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Sampling strategy to describe the temporal hydrochemical characteristics of an alpine proglacial stream
Author(s) -
Gurnell A. M.,
Brown G. H.,
Tranter M.
Publication year - 1994
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.3360080102
Subject(s) - sampling (signal processing) , environmental science , meltwater , linear regression , hydrology (agriculture) , autocorrelation , electrical resistivity and conductivity , statistics , soil science , meteorology , geology , mathematics , snow , geography , computer science , geotechnical engineering , filter (signal processing) , computer vision , engineering , electrical engineering
A hierarchical sampling programme (including continuous monitoring, twice‐daily sampling and sampling at hourly intervals over selected 24 hour periods) was devised to support hydrochemical and hydrological research programmes on an alpine proglacial stream. The rationale for the research and for the sampling programme are explained and the hydrochemical time series generated over an ablation season are analysed to assess the degree to which they support the study aims. It appears that there is no satisfactory substitute for the chemical analysis of at least two water samples taken at approximately maximum and minimum discharge every day, if seasonal variations in meltwater chemistry are to be effectively characterized. Such time series data can be used to estimate Box‐Jenkins transfer function‐noise models between particular solutes (SO 2− 4 , Ca 2+ , Mg 2+ , Na + and possibly K + ) and either discharge or electrical conductivity, which can then be used to fill any short gaps in the data. This approach is not satisfactory even for filling short gaps in the twice‐daily determinations of pH, HCO − 3 and NO − 3 . At the diurnal time‐scale (based on hourly determinations over 24 hour periods) electrical conductivity seems to provide a good surrogate for most of the solutes studied. HCO − 3 , SO 2− 4 , Ca 2+ and Mg 2+ were found to be particularly strongly related to electrical conductivity and there was little if any significant serial autocorrelation in the residuals from all of the simple linear regression relationships that were estimated between individual species and conductivity. It is concluded that the hierarchical sampling design was suitable for the purposes of the study, and that the continuous monitoring of electrical conductivity provides excellent supporting information to the chemical analysis of water samples if it is used carefully as a means of short term calibration and interpolation of the solute record.