Paper No. JAWRA-12-0058-P of the Journal of the American Water Resources Association (JAWRA). Discussions are open until six months from print publication.
Influence of Sampling Frequency on Estimation of Annual Total Phosphorus and Total Suspended Solids Loads1
Article first published online: 7 SEP 2012
© 2012 American Water Resources Association
JAWRA Journal of the American Water Resources Association
Volume 48, Issue 6, pages 1258–1275, December 2012
How to Cite
Jones, A. S., Horsburgh, J. S., Mesner, N. O., Ryel, R. J. and Stevens, D. K. (2012), Influence of Sampling Frequency on Estimation of Annual Total Phosphorus and Total Suspended Solids Loads. JAWRA Journal of the American Water Resources Association, 48: 1258–1275. doi: 10.1111/j.1752-1688.2012.00684.x
- Issue published online: 3 DEC 2012
- Article first published online: 7 SEP 2012
- Received March 2, 2012; accepted July 17, 2012.
- nutrients, monitoring;
- sampling frequency;
- total phosphorus;
- suspended sediment;
- load estimation
Abstract: The determination of sediment and nutrient loads is typically based on the collection and analysis of grab samples. The frequency and regularity of traditional sampling may not provide representation of constituent loading, particularly in systems with flashy hydrology. At two sites in the Little Bear River, Utah, continuous, high-frequency turbidity was used with surrogate relationships to generate estimates of total phosphorus and total suspended solids concentrations, which were paired with discharge to estimate annual loads. The high frequency records were randomly subsampled to represent hourly, daily, weekly, and monthly sampling frequencies and to examine the effects of timing, and resulting annual load estimates were compared to the reference loads. Higher frequency sampling resulted in load estimates that better approximated the reference loads. The degree of bias was greater at the more hydrologically responsive site in the upper watershed, which required a higher sampling frequency than the lower watershed site to achieve the same level of accuracy in estimating the reference load. The hour of day and day of week of sampling impacted load estimation, depending on site and hydrologic conditions. The effects of sampling frequency on the determination of compliance with a water quality criterion were also examined. These techniques can be helpful in determining necessary sampling frequency to meet the objectives of a water quality monitoring program.