massive sand beds attributed to deposition by dense water cascades in the bourcart canyon head gulf of lions northwestern mediterranean sea nowadays the gulf of lions continental shelf and slope are under the influence of dense water cascading wind induced bottom currents and the geostrophic northern current in order to characterize sedimentary activity at the shelf break several interface and piston cores were taken in the bourcart canyon head and a current meter equipped with temperature conductivity pressure and turbidity sensors was moored during the 2003 2004 winter season even if the canyon is not connected directly to continental sources since last glacial maximum detailed grain size x ray and sediment facies analysis of interface cores show that down to 350 m water depth the canyon head is blanketed by up to 1 5 m of structureless muddy medium grained sand 210pbexc activity measurements demonstrate present day sedimentary activity of the canyon head time series of currents with peak velocity reaching 0 37 m s suspended sediment concentration and temperature indicate that dense water cascading is the main process allowing the reworking transport and accumulation of sand within the canyon head even though winter 2003 2004 was characterized by low cascading events compared to other years these sand beds called cascadite constitute a new type of deposit that differs from other typical slope deposits turbidites hyperpycnites contourites in terms of flow duration and sedimentological characteristics they are similar to shallow water contourites they might be time equivalent to the recent turbidites described throughout the deep western gulf of lions basin

living on the edge evaluating the impact of stress factors on animal sediment interactions in subenvironments of a shelf margin delta the mayaro formation trinidad abstract integrating sedimentological and ichnological characteristics of the gelasian mayaro formation along the se coast of trinidad allows recognition of a river dominated and wave influenced shelf edge deltaic succession of the paleo orinoco river developed under strong slope instability four main sedimentary settings and twelve subenvironments developed on and beyond the outer shelf i e at the shelf margin have been identified extreme paleoenvironmental conditions make the succession rarely and sporadically colonized ichnologic evidence suggests that shelf edge deltas are among the most stressful marine environments due to a combination of physicochemical factors in response to the intrinsic sedimentary processes and the relative hierarchy of their influences specific to every subenvironment within any particular subenvironment the relative dominance of the fluvial feeder system the action of waves and rare influence of tides and slope instability determine the combinations and ranking of stress factors river dominated shelf edge delta subenvironments demonstrate the extreme influence of stress factors related to channel activity e g salinity changes high sedimentation and erosion rates flocculation of mud seasonal variations of fluvial flux whereas subenvironments dominated by waves storms and oceanic swells away from the axial feeder s are mostly influenced by barform morphodynamics and its effects on local physiography the paleo orinoco delta is represented not only by the delta lobe s developed at the shelf edge but by delta lobe s formed on the outer shelf as well outer shelf deltaic subenvironments manifest typical ichno sedimentological signatures of a normal wave influenced in this case inner shelf delta being susceptible to extensive gravitational instabilities the delta system suffered from canyonization and smaller gullying and subsequent filling n b hereafter we use the term canyon for both canyons and smaller gullies the shelf edge delta system was also associated with shelf attached mass transport systems such depositional subenvironments dominated by slope instability and sediment gravity flows appear to be the most unconducive for benthic colonization resulting in almost complete absence of bioturbation characterization of the stress factors as the functions of parameters arising from specific sedimentary and or oceanographic processes chemical conditions and preservational constraints specific to each subenvironment leads to the construction of a comprehensive ichnological and depositional analog model for shelf edge deltas in general and for the accommodation driven low latitude shelf edge deltas at an active oblique foreland setting in particular

stable isotopic and biomarker evidence of terrigenous organic matter export to the deep sea during tropical storms abstract the global export of organic carbon oc is intimately linked to the total flux of terrestrial sediment to the ocean with the continental margins receiving 90 of the sediment generated by erosion on land recent studies suggest that a substantial amount of particulate oc poc might escape from the shelf and be exported to the continental slope deep sea sector although the mechanisms and magnitude of such deep sea poc transfer remain unknown here we investigate hyperpycnal flow associated total suspended matter tsm collected from water depths of 3000 m near the bottom of sea floor in the gaoping submarine canyon gsc off southwestern taiwan elemental c n isotopic 13 c 15 n and biomarker compositions of tsm were investigated to understand its biogeochemical characteristics a two end member 13 c mixing model indicates that deep sea tsm contains 90 terrigenous oc while a similar mixing model using 15 n reveals a lower proportion 58 organic biomarkers of tsm suggest contributions from a mixture of resuspended continental margin derived marine organic matter om mar and terrigenous sources revealing that terrestrial oc likely mixes with nitrogen rich marine material during rapid transport this study documents that rapid transfer of terrigenous organic matter om terr into the deeper regions of gsc occurred within a week of typhoon morakot likely through hyperpycnal injection of sediment laden warm freshwater from southern taiwan evidence from this typhoon morakot induced hyperpycnal plume event in taiwan demonstrates that extreme storm events provide an efficient way to export terrigenous oc without oxidation to hitherto unknown water depths of deep sea in the oceania region

kaikoura canyon new zealand active conduit from near shore sediment zones to trench axis channel kaikoura canyon is one of a few major active conduits between a near shore sediment transport system and a deep ocean channel it is the sink for mobile zones of gravel sand and mud that migrate northwards off northeastern south island new zealand it is presently the primary source for the 1500 km long hikurangi channel which supplies overbank turbidites to a filled trench an ocean plateau basin and a distal fan drift swath data seismic profiles side scan sonographs aerial photographs cores grab samples and current meter data are used to define the shape and texture of the canyon and adjacent shelf in order to better understand how coastal processes and canyon interact to supply sediment to the deep ocean kaikoura canyon is 60 km long up to 1200 m deep and generally u shaped in profile its head is within 500 m of the shore and within 200 m of rocky projections from the shore platform in a mountain backed bay without large rivers the canyon head incises the 18 m depth contour and boulders pebble gravel and megarippled coarse sand reach the canyon rim fine sand migrating northward along the shelf under the influence of waves and currents is trapped in a southward projecting canyon head gully which incises the thickest part of the holocene sediment prism it is estimated that about 1 5 106 m3 of sediment falls into the canyon head each year tensional fractures around the canyon rim suggest that sediments in the canyon head gully are unstable gravel turbidites with post last glacial age shells are at or near the seabed in the lower canyon but are blanketed by many thin silt and sand possibly storm generated turbidites in the upper canyon the top gravel contains a twig that is about 170 years old suggesting that the last major collapse in the canyon head coincides with many onshore rockfalls triggered by rupture of a major strike slip plate boundary fault in about 1833 an underlying gravel is about 300 years old and may again coincide with fault rupture most of the large earthquake triggered failures may ignite to form self perpetuating autosuspension flows that feed a 1500 km long deep sea turbidite channel

