oceanography in the kattegat and skagerrak over the past 8000 years in the kattegat between sweden and denmark a large number of cores containing holocene seafloor deposits were investigated stratigraphically sedimentological biostratigraphical and chronostratigraphical variables were especially emphasized palynological and foraminiferal analyses indicate several changes in the oceanographic circulation system in the skagerrak kattegat during the holocene radiocarbon datings and pollen analyses suggest that these changes occurred at 8000 4000 2000 between 1000 and 500 and 300 years b p compilation of stratigraphical data from the region suggests that at about 8000 years b p the english channel opened and the southern jutland current was formed this had a major influence on the skagerrak but only a marginal effect can be traced in the kattegat the major components of the present circulation system in the kattegat skagerrak were established about 4000 years b p and the subsequent changes in the circulation pattern and the inflow outflow system that developed at approximately 2000 500 and 300 years b p are variants of these

removal of systematic seasonal atmospheric signal from interferometric synthetic aperture radar ground deformation time series applying the multidimensional small baseline subset interferometric synthetic aperture radar algorithm to about 1500 envisat and radarsat 2 interferograms spanning 2003 2013 we computed time series of ground deformation over naples bay area in italy two active volcanoes vesuvius and campi flegrei are located in this area in close proximity to the densely populated city of naples for the first time and with remarkable clarity we observed decade long elevation dependent seasonal oscillations of the vertical displacement component with a peak to peak amplitude of up to 3 0 cm substantially larger than the long term deformation rate 0 6 cm yr analysis utilizing surface weather and radiosonde data linked observed oscillations with seasonal fluctuations of water vapor air pressure and temperature in the lower troposphere the modeled correction is in a good agreement with observed results the mean absolute and rms differences are 0 014 cm 0 073 cm and 0 087 cm respectively atmospherically corrected time series confirmed continuing subsidence at vesuvius previously observed by geodetic techniques

late younger dryas to holocene palaeoenvironments of the southern kattegat scandinavia palaeoenvironmental changes since the late younger dryas are reconstructed in the southern kattegat scandinavia and provide a basis for correlating the whole of the north sea skagerrak kattegat

a new method for reconstructing absolute water vapor maps from persistent scatterer insar repeat pass spaceborne interferometric synthetic aperture radar insar has increasingly been used to produce precipitable water vapor pwv maps at a high spatial resolution since the insar principle is based on building the difference between the observations at two acquisition times a large part of the atmospheric phase is lost using pwv data from a global positioning system gps network overlapping with the insar coverage or data from numerical atmospheric models and reanalysis data a combining solution produces absolute pwv maps the lack of dense gps networks the coarse spatial resolution of reanalysis data and the inaccuracy of the models restrict the combined solution therefore this article presents a new approach to reconstruct absolute pwv maps using persistent scatterer insar data in the presence of a single reference data point or a maximum of three by applying this approach to envisat insar data in the dead sea region and comparing the maps to 15 reference meris pwv maps the results show an average of 92 spatial correlation 1 2 mm absolute mean and 1 7 mm standard deviation sentinel 1 data as well show a strong spatial correlation 90 3 with the model data with an average standard deviation of 1 6 mm

applicability of insar to tropical volcanoes insights from central america measuring volcano deformation is key to understanding the behaviour of erupting vol canoes and detecting those in periods of unrest satellite techniques provide the opportunity to do so on a global scale but with some notable exceptions the deformation of volcanoes in the tropics has been understudied relative to those at higher latitudes largely due to technical difficulties in applying interferometric synthetic aperture radar insar we perform a systematic survey of the central american volcanic arc to investigate the appli cability of interferometric synthetic aperture radar insar to volcanoes in the tropics volcano characteristics that may prevent insar measurement include 1 dense vegetation cover 2 per sistent activity and 3 steep slopes measurements of deformation are further inhibited by atmos pheric artefacts associated with 4 large changes in topographical relief we present a systematic method for distinguishing between water vapour artefacts and true deformation our data show a linear relationship c 2 cm km between the magnitudes of water vapour artefacts and volcano edifice height for high relief volcanoes e g fuego guatemala 3763 m a s l above sea level errors are of the order of 4 5 cm across the volcano s edifice but are less than 2 cm for lower relief e g masaya nicaragua 635 m a s l examples such as arenal atitlan and fuego illustrate that satellite acquisition strategies incorporating ascending and descending tracks are particularly important for studying steep sided volcanoes poor coherence is primarily associated with temporal decorrelation which is typically more rapid in southern central america where evergreen broadleaf vegetation dominates land use classification is a better predictorof decorrelation rate thanvegetationindex comparisonof coher ence for different radar wavelengths match expectations high resolution x band radar is best suited to local studies where high resolution digital elevation models dems exist while l bandwavelengths are necessary for regional surveys however this is the first time that relation ships between phase coherence and time perpendicular baseline radar wavelength and land use have been quantified on the scale of a whole volcanic arc

the transition from glacimarine to marine conditions during the last deglaciation in eastern skagerrak the paleoceanographic and paleoenvironmental evolution is described in the eastern skagerrak separable stratigraphic units in seismic profiles and twelve piston cores document a changing balance between erosion and accumulation since the latest deglaciation sediment supply and water depth but also whether the water mass is stratified or not are the important parameters in the processes controlling the depositional environment the cores can be divided into two main units a lower well consolidated and clay rich glacimarine mud with low organic content and a silty sandy marine mud with relatively high organic content the boundary between these two main units consists of an erosional surface overlain by a coarse grained lag the deposition of the lower glacimarine mud started directly after deglaciation at about 18 0 kyr bp a major change in the sedimentation conditions at about 9 0 kyr bp led to a change from depositional to erosional conditions the erosion has presumably removed a great part of the earlier deposits creating the erosional surface which is present in the entire study area several dated samples above and below the erosional surface indicate a hiatus of about 10 kyr in the south the conditions changed again at about 5 0 cal kyr bp allowing accumulation of the marine mud while in the northern part erosive conditions continue to prevail in the northern part the marine mud is only deposited in limited areas preferably sheltered areas along the coast

worldwide initiation of holocene marine deltas by deceleration of sea level rise radiocarbon dated deltaic sequences of holocene age from different parts of the world began to accumulate within a restricted time range from about 8500 to 6500 years ago evaluation of major delta processes indicates that deceleration in sea level rise was the key factor in holocene delta formation within many deltas there is as much as a 2000 year age range between basal deposits in seaward and landward cores this age difference records the progressive landward migration of near mean sea level depositional environments during the lower to mid holocene establishment of a chronostratigraphic framework for holocene delta development provides a fundamental global baseline for distinguishing sea level change from vertical land motion by tectonism and isostasy and for evaluating rates of future marine incursion into low lying deltas

yangtze delta eastern china 1 geometry and subsidence of holocene depocenter abstract stratigraphic analysis of 59 borings serves to define the subsurface configuration of late quaternary deposits of the outer yangtze delta including both subaerial lower plain and its contiguous submerged sector isopachous maps of the holocene sediment section reveal a linear thickened trend parallel to the lower yangtze estuary chongming island which extends seaward southeast to the mid shelf maps depicting depths of the holocene to late pleistocene contact also highlight this thickened northwest to southeast trend and a deep downward bowing depression formed by the sedimentary sequence seaward of the yangtze mouth radiocarbon dated facies in the cores serve to calculate long term averaged subsidence rates for the holocene section 0 1 to 3 0 mm year on land and 1 6 to 4 4 mm year at sea this preliminary information is vital for planning coastal protection erosion salt water intrusion in this densely populated low lying region vulnerable to marine inundation

winds induce co2 exchange with the atmosphere and vadose zone transport in a karstic ecosystem andalusian regional government project geocarbo p08 rnm 3721 european union erdf funds spanish ministry of science and innovation project soilprof cgl2011 15276 e spanish ministry of science and innovation project carborad cgl2011 27493 spanish ministry of science and innovation project geispain cgl2014 52838 c2 1 r marie curie international outgoing fellowship within the 7th european community framework programme diesel project 625988

multidimensional small baseline subset msbas for volcano monitoring in two dimensions opportunities and challenges case study piton de la fournaise volcano abstract space borne synthetic aperture radar sar provides an opportunity for monitoring ground deformation at active volcanoes with high temporal and spatial resolutions modern sar satellites acquire very large volumes of data that no longer can be effectively and efficiently processed and interpreted manually the development of novel automatic processing methodologies is warranted in order to fully utilize big data the multidimensional small baseline subset msbas methodology is an example of the semi automatic processing system for computing temporally dense two dimensional horizontal east west and vertical time series of ground deformation from ascending and descending sar imagery acquired by various satellites here msbas is used for mapping ground deformation at the piton de la fournaise volcano la reunion island france during the february 2012 april 2016 period from radarsat 2 data five volcanic eruptions occurred during the june 2014 october 2015 period producing over 60cm of horizontal and over 30cm of vertical ground deformation well resolved in the msbas derived time series validation of dinsar results by comparison with gnss observations and modeling of the two last and largest eruptions was performed validation showed good overall agreement between dinsar and gnss observations while revealing the benefits and limitations of both techniques modeling of fault and dike geometries attempted to explain the dis proportionally large eastward motion of the eastern flank of the piton de la fournaise volcano that occurred during these eruptions we demonstrated that the simple elastic model consisting of two dikes and a sliding surface can account for the observed ground deformation

ground deformation at soufriere hills volcano montserrat during 1998 2000 measured by radar interferometry and gps abstract we examine the motion of the ground surface on the soufriere hills volcano montserrat between 1998 and 2000 using radar interferometry insar to minimise the effects of variable atmospheric water vapour on the insar measurements we use independently derived measurements of the radar path delay from six continuous gps receivers the surfaces providing a measurable interferometric signal are those on pyroclastic flow deposits mainly emplaced in 1997 three types of surface motion can be discriminated firstly the surfaces of thick valley filling deposits subsided at rates of 150 120 mm year in the year after emplacement to 50 30 mm year two years later this must be due to contraction and settling effects during cooling the second type is the near field motion localised within about one kilometre of the dome both subsidence and uplift events are seen and though the former could be due to surface gravitational effects the latter may reflect shallow

