Differing field methods and site conditions lead to varying bias in suspended sediment concentrations in the Lower Mississippi and Atchafalaya Rivers
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- Data Release: USGS Data Release Datasets of Suspended Sediment Concentration and Percent Fines (1973–2021), Sampling Information (1973–2021), and Daily Streamflow (1928–2021) for Sites in the Lower Mississippi and Atchafalaya Rivers to Support Analyses of Sediment Transport and Delivery
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Abstract
At sites that have been sampled for decades, changes in field and laboratory methods happen over time as instrumentation and protocols improve. Here, we compare the influence of depth- and point-integrated sampling on total, fine (< 0.0625 mm), and coarse (≥ 0.0625 mm) suspended sediment (SS) concentrations in the Lower Mississippi and Atchafalaya Rivers. Using historical field method information, we identified seven sites to test such differences. We found SS samples collected using point-integration tended to have higher concentrations than those collected using depth-integration. However, the presence and magnitude of the bias were inconsistent across sites. Bias was present at the site with less-than-ideal conditions (i.e., non-trapezoidal channel, non-uniform flow) and non-existent at the ideal site location, indicating the bias between sampling methods depends on site sampling conditions. When present, the bias is greater at higher concentrations and at moderate to high flows. At the less-than-ideal site, point-integrated samples can have 16% (total) and 34% (coarse) higher concentrations than depth-integrated samples. When flow effects are removed, this translates to a bias of 19, 9, and 8 mg per liter for total, fine, and coarse SS. When a change in field methods occurs, comparison samples and a rigorous evaluation of those samples are warranted to determine the proper course of action for a particular site. Often, the effect and solution will not be known until several years of comparison samples have been collected under a variety of hydrologic conditions.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Differing field methods and site conditions lead to varying bias in suspended sediment concentrations in the Lower Mississippi and Atchafalaya Rivers |
| Series title | Environmental Monitoring and Assessment |
| DOI | 10.1007/s10661-023-11836-z |
| Volume | 195 |
| Year Published | 2023 |
| Language | English |
| Publisher | Springer |
| Contributing office(s) | Lower Mississippi-Gulf Water Science Center, Central Midwest Water Science Center |
| Description | 1260, 25 p. |
| Country | United States |
| State | Louisiana |
| Other Geospatial | Lower Mississippi River, Atchafalaya River |
| Google Analytic Metrics | Metrics page |