An attempt to link suspended load hysteresis patterns and sediment sources configuration in alpine catchments

Misset, Clément; Recking, Alain; Legoût, Cédric; Poirel, Alain; Cazilhac, Marine; Estèves, Michel; Bertrand, Mélanie

doi:10.1016/j.jhydrol.2019.06.039

Cited by 48 publications

(27 citation statements)

References 58 publications

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“…Figures 10 and 11 showed for the Galabre catchment that the limestone sources that were close to the river and the ones that were close to the outlet exhibited a clockwise hysteresis pattern while the distant ones exhibited an anticlockwise pattern. These results confirmed typical interpretations of discharge-sediment flux hysteresis (Bača, 2008;Misset et al, 2019) and highlighted that the sedigraphs of the different sediment sources were strongly related to their location in the catchments and their structural connectivity. The absence of coherent trends of the ranking of the Tlag,Qs with the one of the mean distances of the sources to the outlet could be related to the distribution of the distances to the outlet of all sediment sources that were generally more scattered than the distribution of the distances to the stream, particularly for the Galabre catchments (Figures 2c,d).…”

Section: 2the Role Of Structural Connectivity On the Dynamics Of Ssupporting

confidence: 87%

How do modeling choices impact the representation of structural connectivity and the dynamics of suspended sediment fluxes in distributed soil erosion models?

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Legoût

et al. 2020

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Abstract. Soil erosion and suspended sediment transport understanding is an important issue in terms of soil and water resources management in the critical zone. In mesoscale watersheds (> 10 km2) the spatial distribution of potential sediment sources within the catchment associated to the rainfall dynamics are considered as the main factors of the observed suspended sediment ﬂux variability within and between runoff events. Given the high spatial heterogeneity that can exist for such scales of interest, distributed physically based models of soil erosion and sediment transport are powerful tools to distinguish the specific effect of structural and functional connectivity on suspended sediment flux dynamics. As the spatial discretization of a model and its parameterization can crucially influence how structural connectivity of the catchment is represented in the model, this study analyzed the impact of modeling choices in terms of contributing drainage area (CDA) threshold to define the river network and of Manning's roughness parameter (n) on the sediment flux variability at the outlet of two geomorphological distinct watersheds. While the modelled liquid and solid discharges were found to be sensitive to these choices, the patterns of the modeled source contributions remained relatively similar when the CDA threshold was restricted to the range of 15 to 50 ha, n on the hillslopes to the range 0.4–0.8 and to 0.025–0.075 in the river. The comparison of both catchments showed that the actual location of sediment sources was more important than the choices made during discretization and parameterization of the model. Among the various structural connectivity indicators used to describe the geological sources, the mean distance to the stream was the most relevant proxy of the temporal characteristics of the modelled sedigraphs.

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Section: 2the Role Of Structural Connectivity On the Dynamics Of Ssupporting

confidence: 87%

How do modeling choices impact the representation of structural connectivity and the dynamics of suspended sediment fluxes in distributed soil erosion models?

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Legoût

et al. 2020

Preprint

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“…The importance of the spatial distribution of sediment sources, and not only their proportion in study catchments, on the dynamic of suspended sediment load have been also observed by Misset et al (). Catchment size can also be an important control on apparent exhaustion of the sediment load—with smaller catchments.…”

Section: Discussionsupporting

confidence: 67%

Understanding the effect of catchment characteristics on suspended sediment dynamics during flood events