a palaeoclimatic and palaeoceanographic record of the last 11 000 14c years from the skagerrak kattegat northeastern atlantic margin marine sediments of about 116 m drilled onshore at skagen near the northernmost tip of jutland denmark provides a continuous and detailed palaeoceanographic and palaeoenvironmental record of the last 11 000 14c years in the skagerrak kattegat the whole younger dryas was characterized by an arctic subarctic environment where the north jutland current flows today instead of being succeeded by a minor climate warming at about 10 600 bp as recorded in the southern kattegat and in the areas strongly influenced by the baltic current and currents along the swedish west coast the changes in components of diatom assemblages combined with previously published benthic foraminiferal data from the present core reflect a two step climatic warming and consequently environmental change during the transition from the younger dryas to the preboreal an abrupt warming of the sea surface waters took place at about 10 100 bp which resulted from the inflow of warm atlantic surface water summer sea surface temperature

a rapid climatic change at the end of the younger dryas in south sweden palaeoclimatic and palaeoenvironmental reconstructions based on fossil insect assemblages a rapid climatic change at the end of the younger dryas in s sweden palaeoclimatic and palaeo environmental reconstructions based on fossil insect assemblages

assessing the reliability and consistency of insar and gnss data for retrieving 3d displacement rapid changes the example of the 2015 piton de la fournaise eruptions abstract insar and gnss are now the best and most developed techniques in the earth sciences to track deformation especially in volcanology in this study we assess the reliability and consistency of these two techniques for measuring 3 d ground displacements and not only the displacement in the direction of the insar line of sight on volcanoes during rapid changes the use of a large amount of satellite data x c l band as well as right and left looking acquisitions made it possible to retrieve the 3 d displacement components with an unprecedented accuracy we carry out this evaluation on the piton de la fournaise volcano where four eruptions occurred in 2015 the comparison between gnss and insar allows us i to describe the deformation pattern associated with these eruptions ii to quantify the discrepancies between insar and gnss and iii to discuss the limits and the complementarities of insar and gnss the ground deformation patterns associated with the four eruptions of piton de la fournaise in 2015 are typical of this volcano with decimeter ground displacements asymmetrically distributed along the dike path evidencing a preferential eastward motion particularly visible thanks to the broad spatial coverage of insar except for the ns component insar and gnss data are in overall agreement with most of the gnss insar residuals

flux and fate of yangtze river sediment delivered to the east china sea numerous cores and dating show the yangtze river has accumulated about 1 16 x 10 12 t sediment in its delta plain and proximal subaqueous delta during holocene high resolution seismic profiling and coring in the southern east china sea during 2003 and 2004 cruises has revealed an elongated similar to 800 km distal subaqueous mud wedge extending from the yangtze river mouth southward off the zhejiang and fujian coasts into the taiwan strait overlying what appears to be a transgressive sand layer this distal clinoform thins offshore from similar to 40 in thickness between the 20 and 30 m water depth to 1 2 in between 60 and 90 m water depth corresponding to an across shelf distance of less than 100 km total volume of this distal mud wedge is about 4 5 x 10 11 m 3 equivalent to similar to 5 4 x 10 11 t of sediment most of the sediment in this mud wedge comes from the yangtze river with some input presumably coming from local smaller rivers thus the total yangtze derived sediments accumulated in its deltaic system and east china sea inner shelf have amounted to about 1 7 x 10 12 t preliminary analyses suggest this longshore and across shelf transported clinoform mainly formed in the past 7000 yrs after postglacial sea level reached its mid holocene highstand and after re intensification of the chinese longshore current system sedimentation accumulation apparently increased around 2000 yrs bp reflecting the evolution of the yangtze estuary and increased land erosion due to human activities such as fanning and deforestation the southward flowing china coastal current the northward flowing taiwan warm current and the kuroshio current appear to have played critical roles in transporting and trapping most of yangtze derived materials in the inner shelf and hence preventing the sediment escape into the deep ocean c 2006 elsevier b v all rights reserved

dynamics and spatial variability of near bottom sediment exchange in the yangtze estuary china abstract this study was conducted to examine the spatial variations in the exchange between near bottom suspended and sea bottom sediments in the yangtze estuary and adjacent region as well as to explore the fate of suspended sediments in the study area the relationship between the sand silt and clay contents of the sediments was analyzed by log ratio analysis which revealed a non linear function for selective deposition and a wide range of grain size distributions in the estuary this finding does not conform to the nearly constant clay silt ratios reported for other tidal basins around the world due to non linear sediment mixing under complex hydrodynamic conditions the sediment exchange processes in the yangtze estuary were quantified based on the principle of mass balance the average grain size distribution of near bottom suspended sediments from the estuary showed that approximately 49 of the riverine sediments accumulated in the mouth bar area while the rest which is primarily composed of fine grained sediments is transferred to the outer estuary and deposited in the form of flocs the spatial distribution of the sediment exchange ratios demonstrated that small amounts of suspended sediment were deposited onto the seabed of the upper estuary exchange ratio 0 8 seaward of the river mouth which implies that this is the present day depocenter of yangtze mud the sediment exchange rates obtained by combining the dimensionless exchange ratios and bulk sediment accumulation rates were found to be 2 3 cm yr in the muddy depocenter which extends to the south of the river mouth from 122 e to 123 e longitude at 31 n latitude

the impact of the three gorges dam on the downstream distribution and texture of sediments along the middle and lower yangtze river changjiang and its estuary and subsequent sediment dispersal in the east china sea abstract the grain size of river sediments changes systematically downstream from source to sink and is influenced by catchment lithology geomorphology hydrology oceanography and in modern settings anthropogenic impacts compared with small gravel bedded river systems less is known about large sandy bed rivers particularly from the river source to marine sink in the present study we examine longitudinal changes in sediment grain size along the middle and lower yangtze river downstream of the three gorges dam tgd and along the major sediment dispersal pathway into the east china sea over a total length of 2100 km we also examine the spatial patterns of seabed sediment grain size in the east china sea adjacent to the yangtze estuary 70 000 km 2 in area in particular we consider the impact of the tgd on the grain size of the riverbed and seabed sediments before the construction of the tgd the relationship between median grain size and distance along the sandy bed of the middle and lower yangtze showed a downstream fining trend that was exponential in form after the tgd was built erosion caused an abrupt gravel sand transition to develop in the section immediately downstream of the tgd in the yangtze estuary flocculation and subsequent deposition of suspended riverine mud during the slack water period between flood and ebb tides led to the formation of an abrupt sand mud transition muddy deposits along the major longshore sediment dispersal route also show an exponential fining trend however towards the open east china sea the modern riverine muds are replaced seawards by older sands the mud margin there was found to have retreated landward significantly over the post tgd period due to erosion driven by the significant decrease in sediment supply from the yangtze river we expect that the impact of the tgd on the grain size of bed sediments in the yangtze river and the east china sea will continue for some time and the change in the grain size of bed sediments there will become more pronounced

a model for the exchange of water and salt between the baltic and the skagerrak abstract a model for the exchange of salt and water between the baltic and the sea the skagerrak is presented because of strong inter basin interactions in the baltic entrance area the model must include the kattegat and the belt sea these are modeled by horizontally homogeneous two layer sub models the most prominent dynamical properties of the sub models are wind driven entrainment flows and rotational baroclinic hydraulic controls the model is driven by a meteorologically forced barotropic transport qh calculated from the freshwater supply to the baltic qf and the sea level fluctuations in the kattegat and turbulent entrainment flows coupled to the wind speed w and in the belt sea also to the barotropic transport the most important bathymetric features of the basins are included the model equations are integrated numerically for a test period of 1 years the stratification in the kattegat as well as in the belt sea is quite well predicted it is found that approximately one half of

study of the recent sediment movement features in the vicinity of deepwater navigation channel yangtze estuary abstract intensive anthropogenic impacts have been implemented in the yangtze estuary during the last several decades which significantly modified the global and local hydro and morpho dynamics subsequently sediment movement characteristics in the vicinity of the deepwater navigation channel dnc change in accordance with such human interactions the present study is focusing on the recent sediment moving features around the dnc in between 2017 and 2019 after the elevation of the partition dike in 2016 five successive in situ regular campaigns for flood and dry seasons together with field surveys pre and post typhoon in 2018 were conducted to collect bottom surface sediment samples sand and silt samples with different physical properties were identified under the normal weather condition sand samples are generally found in the south channel sc and the middle reach of the north passage np whereas silt samples are prevailed elsewhere considering the different features in the grain size distribution curve of sand samples more attentions were paid to the spatiotemporal variations of sand samples grain size parameters of sand samples indicate that under the normal weather condition relatively pure sands with almost no silt constituent exist in the sc whereas relatively mixed sands with certain silt compositions are located in the middle reach of np nevertheless only relatively mixed sands could be found in the sc and there are no sand samples in the np after typhoon events subsequently the recent sediment movement characteristics in the vicinity of dnc were figured out under the normal weather condition relatively mild siltation owing to the back filings from the dike fields and seaward of dnc occurs in the middle and lower reaches of dnc which is consistent with the temporal variations of the magnetism analysis of sand samples in contrast intensive siltation occurs inside the dnc after the extreme weather events which comes from three possible provenances i e overtopping from the south dike back fillings from dike fields and seaward of dnc these findings provide some helpful information for the efficient management and reasonable regulation in the yangtze estuary

process based morphodynamic modeling of the yangtze estuary at a decadal timescale controls on estuarine evolution and future trends abstract understanding the decadal morphodynamic evolution of estuaries and deltas and their controls is of vital importance regarding management for estuarine function and sustainable development this work addresses this issue by applying a process based model system delft3d to hindcast and then forecast the morphodynamic evolution of the yangtze estuary at a decadal timescale forced by the river and tides the model considers sand mud mixture and the variations of river water discharge and sediment discharge the morphodynamic model is validated against three periods i e an accretion period 1958 1978 an erosion period 1986 1997 and a recent accretion period with human activities 2002 2010 model results show good performance with respect to spatial erosion and deposition patterns sediment volume changes and hypsometry curves the model reveals quite different behaviors for mud transport between the dry and wet seasons which is subject to the prescription of river boundary conditions and bed composition we define six scenarios to project evolution to the year 2030 under decreased river inputs and increased relative sea level the simulations reveal that overwhelming amount of erosion will likely occur in the inner and mouth bar area of the estuary particularly the mouth zone will shift from net deposition before 2010 to net erosion by 2030 mainly because of decreasing sediment supply changes in water discharge have minor effects on the projected trend net erosion will be considerable when the sediment supply is extremely low 100 mt yr 1 due to the abundance of erodible modern sediment in the yangtze estuary erosion within the mouth bar area may be unexpected including the deepening of the tidal inlet at east chongming mudflat and the formation of a flood channel on the seaward side of jiuduansha shoal overall the model results provide valuable information for sustainable delta management under changing conditions for both the yangtze system and other similar estuaries and deltas with diminishing sediment supplies

