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A neighborhood statistics model for predicting stream pathogen indicator levels
Because elevated levels of water-borne Escherichia coli in streams are a leading cause of water quality impairments in the U.S., water-quality managers need tools for predicting aqueous E. coli levels. Presently, E. coli levels may be predicted using complex mechanistic models that have a high degre...
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Published in: | Environmental monitoring and assessment 2015-03, Vol.187 (3), p.124-124, Article 124 |
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Main Authors: | , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Because elevated levels of water-borne
Escherichia coli
in streams are a leading cause of water quality impairments in the U.S., water-quality managers need tools for predicting aqueous
E. coli
levels. Presently,
E. coli
levels may be predicted using complex mechanistic models that have a high degree of unchecked uncertainty or simpler statistical models. To assess spatio-temporal patterns of instream
E. coli
levels, herein we measured
E. coli
, a pathogen indicator, at 16 sites (at four different times) within the Squaw Creek watershed, Iowa, and subsequently, the Markov Random Field model was exploited to develop a neighborhood statistics model for predicting instream
E. coli
levels. Two observed covariates, local water temperature (degrees Celsius) and mean cross-sectional depth (meters), were used as inputs to the model. Predictions of
E. coli
levels in the water column were compared with independent observational data collected from 16 in-stream locations. The results revealed that spatio-temporal averages of predicted and observed
E. coli
levels were extremely close. Approximately 66 % of individual predicted
E. coli
concentrations were within a factor of 2 of the observed values. In only one event, the difference between prediction and observation was beyond one order of magnitude. The mean of all predicted values at 16 locations was approximately 1 % higher than the mean of the observed values. The approach presented here will be useful while assessing instream contaminations such as pathogen/pathogen indicator levels at the watershed scale. |
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ISSN: | 0167-6369 1573-2959 |
DOI: | 10.1007/s10661-014-4228-1 |