errors in bathymetric retrievals using linear dispersion in 3 d fft analysis of marine radar ocean wave imagery the phenomenon of ocean wave shoaling and the associated reduction of ocean wave phase speed with decreased water depth provides useful information for inferring water depth d bathymetry in coastal environments one strategy for relating d to phase speed c and wave vector k of long wavelength ocean waves involves using the one dimensional 1 d linear gravity wave dispersion relationship c sup 2 g tanh kd k in principle this approach has limitations because the approach is based on a wkb approximation so it cannot be applied when d varies appreciably over the wavelength of a shoaling wave also the approach is restricted to waves that have small wave height the author uses a set of marine radar image sequences and applies this linear approximation using a 3 d fft analysis of 88 sets of image sequences spaced half an hour apart the author inverts the dispersion relation to solve for d depths between 3 6 and 5 8 m were tested for root mean square rms wave heights offshore between 8 and 3 m the author shows that for low to moderate wave heights the approach does generally retrieve the correct depth in water depths of 5 m and greater for moderate wave rms heights however an increase in the rms wave height from 1 m to 3 5 m produced a much poorer depth estimate proving the need for an application of a nonlinear wave model to the problem the errors also increase with shallower depths as expected as the error dependence on depth and wave height is determined

practical estimation of compression behaviour of dredged clays with three physical parameters understanding the compression behaviour of dredged clays is essential for their effective use with drainage measuring consolidation parameters of dredged clays at high initial water contents is a time consuming and tough work the research team has accumulated the database of 110 one dimensional incremental load consolidation tests for dredged clays based on this database this study proposes a simple method of determining virgin compression of dredged clays using three physical parameters which can be easily measured the compression curves of dredged clays can be divided into the pre yield and the post yield zones basic equations are suggested for describing the compression behaviour of the two zones the associated parameters are correlated with the initial void ratio and the void ratio at liquid limit the predicted compression curves are compared with the measured ones with the accumulated database and the independent data available from literature the error of the void ratios predicted is found to vary within 10 compared with the measured ones in engineering practice the work in this study can be applied instead of the time consuming and tough experiments to simply estimate the compression behaviour of dredged clays

use of nautical radar as a wave monitoring instrument abstract common marine x band radars can be used as a sensor to survey ocean wave fields the wave field images provided by the radars are sampled and analysed by a wave monitoring system called wamos ii developed by the german research institute gkss this measuring system can be mounted on a ship on offshore stations or at coastal locations the measurement is based on the backscatter of microwaves from the ocean surface which is visible as sea clutter on the radar screen from this observable sea clutter a numerical analysis is carried out the unambiguous directional wave spectrum the surface currents and sea state parameters such as wave periods wave lengths and wave directions can be derived to provide absolute wave heights the response of the nautical radar must be calibrated similar to the wave height estimations for synthetic aperture radars the so called signal to noise ratio leads to the determination of the significant wave height hs in this paper wamos ii results are compared with directional buoy data to show the capabilities of nautical microwave radars for sea state measurements

hydraulic conductivity of naturally sedimented and reconstituted clays interpreted from consolidation tests abstract the hydraulic conductivity of naturally sedimented and reconstituted clays is often interpreted using the settlement time curves measured from consolidation tests understanding the accuracy of the interpreted hydraulic conductivity is essential in geological and geotechnical engineering to the best knowledge of the authors such a work has been little reported up to now this study aims at investigating the errors of the interpreted hydraulic conductivity via the comparison between the interpreted values and the measurements the ratios of the interpreted values of hydraulic conductivity over the measurements are examined based on the data from the consolidation hydraulic conductivity tests performed in this study in conjunction with those published by our research team the investigated clays cover wide geological origins and depositional states the geological origins and depositional states are linked with the errors of the interpreted hydraulic conductivity for understanding the roles of these factors in the uncertainty of the interpreted hydraulic conductivity the causes responsible for the discrepancy in hydraulic conductivity between the interpretations and the measurements are identified the probability distribution of the errors of the interpreted hydraulic conductivity is also investigated

