| Abstract: | Methods for estimating daily mean discharges for selected flow durations and flood discharge for selected recurrence intervals at ungaged sites in central Idaho were applied using data collected at streamflow-gaging stations in the area. The areal and seasonal variability of discharge from ungaged drainage basins may be described by estimating daily mean discharges that are exceeded 20, 50, and 80 percent of the time each month. At 73 gaging stations, mean monthly discharge was regressed with discharge at three points—20, 50, and 80—from daily mean flow-duration curves for each month. Regression results were improved by dividing the study area into six regions. Previously determined estimates of mean monthly discharge from about 1,200 ungaged drainage basins provided the basis for applying the developed techniques to the ungaged basins. Estimates of daily mean discharges that are exceeded 20, 50, and 80 percent of the time each month at ungaged drainage basins can be made by multiplying mean monthly discharges estimated at ungaged sites by a regression factor for the appropriate region. In general, the flow-duration data were less accurately estimated at discharges exceeded 80 percent of the time than at discharges exceeded 20 percent of the time. Curves drawn through the three points for each of the six regions were most similar in July and most different from December through March.
Coefficients of determination of the regressions indicate that differences in mean monthly discharge largely explain differences in discharge at points on the daily mean flow-duration curve. Inherent in the method are errors in the technique used to estimate mean monthly discharge.
Flood discharge estimates for selected recurrence intervals at ungaged sites upstream or downstream from gaging stations can be determined by a transfer technique. A weighted ratio of drainage area times flood discharge for selected recurrence intervals at the gaging station can be used to estimate flood discharge at the ungaged site. Best results likely are obtained when the difference between gaged and ungaged drainage areas is small. |
| Genre: | USGS Numbered Series |
| ProdID: | 28046 |
| Citation Author: | Kjelstrom, L. C. |
| Citation Contributing Office: | Idaho Water Science Center |
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| Citation Language: | English |
| Citation Larger Work Title: | |
| Citation LatN: | 47.061 |
| Citation LatS: | 43.8602 |
| Citation LonE: | -112.8885 |
| Citation LonW: | -117.2503 |
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| Citation No Pagination: | |
| Citation Number Of Pages: | 14 |
| Citation Online Only Flag: | |
| Citation Phsyical Description: | iii, 10 p. |
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| Citation Public Comments: | Prepared in cooperation with U.S. Bureau of Indian Affairs |
| Citation Publisher: | U.S. Geological Survey |
| Citation Series: | Water-Resources Investigations Report |
| Citation Series Code: | WRI |
| Citation Series Number: | 94-4120 |
| Citation Search Results Text: | Methods for estimating selected flow-duration and flood-frequency characteristics at ungaged sites in Central Idaho; 1998; WRI; 94-4120; Kjelstrom, L. C. |
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| Citation Year: | 1998 |
| Type: | citation/reference |
| Text: | Methods for estimating selected flow-duration and flood-frequency characteristics at ungaged sites in Central Idaho; 1998; WRI; 94-4120; Kjelstrom, L. C. |
| URL (THUMBNAIL): | http://pubs.usgs.gov/wri/1994/4120/report-thumb.jpg |
| URL (DOCUMENT): | http://pubs.usgs.gov/wri/1994/4120/report.pdf |
| Date Other: | Mon, 1 Feb 1999 00:00 -0600 |
| Publisher: | U.S. Geological Survey |
