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Although many studies have been performed in the northern Gulf of Mexico, there have been a paucity of high-resolution sediment data collected from seabed. New multicores were collected repeatedly at 4 fixed stations in the inner Louisiana shelf on March 12, 2021, July 7, 2021, November 20, 2021, and March 5, 2022, respectively, to study detailed spatial and temporal variations of surficial sediment. Being a very high sediment accumulation zone, Raccoon Island dredge pit and its nearby shelf were selected as our study area and additional six vibracores were collected inside and outside the pit for comparison. This study area is about 140 km west of the modern Mississippi Delta and 70 km southeast of the Atchafalaya Delta. A total of 624 samples from both vibracores and multicores were analyzed for this study. Spatially, our results show that sediment near Ship Shoal was the coarsest and sediment deposited in the pit was the finest. The organic matter was highest inside the pit and lowest near Ship Shoal. The carbonate content was the lowest near Ship Shoal. Temporally, surficial sediments were generally coarser in July and November of 2021 and finer in March of 2021 and March of 2022. Although the Mississippi and Atchafalaya Rivers supply a large amount of sediment during spring season, it takes time for the river-derived sediment to be delivered into the study area. Hurricanes Delta, Zeta and Ida passed this area and greatly impacted sediment transport in the years 2021 and 2022. The comparatively coarser sediment in July and November of 2021 were likely related to the resuspension of some coarse sediment by these hurricane events. Besides the river supply, Ship Shoal and barrier islands are nearby localized sandy sources and inner Louisiana shelf is a widespread mud source. This spatial heterogeneity of surficial sediment interplays with the timing of Mississippi and Atchafalaya River flood season and hurricanes and together dictates the sediment texture. This research on a filled-up dredge pit can benefit future evaluation of the safety of existing oil infrastructure and the feasibility of building new pipelines and platforms after dredging activities. Our results also shed light on the study of river- and hurricane-impacted sediment transport in muddy and mixed-texture passive continental margins around the world. • Pit sediment hasn't reached an equilibrium with ambient environment yet. • Surficial sediments were coarser in July and November and finer in March. • Sediment grain size spatial variations were categorized into four groups. • This research will benefit future coastal restoration and sediment management. [ABSTRACT FROM AUTHOR]

The near-bottom nepheloid layer in the western margin of the Southern Adriatic Sea was monitored for 8-years by measurements acquired at two mooring sites. The two moorings, equipped with CTD probes and ADCPs, are located in the Bari Canyon and in an open slope sector along the Southern Adriatic Margin. These regions are of interest because affected by episodic dense shelf water cascading events whose dynamic has direct implications on deepwater morpho-dynamic, biogeochemical cycles and trophic networks. In this work, the sedimentation flux and its interdecadal dynamic is analysed examining in detail the sedimentary processes triggered by dense water flow through the analysis of the echo records of ADCPs. The integration of hydrodynamic, turbidity and particle grain-size data provided estimates of the sediment flux, separating phases when the flow actively erodes the seabed from phases when particles are transported to the mooring location through density flows. The frequency and velocity of dense-water cascading currents vary in time and space reflecting the capacity of sediment transport. Data analysis demonstrated that the hydrodynamic event that mostly accounts for sediment transfer to the deep basin is represented by current pulses induced by the passage of dense waters. The average annual sediment flux has been quantified and the Bari canyon shows transport more than five time larger than in the open slope sector, confirming that the canyon is the dominant pathway of sediment transfer to the deep basin. In contrast, in the open slope, albeit a minor lateral sediment advection, is impacted by currents that are able to trigger intense resuspension of seabed sediments, which can contribute over 80% of the total solid load. This study allows unravelling the role of cascading in the sediment resuspension and transport processes and is essential to support deciphering the sedimentary records in the study area. The long temporal extent of the dataset used for quantification provides a reliable contribution to the Quaternary sediment budget determination. • The integrated approach proposed in the study made it possible to determine sediment flux during dense water cascade events. • This study allows unravelling the role of cascading in the sediment resuspension and transport processes • The characterization of short-lived events can improve the high-resolution interpretation of the stratigraphic records. • The large temporal extension of the dataset used provides a reliable contribution to the Quaternary sediment budget [ABSTRACT FROM AUTHOR]