particle transport in the bari canyon southern adriatic sea to define the sediment transport pathways along the southern adriatic shelf and slope two oceanographic cruises were carried out in the southern adriatic in july 2004 and in march april 2005 to study the role of the bari canyon system on sediment dispersal three moorings including sediment traps and current meters have been deployed near the bottom at depths of 600 m for one year march 2004 march 2005 two moorings were deployed within the canyon station b in the northern branch and station c in the southern branch and one on the adjacent open slope north of the canyon system station a total mass fluxes tmfs measured by sediment traps were always higher in the canyon than on the adjacent slope the highest values were measured at station c average 8 07 g m 2 d 1 roughly double those of station b 3 07 g m 2 d 1 and the lowest outside the canyon at station a 1 69 g m 2 d 1 the highest tmf were recorded in spring 2004 a period characterized by the lowest water temperatures and the highest current speeds up to 72 cm 1 which were associated with the highest across slope current component along the canyon axes the simultaneous variations of fluxes occurring at the three stations imply that similar processes are active along the entire southern adriatic margin and that they are amplified inside the canyon in spring a vein of southward flowing north adriatic dense water naddw was observed along the adriatic shelf this was related to an enhanced across slope current component which was responsible for the higher particle fluxes both on the open slope and at the canyon stations these data suggest that the bari canyon is an efficient conduit for sediment from the adriatic continental shelf to the deep basin downcore profiles of 210 pb in sediments collected below the traps have been used to estimate sediment mass accumulation rates mars on a century scale on the open slope the annual trap flux recorded in 2004 2005 was lower than mar on the contrary in the bari canyon the annual trap flux was higher than mar indicating that the lateral advection of particles becomes predominant and that a fraction of the particles intercepted by sediment traps was only in transit through the canyon 2007 elsevier b v all rights reserved

observations of the internal tide in monterey canyon abstract data from two shipboard experiments in 1994 designed to observe the semidiurnal internal tide in monterey canyon reveal semidiurnal currents of about 20 cm s 1 which is an order of magnitude larger than the estimated barotropic tidal currents the kinetic and potential energy evidenced by isopycnal displacements of about 50 m was greatest along paths following the characteristics calculated from linear theory these energy ray paths are oriented nearly parallel to the canyon floor and may originate from large bathymetric features beyond the mouth of monterey bay energy propagated shoreward during the april experiment itex1 whereas a standing wave that is an internal seiche was observed in october itex2 the difference is attributed to changes in stratification between the two experiments higher energy levels were present during itex1 which took place near the spring phase of the fortnightly 14 8 days cycle in sea level while itex2 occurred close to the neap phase further evide

nepheloid layer dynamics in the northern portuguese shelf abstract a general hydrographic and nephelometric survey of the nw portuguese continental shelf and upper slope was undertaken under winter and spring conditions the nepheloid layer dynamics along the shelf during three cruises were controlled principally by the following factors a the hydrography of the shelf slope waters i e the nepheloid layers followed isopycnals and water masses b prevalence of upwelling or downwelling circulation over the shelf c dispersion of material by river discharge mainly the douro river d resuspension of mid shelf fine deposits induced by swell e peculiar morphology with the presence of porto canyon and outer shelf rock outcrops the general circulation controls the seaward extension of the nepheloid layers in winter under dominant downwelling conditions an intense bottom nepheloid layer bnl was observed on the shelf due to river borne particle supply and remobilization of mid shelf muddy sediments depth 100 m in this period the bnl increased in thickness to the top of the slope following the isopycnals near the shelf break the bnl detached to form intermediate nepheloid layers inl small inls appear deeper in some areas of the slope a surface nepheloid layer snl appears in the surface water over the shelf and slope in spring biological particles mainly contribute to the snl which is separated from the bnl by a zone of clear water in winter the snl is restricted to the inner shelf where there are high inputs of fluvial particles downwelling circulation probably induces transport of shelf particles to deeper waters in the bnl in spring the predominant circulation was southward upwelling the water column was highly stratified and dispersion of particles in the snl was offshore

survey and explorations of caves in southeastern ethiopia middle stone age and later stone age archaeology and holocene rock art abstract the horn of africa provides the setting for the evolution of early modern humans and their dispersal out of africa as well as for the entry many thousands of years later of pastoralists who brought near eastern and later south asian livestock into africa however significant gaps remain in our understanding of the late upper pleistocene archaeological record of the horn of africa mainly due to the paucity of well stratified sites from the period the discovery in southeastern ethiopia of a number of caves with rich upper pleistocene and holocene archaeological deposits many of which also had rock art depicting domestic animals offers an unprecedented opportunity for exploring the later prehistory of the region in 2007 2008 our survey documented twenty one cave sites and shelters with evidence of cultural deposits including middle stone age msa and later stone age lsa stone artifacts faunal remains and rock art active and fossil speleothems important for paleoclimatic reconstructions and chronology were found from two other caves in eastern and western harerghe test excavations were conducted at three sites with abundant archaeological material documented from stratified deposits at two of these sites gilbo tate and goda buticha the latter is a subject of another paper in this volume rock art was recorded at eighteen sites three of which in western harerghe had not previously been documented at many of the sites much of the art is faded and in a vulnerable state and continued efforts to document and conserve this art are urgently needed

instruments for particle size and settling velocity observations in sediment transport in this paper we describe two sensors for measurement of particle size distribution and settling velocity distribution these measurements are critical to the correct estimation of the true sediment concentration in the field as well as to evaluating models for transport rates of sediments a multi angle measurement of laser scattering is made and inverted to obtain the particle size distribution since small angle scattering is relatively insensitive to particle composition the size distribution measurements are robust and do not require particle refractive index it is shown that with a knowledge of the size distribution true particulate volume concentration can be obtained unaffected in calibration by changes in particle size distribution the data from bottom boundary layer experiments using the instrument show the presence of temporal variability in size distribution associated with the strength of forcing of the boundary layer the importance of these observations lies in the implication that historical data acquired with single parameter optical or other sensors needs to be revisited in the second instrument analyzing the observation of size distributions during settling in a settling column produces settling velocity estimates in this case the history of concentration of each size class is examined to determine the settling velocity without invoking any assumptions of settling regime settling velocity data from a field experiment off the new jersey coast fit the model wf na 0 45 10 23 a 1 2 n

