16 APPALACHIAN AND WHITE MOUNTAIN WATERSHEDS. 



coggin are centered at Berlin, N. H., and Rumford Falls, Livermore 

 Falls, Lewiston, and Brunswick, Me. In the 167 miles between tide 

 water and Umbagog Lake there is a fall of 1,235 feet, of which 610 

 feet is used, corresponding to about 120,000 net horsepower. Of the 

 remaining 625 feet, possibly two-thirds can be utilized, correspond- 

 ing to 60,000 net horsepower, and bringing the total to about 180,000 

 horsepower, or approximately three times that of the Merrimac 

 without its tributaries. 



The streams of the White Mountains, therefore, furnish power for 

 great industries, and are the basis of development for many prosper- 

 ous cities in all the New England States but one. These streams are 

 all influenced vitally in flow by the forest which covers the slopes of 

 the White Mountains. 



APPALACHIAN MOUNTAINS IMPORTANT TO NAVIGATION. 



Timber supply and water power are not the only factors which 

 make the Appalachian Mountains commercially important. All the 

 water gathered by the Southern Appalachian and White Mountains 

 flows to the sea through navigable rivers. With greater elevation 

 than other parts of the watersheds the mountains receive much 

 more rainfall, and with their cooler climate the evaporation is less; 

 hence there is more water to be discharged. Because of the pre- 

 cipitous slopes of the mountains the run-off is far more rapid than in 

 other sections. To this must be added the fact that in the Southern 

 Appalachians there are no natural lakes to gather the flood waters 

 and equalize the flow of streams. There are thus two powerful 

 influences contributing to an extremely heavy discharge from these 

 mountains, and two more contributing to an extremely rapid run-off. 

 Combined, these tend to produce great variability in the flow of all 

 streams which have a large part of their watersheds in the mountains. 



A large regular discharge coming from springs is desirable, a variable 

 surface run-off is bad from every point of view, and so far as possible 

 should be remedied. The variability of the present flow of Southern 

 Appalachian streams is so great that though the average volume 

 would make the streams constantly navigable, they are at extreme 

 flood during a few weeks of the year and at extreme low water during 

 a much longer period. Their low-water stage causes interference 

 and loss to business through the cessation of navigation; their high- 

 water stage often entails damage and loss from floods. 



There is but one natural factor which tends to equalize the flow of 

 Southern Appalachian streams — the forest. In one continuous man- 

 tle, covering ridges, slopes, and coves, it has for untold ages been 

 nature's sole reliance for the proper distribution of rainfall. If storm 

 and deluge came, the downpour fell upon a foot-deep layer of humus, 

 which readily received many times its own weight of water before it 

 allowed any to escape. When filled, it passed on the excess to a soil 

 made porous by myriads of penetrating roots and countless tons of 

 vegetable mold . If drought came, it found the humus and soil filled 

 as a reservoir with water for the steady supply of springs and streams 

 through weeks or months of rainless weather. 



The original forest, then, with its characteristic conditions of shade, 

 undergrowth, humus, and soil, was an effectual distributer of moisture. 



