THE EFFECT OF THE FOREST UPON WATERS 



163 



schiitz have carried more water than the 

 streams of the plain. But what it is nec- 

 essary to know is whether, all other con- 

 ditions being- equal, and the quantity of 

 the rainfall being the same, the rivers 

 issuing from the wooded regions have 

 'a greater or less flow than those whose 

 watersheds have been deforested. 



Without going to Germany for exam- 

 ples, do we not know that the streams 

 that descend from the departments of 

 the Vosges mountains, upon which a 

 good proportion of forest area has been 

 preserved, do not have as frequent nor 

 as disastrous floods as the torrents that 

 plow the slopes of the denuded Alps, 

 or the streams of irregular flow that 

 issue from the deforested Cevennes 

 (Ardeche, Lot, Tarn, Dourbie, Loire, 

 Allier) or from the waste lands of the 

 Central Plateau (Cher, Sioule, Creuse). 

 The proportion of forest area of the 

 Vosges is thirty-five per cent, while that 

 of the Alps of Savoy is twenty-one per 

 cent, that of the Alps of Dauphiny 

 (Isere, Drome, and Hautes-Alpes) 

 thirteen per cent, that of the Alps of 

 Provence (the Lower Alps and Mari- 

 time Alps) is twelve per cent, that of 

 the Central Plateau and of the Ceven- 

 nes, twelve and one-fifth per cent. 



The meteorological bulletin of the 

 department of Aude has given us some 

 facts of value upon the effects of a 

 storm that occurred September 12, 

 1893, which was the most violent of 

 the year and caused considerable dam- 

 age throughout the whole region. All 

 the tributaries of the Aude experienced 

 sudden floods, and that river rose five 

 meters at Saint Marcel. But what oc- 

 curred in the basin of the Salz is more 

 worthy of attention. The storm lasted 

 an hour and a half and there was a 

 rainfall of sixty millimeters. The 

 Blanque River, which unites with the 

 Salz nine kilometers above Couiza, and 

 which, like it, flows down slopes almost 

 entirely denuded, immediately rose one 

 meter and devastated a large amount of 

 property along the river, especially at 

 Rennes-les-Bains ; at Couiza the flood 

 was greater and the frightened inhab- 

 itants feared a repetition of the dis- 



4 



asters of 1891. In the basin of the 

 Rialsesse, which flows into the Salz six 

 kilometers above Couiza, the amount of 

 the rainfall was sixty millimeters, also. 

 However, this river did not overflow, 

 nor cause any damage. It must be 

 noted that if the Salz and the Blanque 

 are fed by streams that flow down de- 

 nuded slopes, the basin of the Rial- 

 sesse, on the contrary, is heavily wooded 

 and 1,680 hectares have been refor- 

 ested. It would be difficult to find a 

 more striking example of the influence 

 of forest cover on floods. 



THE INFLUENCE OF FOREST GROWTH ON 

 SPRINGS 



Mr. Charles Rabot makes use of the 

 assertions of Messrs. Lauda and Wolf- 

 pchiitz to deny absolutely the favorable 

 influence of forests upon the feeding 

 of springs and the regulation of stream- 

 flow. 



However, the relation that exists be- 

 tween deforestation and the disappear- 

 ance of springs is established beyond a 

 doubt. The springs of Bresle dried 

 up about 1840, after clearing ofif a 

 forest of some importance, situated in 

 the parish of Formerie (Oise). The 

 source of the Arrivaux River descended 

 toward Breuil (Somme) one kilometer 

 soon after the forest of Cressy was cut 

 in 1837. The clearings made in the 

 forest of Arronaise were injurious to 

 all the streams that flowed from it to 

 Escaut and Somme. 



Mr. E. Charlemagne has given an 

 instance to the point in the Revue des 

 Eaux et Forets of the disastrous effects 

 that the heedless cutting of forests may 

 have upon stream-flow. After the death 

 of Don Bouthillier de Ranee, the 

 abbe of la Trappe leased the iron works 

 connected with the monastery to pri- 

 vate parties for twelve years. It was 

 necessary, according to the biography 

 of Don Pierre the Dwarf, sub-prior of 

 the monastery, "to destroy the forests 

 of la Trappe in order to maintain the 

 furnace fires, and it is impossible to tell 

 how far-reaching the effects were. The 

 springs soon dried up and the ponds 



