Benchmarking inference methods for water quality monitoring and status classification

Hoseung Jung, Cornelius Senf, Philip Jordan, Tobias Krueger

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

River water quality monitoring at limited temporal resolution can lead to imprecise and inaccurate classification of physicochemical status due to sampling error. Bayesian inference allows for the quantification of this uncertainty, which can assist decision-making. However, implicit assumptions of Bayesian methods can cause further uncertainty in the uncertainty quantification, so-called second-order uncertainty. In this study, and for the first time, we rigorously assessed this second-order uncertainty for inference of common water quality statistics (mean and 95th percentile) based on sub-sampling high-frequency (hourly) total reactive phosphorus (TRP) concentration data from three watersheds. The statistics were inferred with the low-resolution sub-samples using the Bayesian lognormal distribution and bootstrap, frequentist t test, and face-value approach and were compared with those of the high-frequency data as benchmarks. The t test exhibited a high risk of bias in estimating the water quality statistics of interest and corresponding physicochemical status (up to 99% of sub-samples). The Bayesian lognormal model provided a good fit to the high-frequency TRP concentration data and the least biased classification of physicochemical status (< 5% of sub-samples). Our results suggest wide applicability of Bayesian inference for water quality status classification, a new approach for regulatory practice that provides uncertainty information about water quality monitoring and regulatory classification with reduced bias compared to frequentist approaches. Furthermore, the study elucidates sizeable second-order uncertainty due to the choice of statistical model, which could be quantified based on the high-frequency data.
Original languageEnglish
Article number261
Pages (from-to)1-17
Number of pages17
JournalEnvironmental Monitoring and Assessment
Volume192
Issue number4
Early online date2 Apr 2020
DOIs
Publication statusE-pub ahead of print - 2 Apr 2020

Keywords

  • Article
  • Water Framework Directive
  • Ecological status classification
  • Bayesian uncertainty quantification
  • Second-order uncertainty
  • High-frequency monitoring
  • Phosphorus

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