Employing Lagrangian particle tracking models for the study of coastal sediment transport dynamics is highly beneficial as they record the complete history of sediment transport pathways. Correctly simulating bed-particle interactions and its stochastic nature in Lagrangian models is essential to accurately estimate the direction and timescale of sediment transport. In this study we compare and assess the performance of two stochastic approaches for simulating particle erosion and deposition in Lagrangian sediment tracking models: 1) formulations proposed by Soulsby et al. (2011) that calculate probability of particles erosion and deposition from empirically-derived parameters and 2) newly-developed formulations that calculate probability of particles erosion and deposition from physical parameters. The two approaches are evaluated in the Lagrangian sediment tracking model SedTRAILS using a simulation of the dispersal of a pilot ebb-tidal delta nourishment in Ameland Inlet (Wadden Sea, Netherlands) as a case study. Our results show that the new physics-based approach represents the diffusive behavior of the nourished sediment better than the empirical approach. However, the new approach could not be fully validated yet, and the implementation of a slope term for bedload transport in the SedTRAILS transport formulations is necessary to further evaluate the new physics-based approach.

Coastal sediment budgets are a foundational source of information for coastal management decision-making. To quantify these budgets, coastal systems are often divided into “cells” based on jurisdictional boundaries or topography. However, such divisions do not account for the pathways that water and sediment particles actually take. In this study we quantify cell boundaries that emerge from numerical simulations of sand and water pathways in a barrier island-lagoon system in the Netherlands (the Western Wadden Sea). By quantifying Lagrangian particle pathways as a network, we can derive internally well-connected but externally disconnected modules. Here we show that large (O(10 km)) coherent modules develop from flow patterns at tidal timescales (12.5 h), and are persistent through varying tide and weather conditions. Conversely, modules derived from 100 µm sand pathways are less coherent and highly spatially fragmented. The difference in patterns likely relates to the longer timescales associated with sediment transport. These emergent patterns could be used to better inform coastal and estuarine management by providing physics-based sediment cell boundaries.

Tracking coastal sediments can provide useful information about coastal dynamics, thereby helping coastal management. However, the highly dynamic conditions of the coasts makes analyzing the trajectories of a huge number of particles challenging. To solve this limitation, the framework of coastal sediment connectivity is designed. In this framework, recent advances in graph theory are used to quantify coastal systems as complex networks. In this context, sediment sinks/sources and pathways represent the graphical nodes and links, respectively. In this work, we take the first step to evaluate the ability of this newly-developed framework in quantifying the basic processes on a sandy beach. Firstly, we used Delft3D to obtain the velocity field and bed-level changes. Then, the Eulerian results were fed into SedTRAILS to simulate the sediment pathways. We show that the current version of the model can correctly calculate the basic metrics of the sediment-connectivity network (e.g., network link strength which is a proxy for sediment fluxes). More specifically, we show that this framework is capable of exploring the initiation of the rip channel formation.

Luminescence dating methods are widely used to date coastal sediments, while luminescence tracing methods are a novel application to reconstruct coastal sediment pathways. Both methods rely on subaqueous resetting (bleaching) of luminescence signals by light. Differences in bleaching between grains and/or luminescence signals encode information on the light exposure history of individual grains and therefore yield information on past sediment transport. Here we assess the potential of multi-signal single-grain feldspar luminescence to inform about sediment pathways at Ameland tidal inlet in the Dutch Wadden Sea. We also tested whether nourished and native sands can be distinguished based on their luminescence signals.Single-grain infrared stimulated luminescence (IRSL50) and post-IR IRSL (pIRIR) were measured from samples collected from modern sea-floor deposits across the inlet. Equivalent dose (D_e) distributions were assessed using the Central Age Model (CAM), and bootstrapped versions of the Minimum Age Model (bMAM) and Maximum Age Model (bMAX) were applied to the IRSL50 D_e distributions. Spatial trends in CAM and bMAX-De reveal highest inherited doses at the tip of Ameland in the Borndiep channel, decreasing along transport pathways around the ebb-tidal delta. These patterns indicate erosion of Pleistocene sediments in the Borndiep channel and progressive bleaching of luminescence signals upon transport. Low D_e values in shallow areas reflect repeated reworking of Holocene sands within the active layer. Nourished and native sediments show indistinguishable luminescence characteristics for our dataset due to their shared Holocene origin.

