Monday, April 21, 2008

Peachtree Creek
Peachtree Creek is a major stream in Atlanta. It is located entirely within both the city and Fulton County, Georgia, and flows almost due west into the Chattahoochee River just south of Vinings. Like other "Peachtree" names in the area, the name is most likely a corruption of "pitch tree", from the area's many pines and their sticky sap.
Its two major tributaries are North Fork Peachtree Creek and South Fork Peachtree Creek. The northern fork begins at the edge of Gwinnett County and flows southwest, almost perfectly parallel to Interstate 85 through DeKalb County. It ends at its confluence with the southern fork, next to where the highway meets Georgia 400. The southern fork begins in Clarkston and flows west, crossing under part of the Stone Mountain Expressway and quickly back again, west (inside) of the Perimeter. The southern edge of its watershed borders the Eastern Continental Divide.
Since 1912, the river gauge on Peachtree Creek is located where it crosses Northside Drive just east of Interstate 75, just northwest of the Brookwood Split (where Interstate 85 leaves 75). It is located at 33°49′10″N, 84°24′28″W, at 764 feet or 233 meters above mean sea level. A one-inch (25.4 mm) rainfall puts approximately 1.5 billion gallons or almost 6 billion liters into the watershed, by USGS calculations. That watershed (above the gauge only) is 86.8 square miles or 224.8 square kilometers. There is also water quality monitoring equipment there, all transmitted to GOES weather satellites and back down to the USGS in real time. Prior to this current system, daily flow and water quality sampling were done as far back as 1958 and 1959, respectively. Records for this site are maintained by the USGS Georgia Water Science Center.
Flood stage is 17.0 feet or 5.2 meters depth, and due to the heavy urbanization in the area, it often reaches above this mark during heavy storms. Peachtree Creek suffered massive flooding after Hurricane Frances was followed by Hurricane Ivan in September 2004. It reached its highest official flood record ever, which actually washed away its gauge. Late on September 16th, it reached a stage of 22.63 feet or 6.90 meters, a flow of 14,200 cubic feet (106,223 gallons) or 402 cubic meters (402,100 liters) per second, and a width of 450 feet or 137 meters. This is about ten times its normal width, three times its normal speed, and 300 times its normal flow.
The worst flood ever occurred in 1919, when on January 29th it reached a flow of about 21,000 cubic feet (160,000 gallons) or 600 cubic meters (600,000 liters) per second. Another occurred in 1912 just above the 2004 event, another in 1915 just below it. (Prior to the 1940s, there are no records for depth.) Base flow for the stream is about 67 cubic feet per second, and a depth of about 3 feet or 0.9 meters.
Peachtree Creek is also an important part of the area history. Fort Peachtree was built near the creek and the Chattahoochee River to guard against the Cherokee, who were in the Cherokee County territory northwest of the river. During the American Civil War, the Battle of Peachtree Creek was a major battle of the Atlanta Campaign. Pace's Ferry was built across the river near the creek, and Paces Ferry Road still runs roughly parallel to the creek.
Other major creeks in Atlanta include Nancy Creek (which its meets at its end), and Proctor Creek.

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