United States or Iran ? Vote for the TOP Country of the Week !
This is a point of which engineers now take notice, and M. Belgrand, the able officer charged with the improvement of the navigation of the Seine between Paris and Rouen, has devoted much attention to it." Babinet, Etudes et Lectures, iii., p. 185.
Let us be wise in time, and profit by the errors of our older brethren! The influence of the forest in preventing inundations has been very generally recognized, both as a theoretical inference and as a fact of observation; but the eminent engineer Belgrand and his commentator Valles have deduced an opposite result from various facts of experience and from scientific considerations.
Belgrand supposes that the floods of the Seine at Paris are not produced by the superficial flow of the water of precipitation into its channel, but from the augmented discharge of its remote mountain sources, when swollen by the rains and melted snows which percolate through the permeable strata in its upper course.
In some of its inundations it has delivered above 9,500 cubic yards per second, or 400 times its low-water discharge. Belgrand, De l'Influence des Forets, etc., Annales des Ponts et Chaussees, 1854, 1er semestre, p.15, note. The ordinary low-water discharge of the Seine at Paris is nearly 100 cubic yards per second.
Consequently, the widening of a fissure to the extent of one inch might give an additional drainage equal to a square foot of open tubing. The observations and reasonings of Belgrand and Valles, though their conclusions have not been accepted by many, are very important in one point of view.
Word Of The Day