| Abstract: | Uncertainties are unavoidable in water-quality modeling and subsequent management decisions. Monte Carlo simulation and first-order uncertainty analysis (involving linearization at central values of the uncertain variables) have been frequently used to estimate probability distributions for water-quality model output due to their simplicity. Each method has its drawbacks: Monte Carlo simulation‘s is mainly computational time; and first-order analysis are mainly questions of accuracy and representativeness, especially for nonlinear systems and extreme conditions. An improved (advanced) first-order method is presented, where the linearization point varies to match the output level whose exceedance probability is sought. The advanced first-order method is tested on the Streeter-Phelps equation to estimate the probability distribution of critical dissolved-oxygen deficit and critical dissolved oxygen using two hypothetical examples from the literature. The advanced first-order method provides a close approximation of the exceedance probability for the Streeter-Phelps model output estimated by Monte Carlo simulation using less computer time - by two orders of magnitude - regardless of the probability distributions assumed for the uncertain model parameters. |
| Genre: | Article |
| ProdID: | 70017286 |
| Citation Author: | Melching, C. S.; Anmangandla, S. |
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| Citation End Page: | 805 |
| Citation Issue: | 5 |
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| Citation Language: | English |
| Citation Larger Work Title: | Journal of Environmental Engineering |
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| Citation Number Of Pages: | 15 |
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| Citation Search Results Text: | Improved first-order uncertainty method for water-quality modeling; 1992; Article; Journal; Journal of Environmental Engineering; Melching, C. S.; Anmangandla, S. |
| Citation Start Page: | 791 |
| Citation Volume: | 118 |
| Citation Year: | 1992 |
| Type: | citation/reference |
| Text: | Improved first-order uncertainty method for water-quality modeling; 1992; Article; Journal; Journal of Environmental Engineering; Melching, C. S.; Anmangandla, S. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Wed, 1 Jan 1992 00:00 -0600 |
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