preconsolidation pressure of champlain clays part ii laboratory determination a series of conventional and special consolidation tests was carried out on clay samples from 11 sites in the champlain sea basin the results show that for a given clay at a given depth there is a unique preconsolidation pressure strain rate relationship independent of the tests carried out and that the relationships obtained in different champlain clays can be normalized correlations between the preconsolidation pressure values obtained from the different special consolidation tests and the conventional test are established and a method of estimating in situ preconsolidation pressure is suggested keywords preconsolidation pressure laboratory testing techniques strain rate

ocean wave dispersion surface measured with airborne ir imaging system image sequences of the ocean have been collected at long range and low grazing angle with an airborne infrared system the images are geographically registered and 3d frequency wavenumber spectra are calculated and shown to have a strong 2d dispersion surface that is characteristic of wind waves and swell wave directions compare well with in situ measurements and their speeds are consistent with the water depth the authors conclude that temporal sequences of ir images acquired from long distance can provide information for extracting surface wave parameters

current measurement technology for near shore waters abstract this paper summarises recent experiences in scawvex and elsewhere in measuring near shore currents together with subsequent techniques of data analyses in situ instrumentation described includes mechanical rotors electromagnetic and adcp acoustic doppler current profiler deployed on sea bed frames in towed mode and mooring lines surface observations from the ocean surface current radar oscr h f radar system are also included deployments are in estuaries along open coasts and in tidal straits all involving strongly tidal regimes around the uk coasts the characteristics including specific capabilities and limitations of each instrument are listed synoptic comparisons are used to illustrate those components such as the depth mean principal tidal constituents which show good agreement and to highlight other components e g vertical profiles of residuals most sensitive to the system adopted a coordinate system suitable for analysing net fluxes in shallow estuary with large tides is described associated aspects which impact on planning current meter deployments are outlined

estimation of the compression behaviour of reconstituted clays abstract the void index is a relative quantity measuring the position of the current void ratio of a clay against the void ratios of the clay at two specific vertical effective stresses i e v 100 kpa and v 1000 kpa based on this concept a simple systematic tool is proposed for estimating the compression behaviour of reconstituted clays over a wide range of stresses and water contents following the practice of geotechnical engineering computation the compression behaviour of clays is idealised as linear segments in the iv lnp or the void index and the mean effective stress space considering the variation in the available data there are three related but independent models for describing the compression behaviour of reconstituted clays the accuracy of estimation increases with the level of available data the proposed estimation is used to simulate the behaviour of a variety of reconstituted clays over a wide range of stresses and water contents with different levels of available data the estimation is evaluated on the basis of these simulations the proposed estimation can take maximum use of available data and provide a simple yet practical tool for calculating the compression behaviour of reconstituted clays and a basic parameter for geotechnical engineering computations the compression index an empirical equation for the initial compression index is also suggested and verified

application of remote sensing video systems to coastline management problems this contribution evaluates the application of coastal video systems to monitoring and management of coastal stability problems on sandy coastlines specifically video derived parameters coastal state indicators or csis are developed which facilitate the measurement of the shoreline evolution erosion accretion and response to storms seasonal cycles and anthropogenic interventions like beach shoreface nourishment and dredging the primary variable which forms the basis for all the csis discussed in this contribution is the shoreline position derived from time averaged video images these waterlines are used to generate secondary products including shoreline contours at a constant pre defined level intertidal beach volumes and momentary shoreline positions which reflect the sand volume in a meter wide section of the intertidal coast video derived coastal state indicators were verified via comparisons with traditional topographical bathymetric surveying techniques and a good agreement was found in all cases csis were computed for three contrasting sandy coastal environments including an unprotected natural beach a protected beach and a spit firstly results are presented which demonstrate the advantages of coastal video systems over and above infrequent traditional topographic bathymetric surveying methods namely the ability of video derived csis to quantify the magnitude accurate location precise timing and rates of change associated with individual extreme events and seasonal variability in the wave climate secondly video derived coastal state indicators were used to monitor two different types of human intervention including beach nourishments and a dredged pit in a navigation channel the video derived datasets of coastal state indicators offered significant improvement to current czm practices facilitating better timing of management interventions as well as more effective monitoring of the spatial impact and longevity of these actions