atmospheric models gps and insar measurements of the tropospheric water vapour field over mount etna 1 dynamic models of atmospheric movement over the mount etna volcano are used to calculate the path delays affecting radar caused by variable water vapour in the troposphere we compare these model results with the equivalent differential radar interferogram generated by two ers 2 sar images taken 35 days apart and the water vapour delay retrievals from a network of fourteen gps stations distributed over the volcano the atmospheric model delay field agrees wellwith thelong wavelength spatial differences measured by insar and those measured by gps index terms 6924 radio science interferometry 1243 geodesy and gravity space geodetic surveys 3367 meteorology and atmospheric dynamics theoretical modeling 6964 radio science radio wave propagation 8499 volcanology general or miscellaneous citation wadge g et al atmospheric models gps and insar measurements of the tropospheric water vapour field over mount etna geophys res lett 29 19 1905 doi 10 1029 2002gl015159 2002

the multi decadal morphodynamic changes of the mouth bar in a mixed fluvial tidal estuarine channel abstract inner channel mouth bars imb are common and vital geomorphological structures in estuaries that can efficiently promote the progradation of a fluvial delta however these significant structures face serious interferences by natural and human forces this study mainly focuses on imb deposited in the mixed fluvial tidal dominated south passage sp of the changjiang estuary between 1959 and 2018 to reveal how multidecadal morphodynamic variability in a mouth bar responds to natural forcing and human interferences the results show that the volume of the imb in the sp increased from 1128 106 m3 in 1959 to 1636 106 m3 in 1989 and then decreased to 462 106 m3 in 2018 meanwhile the evolution of the imb could be divided into five stages the growing phase 1959 to 1979 which showed a v shape the partial adjustment phase 1999 2003 which showed a crest dent shape the stable phase which showed a flat shape 2004 2010 the partial adjustment phase 2011 2017 when jiangyanan shola inserted into the sp and finally evolved into a flat shape in 2018 fluvial water discharge and suspended sediment discharge ssd did not control the variation in the mouth bar enso events were normally responsible for not only the periodic variations in the landward slope and the water depth of the crest of the imb but also occasional extreme changes in the imb moreover local sandbar insertion sediment from the seaside induced by strong tidal power and intensified engineering projects resulted in the continual shrinkage of the mouth bar by depositing more sediment at the mouth bar our work implies that understanding and governing this imb will bring additional economic benefits to this fast developing society but the protection of this delicate estuarine geomorphology system should still receive great attention

the differences in morphological development between the intertidal flats of the eastern and western scheldt human interventions have a large impact on estuarine morphology the intertidal flats in the eastern scheldt and western scheldt estuaries the netherlands have faced substantial morphological changes over the past decades these changes are thought to be caused by human interventions such as the construction of the storm surge barrier in the mouth of the eastern scheldt and the deepening of the navigation channels of the western scheldt this paper analyses several datasets and numerical simulations of hydrodynamics providing an overview of the various morphological characteristics of the intertidal flats in the two estuaries over time and space apart from the volume area and average height of these areas also the integral steepness of each flat is quantified based on its full geometry the analyses focus on the intertidal flats surrounded by water which allows for a robust comparison between the different flats the intertidal flats in the western scheldt appear to be substantially steeper compared to those in the eastern scheldt the data indicates that a larger average height of a flat is related to a larger steepness despite variations in the evolution of the different flats distinct characteristics of both estuaries are observed an opposed trend is identified over time the flats in the western scheldt have mainly increased in height whereas the flats in the eastern scheldt have lowered after the completion of the storm surge barrier this opposing development is associated with differences in tidal flow velocities in the estuaries which are the result of human interventions

longshore suspended sediment transport and its implications for submarine erosion off the yangtze river estuary abstract coastal currents that originate from large rivers play a key role in delivering sediment to shelf regions quantifying their transport capability is therefore essential to understanding the sediment budgets and the consequent deposition or erosion of coastal areas in february 2012 we observed the sediment transport carried by the min zhe coastal current that originates from the yangtze river mouth and calculated a flux of 18 7 tons per second on a cross shore section in this period the coastal current was at a typical status which allowed us to estimate a total annual sediment transport of 0 27billion tons southward this result was more than three times the present annual yangtze river sediment discharge suggesting that considerable net sediment removal occurs in the coastal regions the sediment transport 0 27 billion tons year is probably the deposition erosion threshold for the east china sea coast north of our study site analysis of historical yangtze river sediment influx records showed that the onset and acceleration of coastal erosion was closely linked with the operation of the three gorges dam tgd upstream of the yangtze river

siltation on a highly regulated estuarine system the magdalena river mouth case northwestern south america abstracts comparison of geo referred bathymetric datasets from 2000 to 2017 at different timescales allowed to analyze changes in the sedimentary balance and to determine patterns of morphological adjustment in the magdalena river south america the magdalena river has one of the highest sediment yields among the major rivers of the world in addition it is a laterally constrained river mouth due to a series of man made structures inhibiting its morphological response thus it provides an illustrative example to study siltation processes in a river mouth system where a low capacity of morphological response interacts with a high magnitude sediment transport regime the river mouth exhibited an overall slow pace deepening trend between 2000 and 2017 however it experienced cyclic shifts between erosive and siltation states both at interannual and intra annual scales the rates of erosion were 310 mm yr 1 on average during the erosional stages whereas sedimentation rates were 293 mm yr 1 on average during the sedimentation stages maximum rates of erosion and sedimentation were 1450 mm yr 1 and 2625 mm yr 1 respectively however intra annual rates of sedimentation erosion were of the same magnitude or larger compared with the interannual rates such high rates and the rapid changes in the sedimentary balance is the result of the cumulative effect of its limited morphological response capacity and its large suspended sediment load these rapid processes generate constraints and threats to navigation particularly at intra annual scales consequently innovative intervention proposals recognizing the rapid transitions and geomorphological adaptations are required for managing this type of river mouths

drowning of the mississippi delta due to insufficient sediment supply and global sea level rise global sea level rise reduced sediment supply and subsidence threaten the stability of the mississippi delta calculations of riverine sediment load and storage indicate that 10 000 13 500 km2 of the delta could be submerged by ad 2100

a high resolution record of lateglacial and early holocene marine sediments from southwestern sweden with special emphasis on environmental changes close to the pleistocene holocene transition and the influence of fresh water from the baltic basin a high resolution study of a marine depositional record 43 m long dated by accelerator mass spectrometry from goteborg gothenburg southwestern sweden shows biostratigraphical and sedimentological changes of environmental significance during the lateglacial and early holocene high accumulation rates are recorded from the onset of the deglaciation of the area ca 13 500 yr bp until 10 300 yr bp by which time approximately 100 m of marine sediments were deposited the early holocene is represented by 10 m only of sediment the influence on the skagerrak kattegat coastal area of the dramatic final drainage of the baltic ice lake at 10 300 yr bp is re evaluated its impact on the distal swedish west coast was limited and sediments that were previously related to this drainage are reinterpreted here it is suggested they reflect resuspension and redeposition of sediments from the large inland lake vanern basin between ca 9500 and 9000 yr bp at 10 200 yr bp a general climatic change and a sudden incursion of warm and saline atlantic water into the norwegian sea occurred and the skagerrak altered environmental conditions with more temperate bottom water conditions in the investigation area

structural evidence for superposition of transtension on transpression in the zagros collision zone main recent fault piranshahr area nw iran abstract the main recent fault of the zagros orogen is an active major dextral strike slip fault along the zagros collision zone generated by oblique continent continent collision of the arabian plate with iranian micro continent two different fault styles are observed along the piranshahr fault segment of the main recent fault in nw iran the first style is a sw dipping oblique reverse fault with dextral strike slip displacement and the second style consists of cross cutting ne dipping oblique normal fault dipping to the ne with the same dextral strike slip displacement a fault propagation anticline is generated sw of the oblique reverse fault an active pull apart basin has been produced to the ne of the piranshahr oblique normal fault and is associated with other sub parallel ne dipping normal faults cutting the reverse oblique fault another cross cutting set of ne sw trending normal faults are also exist in the pull apart area we conclude that the ne verging major dextral oblique reverse fault initiated as a sw verging thrust system due to dextral transpression tectonic of the zagros collision zone and later it has been overprinted by the ne dipping oblique normal fault producing dextral strike slip displacement reflecting progressive change of transpression into transtension in the collision zone the active piranshahr pull apart basin has been generated due to a releasing damage zone along the nw segment of the main recent fault in this area at an overlap of piranshahr oblique normal fault segment of the main recent fault and the serow fault the continuation of the main recent fault to the n

morphodynamic impacts of large scale engineering projects in the yangtze river delta morphodynamics of world s river deltas are increasingly affected by human activities which are of great ecological economic and social implications however impacts of human interventions in deltaic regions are insufficiently understood especially superimposed upon diminishing sediment supplies this study uses the heavily interfered yangtze river delta as an example to address this issue the morphodynamic impacts of the deepwater navigation channel project dncp during 1997 2013 are investigated through process based modeling approach delft3d and bathymetric data analysis the dncp was implemented in the mouth bar area of the yangtze river delta including the twin dikes and 19 groynes with the total length of 132 0 km hydrodynamic simulations indicate that the training walls resulted in weaker tidal flow and longer slack period at the east hengsha shoal ehs and stronger tidal flow at the subaqueous delta thus the ehs is characterized as a sediment accumulation zone after the completion of the training walls subsequently morphological modeling shows enhanced accretion at the ehs and enhanced erosion at the subaqueous delta when the training walls are taken into account numerical experiments further demonstrate that the above changes are mainly attributed to the seaward half of the northern training walls constructed in 2002 2005 this is probably the reason for the observed accretion peak of the ehs in 2002 2007 and the gradual increase in the erosion rate of the subaqueous delta after 2002 the schematized paths of sediment transport after the dncp indicate that sediment eroded from the subaqueous delta serves as an important source for accretion of the mouth bar area it is suggested that siltation promoting projects within the mouth bar area increased shallow shoal accretion and aggravated erosion at the subaqueous delta with the overall erosion of the yangtze river delta due to river sediment reduction large scale estuarine engineering projects substantially increase the complicacy of its morphodynamic pattern which merits close attention for sustainable delta management