The seabed rarely consists solely of bare sand: often other materials, such as shells are present. They can influence sand transport by armoring the bed and modifying its roughness. Biogenic shells come in different shapes and sizes, depending on the mollusc species that produce them. To understand how changes in bivalve species composition affect sediment transport, we need a mechanistic understanding of how shell content and shell shape influence the near-bed flow and sand transport. We performed experiments in a racetrack flume, testing the effect of elongated (Ensis leei) versus rounded (Spisula subtruncata) shells on unidirectional current-driven sand transport. For both types of shells, a higher depth-averaged flow velocity was needed for initiation of motion and a decrease in bedload transport of sand was found. At a shell content of 20%, the threshold of motion of sand increased up to 75%, and bedload transport was reduced by up to 50%. These effects are explained by a balance between roughness-induced turbulence and bed armoring. Compared to a bare bed, shells decreased bed roughness by reducing ripple formation; rounded shells lowered roughness more than elongated shells, which formed roughness elements themselves, but also covered a larger fraction of the bed. However, there was no clear difference between round versus elongated shells on the overall sand transport; only shell content was key for the overall effect. Our results imply that sediment transport is likely overpredicted when a high number of shells is present in the seabed.

Coastal regions face increasing pressure from climate change, sea-level rise, and growing coastal populations. This “coastal squeeze” threatens both the systems’ sustainability and their ecosystem services. Coastal changes depend on the distribution of sediment throughout the system, which evolves continuously through complex transport processes. While we can quantify net morphological changes, this alone provides incomplete understanding of coastal evolution as similar morphological states can result from vastly different sediment movement patterns. Coastline perturbations-deviations from straight coastlines ranging from beach cusps to headlands, deltas, and artificial nourishments-exemplify this challenge. Although their diffusive morphological evolution is well understood, we have limited knowledge of the underlying sediment movement patterns driving this change. This study reveals how coastline perturbations alter sediment transport by tracing particles from origin to destination using Lagrangian tracking at the Sand Engine mega-nourishment. Our results demonstrate that perturbations alter both sediment dispersal and accumulation. During initial stages, the longshore dispersal of sediment is strongly restricted by rapid deposition and burial on both sides of the perturbation. A backward-tracing approach reveals that sediment deposition not only originates directly from the protruding part of the coastline, but also from updrift sources. As coastline perturbations diffuse over time, sediment movement patterns gradually converge toward those of an undisturbed coast. At locations with oblique wave incidence this evolution manifests itself with predominant downdrift dispersal and updrift trapping of sediment from adjacent beaches. The successful application of our Lagrangian approach to this multi-year evolution demonstrates the potential of sediment particle tracking for understanding more complex coastal environments. Increased understanding of sediment pathways enhances our ability to predict and communicate coastal response to interventions, supporting more effective management strategies.

Sea level rise, increased storminess, and changes in sediment supply due to nourishments are all expected to drive coarsening (i.e., ‘sandification’) of muddy coastal sediments in the decades to come. Since the composition of soft-bottom benthic communities is associated with the sediment grain-size and mud content, this may result in habitats becoming less suitable for some species, leading to species shifts. Species-sediment relations can help to predict how this foreseen sandification may affect benthic fauna. We explore and quantify the sandification-sensitivity of benthic communities, with a tidal basin in the Dutch Wadden Sea as a model system. We identify the species' sediment optima and tolerance ranges using non-linear quantile regression models, summarise preference and sensitivity at the community level, and determine the difference between optimal and realised sediment habitat. We find that sediment optima are taxon-specific and that most species in this area are sediment generalists. On community level, there is a difference between the preferred and realised sediment habitat. In many areas, the actual inhabited sediment is coarser and sandier than expected based on the preferences of the resident species. Future sandification of the area would further decrease sediment habitat suitability for benthic communities in these places. This detailed knowledge of area-specific sensitivity of benthos can be used to inform coastal management decisions.