a numerical investigation of the dynamics and structure of hyperpycnal river plumes on sloping continental shelves 1 a 3 d hydrodynamic model regional ocean modeling system is used to investigate the dynamics and structure of hyperpycnal river plumes over sloping continental shelves the focus is on the plume s response to varying slopes and settling velocities ws the idealized model is configured to represent small mountainous river systems during a flood event a hyperpycnal sediment concentration of 60 g l is specified at the river mouth such that the sediment freshwater mixture is denser than the seawater causing the plumes to traverse the shelves as undercurrents a realistic range of shelf slope of 0 001 0 03 is chosen the settling velocity is varied based on river s carrying capacity the model derived velocity profiles and the entrainment rate compare favorably against prior laboratory experiments both cross shore and alongshore momentum balances are primarily between gravitational forcing and bottom friction but the coriolis deflection is significant at the plume core in the alongshore momentum budget i e ekman balance as the slope increases and settling velocity decreases hyperpycnal plumes transition from depositional to autosuspending regime an estimate of critical slope governed by a dimensionless parameter ws3 qb qb is buoyancy input reasonably captures the regime transition in the depositional regime the plume s runout cross shore penetration scales with advective distance increasing slopes and discharge enhance the gravitational forcing and plume velocity leading to an increase in runout in contrast increasing settling velocity shortens the vertical settling time thereby reducing the plume s horizontal footprint for the range of parameters considered the runout of depositional plumes is confined within 15 km from the mouth whereas the penetration of autosuspending plumes is essentially unlimited

linking the infilling of the north branch in the changjiang yangtze estuary to anthropogenic activities from 1958 to 2013 abstract many tidally dominated estuaries of the world are experiencing variations in bottom topography due to changes in natural forcings and intensive human activities here we focus on the morphological evolution of the north branch nb a tidally dominated distributary of the changjiang estuary our analysis is based on long term bathymetric and hydrological data collected between 1950 and 2010 the results show that mean water depth channel volume below 0 m and channel volume below 5 m have respectively decreased by 43 53 and 92 in the last 50 years a reduction of the whole estuarine surface with aggradation in elongated tidal sand bars and erosion at the mouth are the main morphological variations of the nb while a decrease in channel volume below 5 m due to infilling is the second mode of morphological change while the drastic decrease in sediment load from upstream is likely unrelated to the silting of the nb local land reclamation along the banks is directly responsible for the reduction of estuarine surface area and related tidal prism between 1958 and 2013 enhanced flood tide currents resulted in a large import of sediments from offshore into the nb triggering a sustained decrease in channel volume below 0 m it is argued that the recovery of the funnel shaped configuration of the estuary by restoring mud flats over 0 m dredging the southern part of the estuary bend and forbidding land reclamation could prevent the silting of the nb otherwise the nb will likely vanish in few decades

sea level and climatic controls on turbidite occurrence for the past 26 kyr on the flank of the gaoping canyon off sw taiwan submarine canyons are major conduits for delivery of sediments originating from the continental margin into the deep sea here we analyze the effects of changing sea levels and climate e g sediment supply on the frequency of turbidites over the last 26 kyr our study is based on high resolution age controls for turbidites in core md178 10 3291 from a water depth of 2070 m on the flank of the gaoping canyon offshore in sw taiwan unlike most other submarine canyons worldwide the head of the gaoping canyon has remained connected to the river mouth during the recent flooding of the continental shelf our results reveal that turbidity currents are less frequent during periods of sea level lowstand in contrast turbidity currents have been more frequent since 12 kyr bp during the final stage of rising sea level and sea level highstands this may be the result of increased terrestrial sediment delivery due to enhanced rainfall intensity moreover comparing to other source to sink systems the turbidite occurrence in the flank of gaoping canyon through the last glacial cycle might have been more strongly influenced by climatic changes due to short sediment storage response time

particle fluxes dynamics in blanes submarine canyon northwestern mediterranean abstract within the framework of the multidisciplinary recs project and with the aim of describing the particle flux transfer from the continental shelf to the deep basin an array of five mooring lines equipped with a total of five pairs of pps3 3 sequential sampling sediment traps and rcm 7 8 current meters were deployed 30 m above the bottom from march 2003 to march 2004 inside and outside the blanes canyon one mooring line was located in the upper canyon at 600 m depth one in the canyon axis at 1700 m depth and other two close to the canyon walls at 900 m depth a fifth mooring line was deployed in the continental open slope at 1500 m water depth the highest near bottom downward particle flux 14 50 g m 2 d 1 was recorded at the trap located in the upper canyon m1 where continental inputs associated with the presence of the tordera river are most relevant on the other hand the downward fluxes 4 35 g m 2 d 1 in the canyon axis m2 were of the same order as those found in the western flank m3 of the canyon both values were clearly higher than the value 1 95 g m 2 d 1 recorded at the eastern canyon wall m4 the open slope m5 mass flux 5 42 mg m 2 d 1 recorded by the sediment trap located outside the canyon system was three orders of magnitude lower than the other values registered by the inner canyon stations the relevance of our data is that it explains how the transport pathway in the canyon occurs through its western flank where a more active and persistent current toward the open ocean was recorded over the entire year of the experiment off shelf sediment transport along the canyon axis showed clear differences during the period of the study with some important events leading to strong intensifications of the current coupled with large transport of particle fluxes to the deepest parts of the canyon such events are primarily related to increases in river discharge and the occurrence of strong storms and cascading events during the winter in summary in this study it is shown that the dynamics of the water masses and the currents in the study area convert the sharp western flank of the blanes canyon in a more active region that favors erosion processes than the eastern flank which has a smoother topography and where the absence of erosional conditions yields to steadier sedimentary processes

enhanced short term sediment deposition within the nazare canyon north east atlantic abstract in january and may 1999 interface sediments were sampled within the nazare canyon a large submarine canyon that deeply indents the western iberian continental margin ne atlantic at around 39 35n excess 234th profiles were established with high resolution to calculate inventories and bioturbation coefficients a northern transect at 42 n is briefly presented as a reference for the western iberian margin synthesis of these parameters is used to examine short term deposition within the nazare canyon 234thxs was always detected with significant activities on surface in most of the samples along the reference transect and in the adjacent area surface 234th excesses are about 10 20 dpm g 1 in contrast 234thxs reaches very high levels up to 170 dpm g 1 in the canyon there is a large range of variability in inventories and bioturbation rates in relation with depth and location these results show a preferential deposition in the canyon and focus in the upper and middle part of the canyon on a monthly time scale the nazare canyon appears as a significant locus of sedimentation for the western iberian margin

