| Abstract: | The slope-area method can be used to calculate peak flood discharges when current-meter measurements are not possible. This calculation depends on several quantities, such as water-surface fall, that are subject to large measurement errors. Other critical quantities, such as Manning‘s n, are not even amenable to direct measurement but can only be estimated. Finally, scour and fill may cause gross discrepancies between the observed condition of the channel and the hydraulic conditions during the flood peak. The effects of these potential errors on the accuracy of the computed discharge have been estimated by statistical error analysis using a Taylor-series approximation of the discharge formula and the well-known formula for the variance of a sum of correlated random variates. The resultant error variance of the computed discharge is a weighted sum of covariances of the various observational errors. The weights depend on the hydraulic and geometric configuration of the channel. The mathematical analysis confirms the rule of thumb that relative errors in computed discharge increase rapidly when velocity heads exceed the water-surface fall, when the flow field is expanding and when lateral velocity variation (alpha) is large. It also confirms the extreme importance of accurately assessing the presence of scour or fill. ?? 1987. |
| Genre: | Article |
| ProdID: | 70014873 |
| Citation Author: | Kirby, W. H. |
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| Citation End Page: | 138 |
| Citation Issue: | 1-4 |
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| Citation Language: | English |
| Citation Larger Work Title: | Journal of Hydrology |
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| Citation Number Of Pages: | 14 |
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| Citation Search Results Text: | Linear error analysis of slope-area discharge determinations; 1987; Article; Journal; Journal of Hydrology; Kirby, W. H. |
| Citation Start Page: | 125 |
| Citation Volume: | 96 |
| Citation Year: | 1987 |
| Type: | citation/reference |
| Text: | Linear error analysis of slope-area discharge determinations; 1987; Article; Journal; Journal of Hydrology; Kirby, W. H. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Thu, 1 Jan 1987 00:00 -0600 |
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