While adapting to future sea-level rise (SLR) and its hazards and impacts is a multidisciplinary challenge, the interaction of scientists across different research fields, and with practitioners, is limited. To stimulate collaboration and develop a common research agenda, a workshop held in June 2024 gathered 22 scientists and policymakers working in the Netherlands. Participants discussed the interacting uncertainties across three different research fields: sea-level projections, hazards and impacts, and adaptation. Here, we present our view on the most important uncertainties within each field and the feasibility of managing and reducing those uncertainties. We find that enhanced collaboration is urgently needed to prioritize uncertainty reductions, manage expectations and increase the relevance of science to adaptation planning. Furthermore, we argue that in the coming decades, significant uncertainties will remain or newly arise in each research field and that rapidly accelerating SLR will remain a possibility. Therefore, we recommend investigating the extent to which early warning systems can help policymakers as a tool to make timely decisions under remaining uncertainties, in both the Netherlands and other coastal areas. Crucially, this will require viewing SLR, its hazards and impacts, and adaptation as a whole.

Optical turbidity and acoustic sensors have been widely used in laboratory experiments and field studies to investigate suspended particulate matter concentration over the last four decades. Both methods face a serious challenge as laboratory and in-situ calibrations are usually required. Furthermore, in coastal and estuarine environments, the coexistence of mud and sand often results in multimodal particle size distributions, amplifying erroneous measurements. This paper proposes a new approach of combining a pair of optical turbidity-acoustic sensors to estimate the total concentration and sediment composition of a mud/sand mixture in an efficient way without an extensive calibration. More specifically, we first carried out a set of 54 bimodal size regime experiments to derive empirical functions of optical-acoustic signals, concentrations, and mud/sand fractions. The functionalities of these relationships were then tested and validated using more complex multimodal size regime experiments over 30 optical-acoustic pairs of 5 wavelengths (420, 532, 620, 700, 852 nm) and six frequencies (0.5, 1, 2, 4, 6, 8 MHz). In the range of our data, without prior knowledge of particle size distribution, combinations between optical wavelengths 620–700 nm and acoustic frequencies 4–6 MHz predict mud/sand fraction and total concentration with the variation <10% for the former and <15% for the later. The results also suggest that acoustic-acoustic signals could be combined to produce meaningful information regarding concentration and mud/sand fraction, while no useful knowledge could be extracted from a combination of optical-optical pairs. This approach therefore enables the robust estimation of suspended sediment concentration and composition, which is particularly practical in cases where calibration data is insufficient.

At a global scale, deltas are vital economic hubs, in part due to the combination of their access to inland regions via river systems with their proximity to sea. However, with the sea in close vicinity also comes the threat of freshwater contamination by saline seawater, especially during droughts. This study explores the potential of a mitigation measure to estuarine salt intrusion, namely the construction of a (temporary) earthen sill—a measure implemented in the Lower Mississippi River near New Orleans (LA, USA). This study suggests design guidelines on how a sill can be used to mitigate estuarine salt intrusion: the design should focus on the longitudinal placement and the height of the sill, and the mitigating efficiency of the sill reduces with increasing tidal range. Overall, a (temporary) sill has great potential to reduce salt intrusion in salt wedge estuaries if there is sufficient water depth available.

Worldwide, estuaries are increasingly constrained by human interventions, such as wetland reclamations. Intertidal area has an important influence on the extent of estuarine salt intrusion. Previous research has shown conflicting effects of intertidal area on the salt intrusion. Therefore, this study explores this interaction for three estuary classes: (a) salt wedge, (b) partially mixed, and (c) well-mixed. Our findings show that the effect of intertidal area on the salt intrusion depends on the estuary class: enlarging the intertidal area reduces the salt intrusion for salt wedge and partially mixed estuaries, but vice versa for well-mixed estuaries. These opposing responses are explained by the balance between salt fluxes driven by the estuarine circulation versus by the tidal oscillation. In general, enlarging intertidal area results in the suppression of the estuarine circulation. Such system understanding is especially relevant in an era of increasing coastal urbanization.