the coastal depositional system of a small mountainous river a perspective from grain size distributions abstract tseng wen river is a small mountainous river on a wave dominated coast of taiwan the spatial distribution patterns of 17 individual grain sizes offshore near the river mouth show strong morpho textural relationships with the bathymetry which also vary considerably according to the grain size the influence of seven hypothetical factors that could affect the observed grain size patterns were examined individually by using a methodology that combines filtering concept and a multivariate analysis technique eof these factors include the sediments discharged by the river offshore palimpsest sediments sediments eroded from a submarine sand ridge and the remnant river delta the effect of wave sorting and the northward and southward littoral drift the study results indicate that the tseng wen river is the most important source for modern sediments in the study area the reworking of offshore palimpsest sediments is also an important sediment source the agitation by waves is an important sorting mechanism in the study area and the net sediment transport in the study area is northward the findings based on grain sizes are also corroborated by short term observations of the near bed sediment dynamics and transport during the flood season of the tseng wen river

a laboratory evaluation of the laser in situ scattering and transmissometery instrument using natural sediments abstract the lisst laser in situ scattering and transmissometery instrument was designed by sequoia scientific to measure the particle size distributions and concentrations of sediment suspensions in the field environment to understand the lisst s performance with natural sediments from a variety of marine sources several experiments were performed to compare the lisst s results to traditional sieving filtering and weighing techniques the lisst was able to correctly locate the peak of a unimodal particle size distribution and resolve the two peaks of a bimodal distribution if they are separated by at least 1 for sediment sizes of 5 to 250 m unlike a single frequency scattering sensor for sediment concentration which require sediment size specific calibration constants the lisst is able to accurately measure sediment concentration with a single calibration constant for varying size distributions within the size range of 5 to 250 m the lisst was also found to adequately represent the particle volumetric size distribution for two different samples from marine environments

slope transport of suspended particulate matter on the aquitanian margin of the bay of biscay abstract spatial and temporal characteristics of the water masses and the dispersion of the suspended particulate matter were investigated using current meter hydrographic and nephelometric observations gathered during the ecofer experiment 1989 1991 in the cap ferret canyon on the aquitanian margin of the bay of biscay while characteristics of the deep water masses were stable from one year to another large hydrographic change in the upper 500 m related to winter renewal induced by poleward advection of warm and saline water along the continental slope the slope circulation and seasonal eddy activity appear as important dynamical mechanisms that control the entrainment and the dispersion of the suspended particulate matter from the neritic domain to the deep ocean a predominantly northward along slope current with occasional reversal characterizes this circulation the nephelometric structures also showed seasonal changes in the overall suspended particulate matter content but recurrent features such as the presence of intermediate nepheloid layers at the shelf break depth and various depths along the slope 500 1000 and 2000 m were observed these nepheloid layers extended off the slope to about 10 30 km but especially laterally along the slope their presence indicated that suspended particulate matter exchanges between the shelf and the slope occurred mainly in the head of the canyon and along the southern open slope the intermediate nepheloid layers around 500 m depth detached from the slope particularly in regions where the bottom slope is close to critical for the m2 internal tide

partition of suspended and riverbed sediments related to the salt wedge in the lower reaches of a small mountainous river a month long comprehensive field experiment during the beginning of the flood season of a small mountainous river in southern taiwan was carried out in 2004 the major goal of the study was to investigate the effect of hydrodynamic sorting related to the salt water intrusion on the spatial variability of suspended and riverbed sediments and their coupling of different sizes the experiment included the deployment of an instrumented tetrapod near the river mouth with an upward looking adcp and two ctds mounted at 50 and 100 cm above the bed cmab respectively on three different days along the river turbidity salinity and temperature of the water column were profiled and water samples were taken from the surface and near the bed at different stations additionally one sediment sample was also taken from the riverbed suspended sediment concentrations ssc were analyzed for five different sizes i e 500 250 500 63 250 10 63 and 1 2 10 m by filtration for each riverbed sample the size composition was analyzed for the subsample that contained lithogenic and nonlithogenic components and the subsample having major nonlithogenic components organic matter carbonates and biogenic opal was removed the grain size frequency distributions of the riverbed samples were analyzed using a laser particle analyzer the results were grouped into the following size classes 473 249 473 62 249 10 62 and 10 m for comparison with those of the suspended sediments near the riverbed some suspended sediment samples were analyzed for poc and pon some riverbed samples were analyzed for toc statistical methods of linear regression and empirical orthogonal eigen function eof were used in the data analysis two layered estuarine circulation pattern was observed at the tetrapod site the tidally driven salt water intrusion is the major factor influencing the hydrodynamics of the gaoping river which in turn affect the longitudinal and vertical distribution of the suspended sediments and the longitudinal distribution of the riverbed sediments during the flood the intrusion front of the salt wedge creates a dynamic barrier upriver from this barrier the riverbed substrate is coarser composed of sediments mostly coarser than 249 m within the salt wedge the riverbed substrate is finer consisting of mostly mud 62 m the barrier creates a trap on the riverbed immediately seaward from the intrusion front retaining higher percentages of clay sized sediments and toc the barrier also creates partition in the terrestrial and marine sources of organic matter in the suspended and riverbed sediments within the salt wedge the major contributor of riverbed toc is the clay sized marine sediment transport upriver by the intruding seawater the terrestrial poc is a minor contributor to the riverbed toc the riverbed and suspended sediments are coupled most size classes in corresponding suspended and riverbed sediments have a reciprocal relationship negative feedback through resuspension and deposition on the water bed interface the only size class of 62 473 m on the riverbed and 63 250 m in the suspension are co varying positive feedback this size class contains largely a transient floc population that is formed and disintegrated in situ both on the riverbed and in the suspension in the course of a tidal cycle

winter storms induced high suspended sediment concentration along the north offshore seabed of the changjiang estuary abstract fine grained sediments suspended in coastal waters play an important role in submarine topography evolution and associated environment changes the convergence of suspended sediments concentrated near the seabed results in high sediment concentration and contributes significantly to sediment transport in order to investigate the mechanism triggering high suspended sediment concentration ssc we deployed a tripod to the seabed to obtain in situ bottom boundary layer measurements of sediment dynamics and a buoy to the sea surface to collect meteorological and wave data at the northern changjiang river mouth from december 20 2015 to january 20 2016 the high ssc e g 3 g l events were observed together with fluid mud thicknesses of 4 16 cm near the seabed during neap tides when cold air intrusion generated winter storms and strong waves further we found that the high ssc event was mainly resulted from wind waves and sediment resuspension supported by local benthic fluid mud which was associated with three stages at the setting up stage the winter storm brought long duration of strong waves e g significant wave height 1 5 m more than 15 h resulting in a maximum wave current combined bottom shear stress of 3 2 pa and the increase of ssc to 1 g l at the reinforcement stage the strong waves and bottom shear stress lasted for several hours and further increased the ssc to 3 g l at the final decay stage wind waves and the maximum wave current shear stresses decreased significantly with the disappearance of high ssc thus there was no high ssc event observed even with strong wind waves during spring tides because strong wave duration was too short for the reinforcement process the sediment source for the high ssc events was mainly from bottom fluid mud resuspension as well as the advection transport from the adjacent subaqueous changjiang river delta

