Be largely of
brushwood, woven in continuous carpets, or twined into wire-netting.
This veneering process has been successfully employed on the Missouri
River; and in some cases they have so covered themselves with sediments,
and have become so overgrown with willows, that they may be regarded as
permanent. In securing these mats rubble-stone is to be used in small
quantities, and in some instances the dressed slope between high and low
river will have to be more or less paved with stone.
Any one who has been on the Rhine will have observed operations not
unlike those to which we have just referred; and, indeed, most of the
rivers of Europe flowing among their own alluvia have required similar
treatment in the interest of navigation and agriculture.
The levee is the crowning work of bank revetment, although not
necessarily in immediate connection. It may be set back a short
distance from the revetted bank; but it is, in effect, the requisite
parapet. The flood river and the low river cannot be brought into
register, and compelled to unite in the excavation of a single permanent
channel, without a complete control of all the stages; and even the
abnormal rise must be provided against, because this would endanger the
levee, and once in force behind the works of revetment would tear them
also away.
