Sand Wave Migration Research Articles

Self-Burial and Potential Hazards of a Submarine Pipeline in the Sand Wave Area in the South China Sea

AbstractThe hazardous exposure and self-burial of a submarine pipeline were studied based on the investigation of a submarine pipeline in the sand wave area in the South China Sea, as well as on statistical data and mathematical calculations. The results indicate that the pipeline free span in the area was mainly induced by seabed erosion, sand wave movement, and human disturbance. Extreme weather events cause severe impacts on seabed topography and the pipeline condition. The burial status of the pipe is mainly controlled by the evolution of local seabed topographical conditions, i.e., the amount of sediment load and the movement of seabed sand waves. The migration of the continuous small-scale sand waves facilitates the self-burial of pipes, while the migration of isolated large-scale sand waves creates potential hazards for pipelines because of the existing free span continues to grow on both sides of the sand wave.

Application of Grid‐Nesting Technique to Sandwave Migration Simulation I–Ultra‐High Resolution 3D Current Simulation

AbstractWith the Princeton Ocean Model (POM), a model with horizontal resolution of about 200 m is developed to simulate the bottom current field of the small study area in the north of the South China Sea. The grid‐nesting technique is used twice in this model with the high‐resolution bathymetry data measured by multi‐beam equipment. The lateral open boundary conditions of the nested model are selected by numerical experiments. It is proved that this ultra‐high resolution model is able to simulate the residual current of the area with complex ocean topography and is a quick and accurate way to get a three‐dimensional high‐resolution ocean current field of the small sea area with open boundaries. The resolution is nine times that of current international advanced level. The model developed here is also applicable for researches on small‐scale ocean environment.

Process control of the sand wave migration in Beibu Gulf of the South China Sea

Based on the environment characteristics of the Beibu Gulf of South China Sea, a quasi-three-dimensional physical model is built. By coupling the bottom boundary layer with the two-dimensional tidal current field near the seabed surface, the quasi-three-dimensional hydrodynamic numerical simulation is carried out. The sand wave migration process is dealt with by coupling the hydrodynamic model with the sediment transport model. The computational results are shown to be in good agreement with the observed data, which indicates that the quasi-three-dimensional physical model can be used to simulate the migration process for small scale sand waves. Then, based on measured data, the evolution of the sand wave migration is investigated. An effective formula is developed to predict the migration rate, in which not only the effects of the environment but also the features of sand waves are considered.

Spatial differences in sand wave dynamics between the Amsterdam and the Rotterdam region in the Southern North Sea

The optimization of the bathymetric resurvey policy of the Netherlands Hydrographic Service requires insight into sea floor dynamics in the Southern North Sea. To study the spatial variations in sea floor dynamics, the bathymetric archives of the Netherlands Hydrographic Service are analyzed using deformation analysis, a statistical and innovative approach for bathymetric data. Based on the uncertainty of the data, our implementation of deformation analysis selects the significant spatial and temporal parameters, and provides estimates and their uncertainties for those parameters. We focus on sand wave areas in the regions of Rotterdam and of Amsterdam. In those areas, dredging takes place to guarantee a minimum depth. The results reveal a difference in sand wave migration between the two regions, over the past two decades. The dominant wavelengths of the sand waves vary within the regions, but we find a similar wavelength distribution for the two regions. We compare our results to earlier studies of the same sand wave areas in the Rotterdam region, showing similar migration rates, but different wavelengths. It is concluded, based on sand wave dynamics alone, that the Amsterdam region should be assigned a higher resurvey frequency than the Rotterdam region.

