The concentration-discharge slope as a tool for water quality management

Bieroza, Magdalena Zofia and Heathwaite, Ann Louise and Bechmann, M. and Kyllmar, K. and Jordan, P. (2018) The concentration-discharge slope as a tool for water quality management. Science of the Total Environment, 630. pp. 738-749. ISSN 0048-9697

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Abstract

Recent technological breakthroughs of optical sensors and analysers have enabled matching the water quality measurement interval to the time scales of stream flow changes and led to an improved understanding of spatially and temporally heterogeneous sources and delivery pathways for many solutes and particulates. This new ability to match the chemograph with the hydrograph has promoted renewed interest in the concentration-discharge (c-q) relationship and its value in characterizing catchment storage, time lags and legacy effects for both weathering products and anthropogenic pollutants. In this paper we evaluated the stream c-q relationships for a number of water quality determinands (phosphorus, suspended sediments, nitrogen) in intensively managed agricultural catchments based on both high-frequency (sub-hourly) and long-term low-frequency (fortnightly-monthly) routine monitoring data. We used resampled high-frequency data to test the uncertainty in water quality parameters (e.g. mean, 95th percentile and load) derived from low-frequency sub-datasets. We showed that the uncertainty in water quality parameters increases with reduced sampling frequency as a function of the c-q slope. We also showed that different sources and delivery pathways control c-q relationship for different solutes and particulates. Secondly, we evaluated the variation in c-q slopes derived from the long-term low-frequency data for different determinands and catchments and showed strong chemostatic behaviour for phosphorus and nitrogen due to saturation and agricultural legacy effects. The c-q slope analysis can provide an effective tool to evaluate the current monitoring networks and the effectiveness of water management interventions. This research highlights how improved understanding of solute and particulate dynamics obtained with optical sensors and analysers can be used to understand patterns in long-term water quality time series, reduce the uncertainty in the monitoring data and to manage eutrophication in agricultural catchments.

Item Type:
Journal Article
Journal or Publication Title:
Science of the Total Environment
Additional Information:
This is the author’s version of a work that was accepted for publication in Science of the Total Environment. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Science of the Total Environment, 630, 2018 DOI: 10.1016/j.scitotenv.2018.02.056
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/2300/2311
Subjects:
ID Code:
123796
Deposited By:
Deposited On:
01 Mar 2018 13:42
Refereed?:
Yes
Published?:
Published
Last Modified:
24 Sep 2020 03:49