Low-lying, tropical, coral-reef-lined coastlines are becoming increasingly vulnerable to wave-driven flooding due to population growth, coral reef degradation, and sea-level rise. Early-warning systems (EWSs) are needed to enable coastal authorities to issue timely alerts and coordinate preparedness and evacuation measures for their coastal communities. At longer timescales, risk management and adaptation planning require robust assessments of future flooding hazard considering uncertainties. However, due to diversity in reef morphologies and complex reef hydrodynamics compared to sandy shorelines, there have been no robust analytical solutions for wave runup to allow for the development of large-scale coastal wave-driven flooding EWSs and risk assessment frameworks for reef-lined coasts. To address the need for fast, robust predictions of runup that account for the natural variability in coral reef morphologies, we constructed the BEWARE-2 (Broad-range Estimator of Wave Attack in Reef Environments) meta-process modeling system. We developed this meta-process model using a training dataset of hydrodynamics and wave runup computed by the XBeach Non-Hydrostatic process-based hydrodynamic model for 440 combinations of water level, wave height, and wave period with 195 representative reef profiles that encompass the natural diversity in real-world fringing coral reef systems. Through this innovation, BEWARE-2 can be applied in a larger range of coastal settings than meta-models that rely on a parametric description of the coral reef geometry. In the validation stage, the BEWARE-2 modeling system produced runup results that had a relative root mean square error of 13 % and relative bias of 5 % relative to runup simulated by XBeach Non-Hydrostatic for a large range of oceanographic forcing conditions and for diverse reef morphologies (root mean square error and bias 0.63 and 0.26 m, respectively, relative to mean simulated wave runup of 4.85 m). Incorporating parametric modifications in the modeling system to account for variations in reef roughness and beach slope allows for systematic errors (relative bias) in BEWARE-2 predictions to be reduced by a factor of 1.5–6.5 for relatively coarse or smooth reefs and mild or steep beach slopes. This prediction provided by the BEWARE-2 modeling system is faster by 4–5 orders of magnitude than the full, process-based hydrodynamic model and could therefore be integrated into large-scale EWSs for tropical, reef-lined coasts and used for large-scale flood risk assessments.

A submerged, low-relief nearshore berm was constructed in the Pacific Ocean near the mouth of the Columbia River, USA, using 216,000 m³ of sediment dredged from the adjacent navigation channel. The material dredged from the navigation channel was placed on the northern flank of the ebb-tidal delta in water depths between 12 and 15 m and created a distinct feature that could be tracked over time. Field measurements and numerical modeling were used to evaluate the transport pathways, time scales, and physical processes responsible for dispersal of the berm and evaluate the suitability of the location for operational placement of dredged material to enhance the sediment supply to eroding beaches onshore of the placement site. Repeated multibeam bathymetric surveys characterized the initial berm morphology and dispersion of the berm between September 22, 2020, and March 10, 2021. During this time, the volume of sediment within the berm decreased by about 40%to 127,000 m³, the maximum height decreased by almost 60%, and the center of the deposit shifted onshore over 200 m. Observations of berm morphology were compared with predictions from a three-dimensional hydrodynamic and sediment transport model application to refine poorly constrained model input parameters including sediment transport coefficients, bed schematization, and grain size. The calibrated sediment transport model was used to predict the amount, timing, and direction of transport outside of the observed survey area. Model simulations predicted that tidal currents were weak in the vicinity of the berm and wave processes including enhanced bottom stresses and asymmetric bottom orbital velocities resulted in dominant onshore movement of sediment from the berm toward the coastline. Roughly 50% of the berm volume was predicted to disperse away from the initial placement site during the 169 day hindcast. Between 9 and 17% of the initial volume of the berm was predicted to accumulate along the shoreface of a shoreline reach experiencing chronic erosion directly onshore of the placement site. Scenarios exploring alternate placement locations suggested that the berm was relatively effective in enhancing the sediment supply along the eroding coastline north of the inlet. The transferable monitoring and modeling framework developed in this study can be used to inform implementation of strategic nearshore placements and regional sediment management in complex, high-energy coastal environments elsewhere.

