Effects of discharge, wind, and tide on sedimentation in a recently restored tidal freshwater wetland

Abstract

Sediment deposition is one of the key mechanisms to counteract the impact of sea level rise in tidal freshwater wetlands (TFWs). However, information about sediment deposition rates in TFWs is limited, especially for those located in the transition zone between the fluvially dominated and tidally dominated sections of a river delta where sedimentation rates are affected by the combined impact of river discharge, wind, and tides. Using a combined hydrodynamicmorphological model, we examined how hydrometeorological boundary conditions control sedimentation rates and patterns in a TFW located in the Rhine-Meuse estuary in the Netherlands.The modelling results show that net sedimentation rate increases with the magnitude of the river discharge, whereas stronger wind increasingly prevents sedimentation. Sediment trapping efficiency decreases for both increasing river discharge and wind magnitude. The impact of wind storms on the trapping efficiency becomes smaller for higher water discharge. The spatial sedimentation patterns are affected by all controls. Our study illustrates the importance of evaluating both the separate and the joint impact of discharge, wind, and tides when estimating sedimentation rates in a TFW affected by these controls. Such insights are relevant to design measures to reactivate the sedimentation process in these areas. Wetlands also provide various ecosystem services to human wellbeing, for example, the provision of food (e.g., fish) and recreational opportunities, and regulating water quality (Millennium Ecosystem Assessment, 2005). TFWs are vulnerable to sea level rise (SLR) through both increased risk of inundation and possible salt water intrusion (e.g., Anderson & Lockaby, 2012;Burkett & Kusler, 2000).Enhanced sedimentation is considered an effective strategy to prevent further wetland loss in case horizontal wetland migration to higher zones is not possible (Darke & Megonigal, 2003;Kirwan & Megonigal, 2013;Paola et al., 2011). Previous research has indicated that sedimentation rates of wetlands may in general be controlled by factors such as the supply of fluvial sediments (Neubauer, Anderson, Constantine, & Kuehl, 2002;Siobhan Fennessy, Brueske, & Mitsch, 1994), tide, wind (Delgado, Hensel, Swarth, Ceroni, & Boumans, 2013Orson, Simpson, & Good, 1990), vegetation cover (Brueske & Barrett, 1994Darke & Megonigal, 2003;Nardin & Edmonds, 2014;Nardin, Edmonds, & Fagherazzi, 2016;Pasternack & Brush, 2001), wetland shape properties such as average depth/wetland elevation, distance to tidal creeks, and wind fetch lengths (Hupp & Bazemore, 1993;Hupp, Demas, Kroes, Day, & Doyle, 2008;Mitsch et al., 2014;Temmerman, Govers, Wartel, & Meire, 2003b). --------------------------------------------------------------------------------------------------------------------------------This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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

“…This is likely due to the fact that the Kleine Noordwaard study area receives a larger supply of water and sediment from the river Nieuwe Merwede than the Mariapolder that has only a single inlet/outlet and is only subject to tidal in-and outflow. This also confirms the findings of van der and Verschelling et al (2017) that the supply of water and sediment is a major factor for the sediment budget of wetlands…”

The Impact of Waves and Tides on Residual Sand Transport on a Sediment‐Poor, Energetic, and Macrotidal Continental Shelf

“…The best performing calibration run was selected based on the run that scored best for the majority of the metrics considered. The default SWAN parameters and the Fredsøe (1984) bed shear stress formulation performed best, as used in studies of sediment dynamics in combined energetic tide and wave environments elsewhere (Herrling & Winter, 2018;Ridderinkhof et al, 2016;Verschelling et al, 2017). A minimum wind drag coefficient of 0.002 was selected.…”

The impact of climate change on the morphology of a tidal freshwater wetland affected by tides, discharge, and wind

“…Winds play an important role in shaping the morphodynamics of the system. Locally generated wind waves cause a substantial amount of resuspension due to the long fetch lengths across the inundated flats (Verschelling et al, ).…”

“…Depending on wetland location and properties, flooding and sedimentation in TFWs are governed by the combined influence of tides, riverine discharges, and wind (Verschelling, Van der Deijl, Van der Perk, Sloff, & Middelkoop, ). Drowning mechanisms and measures that mitigate the impact of climate change (CC) in these areas, therefore, differ significantly from those in coastal areas, especially if CC also impacts river discharges and wind.…”

“…Drowning mechanisms and measures that mitigate the impact of climate change (CC) in these areas, therefore, differ significantly from those in coastal areas, especially if CC also impacts river discharges and wind. Most research in TFWs has focused on understanding historical and present‐day sedimentation rates and patterns and has shown that sedimentation rates depend on factors such as supply of sediment (Neubauer et al, ), impact of tides and wind (Orson, Simpson, & Good, ; Vandenbruwaene et al, ; Verschelling et al, ), and wetland parameters such as average water depth, wind fetch lengths, and distance to creeks (Delgado et al, ; Hupp & Bazemore, ; Temmerman et al, ).…”