Abstract
Abstract. Fine sediments represent an important vector of pollutant diffusion in rivers. When deposited in floodplains and riverbeds, they can be responsible for soil pollution. In this context, this paper proposes a modelling exercise aimed at predicting transport and diffusion of fine sediments and dissolved pollutants. The model is based upon the Telemac hydro-informatic system (dynamical coupling Telemac-2D-Sysiphe). As empirical and semiempirical parameters need to be calibrated for such a modelling exercise, a sensitivity analysis is proposed. An innovative point in this study is the assessment of the usefulness of dissolved trace metal contamination information for model calibration. Moreover, for supporting the modelling exercise, an extensive database was set up during two flood events. It includes water surface elevation records, discharge measurements and geochemistry data such as time series of dissolved/particulate contaminants and suspended-sediment concentrations. The most sensitive parameters were found to be the hydraulic friction coefficients and the sediment particle settling velocity in water. It was also found that model calibration did not benefit from dissolved trace metal contamination information. Using the two monitored hydrological events as calibration and validation, it was found that the model is able to satisfyingly predict suspended sediment and dissolve pollutant transport in the river channel. In addition, a qualitative comparison between simulated sediment deposition in the floodplain and a soil contamination map shows that the preferential zones for deposition identified by the model are realistic.
Highlights
Recent years have seen a growing awareness of the central role that fine-sediment loads play in transport and diffusion of pollutants by rivers and streams (Walling, 2005)
Suspended sediment can potentially carry important amounts of nutrients and contaminants, such as trace metals of which some are recognized as potentially harmful elements (PHEs)
January 2011 flood event has been chosen for the sensitivity analysis because the flood level and the observed suspendedsediment concentrations were higher than during the December 2011 flood event
Summary
Recent years have seen a growing awareness of the central role that fine-sediment loads play in transport and diffusion of pollutants by rivers and streams (Walling, 2005). Suspended sediment can potentially carry important amounts of nutrients and contaminants, such as trace metals of which some are recognized as potentially harmful elements (PHEs). These threaten water quality in rivers and wetlands and soil quality in floodplains (Carter et al, 2006; Hissler and Probst, 2006). Among the most recent studies on sediment transport modelling in river systems, one can cite Villaret et al (2013) and González-Sanchis et al (2014).
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