The importance of time-varying, non-tidal currents in modelling in-situ sand wave dynamics

Sand waves are found on shallow, sandy seabeds throughout the world and their dynamics may pose an imminent threat to offshore construction. Therefore, there is a pressing need to understand bed level dynamics in sand wave areas. These bed level dynamics lead to variations in sand wave shape and migration rate over time. However, these variations cannot be explained with the present-day process-based sand wave models, which all include a purely periodic tidal forcing. To explain these fluctuations a more intricate description of the hydrodynamics is necessary. The aim of this study is to explore the importance of time-varying, non-tidal currents for sand wave dynamics in the North Sea. We adopted the three-dimensional Delft3D-Flexible Mesh model, and were able to reconstruct time-varying, non-tidal currents on top of the periodic tidal forcing, while significantly reducing computation times. The simulated currents and water levels showed a good agreement with in-situ measurements. Compared to the situation with only tidal forcing, the simulated sedimentation and erosion rates were amplified up to 15 times due to time-varying, non-tidal currents. Additionally, periods of net erosion were found at locations in the sand wave transect where tidally forced models only showed net-sedimentation. It is therefore important to consider time-varying, non-tidal currents when predicting future sand wave dynamics in the field

The grey – green spectrum: a review of coastal protection interventions

In the face of uncertainties around coastal management and climate change, coastal engineering interventions need to be able to adapt to changing conditions. Nature-based solutions and other non-traditional, integrated interventions are gaining traction. However, system-based views are not yet embedded into coastal management strategies. Moreover, the differences in coastal interventions, ranging from hard (‘grey’) to nature-based (‘green’) infrastructure remain understudied. In coastal management it is therefore challenging to work with the grey-green spectrum of interventions with clarity and focus, and to produce results that can be evaluated. The objective of this paper was to examine whether there is a common understanding of: the characteristics and differences between grey and green infrastructure, where interventions sit on this spectrum, and the resilience of grey versus green infrastructure. We conducted an integrative literature review of the grey-green spectrum of coastal infrastructure. We examined 105 coastal protection case studies and expanded the double-insurance framework to ensure an integrative approach, looking at both external and internal factors of resilience. Our review showed that external factors are typically used to characterise the grey-green spectrum. However, although useful, they do not facilitate a holistic comparison of alternative interventions. The additional consideration of internal factors (response diversity, multifunctionality, modularity and adaptive, participatory governance) bridges this gap. The review showed that dikes, reefs, saltmarshes, sand nourishment and dunes span a wider segment of the grey-green spectrum than they are generally categorised in. Furthermore, resilient solutions for adaptation are unlikely to be exclusively engineered or natural, but tend to be a mix of the two at different spatial scales (micro, meso, macro and mega). Our review therefore suggests that coastal planners benefit from a more diverse range of options when they consider the incorporation of grey and green interventions in the context of each spatial scale. We propose that internal resilience should be accounted for when infrastructure options are comparatively evaluated. This consideration brings attention to the ways in which the grey-hybrid-green spectrum of infrastructure enhances value for people.NWO17595Environmental BiologyIndustrial Ecolog

A Global View on Beach Erosion

Coastal zones have long attracted humans and human activities, due to the economic opportunities they offer, their aesthetic value, and the diverse ecosystem services they provide. As a result, coastal zones throughout the world have become heavily populated and developed, with 15 of the world’s 20 megacities (population >10 million) being in the coastal zone. The global coastline is spatially varied and comprises different coastal landforms, such as barrier islands, sea cliffs, sandy coasts, tidal flats, and river deltas. Of these different coastline types, the sandy coasts are highly dynamic in time and space and constitute a substantial part of the world’s coastline. Sandy coasts are highly developed and densely populated due to the amenitiesCoastal Engineerin

Crossing borders in coastal morphodynamic modelling

Sand is the second-most used natural resource behind water and will be under increasingly high demand in coming decades. One of the reasons for this is that, worldwide, sand is more and more applied to counteract beach erosion.This thesis presents new techniques in remote sensing and numerical modelling to better understand beach erosion and predict the dynamics of our sandy coastlines. To this end, it explores the crossing of three types of borders. First, international borders are crossed in a global assessment of historic beach dynamics using satellite imagery. Second, the boundaries between model time scales - from storms to decadal times - are dissolved by means of a new morphodynamic acceleration technique. Finally, the developed seamless modelling approach enables to cross the ever-changing boundary between water and land, where sand moves from the wet to the dry domain and vice versa. This work results in a landscaping model that can better forecast the future behavior of sandy beaches in a changing climate.Coastal Engineerin

Validation, calibration and evaluation of Delft3D-FLOW model with ferry measurements

Civil Engineering and Geoscience

Engineering The Ecosystem Services Of The Sand Motor

To actually design for sandy solutions, designers need to know the key factors that drive ecosystem services. This section will look at the key factors that drive the three main ecosystem services of coastal defense, recreation and nature development, followed by a description of how to evaluate these. Finally, an example of arguable the most important design factor is discussed

The Sand Motor: a nature-based response to climate change. Findings and reflections of the interdisciplinary research program Naturecoast

