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I. Colosimo

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8 records found

Winds of opportunity

The effects of wind on intertidal flat accretion

Journal article - I. Colosimo, D.S. van Maren, D.S. van Maren, D.S. van Maren, P.L.M. de Vet, P.L.M. de Vet, J.C. Winterwerp, Bram van Prooijen

Intertidal ecosystems are threatened by sea level rise and anthropogenic pressures. Understanding the processes controlling the morphodynamic developments of tidal flats is crucial for sustainable management of these systems. Analysis of three extensive fieldwork campaigns carrie ...

Beneficial use of dredged sediment to enhance salt marsh development by applying a ‘Mud Motor’

Evaluation based on monitoring

Report - Martin Baptist, Julia Vroom, Pim W.J.M. Willemsen, Pim W.J.M. Willemsen, Pim W.J.M. Willemsen, M.E.B. van Puijenbroek, Bas van Maren, Pim van Steijn, Marin van Regteren, I. Colosimo

Bij de haven van Harlingen is een innovatieve methode beproefd voor hergebruik van baggerslib om de ontwikkeling van een kwelder te stimuleren: de slibmotor. Bij een slibmotor wordt baggerspecie als een semi-continue bron van sediment zo dicht mogelijk bij een kwelder verspreid o ...

The impact of wind on flow and sediment transport over intertidal flats

Journal article - I. Colosimo, P.L.M. de Vet, P.L.M. de Vet, D.S. van Maren, D.S. van Maren, A.J.H.M. Reniers, J.C. Winterwerp, Bram van Prooijen

Sediment transport over intertidal flats is driven by a combination of waves, tides, and wind-driven flow. In this study we aimed at identifying and quantifying the interactions between these processes. A five week long dataset consisting of flow velocities, waves, water depths, ...

Limited seed retention during winter inhibits vegetation establishment in spring, affecting lateral marsh expansion capacity

Journal article - Marin van Regteren, I. Colosimo, Pepijn de Vries, M.E.B. van Puijenbroek, Victor Sebastiaan Freij, Martin Baptist, Kelly Elschot

Coastal systems worldwide deliver vital ecosystem services, such as biodiversity, carbon sequestration, and coastal protection. Effectivity of these ecosystem services increases when vegetation is present. Understanding the mechanisms behind vegetation establishment in bio-geomorphic systems is necessary to understand their ability to recover after erosive events and potential adaptations to climate change. In this study, we examined how seed availability affects vegetation establishment in the salt marsh–intertidal flat transition zone: the area with capacity for lateral marsh expansion. This requires vegetation establishment; therefore, seed availability is essential. In a 6-month field experiment, we simulated a before and after winter seed dispersal at two locations, the salt-marsh vegetation edge and the intertidal flat, and studied seed retention, the seed bank, and the seed viability of three pioneer marsh species: Salicornia procumbens, Aster tripolium, and Spartina anglica. During winter storm conditions, all supplied seeds eroded away with the sediment surface layer. After winter, supplied seeds from all three species were retained, mostly at the surface while 9% was bioturbated downwards. In the natural seed bank, A. tripolium and S. anglica were practically absent while S. procumbens occurred more frequently. The viability of S. procumbens seeds was highest at the surface, between 80% and 90%. The viability quickly decreased with depth, although viable S. procumbens seeds occurred up to 15 cm depth. Only when seeds were supplied after winter, many S. procumbens and some S. anglica individuals did establish successfully in the transition zone. Viable seed availability formed a vegetation establishment threshold, even with a local seed source. Our results suggest that, although boundary conditions such as elevation, inundation, and weather conditions were appropriate for vegetation establishment in spring, the soil surface in winter can be so dynamic that it limits lateral marsh expansion. These insights can be used for designing effective nature-based coastal protection.@en

Beneficial use of dredged sediment to enhance salt marsh development by applying a ‘Mud Motor’

Journal article - Martin Baptist, T Gerkema, Bram van Prooijen, D.S. van Maren, D.S. van Maren, I. Colosimo, Kelly Elschot, A.V. de Groot, J Cleveringa, E. M.M. van Eekelen, None More Authors