cyclone induced hyperpycnal turbidity currents in a submarine canyon 1 density currents such as turbidity currents are major transport agents in various terrestrial lacustrine and marine environments worldwide however a gap exists between those who study the deposits by turbidity currents turbidite on a field scale and those who study turbidity currents using small scale laboratory experiments and theoretical numerical models we report two typhoon triggered hyperpycnal turbidity current events observed in a submarine canyon our findings verify turbidite sequences with the characteristics of suspended sediment carried by passing turbidity currents that displayed distinct waxing and waning phases our study also confirms the direct link between typhoon triggered hyperpycnal flows in a small mountainous river and turbidity currents in a nearby submarine canyon that transport sediment to the deep sea efficiently

sediment dynamics and post glacial evolution of the continental shelf around the blanes submarine canyon head nw mediterranean abstract the blanes submarine canyon bc deeply incises the catalan continental shelf in the nw mediterranean sea as a consequence of the closeness only 4 km of its head to the coastline and the mouth of the tordera river the canyon has a direct influence on the shelf dispersal system as it collects large amounts of sediment mainly during high energy events multibeam bathymetry backscatter imagery and very high resolution seismic reflection profiles have allowed characterizing the morphology of the continental shelf around the canyon head also identifying sediment sources and transport pathways into the canyon the morphological data have also been used to reconstruct the evolution of the continental shelf during the last sea level transgression so that the current understanding of shelf to canyon sediment exchanges through time could be improved the continental shelf surrounding the bc consists of both depositional and erosional or non depositional areas depositional areas display prominent sediment bodies a generally smooth bathymetry and variable backscatter these include i an area of modern coarse grained sediment accumulation that comprises the inner shelf ii a modern fine grained sedimentation area on the middle shelf offshore tossa de mar and iii a modern sediment depleted area that covers most of the middle and outer shelf to the west of the canyon head erosional and non depositional areas display a rough topography and high backscatter and occur primarily to the east of the canyon head where the arrival of river fed inputs is very small in agreement with this pattern the continental shelf north and west of the canyon head likely is the main source of shelf sediment into the canyon to the north a pattern of very high backscatter extends from the coastline to the canyon head suggesting the remobilization and off shelf export of fines additionally relict near shore sand bodies developed over the barcelona shelf that extend to the canyon head rim constitute a source of coarse sediment high energy processes namely river floods and coastal storms are the main controls over the river shelf canyon sediment exchange river floods increase the delivery of terrigenous particles to the coastal system storms mainly from the east remobilize the sediment temporarily accumulated on the shelf towards the canyon head so that the finer fractions are preferentially removed and a coarse lag is normally left on the shelf floor exceptionally very strong storms also remove the coarse fractions from the shelf drive them into the canyon processes like dense shelf water cascading which is much more intense in canyons to the north of bc and the northern current also contribute to the transport of suspended sediment from far distant northern sources during the last post glacial transgression the bc had a strong influence on the evolution of the inner continental margin as it interrupted the shelf sediment dispersal system by isolating the shelves to its north and south named la planassa and barcelona shelves respectively

morphological evolution of the south passage in the changjiang yangtze river estuary china abstract estuarine morphology of the world s major large rivers have experienced great changes due to intensive anthropogenic activities and natural forcings especially in the changjiang estuary located at the end of the longest river in asia this study focuses on morphological changes of the south passage sp which is one of the 4 channels in the branching estuary at the mouth of the changjiang yangtze river china a multivariate analysis technique of empirical orthogonal eigen function eof method was used to examine the major modes of change in the long term over 26 years water depth data the results show that the morphological changes at the sp could be divided into two stages between 1987 and 1997 the sp had a single stable channel with closure of a cross channel between 1997 and 2012 sp displayed southeastward elongation of a spit into the main channel and westward shoal incision by a cross channel the opening of the sp developed a two channel morphology which stabilized and showed infilling during 2003 2012 the average deposition rate was 10 cm yr in the past 30 years the most dominant morphological changes of sp included the deposition around the upstream opening of the channel the second most important pattern of morphological change was related to the downstream elongation retreat and lateral migration of the spit of the jiangyanan shoal which resulted in the two channel configuration of the sp additionally these morphological changes were not triggered by the decline of the distal sediment source from the upstream but due to the input of proximal sources of the shoal at the upstream opening of the sp and spill over sediment from the north passage via a short cut channel

laboratory and field evaluations of the lisst 100 instrument for suspended particle size determinations abstract advances in technology have resulted in a new instrument that is designed for in situ determination of particle size spectra such an instrument that can measure undisturbed particle size distributions is much needed for sediment transport studies the lisst 100 laser in situ scattering and transmissometry uses the principle of laser diffraction to obtain the size distribution and volume concentration of suspended material in 32 size classes logarithmically spaced between 1 25 and 250 m this paper describes a laboratory evaluation of the ability of lisst 100 to determine particle sizes using suspensions of single size artificial particles findings show the instrument is able to determine particle size to within about 10 with increasing error as particle size increases the instrument determines volume or mass concentration using a volume conversion factor cv this volume conversion factor is theoretically a constant in the laboratory evaluation cv is found to vary by a factor of about three over the particle size range between 5 and 200 m results from field studies in south san francisco bay show that values of mass concentration of suspended marine sediments estimated by lisst 100 agree favorably with estimates from optical backscatterance sensors if an appropriate value of cv according to mean size is used and the assumed average particle aggregate density is carefully chosen analyses of size distribution of suspended materials in south san francisco bay over multiple tide cycles suggest the likelihood of different sources of sediment because of different size characteristics during flood and ebb cycles

