Rivers and Canals
Leveson Francis Vernon-Harcourt
Paperback
(RareBooksClub.com, May 14, 2012)
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1896 Excerpt: ...Rivers. cHAP. the embankments of the river in the autumn of 1887, that a similar raising of the river-bed occurs on this river 1. The embanking ofa river tends rather to improve its scouring capacity by concentrating its flood waters, thereby generally increasing its hydraulic mean depth and consequently its velocity; and therefore the embankments somewhat diminish a river's tendency to deposit its sediment. The limits,however,of deposit are restricted by the embankments; and the alluvial matter which,under natural conditions,would spread over the inundated plains, is confined within the flood channel by the embankments. Accordingly, torrential rivers descending from the mountains, heavily charged with detritus, when their velocity is diminished by the reduction in the fall, deposit the heavier material in their bed which they formerly strewed over the plain, in spite of a larger proportion of the alluvium being carried down by the concentrated current. The rising of the beds of the japan rivers referred to, and of the Yellow River, is clearly due to this cause; and under such conditions, the raising of the embankments to correspond with the rise of the bed, infallibly leads sooner or later to a breaking of the banks, and the discharge of the flood waters of the river into the plains below, a catastrophe which periodically occurs in japan and in the valley of the Yellow River, spreading devastation far and wide. Pumping for Drainage of Land. In some places the land is at such a low level in relation to the watercourses of the district, that it cannot be drained by gravitation; and the drainage waters have to be raised over the protecting banks by pumping, and discharged into the nearest watercourse. This system is extensively adopted in Holland, and i...