Coastal zones are dynamic environments constantly shaped by natural processes and human interventions. Groynes are hard coastal protection structures designed to protect the shoreline from coastal erosion. The urgency of addressing beach erosion has intensified with the growing impact of climate change. However, predicting the efficiency of coastal groynes remains challenging due to the diverse factors influencing their effectiveness, including size, shape, and local conditions. In some instances, these structures may inadvertently exacerbate erosion. This scientific study focuses on modeling the morphological responses of a beach adjacent to an isolated groyne and investigates the potential impacts of climate change on these coastal structures. The study employs numerical models, Telemac2D-Tomawac-Sisyphe coupling [2], to simulate the interactions between waves, sediment transport, and the groyne structure, aiming to enhance our understanding of the complex dynamics governing beach morphology. This study focuses on evaluating the morphological response of beaches to the presence of a coastal groyne, particularly under sea-breeze conditions in Sisal, situated on the northern Yucatan coast of Mexico. More specifically, high- spatial and temporal resolution data from a temporary groyne experiment [3] is employed. Building upon a previous investigation that compared Delft3d model results with field measurements [4], the current research employs the open-source telemac-mascaret software [2] for numerical modeling for calibration and validation (Fig. 1). The findings of this research will provide valuable insights into the vulnerability of coastal structures to climate change-induced alterations in environmental conditions. It aims to contribute to informed coastal management strategies, assisting decision-makers in developing resilient and adaptive solutions for coastal protection. Additionally, the study emphasizes the importance of considering the dynamic interactions between climate change and coastal morphology in the design and maintenance of coastal structures, ensuring their effectiveness and longevity in the face of evolving environmental conditions.

The research focuses on understanding the hydrodynamic and sediment transport processes along Chiasson office spit, Shippagan, New Brunswick, Canada after the strategic placement of 165,000 m3 of dredged sand and gravel material. In this study, will use flow and wave modules to understand the propagation of waves from open water to the coast and their interaction with tides in the nearshore. This approach aids in understanding hydrodynamic conditions and sediment movement along the coast. The Delft3D numerical model will be used to simulate hydrodynamics and sediment transport in the study area. The outcome of the study will offer valuable insights into the large-scale beach nourishment in cold climates, which is crucial for informing future sediment-based Nature-Based Solutions (NBS). The unique environmental conditions, including temperature variations, winter weather cycles and seasonal changes, can significantly influence sediment dynamics and coastal morphological adjustments in such regions. Therefore, studying these factors in the context of the Shippagan beach nourishment project can offer valuable insights into the effectiveness and adaptability of sediment-based NBS in cold climate conditions.

Muddy, fine, and cohesive sediments have the ability to trap and transport pollutants, negatively affecting water quality. In estuarine environments, clay is a fundamental component of cohesive sediment beds. While clay behavior is sensitive to variations in water salinity, clay content also has a critical influence on the development of clay aggregates. Here, we investigated the impact of salinity on the erosion threshold of smectite clays. Using image-based methods and rheologic techniques, we measured the critical shear stress and critical turbulent kinetic energy for erosion, yield stress, flow curves, and aggregate microstructures of a fluorescent synthetic smectite clay named laponite and the montmorillonite clay bentonite. Varying water salinity, clay content, and time after deposition, we have found that mainly salinity controls the formation of aggregate microstructures, leading to two clay states or phases, the gel and phase separation. The salinity-dependent clay phase significantly determines the behavior of the erosion threshold. We further observed that clay content influences the erosion mode with lesser impact from the time after deposition. Our results indicate that aggregate microstructures and clay content drive the rheological changes as well. Our results highlight the need to adapt cohesive sediment transport models in estuarine environments where salinity gradients and fluctuations are prevalent.

This study addresses the impact of a major river engineering project on sediment rates in the Terrebonne Basin, part of the Mississippi River Delta. Our research employs a particle tracking methodology to estimate changes in sediment flux resulting from construction interventions, recognizing the substantial ecological and geomorphological implications of altered sediment dynamics. We utilized the open-source numerical model Anuga[1] to simulate hydrodynamics within the Atchafalaya-Terrebonne basin. Our simulations were validated against a robust dataset, including in situ water level gauges and remotely sensed AirSWOT water surface elevations, ensuring the reliability of our hydrodynamic predictions. To specifically address sediment dynamics, we integrated Anuga's outputs with Dorado[2], an open-source particle tracking model. Dorado was modified to account for particle size variations, transforming it into a comprehensive sediment particle tracking model. By seeding sediment particles of different sizes at strategic points within the river system, we were able to trace the shifts in sediment distribution before and after the implementation of the construction project. Preliminary results highlight a significant alteration in sediment flow rates post-construction, underscoring the effectiveness of our particle tracking approach. Notably, our findings reveal that while the construction project primarily aimed to enhance freshwater influx into the Terrebonne Basin, it concurrently precipitates substantial modifications in sediment fluxes. These alterations could have profound implications on the morphodynamic rates across the wider Mississippi River Delta, potentially influencing both its ecological balance and geomorphological stability. Our study demonstrates the viability of using a particle tracking model for sediment dynamic estimation, offering a cost-effective alternative to integrated sediment transport models. Furthermore, our results underscore the necessity of considering sediment flux changes in the planning and evaluation of river engineering projects to safeguard the ecological integrity and geomorphological progression of vital coastal basins.

This paper introduces various sediment management strategies applied in the Scheldt Estuary to maintain accessibility to the Port of Antwerp (Belgium) and the impact these strategies have on the natural system. The estuary consists of the multi-channel Western Scheldt (in the Netherlands) and a tidal river called the Lower and Upper Sea Scheldt (in Belgium). Both require dredging to maintain the depth for vessels making passage to the Port of Antwerp. Since the early 70’s three subsequent deepening programs took place (1970, 1998 and 2009). Over the years different dredging strategies have been applied to maintain sand conservation and maintain the multi-channel character of the Western Scheldt. As the Scheldt estuary is part of an important ecological network (Natura 2000), all dredged sediments are to be maintained within the system. An elaborate strategy was developed to preserve the physical system characteristics within its natural dynamics. In this new strategy named ‘Flexible Disposal Strategy’, the sediments have been used to establish beneficial morphological evolution, by locally influencing flow patterns, creating low, dynamic, ecologically-valuable areas. Being an adaptive management protocol, it is based on planning, design, implementation, monitoring, evaluation, and adaption of the strategy. To evaluate the success of the disposal strategy, an extensive monitoring program was set up and several evaluation criteria were defined. In the paper the Flexible Disposal strategy will be discussed and a reflection will be made how management strategies, human interventions and sea level rise have impacted the (yearly) maintenance volumes. The analysis that will be presented was part of an evaluation of the Flexible Disposal maintenance strategy as applied over the last 12 years.