sediment dynamics in a submarine canyon a case of river sea interaction this paper presents findings from a 1 month field experiment conducted during the flood season of 2000 on the southern coast of taiwan to examine the delivery of lithogenic siliciclastic sediment to kao ping submarine canyon from the nearby kao ping river and shelf sources and the transport of suspended lithogenic and nonlithogenic particles near the canyon floor collected time series data included simultaneous measurements of coastal winds salinity temperature flow field suspended sediment concentration ssc and size composition of suspended particles at the river mouth and inside the submarine canyon as well as results from seawater and sediment trap data other collected data included river discharge and sediment load and hydrographic measurements along and across the axis of the canyon during the experiment two significant episodic river sediment discharge events occurred relating to a typhoon and extreme precipitation conditions the findings show that theoretically the time difference between sand and clay siliciclastic grains to settle from the sea surface to the canyon floor is on the order of hours to months analogous to a sorting process river plume dynamics and the coastal wind field largely control the delivery of terrigenous fine grained sediment to the canyon inside the canyon the behavior of suspended lithogenic and nonlithogenic particles of different sizes can be differentiated into a coarse grained group sand which forms the drop in population and a fine grained group mud which forms the standing population each group has distinct spectral characteristics the coarse grained group is delivered directly to the canyon by the river effluent and by wave resuspension of the shelf substrate during the study period the net transport of suspended particles near the canyon floor was landward mostly by tidal currents whose direction was also modulated by spring neap tide both lithogenic and nonlithogenic particles contribute to high mass fluxes exceeding 700 g m 2 day 1 in the lower part of the canyon this river sea system represents a type of systems that consist of three geographically separated dynamic entities the river plume the shelf and the canyon under fair weather conditions the river plume and shelf processes are coupled through the tide and wind field the river and canyon form a direct source to sink link via coarse grained siliciclastic sediment during the flood season in both continuous and pulsed fashion in the typhoon season the shelf becomes a pulsed source region for coarse grained sediment

detecting ancient life investigating the nature and origin of possible stromatolites and associated calcite from a one billion year old lake atb acknowledges the hospitality of the north west highlands geopark in july 2017 dw acknowledges funding from the australian research council via the future fellowship scheme ft 140100321

in situ particle size spectra and density of particle aggregates in a dredging plume abstract an in situ laser particle sizer the lisst 100 was used to describe the spatial variation of beam attenuation coefficient in situ particle size spectra and aggregate densities in a dredging plume in the sound oresund between denmark and sweden the results proved that the above mentioned parameters varied significantly within the investigated length of the plume approximately 2 km it is shown how the small single primary particles aggregate and change the in situ particle size spectra into a slightly better sorted and coarser size distribution and at the same time how the mean density of particles aggregates decreases significantly this shift in the state in which the particles exist in the water effectively changes the optical response of the mass of particles suspended in the water it is shown that adequate correlations between mass concentrations and beam attenuation coefficients can only be obtained if parameters describing the in situ quality and state of the mass of particles e g standard deviation of the size spectra and volume concentration is included in the regression from the spatial variation in mean density and in situ particle size it was possible to calculate the spatial difference in settling velocity it was found that the difference in settling velocity was only about a factor of 1 7 because increasing in situ particle size was counter balanced by decreasing mean density furthermore the time scale of flocculation within the plume was found to be in the order of 50 min

the ivaň canyon a large miocene canyon in the alpine carpathian foredeep abstract during the latest early miocene a large drainage system developed in the alpine carpathian foreland transporting sediments through a prominent submarine canyon along the narrow corridor between the south eastern bohemian massif and the waschberg danice unit the canyon followed the alpine carpathian foredeep from lower austria towards the north and northeast into the czech republic 3 d seismic data allow the mapping of this 600 m deep structure over a distance of 25 km and a width of 5 km despite its dimension making it the largest submarine erosive and sedimentary structure of the neogene alpine carpathian foredeep this canyon has not been previously recognised herein it is interpreted as shelf indenting canyon that formed due to a combination of isostatic rebound along a terminating thrust front and sea level change during the terminal early miocene the canyon fill comprises reworked littoral deposits with a typical early miocene tropical micro and macrofauna the exact timing of this refilling remains unclear smaller channel structures in surface outcrops representing potential tributaries of the canyon suggest a more or less synsedimentary filling soon after indention finally the top part of the canyon was eroded around the early middle miocene boundary probably related to a global 3rd order sea level drop and caped by marine marls during the subsequent early middle miocene transgression with the sudden onset of the subsidence of the northern vienna basin during that time the drainage system abruptly moved southward shedding its sediments into the newly opening vienna basin this explains the rather abrupt abandonment of the huge canyon feature whose fan deposits are unknown so far

tidal motions and tidally induced fluxes through la linea submarine canyon western alboran sea detailed observations from two mooring lines deployed in la linea submarine canyon western alboran sea are presented this is a narrow canyon in the sense that its width is always less than the internal radius of deformation tidal currents within the canyon are polarized in the along canyon direction according to its narrow nature they have considerable amplitude values of around 0 5 m s are often observed and are forced by the internal pressure gradients associated with the baroclinic tide that is generated in the surroundings subsequent amplification of onshore baroclinic currents within the canyon accounts for the large amplitude observed cross shelf exchange through the canyon due to tidal motions is different from zero despite the close to zero mean of tidal currents the explanation is based on the asymmetry of water properties flowing up canyon and down canyon some sort of tidal rectification regarding the energy flux the canyon seems to be an adequate conduit to carry energy to the shore estimations made from our observations indicate that energy input onto the shelf per unit length parallel to the shore at the canyon head is enough to maintain mixing on the shelf at intermediate depths

accumulation of modern sediment in quinault submarine canyon abstract twenty box cores have been studied from quinault submarine canyon a major pathway between the washington continental shelf and the deep sea for silt and clay originating from the columbia river sediment accumulation rates on a 100 yr time scale are calculated from profiles of excess 210pb and of 137cs accumulation rates decrease with increasing distance downcanyon from 14 10 2 g cm 2 yr 1 in the upper canyon lower head to 3 10 2 g cm 2 yr 1 in the lower canyon in the upper canyon lower head channel floor areas have a higher mean accumulation rate 12 10 2 g cm 2 yr 1 than channel wall areas 5 10 2 g cm 2 yr 1 the difference in accumulation rate between channel floor and channel wall areas indicates preferential accumulation i e focusing in topographic lows the decrease in accumulation rate from high rates in the channel floors of the upper canyon to low rates in the lower canyon may be caused by progressive depletion of a nepheloid layer source and or may be an artifact of sediment focusing in the upper canyon the silty clay and clayey silt accumulating in the canyon show no significant trend in grain size or clay mineralogy with depth in cores or with distance downcanyon the lack of sorting probably results from the transport of sediment in aggregate form with a nearly random distribution of size and mineralogy within aggregates quinault canyon is accumulating approximately 5 5 10 5 mt of sediment yr 1 the lithogenic component 64 accounts for 1 4 of the columbia river discharge similarity of sediment trap deposition rates including storm events and 210pb accumulation rates indicates that the vertical flux is a major input of sediment to quinault canyon and that storms are important in the accumulation of sediment on a 100 yr time scale

