| Abstract: | A discussion is presented of several parametric and nonparametric statistical techniques for detecting trends in water-chemistry data. The need for reducing the effects of natural variability was recognized and accomplished through the use of regression equations. This report describes the use of storm mass-transport data as a means of improving regression relations, thereby reducing data variability. Selected statistical techniques were applied to 1 urban watershed in Texas, 2 urban watersheds in Minnesota, and 3 rural watersheds in Illinois. For the urban watersheds, single- and paired-site data-collection strategies were considered. The paired-site strategy was much more effective than the single-site strategy for detecting trends. For the rural watersheds, none of the selected techniques proved to be effective at identifying trends, primarily because of a small degree of management-practice implementation, potential errors introduced through the estimation of storm mass transport, and small sample sizes. A Monte Carlo sensitivity analysis was used to determine the percent change in chemistry that could be detected for each watershed. In most instances, the use of regressions improved the ability to detect trends. (USGS) |
| Genre: | USGS Numbered Series |
| ProdID: | 21301 |
| Citation Author: | Walker, J. F. |
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| Citation Language: | ENGLISH |
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| Citation Phsyical Description: | iv, 16 p. :ill. ;28 cm. |
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| Citation Publisher: | U.S. Geological Survey ;
Books and Open-File Reports [distributor], |
| Citation Series: | Open-File Report |
| Citation Series Code: | OFR |
| Citation Series Number: | 93-130 |
| Citation Search Results Text: | Techniques for detecting effects of urban and rural land-use practices on stream-water chemistry in selected watersheds in Texas, Minnesota,and Illinois; 1993; OFR; 93-130; Walker, J. F. |
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| Citation Year: | 1993 |
| Type: | citation/reference |
| Text: | Techniques for detecting effects of urban and rural land-use practices on stream-water chemistry in selected watersheds in Texas, Minnesota,and Illinois; 1993; OFR; 93-130; Walker, J. F. |
| URL (THUMBNAIL): | http://pubs.usgs.gov/of/1993/0130/report-thumb.jpg |
| URL (DOCUMENT): | http://pubs.usgs.gov/of/1993/0130/report.pdf |
| Date Other: | Sat, 1 Jan 1994 00:00 -0600 |
| Publisher: | U.S. Geological Survey ;
Books and Open-File Reports [distributor], |
