Advances in Coastal Hydrodynamic and Morphodynamic Processes Under a Changing Climate

An Overview of Published Articles

Coastal environments are among the most dynamic and complex natural systems on Earth. Beaches, tidal flats, estuaries, and deltaic environments constantly evolve in response to the cyclic interaction between coastal hydrodynamics, sediment transport, and morphological feedback mechanisms, operating across multiple spatio-temporal scales. In recent decades, the increasing pressure from climate change, sea-level rise, and intensifying extremes has amplified the need to decode these complex forcing-response coastal processes and highlight best practices for coastal resilience and sustainable management. These challenges have stimulated significant advances in observational techniques, numerical modeling approaches, and interdisciplinary research frameworks aimed at improving our understanding of coastal dynamics and supporting evidence-based management strategies.

The contributions to this Special Issue highlight recent advances in coastal process research and showcase a range of best-practice approaches applied across diverse dynamic coastal environments worldwide.

Two studies focus on the sedimentary processes across the Mississippi River delta and adjacent Louisiana shelf in the northern Gulf of Mexico. Duxbury et al. (2024) (Contribution 1) provide an in-depth investigation of the sedimentation processes along the Mississippi River delta front, one of the most dynamic coastal environments on earth, focusing on the role of mass-wasting events in shaping deltaic environments. Using sediment cores dated through ^210Pb and ^137Cs geochronology, the authors reconstruct the temporal variability of sediment deposition and identify spatial differences in sediment accumulation patterns across the delta front. Their work provides new insights into the geochronological and stratigraphic characteristics of mudflow deposits and their proximal-to-distal variability. It also contributes to our understanding of the fundamental processes involved in delta construction by identifying accumulation patterns across four key areas of the delta front. Gartelman et al. (2025) (Contribution 2) investigate sedimentary processes of a continental shelf sand body (Eastern Ship Shoal, Louisiana shelf) that acts as an important resource for coastal restoration projects. Their results demonstrate how sediment redistribution and dredging activities influence seabed morphology and sediment composition over time, providing important insights for the sustainable management of such important sand banks.

Other contributions explore the morphodynamic behavior of macro-tidal environments under combined hydrodynamic forcing. Numerical modeling of tidal flat profiles remains challenging due to the complex interactions between waves, tidal currents, and sediment transport, particularly in transitional coastal segments characterized by spatially variable erosion–accretion patterns. In this context, Li et al. (2025) (Contribution 5) investigate the long-term evolution of a macro-tidal flat profile in a transitional coastal segment near Dafeng Port, China. They introduce a one-dimensional morphodynamic model (Delft3d-based), proven to be capable of reproducing interannual erosion–accretion trends and capturing the main mechanisms driving profile evolution. Their results highlight the strong non-linear response of sediment dynamics to wave conditions, with critical hydrodynamic thresholds controlling shifts in erosion and deposition patterns. Similarly, long-term records are used to better understand shoreline variability and support coastal management strategies. Hwang et al. (2025) (Contribution 3) propose a practical framework for defining erosion control lines, targeting shore limits of erosion prevention in macro-tidal coastal environments. The authors analyzed historical shoreline changes and applied probabilistic thresholds that were found to effectively capture spatial variability in shoreline retreat while reducing overestimation in low-erosion areas. This framework provides a valuable basis for evidence-based coastal planning and contributes to improving resilience strategies in highly dynamic macro-tidal settings.

A broader perspective of modeling approaches is provided by Mora-Uribe et al. (2025) (Contribution 7), who systematically reviewed hydro-morphodynamic numerical models in estuarine systems over the past fifteen years. Their study highlights the predominance of 2D depth-averaged models and structured meshes, with Delft3D, TELEMAC, and FVCOM being the most widely used tools. Complementary insights into the modeling of coastal hydrodynamics in complex environments are provided by Lieou et al. (2024) (Contribution 4), who investigate water renewal processes in Shediac Bay (Canada) under three breaching scenarios of the Grande-Digue sand spit, making use of the TELEMAC model. It is shown that spit morphology exerts a strong influence on circulation patterns and renewal times, highlighting the sensitivity of inner-bay hydrodynamics to relatively small geomorphological changes, with important implications for water quality and aquaculture activities in the area.

High-resolution monitoring approaches are further explored by Luppichini (2025) (Contribution 6), who employed UAV-based photogrammetry and advanced GIS techniques to quantify storm-driven geomorphological changes along a vulnerable Mediterranean coastal segment north of Morto Nuovo River in Tuscany, Italy. The study captures rapid shoreline retreat, sediment redistribution, and dune erosion associated with extreme storm events, demonstrating the dominant role of short-term but high-energy forcing in shaping coastal morphology. The role of long-term observational datasets is also highlighted by Trogu et al. (2023) (Contribution 8), who investigate the dynamics of Posidonia oceanica banquettes on an urban Mediterranean beach in Sardinia, Italy, using a coastal video-monitoring system. Their findings reveal strong seasonal and event-driven variability in banquette formation, closely linked to wave conditions and storm activity. Importantly, the study demonstrates the protective function of these natural accumulations in dissipating wave energy and mitigating coastal erosion.

Collectively, the contributions presented in this Special Issue showcase state-of-the-art approaches to investigating coastal hydrodynamic, morphodynamic, and sedimentary processes in complex natural environments across a range of spatiotemporal scales. By integrating field observations, remote sensing, and advanced numerical modeling techniques, these studies significantly enhance our understanding of the complex process–response mechanisms that drive coastal evolution. Such integrated approaches are essential for improving predictive capabilities and supporting effective, evidence-based strategies for the sustainable management of coastal systems and their resources under the pressures of a changing climate and evolving hydrodynamic forcing.