Urbanization Effects on Streamflow in the Atlanta, Georgia Area

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Peters, Norman E.
Rose, Seth
Hatcher, Kathryn J.
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For the period from 1958 to 1996, streamflow and rainfall characteristics of a highly urbanized watershed were compared with less- urbanized and nonurbanized watersheds in the vicinity of Atlanta, Georgia. Water levels in several wells completed in surficial and crystalline-rock aquifers also were evaluated. Annual runoff coefficients (runoff as a fractional percentage of precipitation) ranged from 0.31 to 0.34 and were not significantly different for the urban stream (Peachtree Creek). Peak flows for the largest 25 stormflows at Peachtree Creek were 30 to 80 percent greater than peak flows for the other streams. A 2-day storm recession constant for Peachtree Creek was much larger, that is streamflow decreased more rapidly, than for the other streams. Average low flow of Peachtree Creek was 25 to 35 percent less than the other streams, possibly the result of decreased infiltration caused by the more efficient routing of stormwater and the paving of ground-water recharge areas. The timing of groundwater level variations was similar annually in each well, reflecting the seasonal recharge. Although water-level monitoring only began in the 1980s for the two urban wells, water levels displayed a notable decline compared to non-urban wells since then—this is attributed to decreased ground-water recharge in the urban watersheds due to increased imperviousness and related rapid storm runoff. Likewise, the increased urbanization from the 1960s to the 1990s of the Peachtree Creek watershed produced more runoff than urbanization in the less urbanized Big Creek and Sweetwater Creek watersheds.
Sponsored and Organized by: U.S. Geological Survey, Georgia Department of Natural Resources, Natural Resources Conservation Service, The University of Georgia, Georgia State University, Georgia Institute of Technology
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