DYKE, or DIKE, a word variously used to represent a ditch or trench and also an em bankment, rampart or wall. It is specially applied to an embankment raised to oppose the incursions of the sea or of a river, the dykes of Holland being probably the most notable examples of works of this kind in the world. Owing to the possibility of great loss of prop erty and of life, the punishment of all neglect or for malicious mischief to dykes is extremely severe, one (gplacaat" of Feb. 1726 regulating the inundation in the province of Staten, proclaiming that "anyone cutting dams, dykes, quays, etc., will be punished with death and confiscation of all his property." The dykes which protect the Netherlands and the German coasts of the North Sea go back to the old Roman times. Apparently even before the Romans appeared the Batavians at the mouth of the Rhine protected themselves by dykes. Drusus after the conquest of Holland, 10 ac, built an elaborate system of artificial canals and dykes. Pliny the Elder gives interesting de scriptions of the artificial hills which were erected as places of refuge during the floods.
Among the provinces in North and South Holland which have been protected by dykes may be mentioned the province of Hanover, 618 miles, protecting 770,000 acres of marsh land. On the left bank of the Oder River there is a dyke which protects more than 170,000 acres of land. The dyke at the delta
of the Vistula protects 134,000 acres of land. On the lower Rhine, between the Weser and Holland are 115,000 acres protected by dykes. Along the Loire River are 280 miles protecting 230,000 acres. Along the Po there are 310 miles protecting 850,000 acres. In England there are 1,750,000 acres protected by dykes. Many of the dykes of Holland are raised 40 feet above high-water mark and are wide enough at the top for a general roadway or canal, sometimes for both.
In the United States the term dyke is almost wholly restricted to the structures of more or less permanence built in various ways in the bed of a stream to regulate its flow, narrow the low water cross-section, concentrate the cur rent, increase its local scouring effect and thereby deepen the river channel. The earthen em bankments designed to restrain the flood waters are called levees. The most notable examples are found along the Mississippi River. These levees are placed some little distance back from the river and according to the local conditions vary in height from 2 or 3 feet to over 20 feet. Levee building began many years ago along the lower part of the river and it has been carried on practically continuously ever since. See MISSISSIPPI LEVEE SYSTEM, and REsEavoia.