Diffused pollution modelling as a component of coastal zone management

ABSTRACT Many human activities are concentrated on coastal areas due to trading linkages; suitability of climate; availability of flat, fertile alluvial soils; extensive fish stocks; or aesthetic and recreational purposes. As a result of land use practices which affect coastal water quality, nonpoint pollution sources gain significance. There is a requirement to develop and implement coastal nonpoint source pollution control programs to address these sources affecting coastal waters within the framework of coastal zone management. Watersheds can be managed to control nonpoint source pollution using various models as important planning tools. Such models, within limited degrees of certainty, evaluate the effects of land use practices on receiving waters in terms of water quality and quantity. This study describes the desirable attributes of such a modeling system to assess the impacts of diffused pollution on coastal environments. A watershed scale model called SWRRBWQ (Simulator for Water Resources in Rural Basins; Williams et al., 1985; Arnold et al.,1990) was used for this purpose. The model was applied to one of the sub- watersheds of the Gediz River-Nif Basin as a case study. Extensive field and literature data was collected as a preliminary step within the context of this study. Four simulations were carried out in order to see the effects of agricultural management practices such as application of irrigation, fertilizer and tillage on the streamflow quality and quantity.