integrated satellite interferometry tropospheric noise gps estimates and implications for interferometric synthetic aperture radar products interferometric synthetic aperture radar insar like other astronomic and space geodetic techniques is limited by the spatially and temporally variable delay of electromagnetic waves propagating through the neutral atmosphere statistical analysis of these variations from a wide variety of instruments reveals a power law dependence on frequency that is characteristic of elementary kolmogorov turbulence a statistical model for a major component of the delay fluctuations the wet component has previously been developed by treuhaft and lanyi 1987 for very long baseline interferometry a continuous global positioning system gps network is now in place in southern california that allows estimation of along with geodetic parameters the total delay due to the atmosphere above each site on a subhourly basis these measurements are shown to conform to the treuhaft and lanyi tl statistical model both temporally and spatially the tl statistical model is applied to the problem of insar and used to produce the covariance between two points separated in time and or space the error due to the atmospheric variations for sar products such as topography and surface deformation is calculated via propagation of errors there are two methods commonly cited to reduce the effect of atmospheric distortion in products from sar interferometry stacking and calibration stacking involves averaging independent interferograms to reduce the noise calibration involves removing part or all of the delay using data from an independent source such as total zenith delay estimates from continuous gps networks despite the relatively poor spatial density of surface measurements calibration can be used to reduce noise if the measurements are sufficiently accurate reduction in tropospheric noise increases with increasing number of measurement points and increasing accuracy up to a maximum of n where n is the number of points stacking and calibration are shown to be complementary and can be used simultaneously to reduce the noise to below that achievable by either method alone

holocene sedimentation in the skagerrak interpreted from chirp sonar and core data high resolution chirp sonar profiling in the northeastern skagerrak shows acoustically stratified sediments draping a rough surfaced substratum a 32 metre long sediment core retrieved from the survey area encompasses the entire holocene and latest pleistocene the uppermost seismo acoustic units in the chirp profiles represent holocene marine sediments the lowermost unit is interpreted as ice proximal glacial marine sediments rapidly deposited during the last deglaciation the end of ice proximal sedimentation is marked by a strong reflector interpreted to have been formed during latest pleistocene time as a consequence of rapid ice retreat and drastically lowered sedimentation rate the subsequent distal glacial marine sediments were deposited with initially high sedimentation rates caused by an isostatic rebound associated sea level fall based on correlation between the core and the chirp sonar profiles using measured sediment physical properties and ams 14 c dating we propose a revised position for the pleistocene holocene boundary in the seismo acoustic stratigraphy of the investigated area copyright 2005 john wiley sons ltd

deflation of mount etna monitored by spaceborne radar interferometry ground based measurements of volcano deformation can be used to assess eruptive hazard but require the costly and often hazardous installation and maintenance of an instrument network here we show that spaceborne radar interferometry which has already shown its utility in mapping earthquake related deformation1 can be used to monitor long term volcano deformation two families of synthetic aperture radar images acquired from ascending and descending orbits by the satellite ers 1 and looking at mount etna from opposite sides cover the time period from 17 may 1992 to 24 october 1993 and include the second half of etna s most recent eruption despite artefacts of the interferometric technique we can observe a volcano wide deflation which is an expected consequence of the eruption but which had not previously been appreciated we quantify it using a simple model based on the change of pressure in a sphere located in an elastic half space the modelled deformation increases linearly with time until the end of the eruption our results show that it will be possible to use this technique to detect the inflation of volcanic edifices that usually precedes eruptions

distribution of the right lateral strike slip motion from the main recent fault to the kazerun fault system zagros iran evidence from present day gps velocities article i nfo gps measurements across the kazerun fault system in the zagros mountain belt provide first instantaneous velocities on the different segments these results are closely consistent with the geological fault slip rates over 150 ka implying stable velocities over a longer period the present day strike slip motion is distributed from the main recent fault to the n trending kazerun fault system along a preferential en echelon fault zone included in a more distributed fan shape fault pattern the hormuz salt decoupling layer cannot be the only cause of a sedimentary spreading because seismicity attests these faults are rooted in the basement the dena fault 3 7 mm yr transfers the mrf fault slip mainly to the kazerun 3 6 mm yr and slightly to the high zagros and sabz pushan faults 1 5 mm yr and the kazerun fault further to the kareh bas fault 3 4 mm yr total geological horizontal offsets associated with gps slip rates help inferring precise fault slip onset ages the successive onsets deduced by this approach imply that the right lateral strike slip activity of the mrf has propagated in time southeastward to the dena segment and then to the kazerun segment and to the kareh bas fault

evolution of the jiuduansha wetland and the impact of navigation works in the yangtze estuary china abstract the estuarine wetlands in the yangtze estuary face increasing threats due to large scale engineering projects and huge land requirements as a wetland national nature reserve and important stopover site for migratory shorebirds of the east asian australasian flyway the jiuduansha wetland one of four main islands in the estuary is of both national and international importance since 1998 the previously undisturbed wetland has been considerably modified by the adjacent deep water navigation channel project dnc in order to understand the role of the dnc for the evolution of the jiuduansha wetland we performed a diagnostic study from multiple perspectives including deposition rate area change evolution track geometric characteristics and geomorphological change by coupling gis geostatistics and remote sensing techniques this study demonstrates the impact of the dnc on the jiuduansha wetland in a spatially explicit way multi temporal bathymetric maps and landsat images from before and after the dnc was constructed were adopted to conduct our study we find that deposition has occurred in most parts of the wetland over the past almost 30 years accounting for 67 3 of the total area however over 40 of the study area shows a decreasing trend in deposition rate the spatial distribution of deposition erosion patterns is closely linked to the dnc we also find that the dnc has substantial effects on the evolution of the jiuduansha wetland the 0 2 and 5 m isobaths in the jiuduansha shoal jds as well as in the jiangya shoal jys the upper shoal us and the middle lower shoal mls show different response patterns to the dnc specifically the south training jetty of the dnc has an adsorption effect on the jds above the 2 m isobaths intersecting with it as a result the evolution track geometric and geomorphological characteristics of the jds were markedly altered in the short term our comprehensive analysis suggests that in the future the jds will become more elongated in both the upstream and downstream direction along the south training jetty and that the south side of the jds will be eroded

rapid response of the changjiang yangtze river and east china sea source to sink conveying system to human induced catchment perturbations abstract in order to investigate human impact in the changjiang east china sea source to sink conveying system we analyze the siltation and erosion state of the estuary shelf deposition systems and discuss the response intensity and timing of the depositional system of the changjiang subaqueous delta and the related changjiang distal mud results show that after the three gorges dam was put into operation in 2003 the abrupt reduction of the sediment discharge to the estuary disturbed the equilibrium between the estuary coast shelf deposition systems modifying the siltation erosion balance and seabed sediment types from the changjiang subaqueous delta to its distal mud areas the degree of response to catchment changes diminishes with a larger response lag from north to south of the distal muds influenced by dam emplacements the change of the changjiang east china sea source to sink conveying system can be divided into three stages i e pre 1950 1950 2002 and post 2003 before 1950 the source to sink system remained relatively stable between 1950 and 2002 man made fluvial impoundments created an important sink for terrigenous sediment of the upstream regions but without profound system changes in contrast after 2003 the morphodynamic patterns for the entire mid lower reaches of the changjiang river the subaqueous delta and the distal muds shifted rapidly from siltation to erosion within a short period of time furthermore the upper reaches of the river became disconnected from the source to sink conveying system and the mid lower reaches of the river together with its subaqueous delta and northern distal mud area were converted into net sediment sources as such the sink area has shrunk while the source area expanded for the changjiang east china sea source to sink conveying system

holocene paleoceanography and paleoenvironments of the skagerrak kattegat scandinavia paleoceanographic and paleoenvironmental interpretations based on foraminifera sedimentary data radiocarbon dates and stable isotope measurements were derived from two sections in the skagerrak a 115 m thick holocene marine section drilled onshore at skagen near the northernmost tip of jutland denmark and a 9 m piston core from the skagerrak north of skagen the foraminiferal data show that arctic subarctic environments in the deep skagerrak kattegat area were succeeded by boreal conditions at 9 6 ka this was a result of northward migration of the atlantic polar front and inflow of warm atlantic water into the area through the norwegian channel a gradual warming of the water masses after 9 6 ka is indicated by the data rare foraminifera and high sedimentation rates are found between approximately 8 6 ka and 7 6 ka at both core locations the modern foraminiferal assemblages of the area were fully established at 7 6 ka indicating that the modern circulation pattern in the skagerrak kattegat after the opening of the english channel and the danish straits was not established before this date at 5 5 ka a sudden change to coarser sediments higher energy environments and the appearance of the foraminifer eoeponidella laesoeensis is recorded in the skagen core this indicates a rapid change in the hydrography reflecting altered meteorological and hydrographic conditions in the skagerrak kattegat including a strengthening of the jutland current and increased inflow of north sea water into the kattegat the event is interpreted as a response to cooling at the end of the holocene climatic optimum in late atlantic time and possibly reflects a rapid cooling event of north atlantic surface water masses

revised interpretation of recent insar signals observed at llaima volcano chile we analyzed c band and l band interferometric synthetic aperture radar insar data acquired from 2003 to 2011 to search for volcanic deformations at llaima volcano southern andes 38 69 s 71 73 w there specific environmental conditions steep slopes snow or ice capped summit dense vegetation cover and strong tropospheric artifacts and limited amount of radar data available make it challenging to accurately measure ground surface displacement with insar to overcome these difficulties we first performed a careful analysis of the water vapor variations using medium resolution imaging spectrometer and moderate resolution imaging spectroradiometer near infrared water vapor products and then we inverted wrapped interferograms for both topographic correlated phase delays and a simple model source strength in the light of our results we conclude that there is no detectable ground displacement related to a deep magmatic source for the 2003 2011 period and that most of the fringes observed in the interferograms were produced by tropospheric delays

