Rivers provide numerous benefits to man as avenues of commerce and sources of water supply. Flood plains have rich agricultural soils, and some of the earth’s most heavily populated areas occur along rivers.
Yet the riverine environment can be hazardous. Ancient civilizations struggled against floods while trying to earn a living from the fertile land adjacent to the Nile, Tigris, Euphrates, Indus, and Yellow Rivers. The worst geologic disaster known occurred in 1887 when about 800,000 Chinese lost their lives from the Yellow River flood (Costa and Baker, 1981). Another 100,000 Chinese died when the Yangtze River flooded in 1911. The great flood of 1927 extensively damaged the lower Mississippi River Valley and a flood-control plan was quickly adopted. The Arno River ripped through Florence, Italy, in 1966 and damaged one of the foremost art centers of the world.
Legget (1973, p. 66) has noted that in Central Europe the builders of medieval towns generally avoided the flood plains. They were rightly afraid of floods, and recognized the difficulty of construction on the wet ground adjacent to rivers. The early sectors of the older cities were usually located on the higher ground provided by river terraces. This wise practice was not based consciously on geological training, but utilized the same craft-lore demonstrated by the builders of the Pyramids and other early works (Chapter 1, this volume). Unfortunately, since the late 1800s, buildings on flood plains has steadily increased throughout the world with the growth of major cities to satisfy pressures for urban living.
In the United States, flood-related deaths continue, and annual flood damage is increasing (Rahn, 1986).