The Earth as Modified by Human ActionMarsh, George P. (George Perkins)
History
The Earth as Modified by Human Action
Marsh, George P. (George Perkins)
Conservation of natural resources; Human geography; Nature -- Effect of human beings on; Physical geography
In an elaborate paper on "Irrigation," printed in the United States
Patent Report for 1860, p. 169, it is stated that the volume of water
poured into the Mediterranean by the Nile in twenty-four hours, at low
water, is 150,566,392,368 cubic meters; at high water, 705,514,667,440
cubic metres. Taking the mean of these two numbers, the average daily
delivery of the Nile would be 428,081,059,808 cubic metres, or more than
550,000,000,000 cubic yards. There is some enormous mistake, probably a
typographical error, in this statement, which makes the delivery of the
Nile seventeen hundred times as great as computed by Talabot, and more
than physical geographers have estimated the quantity supplied by all
the rivers on the face of the globe.] This is equal to 323,222,400 cubic
yards per day. In a single day of flood, then, the Ardeche, a river too
insignificant to be known except in the local topography of France,
contributed to the Rhone once and a half, and for three consecutive days
once and one third, as much as the average delivery of the Nile during
the same periods, though the basin of the latter river probably contains
1,000,000 square miles of surface, or more than one thousand times as
much as that of the former.
The average annual precipitation in the basin of the Ardeche is not
greater titan in many other parts of Europe, but excessive quantities of
rain frequently fall in that valley in the autumn. On the 9th. of
October, 1827, there fell at Joyeuse, on the Beaume, no less than
thirty-one inches between three o'clock in the morning and midnight.
Such facts as this explain the extraordinary suddenness and violence of
the floods of the Ardeche, and the basins of many other tributaries of
the Rhone exhibit meteorological phenomena not less remarkable.
[Footnote: The Drac, a torrent emptying into the Isere a little below
Grenoble, has discharged 5,200, the Isere, which receives it, 7,800
cubic yards, and the Durance, above its junction with the Isere, an
equal quantity, per second.--Montluisant, Note sur les Dessechements,
etc., Annales des Ponts et Chaussees, 1833, 2me semestre p. 288.
The Upper Rhone, which drains a basin of about 1,900 square miles,
including seventy-one glaciers, receives many torrential affluents, and
rain-storms and thaws are sometimes extensive enough to affect the whole
tributary system of its narrow valley. In such cases its current swells
to a great volume, but previously to the floods of the autumn of 1868 it
was never known to reach a discharge of 2,600 cubic yards to the second.
On the 28th of September in that year, however, its delivery amounted to
3,700 cubic yards to the second, which is about equal to the mean
discharge of the Nile.--Berichte der Experten-Commission uber die
Ueberschaeemmungen im Jahr 1868, pp. 174,175.
Public-domain text, read in full here on John Shaqi.
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