• prof. dr. Maarten Kleinhans
• Jorn Bosma MSc
• dr. Timothy Price

• Marlies van der Lugt
• Matthieu de Schipper

The coastal region of Suriname is low-lying, flat and vulnerable for anticipated sea level rise and increasing storm frequencies. This area is also essential for agriculture, for fresh drink water from the sandy sediments and for human settlements. Managing such vulnerable and valuable environment requires in-depth understanding of governing processes and interactions steering the system. The coastal system is extremely complex: large mud supplies from the Amazone results in mud banks migrating along the coast influenced by complex wind patterns. These mud banks create opportunities for mangroves that in turn play an important role protecting the coast and for flora/fauna. Apart from natural dynamics, anthropogenic activities such as mangrove removal, sand mining and channel dredging result in ecosystem degradation. Sea level rise and increasing storminess may cause erosion and submersion of the coast. The project contributes to SDG13: Climate Action through developing an innovative, combined model simulating coastal dynamics accounting for interactions between mud banks, waves, winds and mangroves. The model will be used to explore impacts of climate change and human interference aiming at developing sustainable management solutions. Time-series of earth observation images will be analysed to map mangrove dynamics and mud bank migration. The project contributes to SDG4: Education by involving the Suriname University and create awareness by collaborating with local practitioners (WWF, CI, UNDP, WI). Results will profoundly impact longterm coastal protection by providing missing knowledge and innovative tools optimizing coastal management. Together with Wetlands International scalability of expertise to other mangrove coasts (Guianas, Asia) is anticipated.

• prof. dr. Steven de Jong
• dr. Pita Verweij
• Ginny Bijnaar MSc
• dr. Job de Vries MSc

A common measure to prevent erosion of beach-dune systems and warrant coastal safety is to add large amounts of sand on the beach or in the shallow water directly fronting the beach. These nourishments are intended to be redistributed across the beach-dune system by natural processes. Embryonic dunes are a clear expression of this onshore sand transport and may provide suitable indicators for the effectiveness of nourishments, both in terms of safety and ecological impact. In this project, we aim to study how nourishment strategies affect the physical and ecological drivers of embryonic dune development along sandy coasts.

• prof. dr. Merel Soons
• dr. Timothy Price

• drs. Petra Damsa (Rijkswaterstaat)
• drs. Quirijn Lodder (Rijkswaterstaat)

Coastal dunes serve as a natural safety barrier against marine flooding and possess high ecological value with many environmental transitions (wet/dry, salt/fresh). The societal need for safe coasts has resulted in dunes that can withstand the impact of fierce storm waves, but have impoverished natural values and undesirably reduced biodiversity. We now face the challenge of combining coastal safety objectives with nature development to maintain sustainable and climate-proof dunes. This demands profound quantitative understanding of aeolian (wind-blown) processes, rather than of storm-wave processes alone. Wind-blown beach sand allows dunes to grow vertically with sea-level rise, thereby ensuring long-term coastal safety, and is crucial to sustain the dunes’ biodiversity by resetting ecological succession locally and temporally. The overarching aim of the project is to build a next-generation coastal-evolution model that unifies wave-driven (Poseidon) dune erosion with wind-blown (Aeolus) sand supply.

Aeolian transport on beaches is influenced strongly by the moisture of the top few millimetres of sand. Moisture and sand transport interact to create fascinating aeolian bedforms that, in turn, lead to complex spatial and temporal variability in transport. These challenging interactions and feedbacks, coupled to scale issues, currently defy accurate predictions of aeolian sand supply to the dunes. I have recently set up an infrared terrestrial laser scanning method to solve the long-standing problem of precise and rapid moisture measurements over a spatially extensive area. Using integrated field and model studies, three PhD students (Yvonne Smit, Winnie de Winter and Pam Hage) study the determinants of moisture variability, the dynamics of moisture-induced aeolian bedforms, and the spatial and temporal variability in aeolian transport. Simultaneously, a postdoc (Jasper Donker) aggregates our new, detailed process knowledge into a model that realistically allows prediction of sand supply, with its inherent seasonal to multi-annual time scales. In co-operation with stakeholders, we will apply the model in two coastal-safety and dune-biodiversity case studies to guarantee immediate knowledge utilization and dissemination to the public.

