234 iifUNDATiojsrs in wintee. 



ImmdaUons m Winter. 



In the ITortliern United States, although inundations are not 

 very unfrequently produced by heavy rains in the height of sum- 

 mer, it will be found generally true that the most rapid rise of 

 the waters, and, of course, the most destructive " freshets," as 

 they are called in America, are occasioned by the sudden dissolu- 

 tion of the snow before the open ground is thawed in the spring. 

 It frequently happens that a powerful thaw sets in after a long 

 period of frost, and the snow which had been months in accmnu- 

 lating; is dissolved and carried off in a few hours. When the 

 snow is deep, it, to use a popular expression, " takes the frost out 

 of the ground " in the woods, and, if it hes long enough, in the 

 fields also. But the heaviest snows usually fall after midwinter, 

 and are succeeded by warm rains or sunshine, which dissolve the 

 snow on the cleared land before it has had time to act upon the 

 frost-bound soil beneath it. In this case, the snow in the woods 

 is absorbed as fast as it melts, by the soil it has protected from 



rious phenomenon is observed, which is in part easily explained. In rainy 

 weather the waters of the Sestajone are in volume only about one-half those 

 of the Lima, and while the current of the Lima is turbid and muddy, that of 

 the Sestajone appears limpid and I might almost say drinkable. In clear 

 weather, on the contrary, the waters of the Sestajone are abundant and about 

 double those of the Lima. Now the extent of the two valleys is nearly equal, 

 but the Sestajone winds down between banks clothed with firs and beeches, 

 while the Lima flows through a valley that has been stripped of trees and in 

 great part brought under cultivation." 



The Sestajone and the Lima are neither of them what is technically termed 

 a torrent — a name strictly applicable only to streams whose current is not de- 

 rived from springs and perennial, but is the temporary effect of a sudden ac- 

 cumulation of water from heavy rains or from a rapid melting of the snows, 

 while their beds are dry, or nearly so, at othertimes. The Lima, however, in 

 a large proportion of its course, has the erosive character of a torrent, for the 

 amount of sediment which it carries down, even when it is only moderately 

 swollen by rains, surpasses almost everything of the kind which I have ob- 

 served, under analogous circumstances, in Italy. 



Still more striking is the contrast in the regime of the Saint-Phalez and the 

 Oombe-d'Yeuse in the department of Vaucluse, the latter of which became 

 subject to the most violent torrential floods after the destruction of the woods 

 of its basin between 1823 and 1833, but has now been completely subdued, 

 and its waters brought to a peaceful flow, by replanting its valley. See 

 LABussEfeRE, Revue Agric. et Forestihre de Provence, 1866, and Bemts des Eauz 

 et Forets, 1866. 