Haddadchi

Hicks

2019

Hydrological Processes

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Hysteresis in the relationship between suspended sediment concentration and flow during run‐off events is commonly used to inform on sediment sources and hydrological pathways. Less attention, however, has been paid to comparing the water and sediment hydrographs, which provide a more direct appreciation of in‐event sediment dynamics and their relationship with the upstream catchment characteristics. The aim of this study is to better understand the catchment and hydrological controls on the phasing of water and sediment discharges during events and, in particular, to explore what controls sediment concentrations late on event recessions. Continuous records of flow and turbidity data (calibrated to suspended sediment concentration) were collected from 17 catchments across New Zealand for this purpose. Relationships between event sediment yield and peak flow showed, as anticipated, higher event sediment loads were generated in pasture compared with forested catchments and were also higher from catchments in more erodible terrain. One novel result was that these differences were greater during smaller, more frequent events, whereas the loads from larger flood events tended to converge between pasture and forest catchments. Another novel result was that event sediment load tends to be evenly split between rising and falling stages of the hydrograph in pasture catchments, but forested catchments yield more of their event loads on flood recessions, probably because of delayed erosion or more sediment sources remote from the channel network. Land cover, distance of the sediment sources from the monitoring site, and size of the catchments control sediment concentrations late on event recession. Pasture‐dominated and more erodible catchments show longer sediment recessions and therefore stay dirtier for longer time periods. In addition, the size of previous flood events appeared to control the extent of sediment exhaustion after the flood peaks in some catchments.

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“…Human activity strongly interacts with the natural processes of suspended sediment production and transport, on the one hand by practices that enhance soil erosion, like agriculture, mining, and deforestation, and on the other hand with the construction of sediment retention structures such as dams (e.g. Syvitski et al, 2005;Montgomery, 2007;Syvitski and Kettner, 2011;Borrelli et al, 2017). In the context of enhanced soil ero-sion, phenomena like the loss of soil productivity, the reduction of water quality due to higher turbidity and concentration of pollutants, and accelerated reservoir siltation are expected (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Among the sources of temporal variability, the role of hydrometeorological conditions (e.g. rainfall, antecedent wetness conditions, runoff) has been widely investigated, with a particular focus on the shape and direction of the hysteresis loops of the SSC-Q relation (Smith et al, 2003;Seeger et al, 2004;Zabaleta et al, 2007;Duvert et al, 2010;Dominic et al, 2015;Misset et al, 2019). Other sources of variability are the exhaustion of preferential sediment sources, the activation of new ones, and changes in the connectivity of such sources to the river network.…”

Section: Introductionmentioning

confidence: 99%

Modelling impacts of spatially variable erosion drivers on suspended sediment dynamics

2020

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Abstract. Suspended sediment load in rivers is highly uncertain because sediment production and transport at catchment scale are strongly variable in space and time, and they are affected by catchment hydrology, topography, and land cover. Among the main sources of this variability are the spatially distributed nature of overland flow as an erosion driver and of surface erodibility given by soil type and vegetation cover distribution. Temporal variability mainly results from the time sequence of rainfall intensity during storms and snowmelt leading to soil saturation and overland flow. We present a new spatially distributed soil erosion and suspended sediment transport module integrated into the computationally efficient physically based hydrological model TOPKAPI-ETH, with which we investigate the effects of the two erosion drivers – precipitation and surface erodibility – on catchment sediment fluxes in a typical pre-Alpine mesoscale catchment. By conducting a series of numerical experiments, we quantify the impact of spatial variability in the two key erosion drivers on erosion–deposition patterns, sediment delivery ratio, and catchment sediment yields. Main findings are that the spatial variability in erosion drivers affects sediment yield by (i) increasing sediment production due to a spatially variable precipitation, while decreasing it due to a spatially variable surface erodibility, (ii) favouring the clustering of sediment source areas in space by surface runoff generation, and (iii) decreasing their connectivity to the river network by magnifying sediment buffers. The results highlight the importance of resolving spatial gradients controlling hydrology and sediment processes when modelling sediment dynamics at the mesoscale, in order to capture the key effects of sediment sources, buffers, and hillslope hydrological pathways in determining the sediment signal.

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An attempt to link suspended load hysteresis patterns and sediment sources configuration in alpine catchments

Cited by 48 publications

References 58 publications

How do modeling choices impact the representation of structural connectivity and the dynamics of suspended sediment fluxes in distributed soil erosion models?

How do modeling choices impact the representation of structural connectivity and the dynamics of suspended sediment fluxes in distributed soil erosion models?

Understanding the effect of catchment characteristics on suspended sediment dynamics during flood events

Modelling impacts of spatially variable erosion drivers on suspended sediment dynamics

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