interface shear box tests for assessing axial pipe soil resistance the clay interface shear resistance is an important parameter for the design of offshore pipelines which slide on the seabed as a result of thermally induced expansion contraction and lateral buckling this paper presents a methodology for characterising the clay interface resistance and quantifying the effect of drainage and consolidation during or in between shearing episodes models for describing the clay interface resistance during planar shearing are presented and compared to test data for a range of drainage conditions from drained to undrained and including the case of episodic consolidation the test data are from two series of interface shear box tests carried out on marine clays the effects of normal stress level in the low stress range overconsolidation and interface roughness are also examined

origine de la preconsolidation des argiles du saguenay quebec the clays of eastern canada and in particular the saint jean vianney clay in the saguenay region have often been described as clays with a preconsolidation due partly to cementation in order to check this assumption the geological history and the geomorphology of the saguenay region have been analyzed further to the evidence of significant erosion available geotechnical data in the form of variations of water content undrained shear strength and preconsolidation pressure have been analyzed to determine the elevation of the original ground surface in the hypothesis of a preconsolidation resulting from deposition and erosion the results of this analysis are in good agreement with the geological and geomorphological data and they suggest that cementation has had a negligible effect on the preconsolidation of the saguenay clays a regional map of preconsolidation pressures is also presented keywords clay preconsolidation geomorphology erosion shear strength journal translation

on compression characteristics of ariake clays j b burland proposed that the void index aids in assessing the compressibility of various sedimentary clays the extensive data on sensitive ariake clays are used in this study to investigate the

shallow water bathymetry derived from an analysis of x band marine radar images of waves image sequences of surface gravity waves are readily produced by standard marine x band radars these image sequences contain a great deal of information regarding wave parameters and their variation over an area by approaching the analysis of such data using image analysis techniques it is possible to map the variations in wave behaviour in a shallow water area wave celerity and direction can be mapped and inversion algorithms based on linear wave theory used to infer the underlying bathymetry knowledge of the period of the waves is necessary for the analysis and this can also be calculated from the radar data although there is some discrepancy between the figures derived from radar data and from an offshore s4dw instrument these discrepancies are investigated and the results presented three days of data from the holderness ii deployment during 1995 have been analysed and estimates of the bathymetry produced the calculated depths show a mean water level comparable to that read off an admiralty chart for the area and a tidal signal is also clearly superimposed on the data giving confidence in the water depths derived using this technique

application of the linear dispersion relation with respect to depth inversion and remotely sensed imagery remote sensing methods have been developed to estimate bathymetry through the use of a theoretical relationship between wave speed and water depth known as the linear finite depth dispersion equation for surface gravity waves the authors describe a validation effort encompassing several hundred observations of wavenumber magnitude for sea swell frequencies obtained over a wide variety of conditions to investigate possible error sources resulting from the practical application of this relationship these wavenumber estimates were computed from pressure gauge signals using signal processing algorithms that can be equivalently applied to measurements of wave phase as imaged through remote sensors the major goal was to determine the accuracy of the dispersion relation while attempting to minimize errors associated with sensor positioning tidal variations and doppler shifts due to mean currents for water depths outside the surf zone the linear dispersion relation is highly accurate with average depth estimation errors on the order of 3 9 of the observed depth in shallower regions nominally less than 4 m for this field site where wave breaking is evident and nonlinear shoaling effects are more pronounced normalized depth errors of over 50 were commonly observed with most predictions being deeper than observations strong correlation between these bias errors and measured wave heights emphasizes the importance of accounting for wave amplitude in the calculation of shallow water phase speeds for depth estimation a simple depth correction is provided to allow for bathymetry estimation within the surf zone

