The influence of floodplain morphology and river works on spatial patterns of overbank deposition

Abstract

Floodplain topography and related hydraulic patterns of overbank flow constitute a major control on the amounts and patterns of sediment deposition on floodplains. We studied the differences in sediment deposition at two scales along two river branches of the lower River Rhine in the Netherlands: the Waal and IJssel River. Human alterations like levelling and embankment construction have severely impacted the floodplains along the Waal River branch (average discharge: 1500 m 3 ·s -1 ), whereas the relatively wide floodplains along the IJssel River (average discharge: 250 m 3 ·s -1 ) still exhibit their characteristic ridge-and-swale topography and natural levees. We found that, in general, the amounts of sediment deposited sediment decreases with increasing distance to the sediment source. Clay and organic matter content generally increase with decreasing floodplain elevation. These trends are, however, far less pronounced in the Waal River floodplains than in the IJssel River floodplains.Sediment deposited on the IJssel River floodplains also contains significantly more sand than the sediment deposited on the Waal River floodplains, probably because of the absence of minor embankments along the IJssel River and its higher sinuosity. Furthermore, during inundation the individual Waal River floodplains receive more sediment per unit area than the IJssel River floodplains. At the scale of the river branch, however, the conveyance losses in the Waal River are less than in the IJssel River, because of the larger surface area of the floodplains along the IJssel River relative to its water and sediment discharge during flood events. This discrepancy stresses that both the individual floodplain sections and the total river branch should be taken into account when studying the role of overbank deposition as part of a river's sediment budget.

Establishing a sediment budget in the newly created “Kleine Noordwaard” wetland area in the Rhine–Meuse delta

“…Furthermore, a significant negative trend between sedimentation and the height of the location was found, which has also been reported by French and Spencer (1993), Middelkoop and van der Perk (1998), Reed et al (1999), Temmerman et al (2003), and Thonon et al (2007). Although the height and distance from the channel do control sedimentation, their influence is not as strong as observed in most marshes or river floodplains.…”

“…This table suggests that sedimentation is positively related to the suspended sediment concentration. Furthermore, it is widely known from the literature that sedimentation is controlled by the frequency and duration of inundation (French and Spencer, 1993;Middelkoop and van der Perk, 1998;Reed et al, 1999;Temmerman et al, 2003;Thonon et al, 2007), the suspended sediment concentration in the feeding channel French and Spencer, 1993), and the ability of sediment to settle, which is in turn controlled by vegetation (Darke and Megonigal, 2003;Temmerman et al, 2005b;Schile et al, 2014;Mitsch et al, 2014), the flow paths to or within the wetland/compartment (French and Spencer, 1993;Siobhan Fennessy et al, 1994;Reed et al, 1999;Davidson-Arnott et al,2002;Temmerman et al, 2003;Anderson and Mitsch, 2007;Mitsch et al, 2014), and the residence time within the compartment (Asselman and Van Wijngaarden, 2002). Although considerable research has been devoted to sedimentation in wetlands in coastal deltas and river floodplains, remarkably few empirical field studies have been reported on the initial formation and evolution of newly created wetlands.…”

Spatial variability in floodplain sedimentation: the use of generalized linear mixed-effects models

“…The inverse relationship between elevation and sedimentation rate (Walling et al, 1996;Walling and He, 1998) could not be confirmed by this study. As Middelkoop and Asselman (1998) and Thonon et al (2007b) found, this might be attributed to levees and other topographic features. Moreover, high flow velocities at low-lying areas can even reverse this trend at certain flood magnitudes (Asselman and Middlekoop, 1998).…”

Factors controlling sediment trapping in two freshwater tidal wetlands in the Biesbosch area, The Netherlands

“…Previous studies have indicated that sediment deposition in wetlands is controlled by various factors including the flooding frequency, depth, and duration (French and Spencer 1993;Middelkoop and van der Perk 1998;Reed et al 1999;Temmerman et al 2003;Thonon et al 2007;Schuerch et al 2013), the surface area of the wetland, the suspended sediment load (French and Spencer 1993;Asselman and Middelkoop 1998;Morse et al 2004;Noe et al 2016), and the ability of sediment to settle, which in turn, depends on sediment flow paths (French and Spencer 1993;Siobhan Fennessy et al 1994;Reed et al 1999;Davidson-Arnott et al 2002;Temmerman et al 2003;Anderson and Mitsch 2007;Mitsch et al 2014), wind (Orson et al 1990;Delgado et al 2013), and vegetation (Darke and Megonigal 2003;Temmerman et al 2005;Schile et al 2014;Mitsch et al 2014). These studies were mainly conducted in salt marshes or river flood plains; only few field-based studies were undertaken in freshwater tidal wetlands that represent the transition between these environments.…”