A flood may be defined as the occurrence of a flow of such magnitude that the natural banks of a waterway are overtopped and water flows over low-lying adjacent areas or flood plains.
Floods are natural phenomena.
Existing stream channels represent only the normal flow conditions and will, sooner or later, be overtopped by the unusual peak flow. By encroaching on the flood plain, man takes a calculated risk. Sometimes he pays the price of his occupancy. This paper discusses some of the physical relationships involved and indicates the importance and the limitations of land management. Some experimental evidence is reviewed.