western extension of the iberian european plate boundary during the early cenozoic pyrenean convergence a new model abstract a dense seismic net work allows of drawing the western prolongation of the northern boundary of the iberian plate this early cenozoic deformed boundary is disrupted by two prominent nw se transform faults a kinematic reconstruction with a nw late cretaceous lower eocene motion of the iberian plate is proposed the azores biscay rise is interpreted as a short lived subduction zone whereas king s trough could be a transform fault

bathymetry estimation from single frame images of nearshore waves existing methods for determining bathymetry from remotely sensed images of nearshore waves exploit only information on the magnitude of wavenumber k 2pi l ignoring spatial changes in wave direction thetas that can provide information about bathymetry gradients these methods also require wave period information so they can only be used when time series imagery is available we present an algorithm where changes in direction of refracting waves are used to determine underlying bathymetry gradients based on the irrotationality of wavenumber condition depth dependences are explicitly introduced through the linear dispersion relationship the final form of the model is independent of wave period so that all necessary input measurements can be derived from a single aerial snapshot taken from a plane unmanned aerial vehicle or satellite three different methods were tested for extracting wavenumber and angle from images i e two based on spatial gradients of wave phase and one based on integrated travel times between sample locations a tomographic approach synthetic testing using monochromatic and bichromatic waves with and without noise showed that while all three methods work well under ideal wave conditions gradient methods were overly sensitive to data imperfections the tomographic approach yielded robust wave measurements and provided confidence limits to objectively identify unusable areas further tests of this method using monochromatic waves on three synthetic bathymetries of increasing complexity showed a mean bathymetry bias of 0 01 m and a mean rms error of 0 17 m while not always applicable the model provides an alternative form of bathymetry estimation when celerity information is not available

high resolution bathymetry estimates via x band marine radar 2 effects of currents at tidal inlets abstract in this second of two papers the high spatial resolution cbathy depth estimate algorithm is extended to account for the existence of currents aligned with the wave directions the extended algorithm is applied using x band radar image time series collected at two hydrodynamically and morphologically complex environments an ebb tidal shoal new river inlet nc and an estuarine river mouth columbia river or wa even without accounting for doppler effects the depth estimates are capable of discerning the location of channels and shoals over domain sizes of 4 km2 at the ebb tidal shoal and 25 km2 at the estuary mouth however the tidal currents at these sites are shown to strongly modulate depth estimate accuracy when only the intrinsic linear wave dispersion relation neglecting doppler shift effects is inverted low pass filtering of the depth estimate time series via an uncertainty weighted tidal average explicitly attenuates the error oscillations beyond that of the uncertainty weighted kalman filter this post hoc method of compensating for the unmodeled doppler term achieves 0 35 m rmse and 0 02 m shallow bias at the shallow ebb tidal shoal as compared to a concurrent sounding survey but substantial bias remains at the estuary mouth due to asymmetric doppler effects for large following or opposing currents at large relative water depths simultaneous estimation of depth and currents via inversion of the dispersion relation including doppler shifts is more effective at the deep estuary mouth where currents more strongly affect the incident wave field in the estuary channel with locations as deep as 27 m kalman filtered depths achieve 0 92 m rmse and 0 38 m deep bias as compared to a concurrent sounding survey 95 of estimates are within 10 of those surveyed independent of the doppler compensation technique kalman filtered depths can be used to more tightly constrain high resolution current velocity estimates

compression behaviour of reconstituted soils at high initial water contents oedometer tests starting from a very small effective vertical stress of 0 5 kpa were performed on three reconstituted clays with different liquid limits the soils were prepared at various initial water contents ranging from 0 7 to 2 0 times their corresponding liquid limits it is observed that the e log v compression curves show an inverse s shape due to suction pressure resisting deformation similar to that of soft natural clays caused by consolidation yield stress the suction pressure s of the reconstituted clays can be correlated with the ratio of initial void ratio to void ratio at liquid limit e0 el the suction pressure curve defined by a unique relationship between suction pressure s and the normalised void ratio at suction pressure es el is also proposed to distinguish between the pre suction and the post suction states in addition burland s concept of the intrinsic compression line is adopted for correlating the compression curves of various reconstituted clays at high initia