The 2011 Great East Japan Tsunami caused severe morphological changes along the affected coastline on the northeast part of Japan. This study investigates the recovery of river mouths and breaching of sandy coast at the place used to be river mouth in Miyagi Prefecture, Japan after severe erosion induced by the tsunami through analyzing aerial photograph and investigating field data. After several years since the tsunami took place, the morphology of some river mouths has mostly recovered while others still have some damage. Results on the analysis of aerial photograph clearly indicate that the total length of sandy coast on both sides of river mouth plays important role in the recovery process. Moreover, the relevant phenomenon occurring during the morphological recovery process is also investigated. The findings demonstrated the intrusion of sand spit into river mouths due to the tsunami having scoured river mouth deeper than the depth of closure. Interestingly, the intrusion distance was found to be positively correlated with the width of river mouth. In addition, there is an important finding on the practical problem which is related to the intrusion upstream of sand spit. That intrusion shifts the boundary of fresh-sea water upstream, therefore external wave forces must be considered when implementing the design of river structures. [ABSTRACT FROM AUTHOR]

An ability to estimate the large-scale spatial variability of seabed sediment type in the absence of extensive observational data is valuable for many applications. In some physical (e.g., morphodynamic) models, knowledge of seabed sediment type is important for inputting spatially-varying bed roughness, and in biological studies, an ability to estimate the distribution of seabed sediment benefits habitat mapping (e.g., scallop dredging). Although shelf sea sediment motion is complex, driven by a combination of tidal currents, waves, and wind-driven currents, in many tidally energetic seas, such as the Irish Sea, long-term seabed sediment transport is dominated by tidal currents. We compare observations of seabed sediment grain size from 242 Irish Sea seabed samples with simulated tidal-induced bed shear stress from a three-dimensional tidal model (ROMS) to quantitatively define the relationship between observed grain size and simulated bed shear stress. With focus on the median grain size of well-sorted seabed sediment samples, we present predictive maps of the distribution of seabed sediment classes in the Irish Sea, ranging from mud to gravel. When compared with the distribution of well-sorted sediment classifications (mud, sand and gravel) from the British Geological Survey digital seabed sediment map of Irish Sea sediments (DigSBS250), this ‘grain size tidal current proxy’ (GSTCP) correctly estimates the observed seabed sediment classification in over 73% of the area. [ABSTRACT FROM AUTHOR]

Wave and/or current supported gravity-driven sediment flows (GDSFs) cause substantial sediment movement across the continental shelf, contributing to morphological evolution in many regions worldwide. However, they appear to occur episodically and ephemerally and, therefore, it remains a challenge to document them in detail with in situ measurements. Here we present solid evidence of frequent generation of such flows over the shallow sea floor of a muddy open coast. They were triggered by wave resuspension and/or sediment settling from the overlying water column, maintained by wave- and/or current-induced bed stress, and terminated due to upward spreading of bottom sediment within the high concentration layer. Randomly selected GDSF events were analyzed to realize parameterization with a buoyancy-friction model; the resultant bed drag coefficient for two of the cases is higher than the value of 0.003, which is attributed to the additional drag at the interface between the overlying flow and the moving GDSFs. Although short-lived, the observed GDSF events in the three different seasons indicate that they occur more frequently than previously thought. • Multiple events of short-lived gravity-driven sediment flows (GDSFs) were directly observed. • GDSFs were neatly parameterized with a simple but elegant buoyancy-friction model. • GDSFs may occur more frequently than previously believed. [ABSTRACT FROM AUTHOR]

