acceptable before a programme of measures should be implemented. Adequate documentation of expert judgement and statistical uncertainty in pollution budgets and water quality modeling combined with Monte Carlo simulation and Bayesian belief networks , make it possible to give a probabilistic interpretation of “at risk”. Combined with information on abatement costs cost-effective ranking of measures based on expected costs can be undertaken. Combined with economic valuation of water quality, the definition of “disproportionate cost” of abatement measures compared to benefits of achieving “good status” can also be given a probabilistic interpretation. Explicit modeling of uncertainty within a DPSIR framework helps visualize where research and consulting efforts are most critical for reducing uncertainty. Based on data from the Morsa catchment in Norway, the paper discusses the relative merits of using Bayesian belief networks when integrating biophysical modeling results in the benefit-cost analysis of derogations and cost-effectiveness ranking of abatement measures under the WFD. 1 Corresponding author: [email protected] SECOND INTERNATIONAL WORKSHOP ON IMPLEMENTING ECONOMIC ANALYSIS IN THE WATER FRAMEWORK DIRECTIVE PARIS, FEBRUARY 16-17, 2005