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Trends in the chemistry of precipitation and surface water in a national network of small watersheds

January 1, 1996

Trends in precipitation and surface water chemistry at a network of 15 small watersheds ( < 10 km2) in the USA were evaluated using a statistical test for monotonic trends (the seasonal Kendall test) and a graphical smoothing technique for the visual identification of trends. Composite precipitation samples were collected weekly and surface water samples were collected at least monthly. Concentrations were adjusted before trend analysis, by volume for precipitation samples and by flow for surface water samples. A relation between precipitation and surface water trends was not evident either for individual inorganic solutes or for solute combinations, such as ionic strength, at most sites. The only exception was chloride, for which there was a similar trend at 60% of the sites. The smoothing technique indicated that short-term patterns in precipitation chemistry were not reflected in surface waters. The magnitude of the short-term variations in surface water concentration was generally larger than the overall long-term trend, possibly because flow adjustment did not adequately correct for climatic variability. Detecting the relation between precipitation and surface water chemistry trends may be improved by using a more powerful sampling strategy and by developing better methods of concentration adjustment to remove the effects of natural variation in surface waters.

Citation Information

Publication Year 1996
Title Trends in the chemistry of precipitation and surface water in a national network of small watersheds
DOI
Authors Brent T. Aulenbach, R. P. Hooper, O.P. Bricker
Publication Type Article
Publication Subtype Journal Article
Series Title Hydrological Processes
Series Number
Index ID 70019315
Record Source USGS Publications Warehouse
USGS Organization