Modelação Hidrossedimentológica no Canal de Acesso do Complexo Portuário do Maranhão

The Maranhao Harbor Area is the second largest harbor Complex of Latin America for cargo handling and it is located on the western side of Sao Luis Island in Sao Marcos Bay. The hydrosedimentological characterization of the Access Channel of Maranhao Harbor Area was performed using current data review and analysis for numerical modeling application. This paper also provides a method to obtain current pattern predictions from the results of hydrodynamical simulation, and to predict the evolution and migration of sand waves. The sediment transport model pointed to a low sediment transport rate in Area IV, III and II, explaining the smaller migration pattern of these waves when compared with Area I

Downslope-migrating sandwaves and platform-margin clinoforms in a current-dominated, distally steepened temperate-carbonate ramp (Guadix Basin, Southern Spain)

During the Late Tortonian, platform-margin-prograding clinoforms developed at the south-western margin of the Guadix Basin. Large-scale wedge-shaped deposits here comprise 26 rhythms of mixed carbonate–siliciclastic bedset packages and marl beds. These sediments were deposited on a shallow-water, temperate-carbonate distally steepened ramp. A downslope-migrating sandwave field developed in this ramp, with sandwaves moving progressively down the ramp to the ramp-slope, where they destabilized, folded and occasionally collapsed. Downslope sandwave migration was induced by currents flowing basinwards. During the Late Tortonian, the Guadix Basin was open north to the Atlantic Ocean via the Dehesas de Guadix Strait and connected east to the Mediterranean Sea through the Almanzora Corridor. According to the proposed current circulation model for the Guadix Basin for this time, surface marine currents from the Atlantic entered the basin from the northern seaway. These currents moved counter-clockwise and shifted the sediment on the ramp, forming sandwaves that migrated downslope. The development of platform-margin prograding clinoforms by the basinward sediment-transport mechanisms inferred here is known relatively poorly in the ancient sedimentary record. Moreover, these wedge-shaped geometries are similar to those found in some shelves in the Western Mediterranean Sea and could represent an outcrop analogue to (sub)-recent, platform-margin clinoforms revealed by high-resolution seismic studies.

Separating bathymetric data representing multiscale rhythmic bed forms: A geostatistical and spectral method compared

The superimposition of rhythmic bed forms of different spatial scales is a common and natural phenomenon on sandy seabeds. The dynamics of such seabeds may interfere with different offshore activities and are therefore of interest to both scientists and offshore developers. State‐of‐the‐art echo sounding accuracy allows for the analysis of bed form dynamics on unprecedented spatial and temporal scales. However, the superimposition of bed forms complicates the automated determination of morphodynamic parameters of individual bed form components. In this research we present the extension and comparison of two well‐known, automated signal‐processing methods for the 1‐D and 2‐D separation of bathymetric data derived from multibeam echo soundings into different components that each represents a bed form of a particular length scale. One method uses geostatistical filtering, and the other uses a Fourier decomposition of the bathymetric data. The application of both methods in two case studies of the North Sea shows that both methods are successful and that results correspond well. For example, megaripples up to 0.83 m height could be separated from 1.49–2.28 m high sand waves, and regionally averaged lengths and heights of sand waves, as calculated in either method, differ only 0.42–8.2% between methods. The obtained sand wave migration rates differ 7–11% between methods. The resulting morphometric and morphodynamic bed form quantification contributes to studies of empirical behavior and morphodynamic model validation and is valuable in risk assessments of offshore human activities.

Role of a Submarine Bank in the Long-Term Evolution of the Northeast Coast of Prince Edward Island, Canada

Abstract In order to understand regional variations in coastal behavior on Prince Edward Island, Canada, we investigated the role of Milne Bank, a submarine bank at East Point, the eastern tip of the island. The objective was to determine how the bank might facilitate transfer sediment from the eroding north coast to the adjacent sediment-rich south coast. The study utilized grain-size and seismic data collected on Milne Bank in 1989 and multibeam sonar surveys in 1997 and 1999. The disturbing effect of East Point on the hydrodynamic regime controls sediment transport. The northern boundary of the bank is a steep sand wave located where southward tidal and wave-driven currents rounding East Point suddenly decelerate. Sand from the north coast enters Milne Bank and is carried south in a field of migrating sand waves that are shed from the northern bounding sand wave toward the prograding end of the bank. Milne Bank is a major sediment sink, rather than a link between the eroding north coast and the sedimen...