Abstract: Coarse-grained ripples (CGRs) develop within the seafloor depression–sand ridge systems along the Shimizu coast, in the northwestern part of Suruga Bay facing the Pacific Ocean, central Japan. In this paper, we analyze data from high-resolution bathymetry, seafloor observation by an underwater video camera, and high-resolution seismic surveys and seafloor trenching of shallow strata, obtained between 2005 and 2007, to describe their geomorphological and sedimentological characteristics in detail, and to examine the formative processes and maintenance of the systems. In water depths of 5–30m, CGRs occur in seafloor depressions that are approximately 40–70cm deeper than the surrounding sandy seafloor. In many cases, the ripples develop in depressions between shore-normal sand ridges composed mainly of fine sand (<70cm high, 100–400m long) on a relatively narrow shelf. The alongshore width of the sand ridges is 10–100m, and that of the depressions is 10–150m. The CGRs (wavelength<3.5m, height<30cm) have almost shore-parallel crests with a symmetrical or slightly asymmetrical shape, suggesting wave-generated oscillating flows. The crests of the lager ripples are composed of gravel (maximum long axis: 5–8cm) and the troughs consist of fine to very fine sand. The CGR–depression–sand ridge systems develop widely during the passage of typhoons in the summer–autumn seasons. At the narrower shelf, the surface fine-grained sediments and the surface and subsurface coarse-grained sediments, which form the sand ridges and the CGRs respectively, are repeatedly eroded and redeposited during typhoon-related storms. In contrast, active sediments are currently limited to the surface fine deposits on the wider shelf areas. The sediments that make up the CGRs appear to be derived from both modern beach sediments and relict sediments. We postulate that the CGR–depression–sand ridge system appears to be controlled mainly by both seafloor erosion and offshore-directed sediment transport during storms, and these processes may depend on the shelf width. In fact, the sand ridges (covering the CGRs) that imply significant offshore-directed transport only develop on the narrower shelf. The distribution and seabed expression of the CGRs is constrained by the thickness and distribution of surface-covering sandy sediments, such as the sand ridges. This represents a new interpretation of the distribution of CGRs within seafloor depressions on the shelf of an active margin that receives a large supply of sandy and gravelly fluvial sediments, and differs from the processes seen on the sediment-starved shelves of passive margins. [Copyright &y& Elsevier]

Abstract: The observation and prediction of the mobility of the seabed are in high demand with rapidly expanding offshore engineering developments and the increasing urgency to start mitigation against changing coastlines. From repeatedly surveyed sediment wave fields in the Irish Sea, average sediment wave migrations have been mapped, from which broad-scale net sediment transport directions can be derived. The proximity of bathymetric highs and lows seems to redirect sediment migration pathways and increases migration rates by a factor 5 on average via current deflection and amplification. A few hundred sediment waves were analysed geometrically in this study and compared to their migration behaviour, revealing a lack of statistical correlation. Sediment wave lee slope directions, asymmetry indices and other geometrical parameters appear poorly indicative of their degree of mobility in the Irish Sea. A considerable amount of sediment waves counter-intuitively migrate in the direction of their gentle stoss slope, i.e. opposite to the expected sense of migration. Even when considering the limitations of the predominantly 2-dimensional sampling method, these results fundamentally challenge established assumptions on the indicative meaning of sediment wave geometry. They question the validity and robustness of sediment wave migratory predictions based on single geometrical readings that fail to represent the complexity of local hydrodynamics and partial sediment wave modifications. Until predictive tools for sediment wave migration are developed that can pass the test in all aquatic environments, repeat surveying with sonar systems provides the only reliable way to record true natural variability. [Copyright &y& Elsevier]

