UNITED STATES DEPARTMENT OF AGRICULTURE July 29, 1926 Secretary of Agriculture_ Director of Scientific Work---- Director of Personnel and Business Adminis tration_____ Solicitor. Weather Bureau_- Bureau of Agricultural Economics---. Forest Service‒‒‒‒‒ Bureau of Chemistry Bureau of Soils‒‒‒‒‒ Fixed Nitrogen Research Laboratory- Office of Cooperative Extension Work- Federal Horticultural Board____ Packers and Stockyards Administration----- W. M. JARDINE. R. W. DUNLAP. WALTER G. CAMPBELL. C. W. WARBURTON. NELSON ANTRIM CRAWFORD. W. W. STOCK BERGER. CHARLES F. MARVIN, Chief. E. W. NELSON, Chief. THOMAS H. MACDONALD, Chief. LOUISE STANLEY, Chief. C. W. LARSON, Chief. F. G. COTTRELL, Director. E. W. ALLEN, Chief. C. B. SMITH, Chief. CLARIBEL R. BARNETT, Librarian. By WARD SHEPARD, Forest Inspector, Branch of Public Relations, Forest Service By WILLIAM B. GREELEY, Chief, Forest Service Now that the Mississippi floods have awakened us to the need for the most complete insurance possible against the recurrence of such catastrophes, it is essential that the true rôle of forests in flood control be recognized. Nothing will be gained by exaggerating the importance of that rôle. On the other hand, unless forests are permitted to play their part much will be lost. Floods have been a common scourge of the world since legendary times. The Mississippi Valley experienced great overflows of water before its forests had been touched by an ax. Forests can not prevent floods in the face of heavy, long-continued rains or the rapid melting of masses of snow. To control the immense volumes of water suddenly flung upon the earth under such circumstances, in their rush to the sea, we must rely mainly upon the levee or reservoir or diversion channel. But forests, well-sodded pastures, and terraced fields hold back more of the falling water and more of the soil than denuded woodlands, overgrazed hillsides, or eroded farms. This helpful influence can seldom be separated from the other factors affecting the flow of a stream so that it can be measured by itself in exact terms. It may be greater or less on a particular watershed, by reason of the soil, topography, or climate, but when exerted on all the watersheds of a great river basin it is enormous. Forests are better binders of the soil and better surface reservoirs of water than any other form of vegetation on the face of the earth; and the 160,000,000 acres of actual or potential forest land draining into the Mississippi have a real 67677°-28-1 |