Episodic dynamics of a sand wave field

The morphodynamics of a sand wave field in a flood-dominant channel inside Moriches Inlet was monitored for eight weeks during the summer of 2005. Bathymetric data show sand waves on average are 15 m long and 39 cm high with shallow slip faces. The sand waves remained stationary over the eight-week study. The maximum peak current speeds recorded during this study only reached 60 cm/s. This velocity was not sufficient to cause measurable sand wave migration. Analysis based on work by van Rijn suggests that the sand waves of this size would be created when the current velocity exceeds 80 cm/s, conditions not observed during this study. Water level data from Sandy Hook, NJ, and Shinnecock Inlet, NY, show that large tidal ranges occur when a drop in barometric pressure increases the elevation of high tide and strong north winds decrease the low-tide elevation. During these events the current velocity may reach 80 cm/s, which is predicted to be strong enough to produce these sand waves. This study demonstrates that high-energy, episodic events may control sand wave morphology at Moriches Inlet.

Long-term evolution of sand waves in the Marsdiep inlet. I: High-resolution observations

A seven-year long data set from 1998 to 2005 of sand waves in the Marsdiep tidal inlet in the Netherlands is presented. The sand waves are visible on digital terrain models (DTMs) that were compiled from water depths obtained with a ferry-mounted acoustic Doppler current profiler. This multi-year data set allows to study the spatial and temporal evolution of sand-wave migration, height, length, asymmetry, and orientation. Horizontal migration rates were successfully obtained with a simple cross-correlation technique similar to techniques used in particle tracking. The study area can be divided in roughly two halves. In the southern half of the inlet, the sand waves are of the progressive type with area-mean heights of about 3 m and lengths of about 190 m. In the northern half, the sand waves are asymmetrical-trochoidal with area-mean heights of about 2 m and lengths of about 165 m. Across the inlet, the sand waves migrate in the flood direction with rates between 0 and 90 m y - 1 . Only the progressive waves in the southern half migrate in directions perpendicular to their crests. A striking observation is the seasonal variability in height and migration of the sand waves in the northern half of the inlet. The sand-wave heights are about 0.5 m higher in fall than in spring and the migration rates are about 30 m y - 1 higher in winter than in summer. This paper only presents observations and analysis techniques. In a subsequent paper, the ADCP-current data will be applied to explain the spatial and seasonal variability of the sand waves.

Long-term evolution of sand waves in the Marsdiep inlet. II: Relation to hydrodynamics

A discussion is presented about the mechanisms that govern the spatial and seasonal variability in sand-wave height and migration speed in the 4 km wide Marsdiep tidal inlet, the Netherlands. Since 1998, current velocities and water depths have been recorded with an ADCP that is mounted under the ferry ‘Schulpengat’. In this paper, the current measurements were used to explain the sand-wave observations presented in Buijsman and Ridderinkhof [this issue. Long-term evolution of sand waves in the Marsdiep inlet. I: high-resolution observations. Continental Shelf Research, doi: 10.1016/j.csr.2007.10.011]. Across nearly the entire inlet, the sand waves migrate in the flood direction. In the flood-dominated southern part of the inlet, the ‘measured’ (i.e. based on sand-wave shape and migration speed) and predicted bedload transport agree in direction, magnitude, and trends, whereas in the ebb-dominated northern part the predicted bedload and suspended load transport is opposite to the sand-wave migration. In the southern part, 55% of the bedload transport is due to tidal asymmetries and 45% due to residual currents. In addition to the well-known tidal asymmetries, asymmetries that arise from the interaction of M 2 and its overtides with S 2 and its compound tides are also important. It is hypothesised that in the northern part of the inlet the advection of suspended sand and lag effects govern the sand-wave migration. The relative importance of suspended load transport also explains why the sand waves have smaller lee-slope angles, are smaller, more rounded, and more three-dimensional in the northern half of the inlet. The sand waves in this part of the inlet feature the largest seasonal variability in height and migration speed. This seasonal variability may be attributed to the tides or a seasonal fluctuation in fall velocity. In both cases sediment transport is enhanced in winter, increasing sand-wave migration and decreasing sand-wave height. The influence of storms and estuarine circulation on the sand-wave variability is negligible.