Coastal aeolian sediment transport is influenced by supply-limiting factors caused by sediment sorting by grain size. Sorting processes can lead to coarsening of the bed surface and influence the formation of aeolian ripples. However, the influence sorting processes and bedforms might have on the magnitude of the transport is not fully understood. This study explores sorting processes and their influence on the magnitude and mode of aeolian transport by using sediment tracers. Sand was painted in different colors according to particle size and placed on a supratidal beach in Noordwijk, the Netherlands. Several experiments were conducted with varying wind speeds. Surface sampling and cameras tracked the sand color movement on the bed surface, and wind velocity was measured. The tracer experiments showed that ripples developed in moderate wind conditions. Once the ripples had formed, the supply of finer tracer grains in the downwind direction decreased over time, while the supply of coarser grains remained constant. A linear relationship between ripple migration speed and wind speed was found. For higher wind speeds, no ripples or differences in transport of grain size fractions were observed. Instead, alternating phases of erosion and deposition of the bed surface were observed, which could not be related to local variations in wind velocity. Based on these results and literature, a conceptual model was developed for an active bed surface layer with two transport regimes corresponding to moderate (I) and high (II) wind speeds. The conceptual model is intended to guide the selection of aeolian sediment transport models as a function of wind speed, bed characteristics, and upwind sediment supply. For Regime I, transport could be modeled using a linear relationship between sediment transport and wind speed and for Regime II using a third power relationship in combination with a process-based model accounting for supply limitations.

In an era of rising seas and other challenges posed by climate change, coastal regions like the Netherlands are facing ever graver threats. Strategic sand nourishments could mitigate the threat of coastal erosion and sea level rise on barrier island coasts while limiting ecological impacts. However, insufficient knowledge of sediment transport pathways at tidal inlets and ebb-tidal deltas prevents an informed response in these areas.

The main goal of this project was to describe and quantify the pathways that sediment takes on an ebb-tidal delta. To reach this goal, we focused our analyses on Ameland ebb-tidal delta in the Netherlands. Before we could begin to tackle this challenge, we needed to develop new tools and techniques for analyzing a combination of field measurements and numerical models. These include a method for analyzing the stratigraphy and mapping the morphodynamic evolution of ebb-tidal deltas, a new metric for characterizing suspended sediment composition, and innovative use of sediment tracers. We also established a quantitative approach for looking at and thinking about sediment pathways via the sediment connectivity framework, and developed a Lagrangian model to visualize and predict these pathways efficiently.

The techniques developed here are useful in a wider range of coastal settings beyond Ameland, and are already being applied in practice. We foresee that the main impacts of this project will be to improve nourishment strategies, numerical modelling, and field data analysis. This dissertation also points forward to numerous opportunities for further investigation, including the continued development of the connectivity framework and SedTRAILS. By managing our coastal sediment more effectively, we will set the stage for a more sustainable future, in spite of the challenges that lie ahead.

Tropical Cyclones (TCs) are singular storms causing intense wind, large waves, extreme water levels, and heavy rainfall. TCs prove every year to be one of the most destructive natural phenomena worldwide. The quantitative assessment of the hazards resulting from TCs (i.e., flooding and extreme winds) is challenging since satellite data are only available for recent decades, whereas older historical observations are incomplete and less accurate. In addition, long-term prediction through numerical weather forecasting is still limited. This often results in large uncertainties in the definition of TC hazards associated with events with longer return periods or in areas infrequently impacted by TCs. Even when this information is available, for example through statistical sampling of synthetic TC tracks, the numerical modelling of the associated hazards for all the different TC conditions can lead to computational costs which are often infeasible. Several methodologies that overcome the issues of accuracy and computational efficiency currently exist, but these are not generically applicable, and they tend to focus on specific areas only, for example where TCs typically make landfall. The main contribution of this paper is a novel methodology for the estimation and analysis of TC hydro-meteorological conditions and induced hazards. The method is generically applicable and maximizes accuracy while accounting for computational efficiency. Our approach identifies a smaller but representative set of TC tracks (RTCs) that preserves the information about extremes and the frequency of events of the larger population. The method is successfully applied and validated in a case study in the Bay of Bengal, using a set of synthetic TC tracks representing 1000 years of TC climate. For the best-performing configuration, the required number of scenarios and associated computational costs were reduced by 90% while maintaining accuracy in the simulated offshore storm surges, significant wave height, and windspeeds typically within 10% of the prediction based on the original full set of scenarios. This method is globally applicable and greatly improves the efficiency of TC-related hazard estimation, making it particularly valuable for areas with limited historical data.

