Physical Setting And Hydrology

The Upper Chattahoochee River Basin covers 10,130 square miles from the southern slopes of the Blue Ridge mountains, in northeast Georgia, to the West Point Dam at the Georgia-Alabama state line. The flow length of this section is 250 river miles, generally to the southwest. The basin is narrow in relation to its length, the average width being less than 40 miles. Elevations in the Upper Chattahoochee Basin range from approximately 4,000 feet at the headwaters to approximately 635 feet at West Point Lake. Air temperature tends to be cooler in the mountains and warmer in the

Figure 10-2 Location map of Upper Chattahoochee Basin. (River miles shown are distances from Gulf of Mexico.)

southern areas of the basin; the annual air temperature averages about 16°C. Average annual rainfall in the basin is about 54 inches over the basin area of 3,440 square miles. The rainfall tends to be greatest in upland areas and in the southern region of the basin (Cherry et al., 1980; Lium et al., 1979).

Flow in the river is dependent on rainfall and regulation by the hydroelectric generating facilities at Buford Dam and Morgan Falls Dam. High-flow conditions usually occur in the spring and low-flow conditions in late autumn (Figure 10-3). The most pronounced changes in regulated flow have occurred as a result of the construction and operation of the Buford Dam since 1957. In the mid-1960s, the city of Atlanta and the Georgia Power Company modified the Morgan Falls Dam and Reservoir, just upstream of Atlanta, to provide a minimum flow of 750 cfs from Morgan

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