multi interferogram method for measuring interseismic deformation denali fault alaska summary studies of interseismic strain accumulation are crucial to our understanding of continental deformation the earthquake cycle and seismic hazard by mapping small amounts of ground deformation over large spatial areas insar has the potential to produce continental scale maps of strain accumulation on active faults however most insar studies to date have focused on areas where the coherence is relatively good e g california tibet and turkey and most analysis techniques stacking small baseline subset algorithm permanent scatterers etc only include information from pixels which are coherent throughout the time span of the study in some areas such as alaska where the deformation rate is small and coherence very variable it is necessary to include information from pixels which are coherent in some but not all interferograms we use a three stage iterative algorithm based on distributed scatterer interferometry we validate our method using synthetic data created using realistic parameters from a test site on the denali fault alaska and present a preliminary result of 10 5 5 0 mm yr 1 for the slip rate on the denali fault based on a single track of radar data from ers1 2

shoal morphodynamics of the changjiang yangtze estuary influences from river damming estuarine hydraulic engineering and reclamation projects abstract concerns regarding estuarine shoal morphodynamics have increased worldwide because of intensive anthropogenic activities to explore response of estuarine shoals to possible couplings of multiple artificial interferences in river basins and within estuaries the link between the morphodynamic processes of the nanhui shoal nhs which is located along the southern margin of the changjiang estuary the largest estuary in asia and river damming estuarine hydraulic engineering and reclamation projects is discerned in this study the results reveal that the nhs exhibited secular polarization during 1998 2013 with a significant accretion of 1 8 10 8 m 3 landward from the tidal ridge and an erosion of 0 3 10 8 m 3 on the seaward edge respectively forming a steep slope with an elevation between 2 and 3 m meanwhile the nhs morphodynamics could be divided into 3 stages mild accretion with an undisturbed tidal channel during 1998 2002 strong sedimentation with a disrupted tidal channel during 2003 2008 and large scale landward accretion with an infilled tidal channel after 2009 moreover the nhs s volume variations exhibited an 18 month cycle even though an increased area of 35 km 2 above 2 m and a decreased area of 45 km 2 between 2 and 5 m were observed the primary causes of theses periodic changes in the nhs s volume are determined as the fluctuating changjiang water discharge and cyclically altered hydrodynamics of the south passage the deep waterway project dwp and reclamation projects were responsible for the polarization of seaward erosion and landward accretion respectively moreover these reclamation projects dominated the staggered changes in nhs morphodynamics by inducing continuous accretion within the tidal channel compared to estuarine engineering river damming induced dramatic declines in distal sediment may have played a minor role in flat changes of nhs

biostratigraphic and sedimentological evidence of hydrographic changes in the kattegat during the later part of the holocene abstract detailed sedimentological and micropaleontological investigations complemented with 14 c analyses were made in a large number of cores from the kattegat in general the holocene in the kattegat is represented by sediments deposited since 4000 yrs b p resting directly upon glacial sediments sediments formed between the younger dryas and 4000 yrs b p are found in restricted areas near the coast at present day water depths of less than 20 25 m the cores yield evidence of one pronounced hydrographic shift at 4000 yrs b p and two minor changes at 2000 and at about 300 yrs b p these three hydrographic shifts are in addition to sedimentological changes also characterized by the following biostratigraphic markers 1 at 4000 yrs b p the benthic foraminifers nonion labradoricum a different variety of ammonia batavus and a benthic microforaminiferal fauna became established 2 at 2000 yrs b p a pronounced appearance of an algal cyst occurred called here varia type a and 3 at about 300 yrs b p varia type a peaked and subsequently vanished the hydrographic shifts are attributed to changes in the inflow outflow regime between the north sea and the skagerrak kattegat baltic and tentatively to changes in the large scale circulation patterns of the north atlantic

accurate measurements of tropospheric effects in volcanic areas from sar interferometry data application to sakurajima volcano japan abstract the accuracy of surface deformation maps derived from dinsar differential interferomery synthetic aperture radar in volcanic areas is limited by temporal variations of the vertical refractivity profile in the troposphere between the radar data acquisitions due to their dependence on altitude such variations may produce topography related fringes in the computed interferograms the variations should be carefully estimated in a given area so that they can be discriminated with real ground deformation signals in this paper we present a clear example of tropospheric induced fringes reaching up to 2 9 fringes over 1200 m evidenced on sakurajima volcano japan from ers 1 and ers 2 data the analysis of phase altitude correlations based on network adjustments of the interferometric dataset leads to a simple linear model of the tropospheric excess path delay with an rms accuracy of 0 4 cm that might be used for further corrections a more detailed investigation of these phase variations providing accurate measurements of linear and non linear contributions of tropospheric effects is also presented and shows that tropospheric phase delays can be better modeled on sakurajima with a non linear model

insar monitoring using radarsat 2 data at piton de la fournaise la reunion and karthala grande comore volcanoes piton de la fournaise la reunion and karthala grande comore are the two active volcanoes of the southwestern indian ocean a 14 month april 2013 to june 2014 monitoring period was carried out at both volcanoes using synthetic aperture radar interferometry insar techniques on radarsat 2 data thanks to the seas oi survey of environment assisted by satellite in the indian ocean station 21 sar scenes were acquired over this period and insar results revealed the slow subsidence of the dolomieu caldera floor at piton de la fournaise following the 2009 and 2010 eruptions and the subsidence of the whole cone between april and july 2013 at karthala no evidence of any volcanic activity was found for the period april 2013 to june 2014 the use of systematic insar for volcano monitoring is an efficient tool to study effusive eruptions we showed that during periods of unrest insar is able to pick up early signs of a future eruption and monitor secondary phenomena that require no real time data during an effusive crisis it is still difficult to carry out fully operational insar monitoring but using the example of the june 2014 eruption at piton de la fournaise we show that sar data can help with the detection and tracking of lava flows and active flow paths during effusive eruptions based on sar coherence and sar amplitude these preliminary results are very promising for the future of insar monitoring of active volcanoes and highlight the need for near real time access to sar data in the mapping of active lava flows during effusive eruptions this study also revealed the major role of ground stations like seas oi in the efficiency of this monitoring supplying free near real time remote sensing data to the scientific and institutional communities

constructing accurate maps of atmospheric water vapor by combining interferometric synthetic aperture radar and gnss observations over the past 20years repeat pass spaceborne interferometric synthetic aperture radar insar has been widely used as a geodetic technique to generate maps of the earth s topography and to measure the earth s surface deformation in this paper we present a new approach to exploit microwave data from insar particularly persistent scatterer insar psi and global navigation satellite systems gnss to derive maps of the absolute water vapor content in the earth s atmosphere atmospheric water vapor results in a phase shift in the insar interferogram which if successfully separated from other phase components provides valuable information about its distribution psi produces precipitable water vapor pwv difference maps of a high spatial density which can be inverted using the least squares method to retrieve pwv maps at each sar acquisition time these maps do not contain the absolute total pwv along the signal path but only a part of it the components eliminated by forming interferograms or phase filtering during psi data processing are reconstructed using gnss phase observations the approach is applied to build maps of absolute pwv by combining data from insar and gnss over the region of upper rhine graben in germany and france for validation we compared the derived pwv maps with pwv maps measured by the optical sensor medium resolution imaging spectrometer the results show strong spatial correlation with values of uncertainty of less than 1 5mm continuous grids of pwv are then produced by applying the kriging geostatistical interpolation technique that exploits the spatial correlations between the pwv observations

postglacial palaeoceanography in the skagerrak crucial periods of change in the latest glacial to early holocene palaeogeographic and palaeoceanographic evolution in the skagerrak region are portrayed in four time slice maps on a calibrated age scale at 14 0 kyr 11 2 kyr 10 2 kyr and 8 1 kyr the course of palaeoenvironmental events is set in a high resolution chronological framework using images core md99 2286 and a grid of chirp sonar profiles these maps visualize the complex rapid palaeogeographic and palaeoceanographic changes during the glacialinterglacial transition which is characterized by major changes in circulation sediment sources and depositional processes

long term morphological change and its causes in the mersey estuary nw england changes in the morphology of the mersey estuary and their possible causes have been investigated using historical trend analysis and expert geomorphological assessment historical bathymetric charts were digitised and analysed within a gis to provide quantitative estimates of changes in areas and sediment volumes above and below selected elevation planes the results show that the estuary experienced major changes over the last 150 years notably between the late 19th century and ca 1950 an analysis of data relating to possible natural and human factors which could have influenced these changes suggests that training wall construction and dredging in the outer estuary and liverpool bay was the most significant factor contributing to change during this period these activities modified the hydrodynamic and sediment transport regime in a way which enhanced an existing natural tendency for movement of sediment from liverpool bay and the outer estuary into the inner estuary changes in other factors including sea level tidal range wind wave climate freshwater flow and embanking land reclamation were of relatively minor importance between 1950 and 1977 the rate of sediment accumulation in the inner estuary declined as the estuary approached a new condition of dynamic equilibrium and since 1977 there has been a slight net loss of sediment under these conditions the changes in natural forcing factors such as sea level and storminess are likely to have a relatively greater effect on the estuary than in the past

understanding mountain wave phases in ers tandem dinsar interferogram using wrf model simulation repeat pass spaceborne differential synthetic aperture radar interferometry dinsar is commonly used to measure surface deformation however the phase delay due to the atmospheric water vapor has a significant influence on the accuracy of dinsar results on the other hand the signal delay in dinsar can give the spatial variation information of water vapor during the two image acquisitions there are some ripple like phase signals in dinsar which are probably due to the mountain wave in the study area in this paper the weather research and forecasting wrf model is used to simulate the atmospheric delay and compared to the phase delay derived from dinsar results to understand the mountain wave phases in interferograms the results indicate that the ripple like phase signal in the dinsar phase is due to different intensities of the mountain wave in two acquisitions the wrf model can be used to explain the mechanism of mountain wave phase in dinsar which may then hopefully be used for dinsar atmospheric correction