Sandwave migration in Monterey Submarine Canyon, Central California

Repeated high-resolution multibeam bathymetric surveys from 2002 through 2006 at the head of the Monterey Submarine Canyon reveal a sandwave field along the canyon axis between 20 and 250 m water depth. These sandwaves range in wavelength from 20 to 70 m and 1 to 3 m in height. A quantitative measure was devised to determine the direction of sandwave migration based on the asymmetry of their profiles. Despite appreciable spatial variation the sandwaves were found to migrate in a predominantly down-canyon direction, regardless of season and tidal phases. A yearlong ADCP measurement at 250 m water depth showed that intermittent internal tidal oscillations dominated the high-speed canyon currents (50–80 cm/s), which are not correlated with the spring–neap tidal cycle. Observed currents of 50 cm/s or higher were predominantly down-canyon. Applying a simple empirical model, flows of such magnitudes were shown to be able to generate sandwaves of a size similar to the observed ones.

COMPUTATION OF FLOW, TURBULENCE AND BED EVOLUTION WITH SAND WAVES

A vertical two-dimensional morphodynamic model with non-hydrostatic, free surface flow is reported herein. This numerical model can simulate flow and turbulence characteristics over sand waves. Likewise, model can reproduce the sand wave formation and migration process as well as free surface oscillation simultaneously in a moving boundary domain with the implication of generalized coordinate system. A nonlinear k-e model is employed as a turbulence closure. CIP numerical technique is used to resolve advection term of momentum equations. An Eulerian stochastic formulation of sediment exchange process in terms of pick up and deposition function is incorporated to simulate non-equilibrium sediment transport that explicitly considers the flow variability during morphodynamic computation. The numerical model is validated with experimental data on flow and turbulence over fixed dunes as well as laboratory measurement and visualization of dune geometry and migration.

Assessing decadal-scale changes to a giant sand wave field in eastern Long Island Sound

Research Article| February 01, 2006 Assessing decadal-scale changes to a giant sand wave field in eastern Long Island Sound Michael S. Fenster; Michael S. Fenster 1Randolph-Macon College, Environmental Studies Program, Ashland, Virginia 23005, USA Search for other works by this author on: GSW Google Scholar Duncan M. FitzGerald; Duncan M. FitzGerald 2Boston University, Department of Earth Sciences, Boston, Massachusetts 02215, USA Search for other works by this author on: GSW Google Scholar Matthew S. Moore Matthew S. Moore 3Randolph-Macon College, Environmental Studies Program, Ashland, Virginia 23005, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Michael S. Fenster 1Randolph-Macon College, Environmental Studies Program, Ashland, Virginia 23005, USA Duncan M. FitzGerald 2Boston University, Department of Earth Sciences, Boston, Massachusetts 02215, USA Matthew S. Moore 3Randolph-Macon College, Environmental Studies Program, Ashland, Virginia 23005, USA Publisher: Geological Society of America Received: 25 Mar 2005 Revision Received: 07 Oct 2005 Accepted: 11 Oct 2005 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2006) 34 (2): 89–92. https://doi.org/10.1130/G21700.1 Article history Received: 25 Mar 2005 Revision Received: 07 Oct 2005 Accepted: 11 Oct 2005 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Michael S. Fenster, Duncan M. FitzGerald, Matthew S. Moore; Assessing decadal-scale changes to a giant sand wave field in eastern Long Island Sound. Geology 2006;; 34 (2): 89–92. doi: https://doi.org/10.1130/G21700.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Three digital precision bathymetric data sets spanning 16.1 yr enabled a long-term analysis of the geometric, migration, and volumetric changes to large bedforms in a 1 km2 region of eastern Long Island Sound. Whereas a 1 yr study of sand wave mechanics during 1987 provided indirect evidence of long-term southwestward transport, this study adds a June 2003 data set and conclusively demonstrates a basinward (southwestward) progression of sand waves between 7 and 17 m in height. In addition, the modus operandi of sand wave migration during various temporal scales involves crestal flexing, crestal rotation, and differential migration along the crest. A volumetric analysis suggests that the sand waves are in a waning phase of migration and early stage of preservation as sea level rises into the basin and flood-dominant tidal currents decrease in strength. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Sandwave migration predictor based on shape information

