Cost effective management of stochastic coastal water pollution

This study develops a theoretical tool for investigating the impact on cost effective coastal water management from explicit treatment of: coastal pol lutant transports, stochastic pollutant transports in the catchment areas, and wetlands as a pollutant abatement option. It is applied to a relatively well investigated estuary Himmerfjarden, south ol the Swedish capital, Sto ckholm. The theoretical results indicate that all three factors influence c ost effective allocation of measures and associated design of economic inst ruments. The consideration of stochastic pollutant transports will increase costs, but the direction of influence of the other two factors cannot be d etermined without empirical support. The application to nitrogen transport in Himmerfjarden shows that, for target nitrogen reductions given in terms of a percentage of pre-abatement loads, the inclusion of coastal transports in the cost calculations lowers the estimated total costs fur targets inte rpreted in terms of nitrogen loads to the marine water. The alternative inv estigated target interpretation was in terms of nitrogen loads to coastal w aters. Depending an the ability of wetlands to abate nitrogen and to change the variance in pollutant load to the coastal recipients, costs are either increased or decreased as compared to when wetlands are excluded as nitrog en abatement options.