accuracy of bathymetric assessment by locally analyzing radar ocean wave imagery february 2008 in this paper the error source in assessing the bathymetry by a recently presented method the dispersive surface classificator is discussed this method is based on the analysis of x band radar image sequences of sea surface waves to determine spatial maps of hydrographic parameters to implement this objective the radar deduced bathymetry is validating by multibeam echosounder data the accuracy of the method is high in homogeneous areas and reduced at the areas of bathymetric gradient and lower but comparable with multibeam echosounder data under the assumption of the spatial resolution the identification of systematic correlation of the absolute value of the error with the slope is significant and insignificant with the actual depth itself the spatial correlation of the error illustrates that the direction of the wave field influences the neighboring grid cell in the same direction the application of the method during crucial weather conditions is the main advantage and permits the accurate operational nearshore monitoring for several applications

proprietes caracteristiques des argiles de l est du canada the compilation of numerous geotechnical data has allowed the definition of the main physical mechanical and hydraulic properties of marine and lacustrine clays of eastern canada as well as the establishment of correlations between some of these properties the possible uses of these correlations are described this study shows that the clays of eastern canada exhibit a behaviour similar to that of other clays but that they are characterized by a higher degree of structuration keywords physical properties mechanical properties hydraulic properties clays canada correlations journal translation

wind retrieval from shipborne nautical x band radar data in this paper we study the retrieval of wind information from nautical x band radar data in contrast to previous studies where data from stationary research platforms were used this study focuses on data from a moving platform encountering a larger variety of conditions than a platform at a fixed location compared to traditional in situ sensors wind data derived from nautical radar images are much less susceptible to air flow distortion by the platform since the images cover a large area around the ship images collected with a standard nautical hh polarized x band radar operating at grazing incidence exhibit a single intensity peak in upwind direction the wind retrieval method developed here uses a harmonic function that is least squares fitted to the radar backscatter intensity as a function of antenna look direction the upwind direction is given by the direction that corresponds to the peak of the fitted function an empirical model function is derived to retrieve the wind speed from the average radar backscatter intensity contrary to wind retrieval methods that have been proposed before this approach is well suited for data acquired from a moving platform as it functions well even if the radar field of view is partially shadowed and does not require ship motion correction here we focus on data that were collected during two storms using the first storm to derive and the second to test the empirical model functions the method is validated using measurements from two ship based anemometers

on the volumetric strain time curve patterns of dredged clays during primary consolidation thirteen one dimensional consolidation tests with step loading were performed on dredged clays reconstituted at different initial water contents both vertical deformation and pore pressure were measured during primary consolidation which refers to the time dependent compression process associated with the dissipation of pore pressure the pore pressure changes were investigated by considering the maximum and the residual values the development of compression during pore pressure dissipation was analysed to identify the change patterns in volumetric strain time curves three types of change patterns were found during the primary consolidation and the remoulded yield stress was found to be the key factor in classifying the change patterns the inflexion point is absent for types 1 and 2 indicating that the end of primary consolidation cannot be determined by the commonly used taylor and casagrande methods type 3 shows an inverse s shape suggesting that the end of primary consolidation determined ba

determination of bathymetric and current maps by the method disc based on the analysis of nautical x band radar image sequences of the sea surface november 2007 morphodynamic processes in coastal areas are affected by tidal currents and sea state the continuous observation of near coastal areas is important in order to monitor dangerous current regime and bathymetry changes therefore there is an urgent need for remote sensing techniques delivering the important hydrographic parameters with a high spatial resolution dispersive surface classificator disc is a newly developed method based on the analysis of nautical x band radar image sequences of sea surface waves to determine spatial maps of hydrographic parameters e g spatial maps of the bathymetry and the ocean current field the method disc is described and is illustrated by the presentation of results based on a dataset acquired with a ground based x band radar installation mounted on the island of sylt in the german bight the calculated bathymetric maps are verified by multibeam echo sounder observations

