Soil erosion is a natural process accelerated by human activities. Each year, erosion of surface soil from river basins amounts to 60 billion tons, resulting in 24 billion tons of sediment flux to the oceans in the world and almost 25 billion tons of soil lost from agricultural land. From a global point of view, this currently represents a redistribution of soil resources by about 7 per cent each decade with multiple consequences. Much of this sediment moves into the river system, posing many problems for river management and control. By assimilating nutrients and contaminants, sediment has serious implications both in rivers and coastal waters.