Trend analysis of salt load and evaluation of the frequency of water-quality measurements for the Gunnison, the Colorado, and the Dolores rivers in Colorado and Utah

Kircher, J. E.; Dinicola, Richard S.; Middelburg, R. F.

Abstract:

Monthly values were computed for water-quality constituents at four streamflow gaging stations in the Upper Colorado River basin for the determination of trends. Seasonal regression and seasonal Kendall trend analysis techniques were applied to two monthly data sets at each station site for four different time periods. A recently developed method for determining optimal water-discharge data-collection frequency was also applied to the monthly water-quality data. Trend analysis results varied with each monthly load computational method, period of record, and trend detection model used. No conclusions could be reached regarding which computational method was best to use in trend analysis. Time-period selection for analysis was found to be important with regard to intended use of the results. Seasonal Kendall procedures were found to be applicable to most data sets. Seasonal regression models were more difficult to apply and were sometimes of questionable validity; however, those results were more informative than seasonal Kendall results. The best model to use depends upon the characteristics of the data and the amount of trend information needed. The measurement-frequency optimization method had potential for application to water-quality data, but refinements are needed. (USGS)

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USGS Numbered Series

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28041

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Kircher, J. E.; Dinicola, Richard S.; Middelburg, R. F.

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ENGLISH

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v, 69 p. :ill., maps ;28 cm.

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U.S. Geological Survey : Open-File Services Section [distributor],

Citation Series:

Water-Resources Investigations Report

Citation Series Code:

WRI

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84-4048

Citation Search Results Text:

Trend analysis of salt load and evaluation of the frequency of water-quality measurements for the Gunnison, the Colorado, and the Dolores rivers in Colorado and Utah; 1984; WRI; 84-4048; Kircher, J. E.; Dinicola, Richard S.; Middelburg, R. F.