Improved characterization of stream turbidity-discharge behavior using continuous monitoring data
Abstract
Turbidity behavior in streams is a complex and dynamic function of energy conditions and source material availability; however, the primary controls on its behavior and how they vary across time and space are not well understood. Recent increases in the availability of high-frequency stream turbidity data have made it possible to examine relationships that exist between fine-scale stream turbidity and discharge. We examined methods to quantitatively characterize event turbidity-discharge responses by modeling the shape of the hysteresis loops to investigate controls on event-based behavior. A total of ~1400 loop events from 20 catchments in the Mid-Atlantic U.S. were modeled. Several models were considered and compared. They included varying numbers of fitting parameters and combinations of terms such as the discharge rate of change and 'supply' terms. The results indicate that a 3-parameter model including discharge and the discharge rate of change results in an overall mean event Nash-Sutcliffe Efficiency (NSE) of 0.86 (individual catchment means range from 0.73-0.89), which is a modest improvement over a 2-parameter power law model overall mean event NSE of 0.81 (0.69-0.86). The addition of supply-based terms further improved the fit for various aspects of the loop shape at the expense of additional model complexity. Several functional forms for the supply-based terms were investigated, and it was found that the most effective functional form for improving loop model fit varied between catchments. This possibly reflects individual catchment differences in supply pools and/or transport processes. Some correlation between model parameters is present and subsequent work will investigate if this is a problematic mathematical artifact or if this can be leveraged to reduce the number of parameters in the model.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.H53H1509M
- Keywords:
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- 1871 HYDROLOGY Surface water quality;
- 1872 HYDROLOGY Time series analysis;
- 1804 HYDROLOGY Catchment;
- 1847 HYDROLOGY Modeling