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Evaluation of Intra‐annual Variation in U.S. Geological Survey National Water Quality Assessment Ground Water Quality Data
Author(s) -
Rosen Michael R.,
Voss Frank D.,
Arufe Jorge A.
Publication year - 2008
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2007.0052
Subject(s) - groundwater recharge , environmental science , geological survey , sampling (signal processing) , water quality , hydrology (agriculture) , univariate , trend analysis , quality (philosophy) , groundwater , physical geography , statistics , geography , geology , multivariate statistics , aquifer , engineering , ecology , mathematics , paleontology , philosophy , geotechnical engineering , filter (signal processing) , epistemology , biology , electrical engineering
Assessment of ground‐water quality trends under the U.S. Geological Survey National Water‐Quality Assessment Program (NAWQA) included the analysis of samples collected on a quarterly basis for 1 yr between 2001 and 2005. The purpose of this quarterly sampling was to test the hypothesis that variations in the concentration of water‐quality parameters of selected individual wells could demonstrate that the intra‐annual variation was greater or less than the decadal changes observed for a trend network. Evaluation of more than 100 wells over this period indicates that 1 yr of quarterly sampling is not adequate to address the issue of intra‐annual variation because variations seem to be random and highly variable between different wells in the same networks and among networks located in different geographical areas of the USA. In addition, the data from only 1 yr makes it impossible to assess whether variations are due to univariate changes caused by land use changes, hydrologic variations due to variable recharge, or variations caused by ground‐water pumping. These data indicate that funds allocated to this activity can be directed to the collection of more effective trend data, including age dating of all wells in the NAWQA network using multiple techniques. Continued evaluation of data and updating of monitoring plans of the NAWQA program is important for maintaining relevance to national goals and scientific objectives.