Observations and modelling of shoreface nourishment behaviour

Shoreface nourishments are commonly applied for coastal maintenance, but their behaviour is not well understood. Bathymetric data of 19 shoreface nourishments located at alongshore uniform sections of the Dutch coast were therefore analyzed and used to validate an efficient method for predicting the erosion of shoreface nourishments. Data shows...

Impact of sand nourishments on hydrodynamics and swimmer safety

Artificial sand nourishments are a common measure to mitigate coastal erosion problems. Such nourishments can have an impact on currents and waves near the beach, especially when the nourishment has a large size. As nourished beaches often have a recreational function, these altered wave and current patterns may pose a threat to swimmers. This...

Sensitivity of rip current forecasts to errors in remotely-sensed bathymetry

Operational nearshore current forecasts based on numerical model simulations are gaining popularity as a measure to increase the safety of swimmers. Applying remotely-sensed bathymetry in these model simulations is often proposed in order to cope with rapidly changing nearshore bathymetry. Errors in the remotely-sensed bathymetry may...

Behaviour of subtidal sandbars in response to nourishments

The behaviour of subtidal sandbars can be strongly influenced by the introduction of sand nourishments in the coastal system. This study focuses on the impact of nourishments on subtidal bar behaviour at spatio-temporal scales beyond a single nourishment project. It aims to determine the long-term behaviour of subtidal sandbars along an entire...

Impact of coastal forcing and groundwater recharge on the growth of a fresh groundwater lens in a mega-scale beach nourishment

For a large beach nourishment called the Sand Engine – constructed in 2011 at the Dutch coast – we have examined the impact of coastal forcing (i.e. natural processes that drive coastal hydro- and morphodynamics) and groundwater<br/>recharge on the growth of a fresh groundwater lens between 2011 and 2016. Measurements of the morphological change...

Evolution of alongshore bathymetric variability around a mega-scale beach nourishment

The presence of complex nearshore sand bar patterns (i.e. alongshore bathymetric variability) has an impact on local currents, affecting recreational safety and nearshore mixing processes. This study assesses the evolution of alongshore bathymetric variability along the Delfland coast in The Netherlands, over the first 5 years after construction...

impact of beach states on alongshore transport

Impact of spatial variability in the nearshore bathymetry on net sediment transport rates has been investigated for a selection of observed beach states at the Dutch coast. The beach states comprise a longshore bar trough and two transverse bar rip situations, which were present at the large scale Sand Motor nourishment at the Holland coast....

Tidal flow separation at protruding beach nourishments

In recent years, the application of large-scale beach nourishments has been discussed, with the Sand Motor in the Netherlands as the first real-world example. Such protruding beach nourishments have an impact on tidal currents, potentially leading to tidal flow separation and the generation of tidal eddies of<br/>length scales larger than the...

An Automated Method for Semantic Classification of Regions in Coastal Images

Large, long-term coastal imagery datasets are nowadays a low-cost source of information for various coastal research disciplines. However, the applicability of many existing algorithms for coastal image analysis is limited for these large datasets due to a lack of automation and robustness. Therefore manual quality control and site- and time...

Tilt current meter array: Field validation

Measurements of nearshore currents can be performed using a range of existing measurement techniques. Although every technique has its specific benefits, capturing strong spatial gradients in a flow field with sufficiently high spatial resolution often proves to be difficult due to high costs or practical difficulties associated with these...

Tidal dynamics in the sand motor lagoon

The Sand Motor is a mega-nourishment characterized by a very large sand volume of around 20 million m3 placed along the Dutch coast. The Sand Motor is a pilot project to evaluate the performance of an alternative nourishment strategy with respect to different functions of the coastal system. Within the scope of the coastal functions, the hook...

Efficiency of hanging silt curtains in cross-flow

When dredging in sensitive environments, efforts have to be made to limit the free dispersal of suspended fine sediment from the dredging spill. Especially the use of hanging silt curtains as an environmental mitigation measure is widespread. Despite frequent application, their ability to reduce turbidity levels through vertical diversion of...

Field observations of tidal flow separation at a mega-scale beach nourishment

Large beach nourishments are often considered an efficient way to deal with coastal zone management issues, notably coastal erosion. Such large nourishments can act as a geometric perturbation, which might cause the tidal current to detach from the coastline. The Sand Motor is a mega-scale beach nourishment in the Netherlands. Field observations...

Applicability of video-derived bathymetry estimates to nearshore current model predictions

In the framework of swimmer safety, coastal managers desire accurate nearshore current predictions obtained from numerical models. To this end, detailed and up-to-date bathymetry is a necessity. Remote sensing techniques for bathymetry estimation are a promising solution. The focus of this paper is to assess the performance of wavenumberbased...

The art of screening: Effectiveness of silt screens

One of the potential environmental issues associated with dredging in the marine environment is the increase of suspended sediment concentrations (SSC) by generation and dispersion of sediment plumes. This can be mitigated by source control or by the installation of containment barriers like silt screens. This article focusses on hanging silt...

Effectiveness of Silt Screens

Dredging and reclamation works are known to generate significant amounts of turbidity. In most coastal zones around the world, the resulting clouds of suspended fine sediment bring along environmental risks. Dredging contractors take mitigating measures to prevent free spreading of turbidity, which is usually also demanded by their clients and...

Modelling nourishments through the Durban piers: Research of sediment transport and surf conditions

The Durban bight has a very dynamic and variable coastline which is constantly under attack by the Indian Ocean. To protect the Durban harbour from this energetic ocean, already in 1855 breakwaters have been constructed to protect the harbour and prevent sedimentation inside. The construction of these breakwaters and eventually extending these...