A NATIONAL PLAN FOR AMERICAN FORESTRY 



351 



brush cover. Some of the coastal dunes are in motion because of 

 distrubance to the cover or of the inability of vegetation to become 

 established. Occasionally dune movement threatens roads or other 

 improvements, but for the most part, the moving dunes do little 

 damage. 



FACTORS IN STREAM FLOW AND EROSION 



PRECIPITATION 



The East Gulf States receive about 55 inches of rainfall annually. 

 Rains occur throughout the year. Heavy torrential rains are com- 

 mon close to the Gulf and also, to a lesser degree, in the interior. 



SOUTH 



MAJOR INFLUENCE 

 MODERATE INFLUENCE 

 SLIGHT INFLUENCE 



DRAINAGE BASINS 



(T) SAVANNAH RIVER (f) TOMBIGBEE RIVER 



ALTAMAHA RIVER PEARL RIVER 



@ APAUACHICOLA RIVER (?) SUWANNEE RIVER 

 @ ALABAMA RIVER 



FIGURE 5. East Gulf drainages. 



Weather Bureau precipitation records for the Alabama River drainage 

 show a wide variation in the quantity of rainfall that occurs in indi- 

 vidual storms. In one instance in the basin of the Coosa River, a 

 major tributary in central Alabama, the rainfall ranged from 8 to 20 

 inches. 



Rainfall exceeding 2 inches in 24 hours is not uncommon; indeed, 

 summer rains of more than 5 inches in a 12-hour period have been 

 recorded. Storms of such intensity, particularly if the soil happens 

 to contain much moisture at the time, result in major floods and 

 widespread erosion. Some storms cover a relatively narrow belt, 

 others are widespread. Some storms, principally in the fall, originate 

 as tropical hurricanes. Most of the rains causing severe floods come 

 in the winter or spring. 