NatureCoast is the largest research program that focused on the Sand Motor, a large sandy peninsula, constructed in 2011 on the Dutch North Sea coast near The Hague. This unprecedented pilot project involved placing 21.5 million m3 of sand on and in front of the beach with the aim that it would spread along the coast. The Sand Motor is a unique beach nourishment due to its size, the design philosophy behind it, and its multifunctionality. It combines the primary function of coastal protection with the creation of a new natural landscape that also provides new leisure opportunities. From the outset, “learning by doing” has been a crucial part of the project and NatureCoast was an integral part of this. Because of its innovations, the Sand Motor has triggered considerable political and scientific interest from all over the world. Broad research consortia were formed to conduct interdisciplinary research on the Sand Motor.The NatureCoast program was carried out by a consortium of knowledge institutes and universities, and the research was conducted in cooperation with end-users from private companies, research institutes and governmental organizations. The Dutch Technology Foundation (NWO-TTW) provided the largest shareof the project funds. The research in NatureCoast focused on six themes: coastal safety, dune formation, marine ecology, terrestrial ecology, hydrology and geochemistry, and governance. This book presents countless facets of the Sand Motor, but we also hope it demonstrates the scientific merits of interdisciplinary research and how, ultimately, societies can benefit from it.bookEnvironmental Biolog

The Sand Motor: A Nature-Based Response to Climate Change: Findings and Reflections of the Interdisciplinary Research Program NatureCoast

NatureCoast is the largest research program that focused on the Sand Motor, a large sandy peninsula, constructed in 2011 on the Dutch North Sea coast near The Hague. This unprecedented pilot project involved placing 21.5 million m3 of sand on and in front of the beach with the aim that it would spread along the coast. The Sand Motoris a unique beach nourishment due to its size, the design philosophy behind it, and its multifunctionality. It combines the primary function of coastal protection with the creation of a new natural landscape that also provides new leisure opportunities. From the outset, “learning by doing” has been a crucial part of the project and NatureCoast was an integral part of this. Because of its innovations, the Sand Motor has triggered considerable political and scientific interest from all over the world. Broad research consortia were formed to conduct interdisciplinary research on the Sand Motor.The NatureCoast program was carried out by a consortium of knowledge institutes and universities, and the research was conducted in cooperation with end-users from private companies, research institutes and governmental organizations. The Dutch Technology Foundation (NWO-TTW) provided the largest shareof the project funds. The research in NatureCoast focused on six themes: coastal safety, dune formation, marine ecology, terrestrial ecology, hydrology and geochemistry, and governance. This book presents countless facets of the Sand Motor, but we also hope it demonstrates the scientific merits of interdisciplinary research and how, ultimately, societies can benefit from it

The Sand Motor: a nature-based response to climate change. Findings and reflections of the interdisciplinary research program Naturecoast

NatureCoast is the largest research program that focused on the Sand Motor, a large sandy peninsula, constructed in 2011 on the Dutch North Sea coast near The Hague. This unprecedented pilot project involved placing 21.5 million m3 of sand on and in front of the beach with the aim that it would spread along the coast. The Sand Motor is a unique beach nourishment due to its size, the design philosophy behind it, and its multifunctionality. It combines the primary function of coastal protection with the creation of a new natural landscape that also provides new leisure opportunities. From the outset, “learning by doing” has been a crucial part of the project and NatureCoast was an integral part of this. Because of its innovations, the Sand Motor has triggered considerable political and scientific interest from all over the world. Broad research consortia were formed to conduct interdisciplinary research on the Sand Motor.The NatureCoast program was carried out by a consortium of knowledge institutes and universities, and the research was conducted in cooperation with end-users from private companies, research institutes and governmental organizations. The Dutch Technology Foundation (NWO-TTW) provided the largest shareof the project funds. The research in NatureCoast focused on six themes: coastal safety, dune formation, marine ecology, terrestrial ecology, hydrology and geochemistry, and governance. This book presents countless facets of the Sand Motor, but we also hope it demonstrates the scientific merits of interdisciplinary research and how, ultimately, societies can benefit from it.</p

Applying an analogue for a conceptual model for the development of a mega nourishment

This paper discusses the effectiveness of a mega-nourishment project. Mega-nourishment is a new technology for beach nourishment that has recently been developed. It arises as an alternative to beaches where a structural erosion problem is observed and there is the need for continuously nourishments works. A pilot project was implemented near The Hague (The Netherlands) in October 2011, called the Sand Engine [Mulder 2000], however the impacts of such project are widely unknown. From this perspective the study of a natural coastal area that was subjected to similar conditions can generate know how about the impacts of such a project. One of these natural examples is Ameland: one of the Frisian Islands in the Wadden Sea. Ameland experienced large natural nourishment coming from the ebb tidal delta. The nourishment shape and magnitude were in the same order of magnitude of to the Sand Engine project, leading to a comparison point. In the Ameland case this nourishment occurred on 1990`s and on 1993 achieved a similar shape to the Sand Engine pilot project and currently almost all the sediment is already spread. So from the natural case we can assume that the Sand Engine is going to take around 2 decades to spread all the nourished sediment, a special care should be taken in the down-drift coast to avoid early erosion.Hydraulic EngineeringCivil Engineering and Geoscience