Ten rivers in America's future, from volume 2, the Report of the President's Water Resources Policy Commission

page 524

m Mobile Basis. Alabama-Coosa Basin Tombigbee-BIack Warrior Basin MAJOR RIVER SYSTEMS IN THE SOUTHEAST FIGURE 1 crops, or forest cover, and unless other measures are used to control runoff. The climate of the Alabama-Coosa Basin is warm and moist, Avith mild winters and long, hot summers. The frost-free season varies in length from 198 days in the northern valleys to 246 days in the southern part of the basin. Rainfall is abundant and well distributed throughout the year, with the wettest months occurring in winter and early spring. Mean annual rainfall is about 53 inches. Snow rarely falls except in the north where it may occur twice in a winter. Occasional heavy storms may bring from 2.5 to 4.0 inches of rain in a 1-hour period. This area lies in the path of recurring cyclonic storms which bring heavy rains, sometimes as much as 16 inches in 24 hours. Such storms are more prevalent in the lower basin. Though total rainfall over most of the area is adequate for crop production, there are dry periods during the sum- mer which adversely affect the yields of cultivated crops, hay, and pasture. Forests covered nearly this whole area at one time; now about 60 percent of the land is forested. 524