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Reach scale and evaluation methods as limitations for transient storage properties in streams and rivers
Author(s) -
Wörman Anders,
Wachniew Przemysław
Publication year - 2007
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2006wr005808
Subject(s) - tracer , streams , transient (computer programming) , residence time (fluid dynamics) , environmental science , water storage , groundwater , hydrology (agriculture) , calibration , scale (ratio) , tritiated water , soil science , computer science , mathematics , statistics , geology , geotechnical engineering , computer network , operating system , tritium , physics , quantum mechanics , geomorphology , nuclear physics , inlet
The value of stream tracer tests depends on appropriate experimental design, accurate evaluation methods and careful generalization of results with account taken to relevant limitations. This paper examines six calibration methods for transient storage models and effects of parameter errors on model generalizations. The residence time of transient storage and retardation factor varied a factor of 8 and 27, respectively, with the choice of method. Methods that emphasize the tail of the tracer breakthrough, such as optimization of log‐concentrations, are required to provide accurate estimates of transient storage parameters, whereas optimization using normal values can lead to substantial errors. Moment matching techniques require a solute mass‐recovery higher than about 70% for a reliable estimate of the storage capacity. The pumping model provided good estimates of the storage in the hyporheic zone under different stream discharges at two tracer test events with tritiated water in the Hobøl River, Norway. The accuracy of the evaluation of the transient storage parameters decreases with distance in the stream caused primarily by decreasing precision in the measurements and insufficient mass‐recovery. With distance, more and more time‐scales representing the hyporheic zone flow are also manifested as signatures of the tracer breakthrough. In a stream‐landscape groundwater system that is characterized by multiple residence time‐scales, stream tracer results are limited to specific reach distances and need to be supported by theory or other data when generalized to longer distances.