378 A NATIONAL PLAN FOR AMERICAN FORESTRY 



basin on Mississippi floods, the Federal interest predominates. 

 Good fire control and simple forestry measures will maintain good 

 watershed conditions. 



In the uplands portion of the basin, erosion due to farming and 

 pasturage has affected very large areas and is contributing greatly 

 to land abandonment. The eroded soil is being sluiced into the 

 Mississippi River, constituting an added load to a stream that is 

 notorious for the frequent shifts of its channel and for its sand bars 

 and shoals, and necessitating heavy expenditures for dredging to 

 maintain a navigable channel. Abnormal surface run-off, increased 

 by cultivation, swells the flood crests. 



The extensive erosion that is now taking place on the silt uplands 

 calls for definite action. One step would be to prohibit clearing of 

 slopes the grades of which exceed 15 percent and to reforest slopes of 

 this grade that have been used for agriculture. Another would be to 

 reduce pasturage on slopes. Action of this kind would call either for 

 public regulation of forest land or for public ownership of something 

 like 7 million acres of land. The Federal aspects of the problem are 

 far more important than the local aspects. 



Possibly a half million acres should be planted in order to insure 

 prompt control of erosion and betterment of conditions. Planting 

 alone, however, will not hold the soil where great gullies have formed ; 

 the correction of such gullies will require check dams, soil-saving 

 dams, seeding to grasses and weeds as a temporary aid to forest 

 planting, and correction of stream channels. Such extra work will 

 be required on 250,000 acres of the most severely eroded land. 



THE OHIO RIVER BASIN 



The Ohio and its tributaries compose one of the most important 

 watersheds in the United States. Although its area of 203,782 square 

 miles is only 16.5 percent of the whole Mississippi River system, the 

 Ohio and lower Mississippi alone can produce a great flood without 

 assistance from the upper Mississippi River or the other tributaries, 

 the latter usually being in moderate flow when the two greater rivers 

 are in flood. 36 The Ohio is the largest eastern tributary of the 

 Mississippi, and contributes on the average 300,000 second-feet to 

 the flow of the greater river. Within its borders about 17,600,000 



Eeople or 14.3 percent of our population reside. The region contains 

 ne farm lands, great natural resources, industrial cities, and good 

 markets. The boundaries of the Ohio River Basin in relation to the 

 portions of 14 States which it drains are shown in figure 9. 



TOPOGRAPHY 



Wide extremes of surface are exhibited by the Ohio River Basin. 

 In the northern and northwestern portions, level to gently rolling 

 agricultural lands predominate on the drainages of the Wabash, 

 Miami, and Scioto Rivers. The elevation varies from about 300 feet 

 in the Wabash bottoms and 800 feet in eastern Illinois to 1,000 to 

 1,200 feet above sea level in Ohio. South of these level to rolling 

 lands, although the general elevation does not gain, the country be- 



Frankenfield, H. C., 1923 The Spring Floods of 1922. Monthly Weather Review Supplement No. 

 22, p. 5. 