Ebb tidal deltas (ETDs) are highly dynamic features of sandy coastal systems, and coastal management concerns (e.g., nourishment and navigation) present a pressing need to better describe and quantify their evolution. Here we propose two techniques for leveraging the availability of high-resolution bathymetric surveys to generate new insights into the dynamics and preservation potential of ebb-tidal deltas. The first technique is conformal mapping to polar coordinates, using Ameland ebb-tidal delta in the Netherlands as a case study. Since the delta tends to evolve in a clockwise direction around the inlet, this approach provides an improved quantification and visualization of the morphodynamic behaviour as a timestack. We clearly illustrate the sediment bypassing process and repeated rotational migration of channels and shoals across the inlet from updrift to downdrift coasts. Secondly, we generate a decadal scale (1975–2021) stratigraphic model from the differences between successive bathymetries. This stratigraphy showcases the delta's depositional behaviour through space and time, and provides a modern analogue for prehistoric ebb-tidal deltas. During the surveyed period, inlet fills form the largest and most stable deposits, while the downdrift swash platform is the most stable structure over longer periods. Together, these approaches provide new perspectives on ebb-tidal delta dynamics and preservation potential which are readily applicable to other sites with detailed bathymetric data. These findings are valuable at annual to decadal timescales for coastal management (e.g., for planning sand nourishments) and also at much longer timescales for interpreting stratigraphy in ancient rock records.

For successful and sustainable management of barrier islands, a thorough understanding of the ebb-tidal delta dynamics and interactions with the adjacent shorelines are of the utmost importance. Such understanding requires detailed observations and interpretations of the morphodynamics of smaller-scale features such as the individual channels and shoals (referred to as intra-delta dynamics). The intra-delta dynamics of Ameland Inlet (the Netherlands) are studied through analysis of sixteen high-resolution bathymetric surveys, supplemented with an extensive dataset of hydrodynamic observations collected in 2017. The observations are compiled into a synthesis of the morphodynamics of the ebb-tidal delta and its neighboring shorelines, to provide a basis for present day and future coastal management.

Our observations show that Ameland Inlet as a whole can be classified as a typical mixed-energy, wave-dominated system. However, the ebb-tidal delta contains distinct areas that are wave or tide dominated, and these areas evolve with the changing morphodynamics of the ebb delta. Between 2005 and 2021, large morphodynamic changes have occurred on the ebb-tidal delta and continuous erosion of the island tips occurred. Limited wave-sheltering by the ebb-tidal delta exposes the shorelines of the adjacent barrier islands to significant wave-driven sand transports and sand losses. Sediment supply from longshore transport and the erosion of the updrift island Terschelling contributed to the formation, growth and migration of a series of ebb-chutes and lobes, which eventually led to complete relocation of the main channel on the ebb-tidal delta. This main channel relocation took 15 years to complete and is an example of the ebb-delta breaching model of sand bypassing. Changes in the sediment bypassing patterns result in a sediment starved western island tip of Ameland, necessitating repeated sand nourishments under the Dutch coastal maintenance policy. Our observations also confirm the role the ebb-tidal delta as a sand reservoir for the downdrift barrier island. The delta sand body is not a reservoir for the back-barrier basin, since the basin is predominantly supplied with sand eroded from the updrift island of Terschelling.

