eChapter Name: An Ecohydrology Model
9789390512959
eBook Name: WATER QUALITY MODELING: RIVERS,STREAMS AND ESTUARIES
by R. Manivanan
17.1. Introduction
Throughout human history, the coastal plains and Lowland River valleys have usually been the most populated areas over the world (Wolanski et al., 2004). At present, about 60% of the world’s population live along the estuaries and the coast (Lindeboom, 2002). This is degrading estuarine and coastal waters through pollution, eutrophication, increased turbidity, overfishing and habitat destruction. The pollutant supply does not just include nutrients; it also includes mud from eroded soil, heavy metals, radionuclides, hydrocarbons, and a number of chemicals including new synthetic products.
The impact on estuaries is commonly still ignored when dams and irrigation farming are proposed on rivers. In addition, estuaries are often regarded as sites for future development and expansion, and have been increasingly canalized and dyked for flood protection, and their wetlands infilled for residential areas.
All these factors impact on the biodiversity and productivity and hence, the overall health of estuaries and the ecosystem services they provide to humans. They increasingly lead humans away from the possibility of ecologically sustainable development of the coastal zone. Integrated coastal zone management plans are drawn up worldwide but, in the presence of significant river input, most are bound to fail because they commonly deal only with local, coastal issues, and do not consider the whole river catchment as the fundamental planning unit. It is as if the land, the river, the estuary, and the sea were not part of the same system. When dealing with estuaries and coastal waters, in most countries land-use managers, water-resources managers, and coastal and fisheries managers do not cooperate effectively due to administrative, economic and political constraints, and the absence of a forum where their ideas and approaches are shared and discussed (Wolanski et al., 2004).