Migration of offshore seabed waves, which endangers the stability of pipelines and communication cables, is hard to measure. The migration rates are small compared to the measurement errors. Here, sandwave migration rates are determined from the change in the crest position deduced from long time series of bathymetric echo‐sounding data. The crests are identified as local extremes in a bathymetric profile, after low‐pass filtering. This approach is applied to both two‐dimensional data and to profiles along pipelines. A consistent migration rate of several meters per year is found. A strong correlation between the sandwave shape and the migration rate is translated in a migration predictor. The predictor assumes that the sandwaves migrate in the direction of the steepest slope, following a quadratic relation with the asymmetry. Furthermore, it is included that longer waves travel faster but higher waves travel slower. The predictor is calibrated against data from nine areas and validated using three additional areas. An error analysis using markers shows that the error of the predictor is small compared to the noise in the individual crest position observations.

Proterozoic sedimentation and volcanism in the Singhbhum crustal province, India and their implications

The Proterozoic volcano-sedimentary succession comprising successively younger Dhanjori, Chaibasa, Dhalbhum, Dalma and Chandil Formations of the Singhbhum crustal province, India records sedimentation and volcanism in a rapidly changing tectonic scenario. Cooling of the vast volume of Archaean Singhbhum granite possibly induced an isostatic readjustment. The associated tensional regime and deep-seated fractures controlled the formation of the Proterozoic Singhbhum basin. The Dhanjori Formation unconformably overlies the Singhbhum granite and is entirely terrestrial, dominantly fluvial. At the base, the conglomerate deposits, coarse-grained sandstone, and shale represent the distal fringe of an alluvial fan complex. The rest of the formation including the volcaniclastic rocks consists almost entirely of fining-upward fluvial cycles. The base of the Dhanjori Formation is a sequence boundary and the formation itself represents a lowstand systems tract. The Dhanjori volcano-sedimentary succession displays evidence of having passed through passive, as well as, active phases of continental rifting with an increasingly important influence of volcanism on the sedimentation through time. The Chaibasa Formation sharply overlies the Dhanjori Formation and a transgressive lag demarcates their contact. The basal part of the Chaibasa Formation immediately overlying the transgressive lag deposit represents a transgressive systems tract while offshore shales that sharply overlie the shallow marine sandstones up-section represent marine flooding surfaces. The shallow marine subtidal sandstones bear an excellent record of sandwave migration and provide a rare opportunity to unlock the Late Palaeoproterozoic lunar orbital periodicities. Unlike the Chaibasa, the overlying Dhalbhum Formation is entirely terrestrial (fluvial-aeolian) indicating that the Chaibasa-Dhalbhum contact is a sequence boundary. The Dalmas, overlying the Dhalbhum Formation, represents concordant lava outpourings without any break in sedimentation; these lavas are genetically related to mantle plume upwelling in an intracontinental rift setting. The volcano-sedimentary package lying north of the Dalma volcanic belt (Chandil Formation) is of Mesoproterozoic age. The entire Late Palaeoproterozoic volcano-sedimentary package displays post-depositional compressional deformation and greenschist to amphibolite facies metamorphism dated at ca. 1600 Ma, forming the so-called North Singhbhum fold belt. The volcano-sedimentary package lying south of the Dalma volcanic belt was pushed further south towards the Singhbhum granite batholith complex as a result of uplift related to the Dalma plume. The Singhbhum granite batholith acted as a rigid body. This gave rise to a compressional stress regime that induced shearing/thrusting at ca. 1600 Ma along the Singhbhum Shear Zone. The Dalma plume magmatism was possibly part of a ∼1600 Ma global tectono-thermal event.

On the modeling of sand wave migration

We describe a simple mathematical model capable of reproducing the main features of sand wave inception and growth. In particular we focus on the prediction of the migration rates that sand waves undergo because of tidal and residual currents. The model adequately predicts migration rates even for the cases of upstream‐propagating sand waves, i.e., for sand waves which migrate in the direction opposite to that of the residual current. We show that upstream/downstream propagation is mainly controlled by the relative strength of the residual current with respect to the amplitude of the quarter‐diurnal tide constituent and by the phase shift between the semi‐diurnal and quarter‐diurnal tide constituents. Therefore, to accurately predict field cases, a detailed knowledge of the direction, strength, and phase of the different tide constituents is required.

