Technical Note: Assessing a 24/7 solution for monitoring water quality loads in small river catchments

Philip Jordan, R. Cassidy

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Quantifying nutrient and sediment loads in catchments is difficult owing to diffuse controls related to storm hydrology. Coarse sampling and interpolation methods are prone to very high uncertainties due to under-representation of high discharge, short duration events. Additionally, important low-flow processes such as diurnal signals linked to point source impacts are missed. Here we demonstrate a solution based on a time-integrated approach to sampling with a standard 24 bottle autosampler configured to take a sample every 7 h over a week according to a Plynlimon design. This is evaluated with a number of other sampling strategies using a two-year dataset of sub-hourly discharge and phosphorus concentration data. The 24/7 solution is shown to be among the least uncertain in estimating load ( inter-quartile range: 96% to 110% of actual load in year 1 and 97% to 104% in year 2) due to the increased frequency raising the probability of sampling storm events and point source signals. The 24/7 solution would appear to be most parsimonious in terms of data coverage and certainty, process signal representation, potential laboratory commitment, technology requirements and the ability to be widely deployed in complex catchments.
LanguageEnglish
Pages3093-3100
JournalHydrology and Earth System Sciences
Volume15
Issue number10
DOIs
Publication statusPublished - 2011

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catchment
water quality
sampling
monitoring
river
point source
integrated approach
low flow
interpolation
hydrology
phosphorus
nutrient
sediment
method
laboratory

Cite this

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abstract = "Quantifying nutrient and sediment loads in catchments is difficult owing to diffuse controls related to storm hydrology. Coarse sampling and interpolation methods are prone to very high uncertainties due to under-representation of high discharge, short duration events. Additionally, important low-flow processes such as diurnal signals linked to point source impacts are missed. Here we demonstrate a solution based on a time-integrated approach to sampling with a standard 24 bottle autosampler configured to take a sample every 7 h over a week according to a Plynlimon design. This is evaluated with a number of other sampling strategies using a two-year dataset of sub-hourly discharge and phosphorus concentration data. The 24/7 solution is shown to be among the least uncertain in estimating load ( inter-quartile range: 96{\%} to 110{\%} of actual load in year 1 and 97{\%} to 104{\%} in year 2) due to the increased frequency raising the probability of sampling storm events and point source signals. The 24/7 solution would appear to be most parsimonious in terms of data coverage and certainty, process signal representation, potential laboratory commitment, technology requirements and the ability to be widely deployed in complex catchments.",
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Technical Note: Assessing a 24/7 solution for monitoring water quality loads in small river catchments. / Jordan, Philip; Cassidy, R.

In: Hydrology and Earth System Sciences, Vol. 15, No. 10, 2011, p. 3093-3100.

Research output: Contribution to journalArticle

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AU - Cassidy, R.

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