correlations between index tests and the properties of remoulded clays correlations have been developed which relate the compressibility undrained shear strength and permeability of remoulded clays to their atterberg limits and activity the relationships can be used to model a hydraulic fill such as fine grained dredged material or mine tailings prior to deposition they can also be used to estimate the engineering properties of normally consolidated natural clay such as marine sediments the correlations cover a wide range of plasticity index and liquidity index for a wide variety of clays it was found that the activity plays a major role in the compressibility and undrained shear strength and is thus also related to the sensitivity of clays the activity apparently does not affect the permeability but other factors remain to be investigated because compressibility undrained shear strength and permeability are interrelated it can be concluded that if one is known then the other two can be derived hence these three engineering properties are seen as different

the role of combined laser scanning and video techniques in monitoring wave by wave swash zone processes abstract simulating swash zone morphodynamics remains one of the major weaknesses of beach evolution models one of the reasons is the limited availability of data on morphological changes at the temporal scales of individual swash events this paper sets out to present a new hybrid system consisting of 2d 3d laser scanners and several video cameras which was designed to monitor swash zone topographic change on a wave by wave basis a methodology is proposed consisting of sensor calibration and several data processing steps allowing a fusion of different sensors such an approach can improve the performance of several field laboratory optical technique applications for nearshore hydro and morpho dynamic measurements digital elevation models from a 3d scanner were used in the extrinsic camera calibration procedure and reduced the geo rectification errors from 0 035 m dz 10 cm the sediment transport direction and intensity of the monitored swash events was relatively balanced and sediment transport rates ranged between 3 5 kg m 1 s 1 q t 3 5 kg m 1 s 1 extreme transport swash events became rarer as the morphology was reaching equilibrium

the general and congruent effects of structure in natural soils and weak rocks the engineering properties of naturally occurring sedimentary and residual deposits which are usually treated in geotechnical engineering as soils are reviewed and it is shown that usually they have characteristics due to bonded structure which are similar to those of porous weak rock while this structure can arise from many causes its effects follow a simple general pattern that involves stiff behaviour followed by yield this yield can be described in a similar way to that occurring due to overconsolidation although it is a separate phenomenon the effects of structure are as important in determining engineering behaviour as are the effects of initial porosity and stress history which are the basic concepts of soil mechanics as it can be described in a general way it is concluded that structure and its effects should be treated as a further basic concept of equal importance l article passe en revue les proprietes des depots sedimentaires et residuels naturels qui sont nor malement traites comm

on the hydro mechanical behaviour of remoulded and natural opalinus clay shale the geo energy sector makes use of advanced technologies such as shale gas extraction co2 sequestration and nuclear waste geological disposal that rely on the exploitation of shale formations due to the great depths involved in these applications and the difficulties in retrieving intact samples remoulded shale specimens are often adopted for hydro mechanical testing remoulded and intact shales may substantially differ in their hydro mechanical behaviour due to the particular structure of the natural material which is the result of diagenesis and burial history this paper presents an experimental campaign aimed at i characterizing the role of diagenesis and depth for opalinus clay shale and their impact on the hydro mechanical behaviour of the material and ii understanding how representative the behaviour of the remoulded material is with respect to that of the natural shale in this paper the hydro mechanical behaviour of remoulded and intact specimens from the opalinus clay shale formation is investigated by means of a comprehensive oedometric testing campaign the effects of depth and diagenesis on the material behaviour are analysed by testing intact specimens that come from two different sites and depths of the considered shale formation the results highlight a considerably greater stiffness for the natural opalinus clay with respect to the remoulded specimens when the same vertical effective stress is considered together with a significantly lower porosity for the former which is shown to be the result of diagenetic processes rather than solely mechanical compaction a lower swelling sensitivity is also manifested by the natural material with respect to the remoulded specimens as a result of the formation of bonding on the other hand the diagenetic processes do not seem to have a strong impact on the permeability of the material finally creep effects are reduced when diagenesis occurs while they become more relevant when the material is disturbed or remoulded the obtained results provide significant insight into the roles of depth diagenesis and structural disturbance on the hydro mechanical behaviour of the opalinus clay shale