columbia river sediment in quinault canyon washington evidence from artificial radionuclides sediments collected from beneath 1500 2000 m of water in quinault canyon off the coast of the state of washington contain 60co and 152eu which indicate that they are derived from the columbia river the presence of these radionuclides confirms that sediment from the columbia river is transported to and deposited in quinault canyon on a time scale of a few years or less fallout derived 137cs is also present in quinault canyon sediments 137cs can probably be used at other locations to distinguish canyons where deposition of river or shelf derived sediments is active from dormant canyons

the effect of a submarine canyon on the river sediment dispersal and inner shelf sediment movements in southern taiwan abstract this study examines the influence of a submarine canyon on the dispersal of sediments discharged by a nearby river and on the sediment movement on the inner shelf the study area includes the head region of the kao ping submarine canyon whose landward terminus is located approximately 1 km seaward from the mouth of the kao ping river in southern taiwan within the study area 143 surficial sediment samples were taken from the seafloor six hydrographic surveys along the axis of the submarine canyon were also conducted over the span of 1 yr three different approaches were used in the analysis of grain size distribution pattern they include 1 a combination of filtering and the empirical orthogonal eigen function eof analysis technique 2 the mclaren model and 3 the transport vector technique the results of the three methods not only agree with one another they also complement one another this study reveals that the kao ping submarine canyon is relatively a stratified and statically stable environment the hydrographic characteristics of the canyon display seasonal variability controlled primarily by the temperature field and the effluent of the kao ping river the hydrographic condition and the bottom topography in the canyon suggest the propagation of internal tides during the flood season summer of the kao ping river the submarine canyon acts as a trap and conduit for mud exchange between the kao ping river and offshore near the head of the canyon there is a region of sediment transport convergence this region is also characterized by high mud abundance on the seafloor that coincides with the presence of high suspended sediment concentration ssc spots in the bottom nepheloid layer outside the submarine canyon on the shelf where the evidence of wave reworking is strong the northwestward alongshore transport dominates over the southeastward transport which is a common theme on the west coast in southern taiwan

terrestrial and marine n alcohol inputs and degradation processes relating to a sudden turbidity current in the zaire canyon abstract n alcohol biomarkers from sediment trap samples collected during a turbiditic event and surficial sediments on a levee of the zaire canyon equatorial west african margin one of the world s largest and still very active deep sea fans were examined the initial goal was to study the benthic ecosystem in relation to organic matter inputs as the quantity and quality might influence its development two criteria were used the relative abundance of short 20 and long chain c 22 n alcohols derived from marine organisms and higher plants respectively and the ratio of odd to even carbon numbered 20 n alcohols to assess the extent of alteration the material collected in the trap 30 m above the bottom when the turbiditic current occurred exhibited a high abundance of terrigenous n alcohols this trap did collect the turbidity material in contrast to the one located at 400 m the influence of the turbidity current was also revealed in the surficial sediment sampled nine months after the event the initial turbiditic material from the 30 m trap settled on to the sediment and extensive degradation was apparent upon this settling assuming a first order degradation rate the degradation rate constants were 3 4 and 0 9 y 1 for 19 and c 22 n alcohols respectively

sediment budget and transfer of suspended sediment from the gironde estuary to cap ferret canyon abstract a study of the particulate organic carbon content the grain size of suspended sediment and turbidity in a transect between the gironde estuary and cap ferret canyon indicates that particles from the gironde river are transferred to near the bottom of the canyon the separation of turbid estuarine water into bottom and surface nepheloid layers takes place in the gironde itself and in the nearshore zone the development of these two separate turbid layers is due to vertical a turbid surface plume and horizontal bottom layer salinity gradients the bottom nepheloid layer is caused primary by a horizontal supply of suspended sediment from the gironde rather than from resuspension or vertical sedimentation as suggested by other workers on the median and outer shelf the distribution of particles in the water column is influenced by thermal stratification the thickness of the bottom nepheloid layer increases from the estuary towards cap ferret canyon as a function of the thickness of the bottom waters detached nepheloid layers are observed at the shelf break coinciding with isopycnal surfaces due to the presence of cold waters in the cap ferret canyon superimposed advective inputs from the northern part of the shelf and resuspension of particles from mud patches contribute to the supply of particles towards the canyon suspended sediment in transit over the shelf break represents 2 3 of the total discharge from the gironde estuary this is a considerable amount as 50 of the suspended sediment is trapped in the west gironde mud patch and another undefined portion of the gironde sediment load is transported along the coast by tidal currents

effects of a major typhoon on sediment accumulation in fangliao submarine canyon sw taiwan abstract the fangliao submarine canyon cuts across the shelf and slope of southwest taiwan unlike other canyons along this margin there is no obvious connection to an individual fluvial sediment source on land two recent cruises to fangliao canyon provide insight into sedimentation associated with a major typhoon box and piston cores were retrieved from fangliao canyon in early january 2007 after a local earthquake and an extended period of low to moderate river flow in streams that are suspected of contributing sediment to the canyon similar cores were collected from the canyon in early october 2009 following one of the largest typhoons to hit taiwan in the past several decades typhoon morakot delivered several meters of rain to taiwan with the largest river floods occurring in the south and southwest regions in addition the coastal ocean environment was energized by significant wave heights 12 m comparisons of textural radioisotopic and geochemical data reveal likely sediment transport and depositional processes within and surrounding fangliao canyon typhoon morakot caused a layer 10 cm thick and greater throughout the canyon x radiographs of the 2007 cores show limited physical structure in most cases and the 2009 radiographs display obvious changes in sediment density relative to the underlying sediment as well as distinct physical lamination examining signals from different geochemical and radiochemical tracers for terrestrial sediment source indicates that the flood layer deposited by typhoon morakot came from several small mountainous rivers by comparing the results of the 2007 cruise with those from 2009 we gain significant insight to the close linkage between a line source of fluvial sediment and deposition in a submarine canyon as well as the role that tropical storm events can play in delivering sediment to these environments