Watch the 'Bright Minds' movie made by Utrecht University:

And the movie on dune growth by my PhD student Yvonne Smit:

• Winnie de Winter MSc

The Sand Engine pilot project is a concentrated 21 Mm3 shore nourishment (i.e. sand deposition) at the Delfland coast (NL) constructed in 2011. This unprecedented experiment aims to protect the hinterland from flooding by letting natural processes distribute sand over shoreface, beach and dunes, thus constituting a climate-robust and environmentally friendly way of coastal protection. The key objective of NatureCoast is to raise our understanding and predictive capability regarding the various aspects of this type of shore nourishments, up to a level enabling to assess their effectiveness and to export the underlying technology worldwide. This requires understanding the key morphological, hydrological, geochemical, ecological and societal processes governing the evolution, feasibility and acceptability of this kind of nourishments, as well as translating this knowledge to practical guidelines and tools. Since the Sand Engine situation differs significantly from the original situation with an almost-straight coastline, knowledge gaps in all of these areas have to be filled. The Sand Engine and its monitoring data provide a unique opportunity to achieve this.

The NatureCoast project comprises sub-projects on Coastal Safety, Dune Formation, Marine Ecology, Terrestrial Ecology, Hydrology and Geochemistry, and Governance. In total, 12 PhD students and 3 postdoctoral researchers work on this truely national programme. PhD student Jantien Rutten is working within the Coastal Safety sub-project. Her focus is on the morphological evolution of the inter- and subtidal zone of the Sand Engine on time scales of days to years. She is using an extensive data set of in-situ jet-ski surveys, supplemented with Argus video imagery and X-band radar data. Of particular interest are the performance of both remote sensing techniques in building high-resolution data sets of bed elevation and the striking alongshore variability in sandbar behaviour along the Sand Engine because of its strongly curved nature. In 2014 Jantien participated in MegaPex, an international field experiment hosted by Delft University of Technology to measure crucial data on the (among other topics) hydrodynamics and morphological evolution of the Sand Engine under high-wave conditions.

Here is a movie that outlines the NatureCoast project:

And this movie illustrates the MegaPex experiment:

Process-based morphodynamic models are key tools to predict coastal evolution in response to human activities, such as nourishments and beach-restoration projects, and to natural variations in the wave climate, including storms and hurricanes. While modelling efforts of sea-bed evolution in water depths exceeding ~2 m are now reasonably successful, efforts for shallower depths have commonly failed. Thus, the predictive understanding of the evolution of our sandy beaches is inadequate. We do know that in these shallow depths, the almost vertical, strongly aerated walls of broken waves, termed bores, inject turbulent eddies into the water column. We aim to examine and model the effects of surface-generated turbulence on sand suspension and transport beneath bores. PhD student Joost Brinkkemper uses the large-scale Bardex II laboratory data set of turbulence and sand concentrations, combined with information of small-scale bed patterns (wave ripples), to progress our understanding of sand transport processes in shallow water. In the final year of the project, he will use the insights gained to develop a new, well-founded, practical sand transport formulation that can be implemented into Dutch operational coastal-evolution models.

Storm-generated wind waves create secondary waves - termed infragravity waves - that have typical periods of 20 to 200 s. Infragravity waves can become more than 1 m in height near the shore and are responsible for beach and dune erosion. We have collected field and laboratory data sets on gently sloping (1:80) beaches that completely change the textbook view on infragravity-wave dynamics. In particular, our data demonstrate that, in contrast to observations on steeper (1:10-1:30) beaches, infragravity waves dissipate most of their energy close to the shore and do not reflect to form a standing pattern. PhD student Anouk de Bakker will explore the cause(s) of the infragravity energy dissipation and use numerical modelling to examine the generality of her findings for other beach slopes. In the final year of her project Anouk will examine how this energy dissipation affects infragravity-wave induced sand transport, and hence the magnitude of beach erosion.