Abstract: In this paper, transport pathways for coarse sediments were studied on an artificial pebble beach located at Marina di Pisa (Tuscany, Italy). Radio frequency identification (RFID) technology was used to trace the pebbles. The RFID technique is an inexpensive and reliable methodology that is used to address sediment displacement along the coastline. The use of low-frequency radio signals (125kHz) enabled the detection of the marked pebbles within a range of 40cm on the underwater and subaerial portions of the beach. About one hundred pebbles were sampled on the beach and paired with passive transponders. The tracers were released along a series of cross-shore transects (March 2009). The pebbles were injected on the fair-weather berm, on the swash zone, and on the step crest along each transect. The recovery campaign was carried out in May 2009. Fifty-three pebbles were detected; this number is rather high given the intensity of the three storms that hit the coast during the period of the experiment and the significant reworking that this beach is subjected to even under fair-weather conditions. The analysis of the tracer pathways highlighted twofold convergent longshore movement on the beach. The trajectories indicated that the longshore movement dominated the cross-shore movement, but there was no prevailing transport direction. To explore the morphology of the sea bottom fronting the beach, a topographic survey was carried out using an echo sounder. The survey showed the presence of two distinct shoals 20m off the coastline that are responsible for the resulting coarse sediment transport. These results confirm that even mild sea bottom irregularities may significantly affect sediment transport dynamics along a beach, suggesting that accurate planning for defense schemes such as artificial coarse replenishment must begin with an in-depth knowledge of the morphology of the sea floor. Such information may increase the durability and/or the efficiency of the intervention. [Copyright &y& Elsevier]

Abstract: How will Australia''s shelf and coastal seabed respond to climatic stress? Climate change is likely to impact ocean circulation, ocean temperature and salinity and sea-level fluctuations. Recent global ocean models have increased in reliability and predictability, with considerable advances in coupling climatic, oceanographic and sedimentary processes. Several models have been successful in reproducing surface sediment transport in both coastal and deep-sea areas. However, studies have yet to attempt a predictive assessment of how climate change influences long-term regional seabed responses. Using a process-based stratigraphic forward model, we have developed a method that could be applied worldwide to assess the impact of climate change-driven ocean perturbations on the seabed. Here, we present results of a fifty-year seabed sediment transport forecast of selected regions of the Australian Shelf. The results depict changes to sediment composition and seabed topography as a consequence of climate change-driven sediment mobility, erosion and carbonate growth. The predicted maximum of seabed changes is around 2m of erosion or accretion over the next fifty years. Most of the near-shore seabed sediments are coarsening due to combined effects of waves and tides. Increasing floods, storms and cyclonic events lead to significant changes to many coral reefs. [Copyright &y& Elsevier]

Abstract: A new approach to examine event-scale sedimentation is described that establishes a direct connection between water-column signals and changes in the seabed. The Po River (Italy) shelf is a good case study due to the dominant impact of winter storm events on sediment transport and the availability of coincident measurements necessary for the analysis. Repeated deployments of an instrumented bottom-boundary-layer tripod at this site have produced a nearly continuous record of sediment transport over ∼2.5y. Sediment cores were collected every ∼3mo during this time, and seabed inventories of 7Be (half-life 53.3d) were used to determine net sediment deposition or erosion during each deployment. Comparison of these values with the net elevation change obtained from the tripod altimeter shows good agreement, varying from ∼2cm deposition to ∼1cm erosion. The altimeter''s use is extended to quantify the net seabed change that results from individual storm-induced sediment resuspension events, lasting from days to weeks. Within each event, analysis of the altimeter record has proved challenging likely due to changes in sediment porosity that occur during a storm event. However, net erosion and deposition that occurs over an event can be evaluated and was found to be <1cm. Maximum resuspension and active-layer depths can be determined with suspended-sediment data and bottom-shear-stress calculations, and these depths are generally on the order of millimeters. Different aspects of the sediment dynamics are captured by the measurements, each of which is subject to instrument limitations. In particular, resuspension and active-layer depths reflect transient changes in erosion and deposition, whereas the altimeter records the net change in seabed height, including both transient changes and sediment flux divergence. [Copyright &y& Elsevier]