two scales of inflation at lastarria cordon del azufre volcanic complex central andes revealed from asar envisat interferometric data abstract asar envisat interferometric synthetic aperture radar insar data collected over the lastarria cordon del azufre complex chile argentina between march 2003 and may 2005 show the persistence of the large wavelength ground inflation revealed by pritchard and simons in 2002 from the analysis of ers insar data nature 418 2002 167 170 after reducing the tropospheric contribution in the interferograms using a combination of data network adjustment and analysis of modis images we produced an accurate interferometric time series showing a 2 yr long temporal evolution of the ground displacements patterns two distinct inflating signals are detected the main signal covers an elliptical area with a 45 km nne ssw major axis and a 37 km minor axis it is correlated with a regional topographic dome we estimated its maximum inflation rate to 2 5 cm yr 1 we inverted the insar data for a range of source geometries spherical prolate ellipsoids penny shaped cracks the inferred source parameters for 2003 2005 period are consistent with an over pressured reservoir at shallow to intermediate crustal depths 7 15 km with an average volumetric rate of inflation of about 14 106 m3 yr 1 in addition to this main signal a new feature highlighted by the asar data is short wavelength inflation 6 km wide at the location of lastarria volcano on the northern margin of the large wavelength signal we explain this short wavelength signal by a spherical over pressured source lying 1000 m below the summit of lastarria volcano we estimate the average volumetric rate of inflation during the observation period to be 35 103 m3 yr 1 it is remarkable that both volumetric variations for the large and small inflations exhibit the same evolution during the 2003 2005 period suggesting that both processes could be related on the basis of the inversion results and of arguments provided by field evidences and a morpho structural analysis of the digital elevation model of the area we propose that the deep source have a magmatic origin while the shallow source is most likely related to hydrothermal fluids in our interpretation the on going deformation processes observed at lastarria cordon del azufre volcanic complex could represent an evolving pre caldera silicic system further field geological and geophysical investigations will be required to confirm these hypotheses and refine the proposed model mostly based on satellite observations

volcano wide fringes in ers synthetic aperture radar interferograms of etna 1992 1998 deformation or tropospheric effect mount etna 3300 m is the volcano that has been first and most studied by differential synthetic aperture radar previous papers gave evidence for a large scale deformation of the entire edifice consistent with unrest episodes but with a poor fit with classical elastic models also atmospheric effects on mountainous areas are known to be very significant accordingly interferograms may reflect both deformation and tropospheric effects we investigate here the possibility of evaluating and correcting tropospheric effects directly from the interferograms from 38 ers synthetic aperture radar ascending scenes taken from 1992 to 1999 we have computed 238 interferograms the amount of data allows us to analyze how the coherence is maintained over long periods of time and thus how it reveals the location of permanent scatters from a simple analysis of phase elevation relation we give evidence for the clear difference in pattern between stratified tropospheric effects and large scale deformation produced by a source in a three dimensional elastic body with topography using combination of inversion processes we analyze both deformation source and tropospheric effects for the complete set of 238 interferograms finally time evolution of the parameters and modeling probability estimation are retrieved for each sar image estimated relative change in tropospheric delay varies in time from 2 7 to 3 0 1 2 fringes they are consistent with other tropospheric estimations at etna based on ground met and global positioning system observations on the same period of time magmatic volume variations remain below error bars and thus cannot be estimated properly finally some of the interferograms may be entirely explained by the difference in tropospheric conditions between the two acquisition periods without the need to invoking a deformation of the volcano

correction for interferometric synthetic aperture radar atmospheric phase artifacts using time series of zenith wet delay observations from a gps network 1 radar interferograms provide precise millimeter level measurements of crustal deformation at fine resolution over wide areas the dominant error source in many interferograms results from spatial heterogeneity of the wet component of atmospheric refractivity resulting in excess path length of the radar signal propagating through the neutral atmosphere in this report we introduce a method to compensate for atmospheric phase artifacts in a radar interferogram using spatially interpolated zenith wet delay zwd data obtained from a network of global positioning system gps receivers in the region imaged by the radar our method based on taylor s frozen flow hypothesis uses gps data recorded prior to and after the individual radar acquisition times to infer denser spatial networks of control points for interpolation than is suggested by the sparse and irregular spatial distribution of gps receivers we test this approach by correcting phase fluctuations observed in a radar interferogram over an area covered by the southern california integrated gps network stations using maps of atmospheric delay interpolated from the denser network of gps zwd measurements generated by our method we find that the largest improvement results from removing an altitude dependent model derived from the gps data the uncorrected interferogram in our example has an rms fluctuation of 16 1 mm which falls to 8 6 mm after the altitude correction a map derived from zwd measurements recorded only at the instances of radar acquisition reduced overall fluctuations in the data from 8 6 to 8 1 mm rms while using the inferred denser network reduces the error further to 7 5 mm rms most of this residual variation is due to decorrelation of the signal and does not result from atmospheric propagation however after smoothing to remove decorrelation noise the residual drops from 4 7 to 3 9 mm gps stations only and then to 2 7 mm rms when the denser network algorithm is used

changing pattern of accretion erosion of the modern yellow river huanghe subaerial delta china based on remote sensing images abstract the yellow river shifted from the diaokou course to the qingshuigou course in 1976 and shifted again at the north bank of the qingshuigou course in 1996 as a result the entire modern yellow river delta has experienced complicated patterns of erosion and accretion multitemporal remote sensing data of landsat mss and tm from 1976 to 2000 totaling twenty scenes were used to examine the changing pattern of accretion and erosion of the modern yellow river subaerial delta with gis tools during the period 1976 to 2000 the maximum erosion occurred at the head of the last two abandoned promontories diaokou and shenxiangou promontories where the coastline retreated landward over 7 and 4 5 km respectively with mean net erosion rates of 0 29 and 0 19 km a respectively in contrast the maximum accretion occurred at the head of the qingshuigou promontory where the coastline advanced seaward over 20 km with a mean net accretion rate of 0 83 km a the coastline at the head of the q 8 promontory also advanced seaward 7 km with a mean net accretion rate of 0 29 km a during the period 1996 to 2000 total area of the diaokou and shenxiangou promontories was reduced by 141 3 km 2 with a mean net erosion rate of 6 03 km 2 a total area of the qingshuigou and q 8 promontories increased by 384 16 and 11 88 km 2 respectively with mean net accretion rates of 16 4 and 3 03 km 2 a respectively relative to the diaokou shenxiangou and qingshuigou promontories the west area of the diaokou promontory and south area of the qingshuigou promontory were relatively stable although minor erosion occurred the general pattern of accretion and erosion of the modern yellow river subaerial delta was divided into three stages rapid accretion stage 1976 1984 accretion erosion adjustment stage 1985 1995 and slow erosion stage 1996 present the factors affecting the pattern of erosion and accretion over the yellow river delta such as structural geology the yellow river sediment discharge coastal processes meteorological conditions human activity sea level rise and land subsidence were summarized the cumulative area of increase over the entire subaerial delta is closely correlated with the cumulative yellow river sediment discharge wave induced longshore current is the major driving force to transport sediment from eroded areas along the last two abandoned promontories diaokou and shenxiangou promontories mostly westerly and partially easterly together with these coastal processes is the geographical shift of the yellow river course associated with its discharge regime after 1976 leading to the accretion along the present qingshuigou promontory and then the q 8 promontory

late glacial and holocene paleoceanography in the skagerrak from high resolution grain size records abstract high resolution grain size analyses of the ams 14c dated 32 m long core md99 2286 from the northeastern skagerrak were performed in order to study late glacial and holocene paleoceanographic and sedimentary changes all ages in this study are given in calibrated thousand years before present ad 1950 abbreviated kyr unless otherwise noted the distinct ending of ird ice rafted debris in core md99 2286 which was retrieved from a location down current from the final calving ice margin in the region indicates that iceberg calving in the skagerrak ended between 10 6 and 10 2 kyr a clay rich sequence in core md99 2286 deposited between 11 3 and 10 3 kyr is attributed to outflow from the baltic basin across south central sweden the sequence is correlated to similar units from cores along the swedish west coast the onset of this clay rich deposition occurs progressively later in cores further south along the coast supporting a previous hypothesis that differential glacio isostatic uplift caused a southward migration of the baltic outflow from the otteid stenselva to the gota alv outlet a distinct coarsening towards younger sediments in core md99 2286 indicates a hydrographic shift at 8 5 kyr which is correlated to a shift previously reported in the skagerrak kattegat and the norwegian channel this shift reflects the establishment of the modern circulation system in the eastern north sea as a consequence of the opening of the english channel and the danish straits and increased atlantic water inflow and the subsequent development of the south jutland current a general trend of coarsening poorer sorting and increasing variability from 8 5 kyr until the present indicates increasing strength and influence of the variable south jutland current a series of changes from ca 6 3 to ca 3 8 kyr in core md99 2286 reflects strengthening of the jutland current towards the present day sedimentation system in the skagerrak kattegat these changes are correlated to previously reported hydrographic shifts at 5 5 14c years bp in the skagerrak and at 4 0 14c years bp in the kattegat it is suggested that these shifts were separate features of a transitional period related to strengthening of the current system the resulting changes are differently manifested in different parts of the skagerrak kattegat due to the complex circulation system the last 800 years are characterised by poorly sorted sediments with a relatively high and variable proportion of coarse material reflecting a circulation system significantly modified by regional climatic conditions especially the general wind directions and storm frequency over the southern north sea

