Turbidity as a Surrogate for the Estimation of Suspended-Sediment Concentrations in Mississippi Streams

Author(s): Runner, M. ;  Stocks, S.

The U.S. Geological Survey currently collects suspended-sediment concentration data at more than 25 hydrologic monitoring stations in Mississippi. Data are collected to describe suspended-sediment concentrations and loads over the range in discharge for these stations and to determine if trends in the sediment-discharge relation exist, as well as describe changes in those trends. Where sufficient data are collected, they can be used to compute the load of sediment transported in suspension during storm events.

Traditional methods for obtaining suspended-sediment concentration data require the collection of water samples that are shipped to a laboratory for analysis. Depending on a variety of factors, it can take up to 6 months from the time of sample collection to receipt of laboratory results. To expedite the availability of these data to the cooperators, which will allow decisions to be made in a timely manner, the U.S. Geological Survey began a study to develop a method to estimate suspended-sediment concentrations using a surrogate. The method is based on the success of previous studies, which indicated that for streams with certain hydrologic and sediment characteristics, site-specific relations between turbidity and suspended-sediment concentrations could be developed, which allow the estimation of the sediment concentration.

For this study, turbidity data are being collected by using two methods. First, in situ water-quality monitors are installed at two continuous-record stations where discrete suspended-sediment concentration data are collected. Turbidity data are collected on a regular time interval, generally every 15 minutes, by water-quality monitors deployed in the water at these stations. The measured turbidity values are compared with the suspended-sediment concentrations in water samples collected by using automatic pumping samplers. Second, water samples collected at locations without continuous water-quality monitors are analyzed for turbidity by using a bench-top turbidity meter prior to the samples’ shipment for analysis. Water samples collected at stations with continuous water-quality monitoring are also analyzed using the bench-top meter so that comparisons can be made between the two methods.

Preliminary results indicate that reasonable turbidity-sediment relations can be developed for many of the stations that are currently being tested as part of this program. These relations could provide a means to estimate suspended-sediment concentration for water samples collected by automatic pumping samplers, as well as provide a means to reduce the costs associated with collecting data necessary for the evaluation of environmental projects.


Technical Presentations

  • Delta Water Quality
  • Delta Water and Agriculture
  • Wetlands
  • Water Quality
  • Sediments
  • Non-Point
  • Management and Sustainability
  • Wood Treatment
  • Modeling
  • Soil and Water Treatment


Responsible Site Design: Implementing Innovative Stormwater Management Strategies

The primary goal of the workshop is to create a dynamic learning experience that examines the role of stormwater management in the built environment. The workshop will focus on integrating ecologically sound water management approaches into site design. After the workshop, attendees will be familiar with the following concepts and technical issues:

  • Knowledge of the stormwater treatment chain
  • Knowledge of the impact of land use codes on stormwater management
  • Application of a design process that mitigates the effects of stormwater on-site
  • Knowledge of the relationship between land use codes and design for innovative stormwater management


For information contact:
Jessie Schmidt
Box 9680
Mississippi State, MS 39762