shelf edge erosion sediment failure and inception of bari canyon on the southwestern adriatic margin central mediterranean abstract we investigate the impact of regional tectonic setting and sedimentary dynamics on the onset of bari canyon the main sediment conduit on the southwestern adriatic margin sam since the middle pleistocene deposition on the sam a foreland basin relative to the southern apennines was primarily controlled by glacio eustatic cycles however a number of tectonic structures active since the early cenozoic impacted on the stacking of progradational deposits and on the overall slope setting and stability along the sam four depositional sequences accomplished the progradation of the shelf margin between ca 450 kyr bp and the last glacial maximum lowstand ca 20 ka bp these sequences are variably dissected by two large scale erosional features on the upper slope 1 bari canyon and 2 gondola slide headscarp further north the shelf facing these two major erosional structures shows several smaller scale incisions that merge with the sequence boundaries between each of the four stacked depositional sequences the distribution of these erosional features reflects the location of tectonic structures that are still active suggesting that both the intense erosion and the sediment failure in these areas were enhanced by tectonic deformation we define the age of these older episodes of shelf edge erosion and mass wasting that were conducive to the inception of bari canyon as we know it today moreover we envisage the following predisposing factors as responsible for the inception and subsequent evolution of bari canyon a long term regional uplift and margin tilt likely controlling the lateral variability in shelf width and shelf slope profile b rapid margin progradation during the deposition of middle late pleistocene sequences c recent tectonic deformation resulting in gentle folds growing during the canyon evolution

a review of rock art dating in the kimberley western australia this paper critically reviews the various approaches used to estimate the age of the rock art in the kimberley region of western australia they include i the relative superimposition of styles ii the use of diagnostic subject matter depictions of extinct animals stone tool technology introduced european and asian objects and animals iii the recovery of a painted slab from a dated archaeological unit iv radiocarbon dating of beeswax figures charcoal pigments organic matter in overlying mineral deposits and accreted paint layers oxalate rich crusts and amorphous silica skin pollen grains from an overlaying mud wasp nest and v optically stimulated luminescence osl dating of quartz grains from overlying mud wasp nests future directions for rock art dating in the kimberley include uranium series dating of overlying and underlying mineral deposits

from the highest to the deepest the gaoping river gaoping submarine canyon dispersal system abstract there are many different source to sink dispersal systems around the world and the gaoping river gpr gaoping submarine canyon gpsc provides an example especially as a canyon captured system the gpr a small mountainous river having an average gradient of 1 150 and the gpsc which links the river catchment to the deep sea basin represent two major topographic features around sw taiwan together they constitute a terrestrial to marine dispersal system that has an overriding impact on the source to sink transport of sediment in this region the gpsc extents from the mouth of the gpr through the shelf and slope and into the northeastern manila trench a distance of about 260 km it is a major conduit for the transport of terrestrial sediment and carbon to the south china sea and the landward transport of particles of marine and biological origin in the gpsc the dominant mode of suspended sediment transport is tidal oscillations and the net direction is up canyon in contrast sediment transport associated with episodic gravity driven events is down canyon the steady sedimentation of the tidal regime results in hemipelagic mud across the canyon floor whereas the gravity driven hyperpycnal regime causes turbidite erosion and deposition along the canyon thalweg typhoon induced river floods often lead to hyperpycnal plumes at the river mouth which directly and indirectly ignite hyperpycnal turbidity currents in the canyon forming an effective agent for transporting large amounts of terrestrial organic material modern and fossil carbon to the south china sea basin therefore the gpr gpsc represents a source to sink system in which terrestrial sediment in a mountainous catchment is promptly removed and transported to the deep sea by episodic gravity flows this is also a pathway by which modern terrestrial organic carbon is quickly and effectively delivered to the deep sea

identification of pigments used in rock art paintings in gode roriso ethiopia using micro raman spectroscopy in this paper we present results on the rock art painting materials from the gode roriso rock shelter located in the eastern hararghe region of ethiopia this analysis included x microfluorescence micro raman spectroscopy and microstratigraphy as far as the results of the analysis are concerned a white natural wax beeswax carbon black and iron oxides a mixture of haematite and magnetite along with charcoal particles forming as a red colourant have been applied on a natural substrate constituted of granite containing feldspar crystalline forms although very much a science based piece of research the results have far reaching outcomes for understanding the sequencing of pigment application

potential role of event driven sediment transport on sediment accumulation in the cariaco basin venezuela abstract a sediment density flow was observed in the eastern cariaco basin during september 2008 evidence suggests that this flow was likely triggered by a magnitude 5 2 earthquake that occurred on august 11 2008 with an epicenter located at 10 51 n 64 17 w off the city of cumana venezuela elevated suspended sediments near the bottom were observed at the mouth of the manzanares canyon 90 g m 2 over a depth of 165 m and decreased to 11 g m 2 over a depth of 40 m 42 km away from the canyon s mouth at the cariaco ocean time series site the sediment flux associated with this single event was 10 of the total annual sediment flux that typically reaches the cariaco basin deep seafloor carbon to nitrogen ratios and isotope composition confirm that most of the organic matter transferred by the sediment flow was of continental origin c n ratios of 17 67 13c of 27 04 and 15n of 6 83 our observations contribute to the growing body of evidence that suggests that submarine canyons are rapid efficient sediment conduits of particles from shallow to deep waters and that they should be included in efforts to constrain estimates of sediment and terrestrially derived carbon transport from the continental shelves to the deep ocean

a thirteen year record of bathymetric changes in the north passage changjiang yangtze estuary article i nfo the mouths of major rivers in the world have always been important waterways and as a result subject to significant human intervention therefore it is necessary to understand the coupling of natural processes and human intervention in the sediment movement and deposition to determine long term morphodynamic evolution in the mouth regions of major rivers a multivariate technique was used to analyze high resolution bathymetric data from the north passage of changjiang yangtze river which is the vital shipping channel in the mouth region and for the entire changjiang waterway our findings show that there are two modes of bathymetric changes the first mode represents 85 of the variability which includes the deposition in the peripheral groin fields along the shipping channel and deepening of the shipping channel which is primarily due to the channel maintenance the second mode represents 6 of the variability of the river mouth shoal seaward migration and size reduction attributable to the declining sediment discharge of the changjiang

on the links between a river s hyperpycnal plume and marine benthic nepheloid layer in the wake of a typhoon abstract in 2010 two moorings each configured with a ctd and an adcp one with an additional non sequential sediment trap nsst were deployed in the head region of the gaoping submarine canyon 3 days after the typhoon induced peaks of the runoff and suspended sediment concentration ssc of the gaoping river in southern taiwan our data show a demarcation between tidal and hyperpycnal regimes in the temperature salinity and flow fields the latter existed in the first 5 days out of the 18 day deployment as defined by higher water density due to high ssc several lines of evidence indicate the presence of the tail end of a hyperpycnal turbidity current htc including the retention of warm water near the canyon floor high ssc down canyon directed residual flow and its vertical structure and high terrestrial fraction larger than 70 of the organic particles carried by the flow the decreasing mass flux during the deployment is also an indication of a waning htc our findings also show that the vertical flow structure and the direction of the gravity driven down canyon htc were retarded by the instantaneous up canyon directed tidal oscillations in the submarine canyon