384 
RIVER EMBANKMENTS. 
river inundations—for no one disputes its importance in pre¬ 
venting the formation and limiting the ravages of mountain 
torrents—floods will always occur in years of excessive precip¬ 
itation, whether the surface of the soil be generally cleared or 
generally wooded. 
Physical improvement in this respect, then, cannot be con¬ 
fined to preventive measures, but, in countries subject to dam¬ 
age by inundation, means must be contrived to obviate dangers 
and diminish injuries to which human life and all the works 
of human industry will occasionally be exposed, in spite of 
every effort to lessen the frequency of their recurrence by 
acting directly on the causes that produce them. As every 
civilized country is, in some degree, subject to inundation by 
the overflow^ of rivers, the evil is a familiar one, and needs no 
general description. In discussing this branch of the subject, 
therefore, I may confine myself chiefly to the means that have 
been or may be employed to resist the force and limit the 
ravages of floods, w T hich, left wholly unrestrained, would not 
only inflict immense injury upon the material interests of man, 
but produce geographical revolutions of no little magnitude. 
a. River Embankments. 
The most obvious and doubtless earliest method of pre¬ 
venting the escape of river waters from their natural channels, 
and the overflow of fields and towns by their spread, is that of 
raised embankments along their course. The necessity of such 
embankments usually arises from the gradual elevation of the 
bed of running streams in consequence of the deposit of the 
earth and gravel they are charged with in high water; and, as 
we have seen, this elevation is rapidly accelerated when the 
highlands around the headwaters of rivers are cleared of their 
forests. When a river is embanked at a given point, and, con¬ 
sequently, the water of its floods, which would otherwise 
spread over a wide surface, is confined within narrow limits, 
the velocity of the current and its transporting power are aug¬ 
mented, and its burden of sand and gravel is deposited at some 