behaviour of a sensitive marine sediment microstructural investigation the aim of this study is to characterise along various stress paths the microstructural evolution of a deep water marine sediment from the gulf of guinea gog results obtained at the macroscopic level have shown that the phenomenological behaviour of the gog sediment is explained by the properties of remoulded samples given by the isotropic and critical state lines and by the properties of the intact samples given by the damage evolution of the inter aggregate bonds microstructural investigations conducted by mercury intrusion porosimetry and scanning electron microscopy demonstrate that the volumetric strains measured at the macroscopic level come from inter aggregate pore variations associated with the degrading of the inter aggregate bonds the mechanism responsible for reorienting the particles appears to apply in the case of the remoulded sediment as for the natural sediment it is first necessary to increase the isotropic consolidation stress towards higher values in order to break the bonds between the aggregates before it becomes possible to activate the particle reorientation mechanism and thus approach the remoulded behaviour

neotectonics of coastal jeffara southern tunisia state of the art abstract helped by the studies and results of previous researchers we herein study the neotectonic of the coastal jeffara with the input of numerous 2d reflection seismic profiles onshore combined with digital elevation model analyses issued from srtm and field works acquired and available data were then integrated within a gis geodatabase where jerba zarzis and jorf appear to be part of a n s pull apart basin within a nw se transtensive right lateral major fault zone our structural geologic and geomorphologic analyses confirm and prove the presence of nnw sse right lateral en echelon tension gashes nw se aligned salt diapirs numerous active folds offsets en echelon folds and so on they are associated with this major right lateral nw se transtensive major coastal jeffara fault zone that affect the holocene and the villafranchian deposits we therefore confirm herein a new structural geodynamic jeffara model due to the post lower cretaceous northward migration of northern african to the eurasian plates this nw se transtensive fault zone is interpreted as a part of the southern branch of the eastward sahel block extrusion toward the free mediterranean sea boundary therefore this geodynamic movement may explain the presence offshore of small elongated nw se n s and ne sw transtensive basins and grabens with petroleum interest to conclude at the regional scale the structural geomorphologic approach combined with both field work and 2d reflection seismic profile analyses appear to be an excellent tool to prove and confirm the nw se right lateral transtensive extrusion fault zone of the coastal jeffara

estimation of wave phase speed and nearshore bathymetry from video imagery a new remote sensing technique based on video image processing has been developed for the estimation of nearshore bathymetry the shoreward propagation of waves is measured using pixel intensity time series collected at a cross shore array of locations using remotely operated video cameras the incident band is identified and the cross spectral matrix is calculated for this band the cross shore component of wavenumber is found as the gradient in phase of the first complex empirical orthogonal function of this matrix water depth is then inferred from linear wave theory s dispersion relationship full bathymetry maps may be measured by collecting data in a large array composed of both cross shore and longshore lines data are collected hourly throughout the day and a stable daily estimate of bathymetry is calculated from the median of the hourly estimates the technique was tested using 30 days of hourly data collected at the sandyduck experiment in duck north carolina in october 1997 errors calculated as the difference between estimated depth and ground truth data show a mean bias of 35 cm rms error 91 cm expressed as a fraction of the true water depth the mean percent error was 13 rms error 34 excluding the region of known wave nonlinearities over the bar crest the accuracy of the technique improved and the mean rms error was 20 cm 75 cm additionally under low amplitude swells wave height h 1 m the performance of the technique across the entire profile improved to 6 29 of the true water depth with a mean rms error of 12 cm 71 cm

