Residual currents and long-term transport

Estuaries, bays, and contiguous coastal seas of the world are the most valuable and yet most vulnerable marine ecosystems. For centuries, society has placed enormous value on coastal areas for living, working, and recreation. In nearly all regions of the world, the largest population is distributed along the coastlines. The marine ecosystems provide food, shelter, and spawning grounds for fisheries, and refuge and sanctuary for wildlife. Dramatic increases in the population living in coastal regions have changed the pattern of land use and the movement of sediments. Obviously, these changes have not come without a price. Accompanying the coastal population increase is competition for the use of estuarine and coastal resources: the diversion of fresh water for irrigation and the discharge of waste water into these systems. The changing patterns of water use have resulted in deterioration of water quality, and in irreversible impacts on many marine ecosystems. All of these alterations directly affect the economic development and the quality of life in adjacent regions.