Beaches are one of the most important economic and environmental zones along coasts everywhere. In the United States alone, there are over 19,000 miles of beaches, 500 miles of which are within designated National Parks. Beaches are the boundaries between land and sea. A large part of the human population lives within driving distance of a beach. One of the recent environmental problems of importance is the increasing loss of beaches due to erosion of the shorelines.

Sediments, transported from inland resources, stock the rich supply of sands on beaches. Rivers drain inland valleys and plains and carry eroded particles from their source to their final deposition at sea. An enormous amount of sand and mud is carried by rivers such as the Nile and Mississippi. These rivers nourish farmers' lands and provide transport for economic goods. Because of their value, they are not...