Abstract: A comprehensive numerical model is developed to predict the transient wave propagation, sediment transport, morphological change, and the elastodynamic responses of seabed due to breaking solitary waves runup and drawdown over a sloping beach. The individual components of the numerical model are first validated against previous analytical, numerical, and experimental results. The validated numerical model is then used to simulate breaking solitary wave runup and drawdown over a fine sand beach, where the experimental results are presented in (Young et al. 2010b. Hydro- and morpho-dynamic modeling of breaking solitary waves over a fine sand beach. Part I: Experimental study). The strengths and weaknesses of the model are assessed through comparisons with the experimental data. Based on the results, sediment transport mechanisms and wave–seabed interactions in the nearshore region are discussed. [Copyright &y& Elsevier]

Abstract: Measurements of the cross-shore suspended sediment flux obtained from a planar and barred beachface have been used to investigate the propensity for wave-driven onshore sediment transport during medium energy conditions. Three processes capable of transporting sediments onshore–flow velocity skewness, wave asymmetry and bed-ventilation were investigated to determine their relative importance. Onshore-directed flow accelerations under the steep front face of asymmetric waves were significantly correlated with sediment suspension, whilst the effects of flow skewness and bed-ventilation were discounted. An acceleration-modified form of the Meyer-Peter-type formula is used as initial attempt at modelling the onshore transport using a temporal filter to modify the bed shear stresses. [Copyright &y& Elsevier]

Abstract: The shoreface, a complex and poorly understood part of the coastal zone, plays a critical role in sediment transport processes between the beach and the inner shelf. This two-year study examined the surface and subsurface architecture and the process-response mechanisms of a high-energy, steep and geologically constrained shoreface segment (1–20 m depth) in Northern Ireland. Fourteen sequential bathymetric surveys, covering an area of ~2 km2, were compared and analysed in order to investigate seabed changes and their relationship to wave and wind forcing. Results reveal that the shoreface is highly dynamic and complex. An examination of high-energy conditions and lower-than-average energy conditions revealed significant periods of both accretion and erosion. These complex morphodynamic responses are attributed mainly to a combination of antecedent (pre-survey) morphology, differences in wind forcing and coastal surges. A comparison of seabed changes over 2 yr reveals net shoreface accretion, which is attributed to inner-shelf to shoreface sediment transport. Over the same period, the adjacent West Strand beach showed moderate erosion. The study provides information on the morphodynamics of a steep, high-energy embayment shoreface, a coastal environment which has received little previous attention. [Copyright &y& Elsevier]

Abstract: The extensive longshore sediment transport system along the SE margin of Australia transports yearly 500,000 m3 of sand from the Gold Coast of southern Queensland north towards Fraser Island. Fraser Island, which consists of 203 km3 of quartz sand, is presently not increasing in size and north of the island quartz sand is replaced by carbonate sand. Recent multibeam sonar seafloor imagery and sediment analysis has established that the transported sand is being diverted by strong ebb tidal flow over the continental shelf edge onto the Tasman Abyssal Plain through a series of active gullies that incised the continental slope. Foraminiferal distribution patterns on the shelf and slope are closely linked to the variable ocean floor morphology and associated physical processes. In sample locations outside the continental slope gullies, areas unaffected by downslope sediment transport, foraminiferal assemblages gradually change in accordance with bathymetric zones and their prevailing ecological parameters. Species diversity, evenness, the proportion of infaunal species and the abundance of agglutinated taxa all increase with depth. Assemblages within gullies of the clastic sand transport route are significantly different. Estuarine and shelf species are transported over the shelf break and mix with typical slope species along the transport path, resulting in continued high species diversities. As the sediment and faunal load enters the abyssal plain, a faunal portion continues to travel within the Capricorn Sea Valley to over 4000 m depth. The erosional nature of gullies results in reduction of agglutinated species. Subtle topographic features such as ridges or levees within the canyon and deep-sea valley act as protection from the main erosional sand transport pathway and support the presence of fragile and erect suspension feeders. Foraminiferal distribution patterns would have received an entirely different biofacies interpretation without linking them to ocean floor processes as revealed through multibeam sonar imagery. [Copyright &y& Elsevier]

