Abstract
Abstract Monitoring provides data and information necessary for water quality assessment, but often it is prohibitive, especially when frequent sampling is required. In this study, we explored feasible sampling intervals for improved efficiency of nonpoint source (NPS) pollution assessment. We compared NPS pollutant loads calculated with concentration samples collected at 1, 2, 3, 4, and 6-hour intervals for the first 24 hours of 13 storm events and investigated the effect of different sampling intervals on load estimation for three watersheds that have different land uses. When compared to load estimates made from concentrations sampled at the reference (1-hour) interval, differences in load estimates were less than 10% in the cases of the 2-hour and 3-hour intervals in the urbanized and agricultural watersheds, respectively, except in the case of suspended solids (SS). When it comes to the total load estimation, up to 3-hour interval sampling provided load estimates with acceptable accuracy, except for SS. Thus, the 3-hour sampling interval was considered feasible for long-term pollutant load assessment, while the 2-hour sampling interval was suggested for SS. Such findings are expected to facilitate NPS pollution assessment by providing information required to improve monitoring efficiency.
Highlights
This study showed that the sampling intervals of equal to or less than 3 hours could provide Nonpoint source (NPS) pollutant load estimates with an acceptable accuracy of 10% difference in a watershed (i.e., PYJ) with mixed land uses including agriculture and urban
The urbanized watershed, JS, required more frequent sampling as pollutant loads tend to concentrate in the beginning of a storm event
This study demonstrated that there is a trade-off between the accuracy and sampling intervals of NPS pollutant monitoring, and the 3-hour sampling interval could improve monitoring efficiency while providing acceptable long-term NPS load estimates, except for SS
Summary
Nonpoint source (NPS) pollution is closely associated with hydrological processes including the generation and. Water Supply | 21.2 | 2021 variable pollutant generation and transport processes, and it is recommended as a method to quantify NPS pollution (Halliday et al ; Frazar et al ). Such a monitoring strategy is required to establish control measures and identify the characteristics of NPS pollutants (Kirchner et al ; Kal et al ). Factors that affect uncertainty in data produced by automated samplers (sampling threshold, sampling interval, discrete or composite sample type) have been evaluated and discussed (e.g., Shih et al ; Miller et al , ; Stone et al ; Harmel et al, , , b; King & Harmel , ; Harmel & King ; Harmel et al )
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