rapid strain accumulation on the ashkabad fault turkmenistan from atmosphere corrected insar 1 we have measured interseismic deformation across the ashkabad strike slip fault using 13 envisat interferograms covering a total effective timespan of 30 years atmospheric contributions to phase delay are significant and variable due to the close proximity of the caspian sea in order to retrieve the pattern of strain accumulation we show it is necessary to use data from envisat s medium resolution imaging spectrometer meris instrument as well as numerical weather model outputs from the european centre for medium range weather forecasts ecmwf to correct interferograms for differences in water vapor and atmospheric pressure respectively this has enabled us to robustly estimate the slip rate and locking depth for the ashkabad fault using a simple elastic dislocation model our data are consistent with a slip rate of 5 12 mm yr below a locking depth of 5 5 17 km for the ashkabad fault and synthetic tests support the magnitude of the uncertainties on these estimates our estimate of slip rate is 1 25 6 times higher than some previous geodetic estimates with implications for both seismic hazard and regional tectonics in particular supporting fast relative motion between the south caspian block and eurasia this result reinforces the importance of correcting for atmospheric contributions to interferometric phase for small strain measurements we also attempt to validate a recent method for atmospheric correction based on ecmwf era interim model outputs alone and find that this technique does not work satisfactorily for this region when compared to the independent meris estimates

the alteration of lateral circulation under the influence of human activities in a multiple channel system changjiang estuary abstract extensive coastal engineering activities including channel dredging and constructions of large infrastructure have greatly altered hydrodynamics in the changjiang estuary while the changes in longitudinal circulation have been well documented limited studies have focused on the alteration in lateral circulation and its impact on estuarine circulation in the changjiang estuary lateral circulation in an estuary plays an important role in modulating estuarine circulation sediment transport and morphological change different from many of previous numerical studies we utilize an unstructured grid numerical model configured in a way to allow inundation over dikes and tidal flats numerical model experiments show significant changes in lateral circulation and stratification along the north passage in response to the altered geometry and bathymetry due to the channel deepening and the dike construction both the channel deepening and the dike construction led to an enhanced stratification further analysis suggests that the along channel the lateral and the vertical including up and downwelling and vertical mixing effects are all important in modulating the intra tidal stratification destratification process the channel deepening enhances both the lateral and the vertical effects around the high water slack the construction of dikes that completely blocks the lateral water exchange between the north passage and surrounding tidal flats changes the system from a multiple channel system into a single channel system with dike construction the estuarine circulation tends to have a horizontally sheared pattern with weaker friction and a stronger stratification

holocene climatic development in skagerrak eastern north atlantic foraminiferal and stable isotopic evidence a high resolution multiproxy study of core md99 2286 reveals a highly variable hydrographic environment in the skagerrak from 9300 cal yr bp to the present the study includes foraminiferal faunas stable isotopes and sedimentary parameters as well as temperature and salinity reconstructions of a c 29 m long radiocarbon dated core record the multivariate technique fuzzy c means was applied to the foraminiferal counts and it was extremely valuable in defining subtle heterogeneities in the foraminiferal faunal data corresponding to hydrographic changes the major early mid holocene littorina transgression led to flooding of large former land areas in the north sea the opening of the english channel and danish straits and initiation of the modern circulation system this is reflected by fluctuating c n values and an explosive bloom of hyalinea balthica a slight indication of ameliorated conditions between 8000 and 5750 cal yr bp is related to the holocene thermal maximum a subsequent increase in

tropospheric corrections of sar interferograms with strong topography application to etna the accuracy of spaceborne geodetic techniques including sar interferometry is limited by the time and spatial variation and altitude dependance of the propagation delay of electomagnetic waves in the lower troposphere particularly in mountainous areas in this paper we use a 1d model developed for tropospheric corrections of gps and doris measurements to correct sar data the differential tropospheric delay is computed at each pixel of the interferogram from ground temperature humidity and pressure using two empirical parameters calibrated from several radio soundings acquired in various latitude and climate conditions it is shown that with such a model given the 3300 meters topography of etna tropospheric variations can generate up to 4 phase rotations between the top and the bottom of the volcano in 16 out of the 20 interferograms processed with images acquired between august 1992 and october 1993 correction of the tropospheric effect reduces the number of fringes associated with the 1991 93 eruption from previous estimates the remaining deformation is consistant with a deforming source located at a depth of 14 1 km during the second half of the eruption the subsidence rate at the top of the volcano is roughly stable at 13 3 mm month these values are in good agreement with tiltmeter data collected on etna during the same period and with the estimated volume of erupted material no significant deformation can be observed during the last month of eruption inflation of the volcano seems to resume immediately after the end of the eruption at a rate of 3 mm month

lateglacial and holocene sediment sources and transport patterns in the skagerrak interpreted from high resolution magnetic properties and grain size data lateglacial and holocene changes in circulation sedimentation and provenance in north eastern skagerrak were studied using high resolution mineral magnetic and grain size data from the 32 m long i

sudden changes in north atlantic circulation during the last deglaciation sudden changes in the flow of warm atlantic surface waters into the norwegian sea occurred frequently during the last deglaciation typically involving shifts in sea surface temperature of 5 c in fewer than 40 years these led to equally large and rapid changes in atmospheric temperatures and to shifts in atlantic deep thermo haline circulation and ice sheet melting rates

historical changes in 239pu and 240pu sources in sedimentary records in the east china sea implications for provenance and transportation abstract concentrations and isotopic compositions of plutonium pu are widely used for its source identification and to determine transport processes of pu associated particulate matter and water we investigated the concentrations of 239pu and 240pu and their ratios in a number of sediment samples from the east china sea ecs collected in the summer of 2013 august 6 28 the 239 240pu activity concentrations in surface sediment samples were found to range between 0 048 and 0 492 bq kg 1 and the 240pu 239pu atom ratios showed a similar trend as that of the 239 240pu activities the pu atom ratios ranged from 0 158 to 0 297 and were mostly higher than the mean global fallout value of 0 18 the 239 240pu inventories in the ecs varied widely from 2 to 807 bq m 2 with the highest values commonly found in the coastal areas in the yangtze estuary the mean 239 240pu activity concentration is close to the estimated value of the suspended material from the yangtze river catchment 0 18 bq kg 1 and the 240pu 239pu atom ratio was found to be 0 18 which indicates that the yangtze river input is the dominant source of pu for this area the total annual yangtze river input of 239 240pu was estimated to be 2 4 10 10 bq which is small compared to the total amount of 239 240pu buried 3 1 10 13 bq in the whole ecs the pacific proving ground input appears to be the dominant source of pu to the ecs accounting for 45 52 of the total inventory the fractional amount of 239 240pu scavenged from the total 239 240pu transported by the kuroshio current kc and taiwan warm current twc into ecs sediments is estimated to be 10 our study shows that the 240pu 239pu atom ratio is useful not only to obtain a better insight of the biogeochemistry influenced by the kc but also to trace the long range transport of other particle reactive species besides the sedimentation rates obtained based on the penetration depths of 239 240pu and vertical profiles of excess 210pb agree within uncertainties which suggests that 239 240pu can potentially be used as a chronostratigraphic time marker in the marine environment

a review of the history of the baltic sea 13 0 8 0 ka bp abstract the dynamic history of the baltic sea during the millennia following the last deglaciation has been one of the main topics for many generations of quaternary geologists around the baltic sea based on the present state of knowledge and certain hypotheses a model for the development during the baltic ice lake yoldia sea and ancylus lake stages are presented the oresund strait was the threshold of the initial stage of the baltic ice lake and was eroded down to bedrock as a result of the isostatic uplift the emerging threshold forced the baltic ice lake to rise above sea level at ca 12 0 ka bp this gradual up damming ended at ca 11 2 ka bp when the large glacial lake was lowered 5 10m by possible subglacial drainage at mt billingen a glacial readvance during the younger dryas ended a ca 400 year long land bridge between sweden and the continent by blocking the former drainage route once again the baltic ice lake had to rise above sea level to be drained over the oresund strait at ca 10 5 ka bp a gradual ice recession began and 200 years later when the receding ice sheet could not withhold the up dammed water masses the final drainage of the baltic ice lake occurred which rapidly lowered the water level within the baltic basin with ca 25 m and ended the baltic ice lake stage the next stage the yoldia sea was characterized by a complex pattern of relative sea level changes with large differences within the baltic basin a very restricted baltic sea in the south and thus an extensive landbridge at ca 9 9 ka bp a short 100 200 years saline ingression is seen in the baltic sediment records from stockholm in the north to the southernmost parts of the yoldia sea the gradually shallower strait in south central sweden the narke strait ended the saline influence 300 400 years later the two remaining outlets west of lake vanern gota alv and otteid steinselva had become too shallow to swallow the outflowing yoldia sea waters at this stage the baltic lake vanern level could thus not fall in pace with the relative sea level fall outside the outlet areas this was the isolation of lake vanern and the baltic from the sea and the beginning of the ancylus lake since the water depth of the larger gota alv outlet had to be more or less maintained the ancylus lake level had to rise in pace with the uplift of the outlet region this caused a significant and rapid transgression 10 30 m in ca 300 years in the southern baltic which flooded large areas with recently immigrated pine forests since the oresund strait during the yoldia sea stage had been uplifted more than southerly areas the ancylus transgression ended with a new drainage pathway at ca 9 2 ka bp through the darss sill area in the southern baltic and northwards through the store belt strait this so called dana river had cut off the former large land bridge the quaternary deposits of this new threshold were eroded and a fairly rapid regression set in at ca 9 0 ka bp the dana river had eroded down to the sea level which isolated lake vanern from the ancylus lake and created a land bridge between southern sweden and northwards ca 800 years later when the sea level rose above the oresund threshold marine water could enter the baltic and at ca 8 0 ka bp brackish water characterized the southern baltic this marks the end of the ancylus lake

