Figure 16. -Typical open farm 

 ditch, which may be fed by under- 

 surface tile as well as by surface 

 drainage. 



J. S. BUREAU OF AGRICULTURAL ENGINEERING 



Figure 17. Muck land drained dry 

 and destroyed by fire. 



OF BIOLOGICAL SURVEY 





Figure 18. This large trunk ditch 

 indicates what a vast quantity of 

 water is rushed to the rivers. 



J. S. BUREAU OF AGRICULTURAL ENGINEERING 



Figure 19. Overdrainage, flashy 

 wet-season run-off, eroded banks; 

 diminished ground-water supply, 

 lessened seepage, scant dry -season 

 flow. 



U. S. SOIL CONSERVATION SERVICE 