Abstract: High resolution beach–inner shelf bathymetric profile surveys combined with wave data and sediment samples have been used to examine short-term morphological changes of the seabed at the eastern part of Abu Qir Bay. The profile survey covered ∼4.5 km alongshore and ∼9.5 km offshore to a 15-m water depth. These profiles were surveyed seven times between October 2001 and October 2002, showing changes during storms and the following recovery periods. Significant wave heights of storm waves (blown from the N and NNW) and fair weather waves (coming from the NW and NNE) were recorded between 2.0–5.0 m and <2.0 m, respectively. During storm periods, waves move sand from north to south and from the beach face and surfzone seaward to the upper shore face. The intervening periods between storms (swells of fair weather condition) are characterized by sediment redistribution from the northern or the southern parts toward the center of the bay. Mapping of computer-generated bathymetric surveys is used to interpret vertical seabed changes (erosion/accretion patterns) and to delineate sediment transport pathways. Linking this information with the spatial concentration of high intensity magnetic minerals (ilmenite and magnetite) in beach and seabed sediments helps to detect reversals in the directions of sediment transport to the north and to south, but with a general southward net pattern. The recognized outcrops of submerged rocks provide documented evidence that the shore-parallel late Pleistocene carbonate ridges, now subaerially exposed along the shore of Alexandria, extend further eastward on the seabed of Abu Qir Bay. [Copyright &y& Elsevier]

Abstract: Seabed pockmarks, the manifestation of the natural process of fluid escape at the seabed, are a widespread feature of the equatorial West African continental margin. Pockmarks occur singly, in small groups, in large random fields and in organized arrays or ‘pockmark trains’. Pockmark trains are associated with areas of steeper seabed gradient and evolve though time to form deep gullies. Pockmark gullies may exceed 1 km in width and extend for 10–20 km down slope, and form through the interaction of slope failure and fluid escape processes. Gullies maintain a rugose internal geometry throughout their development and do not represent sediment transport pathways to the deep basin. The geological processes that form seabed pockmarks and pockmark gullies are active today and these features may represent a hazard to subsea infrastructure. [Copyright &y& Elsevier]

Abstract: This study presents the results of a long-term monitoring program of bed level changes measured during 8 yr at an intertidal mudflat in a microtidal, temperate coastal lagoon. Additionally, bed level measurements obtained at a 10-min temporal resolution at the same tidal flat and at the bed of a nearby tidal channel are presented. Short-term changes in bed level are one or two orders of magnitude larger than the annual net-deposition rate, which shows that the environment is highly dynamic with respect to erosion, transport and deposition of fine-grained sediment. Some seasonality in the bed level changes was observed and there is a tendency for mudflat deposition in spring, summer and early autumn and erosion during the rest of the year, but interannual variations are large and different parts of the mudflat show different seasonal signals. A close coupling between sub- and intertidal deposition and erosion was observed. The time-series showed that some of the material eroded from the mudflat was not exported to the open sea, but instead temporarily deposited in a nearby shallow tidal channel and later returned to the mudflat during calmer weather conditions. These findings support previously published hypothesis and results of modelling studies. Based on the observed abundance of fine-grained sediment at the study sites and the high accretion rates generally found on fine-grained tidal flats in the Danish Wadden Sea area, it is argued that these fine-grained tidal flats are not seriously threatened by the expected sea level rise in the 21st century. [Copyright &y& Elsevier]