As demonstrated in this study, the intra-delta dynamics of an ebb-tidal delta are complex and can change drastically through time. Only through detailed measurements and observations can all the intricate interactions that take place be unravelled.

Coral reefs represent an efficient natural mechanical coastal defense against ocean waves. The focus of this study is La Saline fringing coral reef, located in the microtidal West of La Réunion Island in the Indian Ocean, frequently exposed to Southern Ocean swell and cyclonic events. The aim is to provide a better understanding of the reef's coastal defense characteristics for several Southern Ocean swell events. Pressure sensors were placed across the reef to measure water level fluctuations and to study wave transformation. A numerical model (XBeach surfbeat), validated using field observations, was used to deepen understanding of wave transformation, wave setup and runup. Field measurements and model outputs show that as gravity waves dissipate over the reef, and frequency-dependent dissipation of infragravity waves by bottom-friction occurs, the reef acts as a low-pass filter. Wave-induced setup is found to be the dominant hydrodynamic component. Setup and runup are each 98% and 79% driven by the offshore significant wave height, and 2% and 21% driven by the tide. The modulation of the water level by setup is the main contributor to runup in the fringing reef. At semidiurnal timescales, setup and runup are in antiphase with tidal variations as lower water levels result in higher gravity wave energy dissipation, setup and runup. Simple-to-use transfer functions relating incident wave characteristics to these hydrodynamic components are proposed. The effects of bottom friction and water level on the defensive capacity of the coral reef highlight future implications of structural damage and sea level rise.

Estuaries and coasts can be conceptualized as connected networks of water and sediment fluxes. These dynamic geomorphic systems are governed by waves, tides, wind, and river input, and evolve according to complex nonlinear transport processes. To predict their evolution, we need to better understand the pathways that sediment takes from source through temporary storage areas to sink. Knowledge of these pathways is essential for predicting the response of such systems to climate change impacts or human interventions (e.g., dredging and nourishment). The conceptual framework of sediment connectivity has the potential to expand our system understanding and address practical coastal management problems (Pearson et al., 2020). Connectivity provides a structured framework for analyzing these sediment pathways, schematizing the system as a series of geomorphic cells or nodes, and the sediment fluxes between those nodes as links (Heckmann et al., 2015). Once organized in this fashion, the resulting network can be expressed algebraically as an adjacency matrix: sediment moving from a given source to different receptors. There is a wealth of pre-existing statistical tools and techniques that can be used to interpret the data once it is in this form, drawing on developments in other scientific disciplines (Newman, 2018; Rubinov & Sporns, 2010). Lagrangian flow networks have been increasingly used to analyze flow and transport pathways in oceanographic and geophysical applications (Padberg-Gehle & Schneide, 2017; Reijnders et al., 2021; Ser-Giacomi et al., 2015). However, this approach has not yet been adopted to analyze coastal or estuarine sediment transport, and requires a multitude of field measurements or numerical model simulations. Lagrangian particle tracking has been widely used to assess connectivity in the context of oceanography and marine ecology (Hufnagl et al., 2016; van Sebille et al., 2018), because the models record the complete history of a particle’s trajectory, not only its start and end points. Particle tracking models are also relatively fast and lend themselves well to parallel computing (Paris et al., 2013). This approach thus permits a faster and more detailed analysis of sediment connectivity than existing Eulerian approaches (e.g., Pearson et al., (2020)). Although several Lagrangian sediment transport models have been developed (e.g., (MacDonald & Davies, 2007; Soulsby et al., 2011)), they have not been used to support connectivity studies. Hence, there is a need for Lagrangian sediment particle tracking tools tailored to predicting sediment transport pathways and determining connectivity of complex coastal systems. To meet this need, we developed a Lagrangian sediment transport model, SedTRAILS (Sediment TRAnsport vIsualization & Lagrangian Simulator) and used it to develop a sediment connectivity network. Our approach provides new analytical techniques for distilling relevant patterns from the chaotic, spaghetti-like network of sediment pathways that often characterize estuarine and coastal systems. We demonstrate a proof of concept for our approach by applying it to a case using these tools.