Hysteresis in suspended sediment to turbidity relations due to changing particle size distributions
Article first published online: 9 SEP 2013
©2013. American Geophysical Union. All Rights Reserved.
Water Resources Research
Volume 49, Issue 9, pages 5487–5500, September 2013
How to Cite
2013), Hysteresis in suspended sediment to turbidity relations due to changing particle size distributions, Water Resour. Res., 49, 5487–5500, doi:10.1002/wrcr.20394., and (
- Issue published online: 23 OCT 2013
- Article first published online: 9 SEP 2013
- Accepted manuscript online: 5 JUL 2013 03:59PM EST
- Manuscript Accepted: 27 JUN 2013
- Manuscript Revised: 24 JUN 2013
- Manuscript Received: 1 MAR 2013
- sediment transport;
- particle size distribution
 Turbidity (T) is the most ubiquitous of surrogate technologies used to estimate suspended-sediment concentration (SSC). The effects of sediment size on turbidity are well documented; however, effects from changes in particle size distributions (PSD) are rarely evaluated. Hysteresis in relations of SSC-to-turbidity (SSC∼T) for single stormflow events was observed and quantified for a dataset of 195 concurrent measurements of SSC, turbidity, discharge, velocity, and volumetric PSD collected during five stormflows in 2009–2010 on Yellow River at Gees Mill Road in metropolitan Atlanta, Georgia. Regressions of SSC-normalized turbidity (T/SSC) on concurrently measured PSD percentiles show an inverse, exponential influence of particle size on turbidity that is not constant across the size range of the PSD. The majority of the influence of PSD on T/SSC is from particles of fine silt and smaller sizes (finer than 16 µm). This study shows that small changes in the often assumed stability of the PSD are significant to SSC∼T relations. Changes of only 5 µm in the fine silt and smaller size fractions of suspended sediment PSD can produce hysteresis in the SSC∼T rating that can increase error and produce bias. Observed SSC∼T hysteresis may be an indicator of changes in sediment properties during stormflows and of potential changes in sediment sources. Trends in the PSD time series indicate that sediment transport is capacity limited for sand-sized sediment in the channel and supply limited for fine silt and smaller sediment from the hillslope.