THE EFFECT OF THE FOREST UPON WATERS 



159 



per cent ; floods in the rivers became 

 more rapid, channels were filled with 

 debris, and bridges were carried away. 

 In Sicily, deforestation has likewise had 

 the effect of raising the level of the 

 river beds ; in the province of Campo- 

 basso (Molise) cuttings made over one- 

 third of the land surface deepened the 

 beds of the streams greatly, and caused 

 the breaking down of the river banks 

 to such an extent that one-tenth of the 

 ground was carried away. Reforesta- 

 tion has produced opposite effects in 

 the province of Grosseto (Tuscany), 

 Avellino (Campania), and Sondrio 

 (Lombardy). In Sondrio reforestation 

 diminished the floods. Mr. Ponti also 

 cites the floods of the Adda in 1806 and 

 1817, and of the Malero, 1834, which 

 followed very closely upon deforesta- 

 tion. 



We will discuss at greater length 

 Mr. Lokhtine's paper, which treat? 

 above all of the action of forest veg- 

 etation on the flow of springs and 

 streams. This savant cites numerous 

 examples of streams that have dried up 

 and disappeared following deforesta- 

 tion. It is in this way, he says, that 

 the springs around Rome, Vienna, and 

 Constantinople disappeared after cut- 

 tings had been made on the hills that 

 surround these cities. 



A Roman aqueduct brought to Or- 

 leans water from hot springs. There is 

 not a trace left of these springs to-day. 

 Becquerel reported the case of a stream 

 of Caiman, in the commune of Labru- 

 guiere (Tarn), which in former times 

 furnished power for several fulling 

 mills ; after the deforestation of the 

 slopes of the Black Mountain, this 

 stream was subject to sudden floods 

 and its flow diminished to such a de- 

 gree that work could no longer be car- 

 ried on. After the denuded areas had 

 been reforested, the flow increased and 

 became more regular ; the mills were re- 

 opened and could be operated uninter- 

 ruptedly. 



The hills that surround Heilbronn 

 (Wurtemberg) are covered with a for- 

 est growth, which is subject to regular 

 cuttings made every twenty years. It 



has been declared that the flow from 

 the springs diminished when the soil 

 was denuded following a cutting, and 

 that it increased when the forest growth 

 had gained possession of the ground 

 again. 



Marchal cites similar cases in Switz- 

 erland. The Swiss engineer, R. Lau- 

 terburg, states that, for an equal area, 

 springs issuing from forested water- 

 sheds have a flow five to ten times 

 greater than those from denuded water- 

 sheds. According to the same author, 

 the destruction of the forests that took 

 place in the canton of Tessin during 

 the first half of the nineteenth century 

 reduced by more than one-quarter the 

 flow of the Adige during low-water pe- 

 riods. 



Messrs. Shriner and Copeland, who 

 mapped four townships around Monroe 

 (state of Wisconsin, United States) in 

 1904, observed that the percentage of 

 forested area in this region had been 

 reduced in a period of seventy years 

 from eighty-three to six per cent. The 

 water level of the rivers had lowered 

 steadily ; the consequences of deforesta- 

 tion had become more apparent than 

 ever since 1887. More than forty kilo- 

 meters of streams are dry during the 

 entire year ; numerous mills have ceased 

 to operate. 



In Kazan, on the tributaries of the 

 Sviyaga River, there were formerly 

 seventy mills which operated steadily. 

 Scarcely thirty are left, which are idle 

 during the summer for lack of water, 

 and are operated with one-third as 

 many millstones as formerly. 



The influence of forest vegetation on 

 the flow of springs and uniformity of 

 stream-flow is manifested very clearly, 

 says Mr. Tour sky, in the upper basin of 

 the Dnieper, where all the streams and 

 small rivers issue from forested territory 

 and have a regular and constant flow, 

 [n central Russia, on the contrary, de- 

 forestation has dried up the streams ; in 

 the grounds surrounding ancient ma- 

 norial houses, fish-ponds have dried tip 

 and there is no water in the parks, 

 where streams formerly flowed under 

 ornamental bridges of bizarre forms. 



