Editorial: Sediment dynamics and geohazards in estuaries and deltas–volume II

Estuaries and deltas are among the regions with the most intense land-sea interactions. The evolution of their sediments is jointly controlled by multiple factors, including fluvial sediment supply, wave action, tidal processes, and anthropogenic activities (Li et al., 2020; Syvitski et al., 2022; van de Vijsel et al., 2024). In particular, wave-current coupling regulates the hydrodynamic structure of the near-bed boundary layer, thereby further influencing sediment entrainment, resuspension, and transport (Li et al., 2021; Liu et al., 2026). Meanwhile, under the combined influence of long-term cyclic loading, extreme hydrodynamic conditions, and engineering disturbances, seabed sediments readily accumulate excess pore water pressure and undergo plastic deformation. These mechanical responses can degrade the effective stress state and shear strength, thereby increasing the risk of seabed deformation, sediment liquefaction, and submarine landslides (Saathoff and Achmus, 2024; Liu et al., 2025). With the rapid expansion of marine infrastructure, including offshore wind farms, submarine pipelines, and reef-island engineering, sediment-structure interactions, sediment-structure interface responses, and the identification and prediction of submarine geological hazards under complex environmental conditions have become central research priorities (Roger et al., 2024; He et al., 2025).

As the second volume of this Research Topic series, this collection continues to address the core scientific themes of sediment dynamics and geohazards. It comprises four original research articles focusing on two principal areas: the mechanical responses of estuarine and deltaic soils under complex loading and environmental conditions and the artificial intelligence-assisted identification of submarine pipelines. Collectively, these studies deepen our understanding of the mechanical behavior of estuarine and deltaic sediments and the associated geohazard processes.

The mechanical properties of these sediments are key factors in controlling submarine foundation settlement, the stability of marine engineering structures, and their long-term deformation. Moreover, strength degradation and pore-water pressure evolution play important roles in governing the initiation and development of geohazards such as submarine liquefaction and landslides (Liu et al., 2013; Keane, 2019; Tong et al., 2010; Tran et al., 2024). Wu et al. investigated complex cyclic stress paths induced by wave loading through a series of axial-torsional coupled cyclic loading tests. Their study revealed the volumetric strain accumulation behavior of saturated fine sand from the Yellow Sea and established an irreversible strain increment model based on the equivalent cyclic stress ratio. Kong et al. investigated the coupled effects of temperature and normal stress, systematically characterizing the cyclic shear response of the marine silica-sand-geogrid interface across a wide temperature range. Tang et al. investigated the pronounced crushability of calcareous sand through direct-shear creep tests and developed an empirical creep model that incorporates particle breakage, thereby improving the characterization of time-dependent deformation in the foundations of South China Sea reef-island environments.

In addition to studies of sediment mechanics, the rapid and accurate identification and localization of submarine pipelines are equally essential for geohazard monitoring and engineering safety in deltas characterized by active sediment dynamics (Zhang et al., 2022; Feng et al., 2023). Wei et al. evaluated the performance of three convolutional neural networks–AlexNet, GoogLeNet, and VGG-16- for the automated detection of submarine pipelines in the Yellow River Estuary using side-scan sonar imagery. Their results showed that GoogLeNet achieved the best balance between accuracy and computational efficiency, offering a practical technical approach for the high-frequency monitoring of submarine infrastructure.

By addressing complex cyclic loading, temperature-stress coupling, creep modeling, and intelligent image-based identification, the contributions in this volume advance the understanding of the mechanical responses of estuarine and deltaic sediments and the associated geohazard processes. They provide a theoretical basis and technical references for seabed deformation and settlement assessment, engineering risk evaluation, and coastal protection.

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Footnotes

Edited and reviewed by: Wouter Buytaert, Imperial College London, United Kingdom