BYBEE-MALOTT : THE FLOOD OP VMo 



221 



increases the immediate run-off, makes the flood stages higher, 

 and the low water stages lower. 



14. Deforestation causes an increase of soil erosion. 



15. Natural reservoirs on large streams tend to make the flow 

 constant. 



16. Where relief and geologic structure permit, artificial 

 reservoirs may be constructed, holding back part of the flood waters 

 which may be used for municipal supply, power and local irrigation. 



17. It is a demonstrated fact that irrigation in a humid climate 

 will greatly increase the crops and guard against drouth. 



18. Along much of its course White River flows two miles 

 to get one. In many places a two-mile stretch of river could be 

 reduced to less than a mile by making a cut-off. 



19. In many cases a series of dynamite charges could be used 

 to open up the new channel instead of the expensive method of 

 dredging. 



20. Shortening the course increases the fall, which will be 

 distributed up and down the channel. 



21. By doubling the velocity, the transporting power is in- 

 creased sixty-four times. 



22. As soon as the water spreads out over the. banks it takes 

 a more direct course, thus having its velocity increased. However, 

 the friction is greater and tends to check the current. 



23. A meander increases in size up to a certain stage and then 

 the current which has been cutting on either side of the neck meets 

 and a cut-off is perfected. 



24. A cut-off generally throws the current to the opposite 

 side of the stream, thus starting a new meander. 



25. Stumps, trees, hay stacks, posts, and buildings on the 

 flood plain may cause the current to cut holes. 



26. Under the top soil which is from one to ten feet in depth 

 is a layer of sand and gravel, which is easily moved by running water, 

 causing the top soil to cave or fall in. 



27. This gravel and sand shows that the stream has been 

 shifting back and forth across the valley for a long time. 



28. These beds of sand and gravel were formerly sand and gravel 

 bars and in many cases show the structure. 



29. Sand and gravel were deposited in areas up to 80 or 100 

 acres, and from a few inches up to ten feet in depth. 



30. As a rule this sand was deposited upon good farming land, 



31. Silt was deposited at the junction of the two forks in 

 greater quantitie^^ than elsewhere. The next largest nrea of silt 



