34 ELEMENTARY FORESTRY. 



of the streams, hitherto equable and continuous, has become 

 fitful and uncertain. Floods and drouth alternating clearly 

 indicate that the natural physical conditions of the region 

 have been unduly disturbed. In winter and early spring, 

 when heavy masses of snow have been accumulated on treeless 

 precipitous slopes, snow and landslides frequently occur with 

 disastrous result to life and property. Even thus early in the 

 present season a considerable number of valuable lives have 

 been sacrificed in this manner." 



THE DISTRIBUTION OF WATER. 



The distribution or "run-off" of the water is often a more 

 important factor in its economy than the quantity available. 

 It is influenced by the surface conditions of the soil cover, by 

 the porosity and structure of the soil and by the slope. There 

 are two kinds of run-off, the surface run-off and the under- 

 ground run-off. The former is likely to do injury by eroding 

 the soil, while the latter is generally beneficial to vegetation 

 in the formation of springs and in raising the water level in 

 the soil. It is evident that the less surface drainage and the 

 more underground drainage the greater the spring-water sup- 

 ply and vice versa. We are, therefore, interested in deter- 

 mining the factors that increase underground drainage and 

 reduce the surface flow. 



It is plain that whatever retards the flow of water over the 

 land aids it in sinking into the soil. We find this exemplified 

 in swamps where the soft, rough ground retards the surface 

 flow, and in forests where the foliage checks the water in its 

 descent to the ground and the forest floor retards the surface 

 run-off. Theoretically such a cover should promote the flow 

 of springs and maintain the height of water in wells, and in 

 practice we find that this is often the case. In some cases 

 springs had entirely disappeared after the clearing of 

 near-by forests but have commenced their regular flow since 

 the trees have been allowed to grow again. Springs in turn 

 influence the flow of water in rivers so that forests about the 

 headwaters of streams often have a most potent effect in 

 maintaining their flow. There is in fact no influence of the 

 forest that is of greater importance in the distribution of water 