We test an innovative approach to beneficially re-use dredged sediment to enhance salt marsh development. A Mud Motor is a dredged sediment disposal in the form of a semi-continuous source of mud in a shallow tidal channel allowing natural processes to disperse the sediment to nearby mudflats and salt marshes. We describe the various steps in the design of a Mud Motor pilot: numerical simulations with a sediment transport model to explore suitable disposal locations, a tracer experiment to measure the transport fate of disposed mud, assessment of the legal requirements, and detailing the planning and technical feasibility. An extensive monitoring and research programme was designed to measure sediment transport rates and the response of intertidal mudflats and salt marshes to an increased sediment load. Measurements include the sediment transport in the tidal channel and on the shallow mudflats, the vertical accretion of intertidal mudflats and salt marsh, and the salt marsh vegetation cover and composition. In the Mud Motor pilot a total of 470,516 m3 of fine grained sediment (D50 of ∼10 μm) was disposed over two winter seasons, with an average of 22 sediment disposals per week of operation. Ship-based measurements revealed a periodic vertical salinity stratification that is inverted compared to a classical estuary and that is working against the asymmetric flood-dominated transport direction. Field measurements on the intertidal mudflats showed that the functioning of the Mud Motor, i.e. the successful increased mud transport toward the salt marsh, is significantly dependent on wind and wave forcing. Accretion measurements showed relatively large changes in surface elevation due to deposition and erosion of layers of watery mud with a thickness of up to 10 cm on a time scale of days. The measurements indicate notably higher sediment dynamics during periods of Mud Motor disposal. The salt marsh demonstrated significant vertical accretion though this has not yet led to horizontal expansion because there was more hydrodynamic stress than foreseen. In carrying out the pilot we learned that the feasibility of a Mud Motor depends on an assessment of additional travel time for the dredger, the effectiveness on salt marsh growth, reduced dredging volumes in a port, and many other practical issues. Our improved understanding on the transport processes in the channel and on the mudflats and salt marsh yields design lessons and guiding principles for future applications of sediment management in salt marsh development that include a Mud Motor approach.@en

Sediment Disposals in Estuarine Channels Alter the Eco-Morphology of Intertidal Flats

Journal article - P.L.M. de Vet, P.L.M. de Vet, Bram van Prooijen, I. Colosimo, Tom Ysebaert, Tom Ysebaert, Tom Ysebaert, P.M.J. Herman, P.M.J. Herman, Zhengbing Wang, Zhengbing Wang

Dredging of navigation channels in estuaries affects estuarine morphology and ecosystems. In the Western Scheldt, a two-channel estuary in the Netherlands, the navigation channel is deepened and the sediment is relocated to other parts of the estuary. We analyzed the response of ...

Variations in storm-induced bed level dynamics across intertidal flats

Journal article - P.L.M. de Vet, P.L.M. de Vet, Bram van Prooijen, I. Colosimo, N. Steiner, N. Steiner, Tom Ysebaert, Tom Ysebaert, Tom Ysebaert, P.M.J. Herman, P.M.J. Herman, Zhengbing Wang, Zhengbing Wang

Hydrodynamic forces on intertidal flats vary over a range of temporal and spatial scales. These spatiotemporal inhomogeneities have implications for intertidal flat morphodynamics and ecology. We determine whether storm events are capable of altering the long-term morphological e ...

The Importance of Wind-induced Sediment Fluxes on Tidal Flats

Abstract - I. Colosimo, Bram van Prooijen, D.S. van Maren, J.C. Winterwerp, A.J.H.M. Reniers

Port maintenance and nature preservation are two often conflicting aspects of coastal management. Within a Pilot Project in the Western Wadden Sea (the Netherlands - see Figure1a) we test a win-win solution that could reduce harbour siltation while simultaneously stimulate saltma ...

Contributed

1 records found

Estimating the roughness of muddy beds

A study based on in-site measurements and numerical modeling

Master thesis - H.J. Speerstra, P.M.J. Herman, D.S. van Maren, I. Colosimo, T.J. Zitman

Bed roughness is an important parameter for the prediction of sediment transport as well as calculating flow conditions near the bed. Numerical models are extensively used to make these predictions. In these models it is fundamental to have proper values for bed roughness. The bed roughness is being estimated using a dataset from an ongoing pilot project in the Dutch western Wadden Sea. This dataset consists of 40 days of velocity measurements using ADV (8 Hz) and ADCP (1 Hz) instruments and concentration of SPM measurements using OBS instruments. To estimate the bed roughness, the dataset is analyzed using four methods for calculating the bed shear stress. The logarithmic profile, turbulent kinetic energy, vertical turbulent kinetic energy and the Reynolds stress method. The data has been processed and averaged per tidal phase, so statistical analysis can be applied to it. From this analysis, it is found that the concentration of SPM increases at 6 cm with increasing wind speed. As a result of this increasing of SPM the bed roughness also increases. This leads to the hypothesis that suspended sediment makes the bed rougher, and is not primarily governed by horizontal advection but also local resuspension. A 1DV numerical model is used in which horizontal advection is excluded to test this hypothesis. Simulations are performed with stationary boundary conditions, using combinations of water depth (0.2 to 2.8 m) and velocities (5 cm/s to 70 cm/s). These simulations are imposed with an initial homogeneous concentration. For every combination, the concentration is increased gradually until the concentration profile becomes L-shaped. Besides simulations with stationary conditions, timeseries of water depth and velocity are used to simulate one tidal cycle. All simulations performed with this numerical model do not take wind and waves into account and water-bed exchange is excluded. From the simulations with stationary boundary conditions the roughness is calculated using the LP method. It is found that bed roughness increases with increasing initial homogeneous concentration. From the simulation of one tidal cycle, it is found that the roughness increases towards the turn of the tide. After the turning of the tide, the concentration profile becomes L-shaped, and the roughness is decreased. The concentration profile becomes homegeneous again after a certain threshold of velocity and waterdepth and at the same time the roughness increases again. During a tidal cycle, it is possible to have a collapsed concentration profile, which indicates a lower bed roughness and thus a smoother bed.