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

downstream sedimentary and geomorphic impacts of the three gorges dam on the yangtze river abstract although large dams have been constructed and continue to be constructed on many rivers the lack of long term gauging data often makes it difficult to document either reservoir sedimentation or the dams downstream impacts more than 50 years of water and sediment data from 20 gauging stations within the yangtze river s basin provide us a unique opportunity to delineate the impacts from the three gorges dam tgd the world s largest dam during the first decade after tgd completion in 2003 1 8 gt of sediments were trapped in the three gorges reservoir tgr the tgr s sediment retention rate increased from 65 during the first three years of operation to 85 by 2008 2012 when the tgd was in normal operation in the low discharge drought years of 2006 and 2011 reservoir retention exceeded 90 sedimentation in the tgr has been discontinuous the most prominent depocenters being at the broad section near the up river entrance to the reservoir and just upstream of the dam where sediment thickness locally exceeds 60 m median size of the sediments trapped in the tgr is 11 m whereas sediments discharged from the tgr are finer than 5 m as a result of sediment retention in the tgr the river downstream has been eroded at a rate of 65 mt yr riverbed sediments have coarsened considerably in the first several hundred kilometers downstream of tgd sediment discharge into the yangtze estuary as measured at the datong downstream gauging station decreased by 130 mt yr relative to the normal water years of 2001 2002 nearly 90 of which can be attributed to the tgd with planned construction of large upstream cascade reservoirs the amount of sediment entering the tgr will decline dramatically thus reducing sedimentation in the tgr and thereby extending its lifespan by the end of the 21st century the tgr should have retained more than 80 of its original storage capacity sediment outflow from the tgr will likely be less than 15 mt yr compared to 50 mt yr at present even with downstream channel erosion the long term average sediment discharge into the yangtze estuary in future decades most likely will decrease to ca 110 mt yr only 20 of its level in the 1960s and further delta erosion is expected

radar interferogram filtering for geophysical applications the use of sar interferometry is often impeded by decorrelation from thermal noise temporal change and baseline geometry power spectra of interferograms are typically the sum of a narrow band component combined with broad band noise we describe a new adaptive filtering algorithm that dramatically lowers phase noise improving both measurement accuracy and phase unwrapping while demonstrating graceful degradation in regions of pure noise the performance of the filter is demonstrated with sar data from the ers satellites over the jakobshavns glacier of greenland

exploratory morphodynamic hindcast of the evolution of the abandoned yellow river delta 1578 1855 ce abstract the abandoned yellow river delta ayd which formed when the yellow river flowed into the southern yellow sea between 1128 and 1855 ce is a representative example of the sensitivity of deltas to modifications in their environments in this study we established a process based morphodynamic model to explore the morphological evolution of one such large scale fine grained delta the ayd before 1855 ce the uncertainties in the model settings which are inevitable when historical data are insufficient were assessed together with the corresponding influences on the evolution of the deltaic system by considering a series of scenarios the results indicate that the strength of local tidal forcing is the key factor that determines the shape and evolutionary trend of the delta sediment input discharge and the slope of the initial coastal profile have a considerable effect on the overall size of the delta and the relative ratio between subaerial and subaqueous parts of the delta respectively based on the evaluation of the uncertainties and a comparison with historical maps the simulated ayd was evaluated to be reliable through an analysis of the temporal delta evolution and residual sediment transport the morphological evolution of the ayd before 1855 ce was investigated the southern delta grew as the shoals merged with the mainland which is in agreement with an existing hypothesis zhang 1984 whereas the accretion of the northern delta was independent from the shoals in the northern part additionally suggestions are made regarding the distribution of the ayd at the end of its progradation stage which provides fundamental information for analyzing subsequent erosion processes since 1855 ce this study differs from existing studies on the ayd which are all based on geological approaches it provides insight into the evolution of the ayd through an alternative means viz a process based morphodynamic modeling approach

accounting for atmospheric delays in insar data in a search for long wavelength deformation in south america insar has been successfully used to observe the deformation of the earth s surface from many processes but mostly dealing with relatively large signals 1 cm over short wavelengths 100 km we use interferometric synthetic aperture radar insar data from two orbital tracks in northern chile to study the feasibility of imaging the broad interseismic ground deformation signal from the nazca plate subduction in order to measure 1 5 cm year of ground motion across 1000 km of satellite track length due to interseismic loading of the subduction interface the atmospheric contribution cannot be ignored we attempt to remove the atmospheric signal using global weather models and by estimating atmospheric parameters directly from the insar data due to the poor temporal and spatial resolutions of the weather model this method fails to produce reliable results the empirical model reduces the phase variance in the interferograms but leaves a residual signal that continues to mask the interseismic signal which demonstrates the importance of carefully applying corrections to the data as they can significantly affect any interpretation that is based on the corrected observations although the methods presented here are not suited for removing all atmospheric path delays this paper does provide suggestions about improvements that can be made to corrective techniques methods that should be further developed are the following 1 corrections with independent and direct observations of atmospheric properties e g continuous gps or satellite observations e g the meris sensor 2 improvements using empirical corrections either in conjunction with a deformation model or constrained by real atmospheric structures and 3 further work with high resolution and improved weather models

the influence of human activities on morphodynamics and alteration of sediment source and sink in the changjiang estuary abstract several works have discussed the morphological evolution in the changjiang estuary cje in recent years the erosion of its subaqueous delta in recent decades has been ascribed to a decline in fluvial sediment input however the interaction between the reduction of riverine sediment load and human activities in the estuary that could have caused morphological change has not been considered in this work we provide evidence on the morphological evolution around the delta front zone since 1986 and use a numerical model to explore the correlation between the change in hydrodynamics and the evolution pattern bathymetric data analysis suggests a decrease of net accretion rate from 16 7 mm year 1986 1997 to 9 1 mm year 1997 2010 in the study area spatially the tidal flats accreted whereas the subaqueous delta switched from deposition between 1986 and 1997 to erosion between 1997 and 2010 we used two indicators tidal energy dissipation and erosion rate to quantify the change in hydrodynamics and found that the erosion of the subaqueous delta in recent decades can readily be explained by the alteration of the hydrodynamics the newly built navigation training works in the north passage had a significant effect on the estuarine hydrodynamics resulting in a local morphological adjustment this erosion generated a new source of sediments to maintain the high suspended sediment concentration and tidal flat progradation the erosion of the subaqueous delta may continue and gradually slow down until the altered hydrodynamics and morphology reach an equilibrium state in the future

nile delta extreme case of sediment entrapment on a delta plain and consequent coastal land loss abstract accelerated erosion of egypt s nile delta coast during this century has generally been attributed to construction of two dams at aswan entrapment of sediment in lake nasser behind the high dam and effects of barrages and river control structures on river nile deposition below aswan also considered important are natural factors including delta subsidence rising sea level and strong coastal current processes this study proposes that more influential in controlling coastal land loss is the near complete entrapment of modern and reworked nile sediment on the nile delta plain sediment is primarily retained in an extremely dense network of irrigation and drain channels and also in wetlands in the northern delta the increased number of artificial canals more than 10 000 km of waterway is a response to egypt s drive to augment its much needed agricultural production by perennial irrigation the drastically reduced amount of sediment now reaching the sea discharged primarily from lagoon outlets and several canal mouths is removed by strong easterly directed coastal and innermost shelf currents the nile delta is an extreme example of a depocenter which has been completely altered by man from an active prograding delta to a locally eroding coastal plain

late weichselian environmental history in southeastern sweden during the deglaciation of the scandinavian ice sheet abstract late weichselian litho bio and chronostratigraphy 14 c and varves in southeastern sweden provide a detailed picture of the deglaciation pattern and dynamics shore displacement late glacial sedimentation and history of the landscape vegetation and climate two plausible glacial models were tested against lithologic chronologic and climatic data permafrost at and outside the ice margin and topographic conditions beneath the ice apparently caused inward spread of frozen glacier bed conditions this led to a buildup of a large zone of debris rich basal ice a climatic amelioration about 12 700 yr b p changed the temperature profile in the ice sheet deposition of basal melt out till began at the previously frozen glacier bed and a rapid recession of the clean ice set in thin exposed debris rich basal ice which was separated from the active ice margin about 150 yr later in this zone of stagnant ice there followed a 200 300 yr period marked by subglacial and supraglacial melt out and resedimentation forming a large hummocky transverse moraine the mild climate favored rapid plant immigration and a park tundra was established the gradual closing of the landscape was interrupted by a 100 to 150 yr period of tundra vegetation and a cool dry climate with local vegetational differences caused by differences in soil moisture about 12 000 yr b p a second climatic amelioration set in and during the next 1000 yr a birch and pine woodland gradually developed soils stabilized and empetrum heaths became abundant as the climate gradually deteriorated at the end of this period by 11 000 yr b p the area had become a tundra again with scattered birch stands dominated by herbs such as artemisia chenopodiaceae grasses and sedges some 500 yr later a birch pine woodland again succeeded and within about 500 yr the vegetation changed to a rather closed woodland as the climate ameliorated further however the time lag between climatic and vegetation change was considerable

tripod measured residual currents and sediment flux impacts on the silting of the deepwater navigation channel in the changjiang estuary four bottom mounted instrument equipped tripods were deployed at two sections spanning the region characterized by severe sedimentation rates in the deepwater navigation channel dnc along the north passage of changjiang estuary in order to observe currents near bed suspended sediment and salinity seaward residual currents predominated in the up estuary section in contrast a classical two layered estuarine circulation pattern occurred in the down estuary section flow moved seaward in the upper layer and a heavier inflow driven by the salinity gradient moved landward in the lower layer the near bed residual currents in the up estuary section and the down estuary section acted in opposing directions which implies that the region is a convergence zone of near bed residual currents that trap sediment at the bottom the maximum salinity gradient at the maximum flood current indicates the presence of a strong front that induces sediment trapping and associated near bottom convergence of sediment which explains the high sedimentation rates in this section of the estuary

late and postglacial sea level changes in the kattegat the consequences to different coastal aquifers on the islands zealand and anholt abstract fluctuations in sea level influence the condition of coastal groundwater aquifers in this paper the palaeo hydrology of anholt and part of zealand and its dependence on the sea level history of kattegat will be analyzed the late and postglacial sea level changes in kattegat are outlined and the consequences analyzed for late and postglacial ice movement and for two different coastal aquifers a simple unconfined aquifer at the island anholt and a complex confined limestone aquifers around roskilde on zealand data are presented which provide a description of how sea level changes have influenced and formed the island anholt this geological history can be used to provide information on the development of the salt fresh groundwater interface under a sand island the center of anholt was covered by the sea at 6 ka and has now an ideal ghyben herzberg freshwater lens this means that the present equilibrium between the saltwater and freshwater has been established in less than 6000 years limestone aquifers on zealand show no ideal ghyben herzberg freshwater lens detailed 3 d mapping of a study area around roskilde and isefjord has revealed how low sea levels around 50 30 ka cause development of karst structures and deep erosion channels in the limestone later filled with high permeable sand and gravel these channels drain the groundwater to subsea springs working as natural pumps resulting in a freshwater lens much thinner than the equilibrium