| Abstract: | The effects of flood-detention reservoirs on peak discharges along downstream reaches in six urban drainage basins in Gwinnett County, Georgia, were studied during 1986-93 using the U.S. Geological Survey‘s Distributed Routing Rainfall-Runoff Model (DR3M). Short-term rainfall-runoff data were collected at selected stations in six urban drainage basins in Gwinnett County. The basins range in size from 0.10 to 0.37 square miles and contain from 15- to 35- percent impervious areas. Each basin contains from two to six flood-detention reservoirs. The DR3M was calibrated using short-term rainfall-runoff data collected (1986-92) at each station. The model then was used to simulate long-term (1898-1980) peak discharges for these stations for conditions representing various amounts of detention ranging from the existing condition with all flood-detention reservoirs in place to the natural condition with no reservoirs. Flood-frequency relations were developed from the simulated annual peak discharges for each of these conditions by fitting the logarithms of the annual peak discharge data to a Pearson type III distribution curve. The effect of each flood-detention reservoir on peak discharges downstream was determined by comparison of peak discharges simulated with and without the flood-detention reservoirs. The cumulative effect of all flood-detention reservoirs in a basin on peak discharges downstream was determined by comparison of peak discharges for a flood with a given recurrence interval simulated with and without the reservoirs. Results of these comparisons indicate that removal of an individual flood-detention reservoir during simulations changes peak discharges from - 1 to 24 percent for the 2-year recurrence interval, from - 1 to 27 percent for the 10-year recurrence interval, and from -2 to 31 percent for the 100-year recurrence interval. The cumulative effect of removing all of the reservoirs from each of the six basins during simulation increases peak discharges from 1 to 38 percent for the 2-year recurrence interval, from 1 to 37 percent for the l O-year recurrence interval, and from 3 to 31 percent for the 100-year recurrence interval. In this study of six basins, several factors influenced the effect of flood-detention reservoirs on peak discharges downstream. The contributing drainage area, the maximum storage capacity, the outflow-structure capacity, and the elevation-to-storage relation of the flood-detention reservoir affected peak discharges in several basins. The location in the drainage basin and number of flood-detention reservoirs affected peak discharges in some basins. |
| Genre: | USGS Numbered Series |
| ProdID: | 27670 |
| Citation Author: | Hess, G. W.; Inman, E. J. |
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| Citation Language: | ENGLISH |
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| Citation Phsyical Description: | v, 35 p. :ill., maps ;28 cm. |
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| Citation Publisher: | U.S. Geological Survey, |
| Citation Series: | Water-Resources Investigations Report |
| Citation Series Code: | WRI |
| Citation Series Number: | 94-4004 |
| Citation Search Results Text: | Effects of urban flood-detention reservoirs on peak discharges in Gwinnett County, Georgia; 1994; WRI; 94-4004; Hess, G. W.; Inman, E. J. |
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| Citation Year: | 1994 |
| Type: | citation/reference |
| Text: | Effects of urban flood-detention reservoirs on peak discharges in Gwinnett County, Georgia; 1994; WRI; 94-4004; Hess, G. W.; Inman, E. J. |
| URL (THUMBNAIL): | http://pubs.usgs.gov/wri/1994/4004/report-thumb.jpg |
| URL (DOCUMENT): | http://pubs.usgs.gov/wri/1994/4004/report.pdf |
| Date Other: | Sat, 1 Jan 1994 00:00 -0600 |
| Publisher: | U.S. Geological Survey, |
