Management of eutrophicated coastal zones

To manage coastal zones suffering from eutrophication in the presence of spatial heterogeneity requires an understanding regarding the complexity of such problem. This thesis contributes to the understanding about setting an optimal policy design for sources whose effect on the recipient varies spatially. The first three articles considers the nitrogen load to the Stockholm archipelago caused by emission sources within its river basin, while the fourth consider the nitrogen load to the Baltic Sea originating from a smaller part of this coastal zone, Himmerfjärden, and its catchment area. Article I shows that efficiency in coastal zone management is only possible if abatement costs are connected to the damage on the recipient. Articles II and III estimates efficiency losses of uniform policy instruments in the presence of spatial heterogeneity with respect to sources. While article II compares the cost between a cost-effective policy and a uniform percentage reduction by one type of abatement measure, article III compares three types of uniform policy with a cost-effective using four different types of abatement measures. Article II and III indicates significant efficiency losses of uniform policies. Article IV introduces the uncertainty aspect of the management problem described in article I, and how it affects cost as well as the cost-effective allocation of abatement measures. The thesis indicates potential gains of using a spatially differentiated policy instrument in reducing the effects of eutrophication in the Stockholm Archipelago, and highlights the complexity of coastal zone management in general