Building dams is one of the oldest technical activities applied for the benefit of large human groups. Dams made of soil and rock have been known since the 3rd millennium before Christ. Schnitter (1987) nominates not less than 34 dam structures existing at the beginning of our chronology in all civilizations of ancient times. The largest of these was 30 m in height. Even in our day this would be defined as a ‘large dam’. At the end of the 16th century the list includes about 300 structures, serving almost exclusively for water storage. Of course, land irrigation, water supply and flood control have been the prevailing functions.