title: A multivariate based event detection method and performance comparison with two baseline methods.
abstract: Early warning systems have been widely deployed to protect water systems from accidental and intentional contamination events. Conventional detection algorithms are often criticized for having high false positive rates and low true positive rates. This mainly stems from the inability of these methods to determine whether variation in sensor measurements is caused by equipment noise or the presence of contamination. This paper presents a new detection method that identifies the existence of contamination by comparing Euclidean distances of correlation indicators, which are derived from the correlation coefficients of multiple water quality sensors. The performance of the proposed method was evaluated using data from a contaminant injection experiment and compared with two baseline detection methods. The results show that the proposed method can differentiate between fluctuations caused by equipment noise and those due to the presence of contamination. It yielded higher possibility of detection and a lower false alarm rate than the two baseline methods. With optimized parameter values, the proposed method can correctly detect 95% of all contamination events with a 2% false alarm rate.
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China. Electronic address: shumingliu@tsinghua.edu.cn.
authors.forename: Shuming
authors.initials: S
authors.lastname: Liu
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Kate
authors.initials: K
authors.lastname: Smith
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Han
authors.initials: H
authors.lastname: Che
mesh_terms: D000465:Algorithms; D003199:Computer Systems; D004784:Environmental Monitoring / Q000379:methods*; D015999:Multivariate Analysis; D015203:Reproducibility of Results; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000592:standards; D014877:Water Pollution, Chemical / Q000032:analysis* / Q000517:prevention & control; D060753:Water Quality / Q000592:standards; D014881:Water Supply / Q000592:standards
chemical_list: D014874:Water Pollutants, Chemical
keywords: Contaminant classification; Conventional sensor; Early warning system; Euclidean distance; Pearson correlation; Water quality