disturbance of the bothkennar clay prior to laboratory testing interpretation of laboratory tests in the characterization study of the bothkennar clay required an assessment to be made of the effects of disturbance prior to testing disturbance is shown to have occurred as a result of tube sampling sample transport and specimen preparation the effects of disturbance in the clay are to reduce the mean effective stress in the sample and shrink the initial bounding surface the consequences of these changes are illustrated for the case of unconsoli dated undrained triaxial tests undrained triaxial compression and extension tests after reconsolidation to in situ stress and oedometer tests reduction in peak strength stiffness yield stress and post yield compressibility are shown to be a consequence of disturbance the evaluation of sample quality on the basis of strains during reconsolidation is examined l interpretation des essais de laboratoire dans l etude de caracterisation de l argile de bothkennar necessita l evaluation des effets du remaniement avant essai

an approach to determining nearshore bathymetry using remotely sensed ocean surface dynamics this paper describes a spatially one dimensional algorithm developed to estimate water depths from remotely sensed information of the water surface using extended boussinesq equations local phase speed estimates are obtained using a least squares approach from spatial profiles of surface elevation orbital velocity lagged in time inversion algorithms have been developed for both linearized and fully nonlinear boussinesq equations to calculate the depth in all cases synthetic input data are generated using a fully nonlinear time dependent boussinesq model wave conditions including monochromatic and irregular waves are simulated in the model mean flow effects are included in the inversion algorithm to account for currents for monochromatic wave conditions there is good agreement between the actual and estimated depth and particle kinematics the fully nonlinear method as compared to the linearized inversion improves the depth prediction by 10 for the test case considered irregular wave conditions were simulated using time series generated for a tma spectrum with varying values of the peak enhancement factor the error in the inverted depths increased in the deeper part of the bathymetry as the wave train become more broad banded for monochromatic waves in the presence of weak currents the modified algorithm including mean flow effects is seen to improve the inverted depth by 10 over the original formulation

workability compressibility and hydraulic conductivity of zeolite amended clayey soil calcium bentonite backfills for slurry trench cutoff walls soil bentonite slurry trench cutoff walls using backfill consisting of on site sandy soil and na bentonite are extensively used as engineering barriers for the purpose of achieving relatively low hydraulic conductivity the amendments such as zeolite to backfill are considered to improve the contaminant sorptive capacity at some sites local clayey soil ca bentonite and natural zeolite may be available for an alternate backfill however studies on the workability in terms of slump compressibility and hydraulic conductivity of such zeolite amended clayey soil ca bentonite backfills for the cutoff walls are very limited this paper presents a comprehensive laboratory investigation on the workability compressibility and hydraulic conductivity of fine grained zeolite amended clayey soil ca bentonite backfills using several series of slump and oedometer tests kaolin is used as the model clayey soil and it is amended with various amounts of ca bentonite 7 8 8 4 and zeolite 10 40 to prepare zeolite amended kaolin bentonite backfills the test results are compared with previous studies on zeolite amended sandy soil na bentonite backfills as well as compacted zeolite bentonite liners to assess the effects of zeolite content and zeolite grain size on the compressibility and hydraulic conductivity the results indicate that the water content required to achieve a target slump 100 150 mm for the backfills increases with increasing zeolite content liquid limit can be a useful index for a preliminary estimation of the water content required to achieve the target slump for the backfills presented in this study and zeolite amended sandy soil na bentonite backfills reported in previous studies the results reveal that the hydraulic conductivity of the zeolite amended clayey soil ca bentonite backfills with void ratio ranging from 0 54 to 1 45 is generally lower than the typical regulatory limit 10 9 m s the addition of fine grained zeolite has insignificant influence on the compressibility and hydraulic conductivity of both clayey soil ca bentonite and sandy soil na bentonite backfills a proposed empirical method based on the framework of kozeny carman equation can predict the hydraulic conductivity of zeolite amended clayey soil ca bentonite backfills values within the range of 1 3 to 3 times those calculated from the oedometer tests the proposed method is also shown to estimate the hydraulic conductivity of the compacted zeolite bentonite liners from previous studies with reasonable accuracy additional research is recommended to evaluate the proposed zeolite amended backfill using tap water and also by direct measurement of hydraulic conductivity using falling head or constant head testing method