Migration and sedimentology of longshore sandwaves, Long Point, Lake Erie, Canada

AbstractThis paper describes the formation, migration and sedimentology of sandwaves along the distal end of Long Point, a 40 km long spit in Lake Erie. Some seven to nine sandwaves occur in a zone over the last 14 km of the spit. They are characteristically 50–100 m wide at the downdrift end, range in length from 350 m to > 1500 m and migrate alongshore at rates that are typically 100–300 m year−1. Measurements over a 7‐year period show two forms of alongshore sandwave migration: (1) a migratory jump; and (2) downdrift accretion. The migratory jump is commonly 200–500 m year−1 and results from the onshore migration and welding of an inner nearshore bar to the downdrift end of the sandwave. This in turn leads to emergence of the bar over a distance of several hundred metres downdrift of the sandwave and isolation of the trough landward of the bar. Infilling of the trough abstracts large volumes of sediment from the local sediment transport system and may affect movement of the sandwave in the following year or movement of the next sandwave downdrift. Downdrift accretion commonly results in migration of 50–150 m year−1 and results from the refraction of waves around the distal end of the sandwave and episodic accretion of small swash bars. This mechanism occurs less frequently and appears to reflect a local condition of lower sediment abundance, often triggered by a large migratory jump in the previous year. The process of bar emergence and infilling produces a distinct suite of sedimentary structures associated with the infilling of the landward trough and building of the sandwave berm. The initial shoreline perturbation that generates the sandwave results from onshore migration and welding of inner nearshore bars, and the development and growth of the sandwaves is promoted by refraction of highly oblique waves.

Migrating sand waves

A simple mathematical model is described, which reproduces the major features of sand waves' appearance and growth and in particular predicts their migration speed. The model is based on the linear stability analysis of the flat configuration of the sea bottom subject to tidal currents. Attention is focused on the prediction of the complex growth rate Γ that bottom perturbations undergo because of both oscillatory fluid motions and residual currents. While the real part Γ r of Γ controls the amplification or decay of the amplitude of the bedforms, the imaginary part Γ i is related to their migration speed. Previous works on the migration of the sand waves (Nemeth et␣al. 2002) consider a forcing tide made up by the M2 constituent (oscillatory period equal to 12 h) plus the residual current Z0 and predict always a downcurrent migration of the bedforms. However, field cases exist of upcurrent-migrating sand waves (downcurrent/upcurrent-migrating sand waves mean bedforms moving in the direction of the steady residual tidal current or in the opposite direction, respectively). The inclusion of a tide constituent characterized by a period of 6 h (M4) is the main novelty of the present work, which allows for the prediction of the migration of sand waves against the residual current Z0. Indeed, the M4 tide constituent, as does also the residual current Z0, breaks the symmetry of the problem forced only by the M2 tide constituent, and induces sand-wave migration. The model proposed by Besio et␣al. (2003a) forms the basis for the present analysis. Previous works on the subject (Gerkema 2000; Hulscher 1996a,b; Komarova and Hulscher 2000) are thus improved by using a new solution procedure (Besio et␣al. 2003a) which allows for a more accurate evaluation of the growth rate for arbitrary values of the parameter r, which is the ratio between the horizontal tidal excursion and the perturbation wavelength.

Mathematical modelling of sand wave migration and the interaction with pipelines

A new method is presented for identifying potential pipeline problems, such as hazardous exposures. This method comprises a newly developed sand wave amplitude and migration model, and an existing pipeline–seabed interaction model. The sand wave migration model is based on physical principles and tuned with field data through data assimilation techniques. Due to its physical basis, this method is trusted to be more reliable than other, mostly engineering-based methods. The model describes and predicts the dynamics of sand waves and provides the necessary bed level input for the pipeline–seabed interaction model. The method was tested by performing a hindcast on the basis of survey data for a specific submarine gas pipeline, diameter 0.4 m, on the Dutch continental shelf. Good agreement was found with the observed seabed–pipeline levels. The applicability of the method was investigated further through a number of test cases. The self-lowering of the pipeline, in response to exposures due to sand wave migration, can be predicted, both effectively and efficiently. This allows the use of the method as a tool for pipeline operation, maintenance and abandonment.