Abstract: Identified in 1996, during an environmental survey for the Atlantic Frontiers Environment Network, the Afen Slide lies around 95 km northwest of the Shetland Islands. The head of the slide is at a water depth of 830 mbsl, and the debris lobe stretches to over 1120 mbsl along a slope varying from around 0.7° to 2.5°. The overall length (head scarp to toe of lobe) of the slide is in excess of 12 km, and the maximum width attained is around 4.5 km. The relative timing of the various phases can be determined from the morphology, imaged using seabed picks from 3D exploration seismics, and high-resolution deep-tow boomer data. These seem to show at least four major phases of failure and several distinct modes of sediment transport, ranging from hydroplaning to block sliding. The most likely trigger for the failure is a seismic event focused on the nearby Victory Transfer Zone. Sensitising factors include the presence of contouritic sands directly beneath the surface of rupture. These would serve as a plane of weakness and, under seismic loading, may further weaken due to liquefaction. Indeed, previous studies have shown that the slope in this area is stable in the absence of external triggers. The processes of sediment transport subsequent to failure are also investigated using sediment cores, as well as the 2D and 3D seismic, and appear to indicate that flow transformation occurred in at least the first phase of mass movement. [Copyright &y& Elsevier]

Sediment cover over mid-ocean ridges is expected generally to thicken with seafloor age and distance from spreading center, reflecting symmetric sediment accumulation on both flanks of the ridge. In high quality reflection seismic records and sediment echosounding measurements recently collected across the East Pacific Rise we find a strong asymmetric distribution of sediments. On the eastern flank in the EXCO (Exchange between Crust and Ocean) area at 15°S sediment thickness increases only slowly with distance from the spreading axis, and hence crustal age, to about 15 m on 4.5 Ma old crust and 30 m on 7 Ma old crust. Sediments are draping the basement rather than ponding. On the western flank sediment was sampled that is already 70 m thick on 4.5 Ma old crust and up to 150 m on about 7 Ma old crust. Sediment ponds imply efficient transport by gravitationally driven turbidity currents. Sediment accumulation on the western ridge flanks and the rather flat seafloor indicate a redistribution of sediments. Accumulation of sediments corresponds with the extreme asymmetry of a helium plume at 15°S in the South Pacific. A tongue of high 3He extending westward from the rise near 2500–2700 m depth and a corresponding tongue of high temperature suggesting that the helium plume introduced by hydrothermal activity on the EPR spreading axis is being carried westward by abyssal currents. Fall-out of hydrothermal plumes may contribute and intensify sedimentation on the western flanks. However, it is reasonable to hypothesize that hydrothermal plumes are important agents in the dispersal of the larvae of hydrothermal vent fauna and may be responsible for the enhancement of pelagic zooplankton biomass resulting in a larger mass of pelagic rain. [Copyright &y& Elsevier]

Integrating field observations in the high-erosion rate region of the Chinese coastal zone (northern estuary of the Yellow River) were used to investigate the role of wave–seabed interactions in seabed erosion, combined with laboratory erosion experiments on the variations in sediment erodibility due to cyclic wave loading. The field results highlight a strong erosive event that occurred in the presence of high waves, during which the seawater turbidity increased sharply from 50 FTU to 600–800 FTU and the bed elevation decreased by 7.7 mm/h over 27 h. The laboratory results attribute this type of erosion to the contribution of wave actions on seabed sediments, where the waves probably acted as a plough and reduced the threshold velocity and critical shear stress values, thus enhancing sediment transport that also occurs due to the shear effect of near-bed currents during fair-weather conditions. Wave-induced liquefaction, characterised by the uneven build-up of excess pore pressures at different buried depths, may also enhance sediment erosion by generating vertical pore water seepage within the sediment and inducing internal sediment re-suspension. The field observations allowed us to construct a regional mathematical model of seabed erosion that parameterises the wave–seabed interactions, as well as to explore the implications of this model for extensive erosion of Yellow River estuarine sediments. This research represents a major step towards validating the critical role of wave-induced interactions in extensive sediment erosion events within a shallow estuarine system. • Yellow River estuarine sediments are subjected to extensive erosion. • This study examined the role of wave–seabed interactions in the problematic erosion. • Significant resuspension was detected in the presence of high waves during a storm. • Erosion was related to multiple factors including excess pore pressure. • A regional model was built to estimate erosion fluxes under waves of varying intensity. [ABSTRACT FROM AUTHOR]