the penetration of kuroshio water into the sea of japan abstract the nonlinear leakage of kuroshio water via the tsushima strait into the sea of japan is examined using a reduced gravity analytical model the flow in our conceptual model results from the zonal sea level difference between the pacific ocean and the sea of japan the landmasses separating the pacific from the adjacent sea of japan are represented by thin walls and the tsushima strait whose width is larger than the rossby radius is represented by a gap the gap is initially closed and the problem is treated as an adjustment process resulting from an abrupt opening of the gap steady analytical solutions for the final state associated with the adjustment are constructed using the integrated momentum equation on a plane conservation of energy and potential vorticity also a perturbation expansion in l f0 the ratio of the change in the coriolis parameter as one moves from the gap to the boundary current separation latitude to the coriolis parameter at the center of the gap is used

macroscale wide nutrient inversions in the subsurface layer of the japan sea during summer the nutrient concentrations at depths of 0 200 m in the southern area of the japan sea were investigated at 97 stations during six cruises between june and october in 2013 and 2014 the nutrient concentrations at the surface were depleted to less than 0 1 m except for silicates which remained at 0 8 5 m and increased below the nutricline at depths of 20 125 m the vertical profiles of nitrate silicate and or phosphate concentrations between 131 30 e 139 40 e and 35 50 n 40 40 n showed a peak in the subsurface layer at 40 71 and 6 stations respectively and nutrient inversions occurred at macroscale widths the subsurface nutrient maximum occurred at depths of 20 150 m in waters at temperatures of 15 16 c and potential densities of 25 3 25 5 on average the depths of the subsurface nutrient maximum were generally associated with a salinity maximum originating in the bottom water of the shallow tsushima strait the nutrient inversions were disturbed by phytoplankton consumption as indicated by the presence of the subsurface chlorophyll maximum at the same depth or below the salinity maximum at stations without nutrient inversions therefore it was inferred that remineralization of nutrients near the bottom from the east china sea to the tsushima strait and horizontal advection by the tsushima warm current below the euphotic layer induced macroscale subsurface nutrient inversions in the southern japan sea

ground penetrating radar and its use in sedimentology principles problems and progress abstract ground penetrating radar gpr also referred to as ground probing radar surface penetrating radar subsurface radar georadar or impulse radar is a noninvasive geophysical technique that detects electrical discontinuities in the shallow subsurface

a linear stratified ocean model of the coastal undercurrent the linear stratified ocean model of mccreary 1981 is used to study the wind driven response of the ocean near an eastern coast the model can be regarded as an extension of the inviscid models of lighthill 1969 and of gill clarke 1974 that allows the vertical diffusion of heat and momentum into the deep ocean solutions are still found as expansions of vertical normal modes vertical mixing affects each mode as a linear drag with a drag coefficient that increases rapidly with mode number n a zonally uniform band of steady equatorward winds forces the ocean and the resulting flow field has many features in common with observations at eastern boundaries there is a surface equatorward jet and a poleward coastal undercurrent confined within 10 20 km of the coast both currents extend well poleward of the wind band upwelling does not reach great depths but occurs only above the core of the undercurrent weak downwelling occurs at greater depths there is offshore ekman drift in the surface mixed layer and return flow at a depth slightly above the core of the undercurrent the baroclinic alongshore pressure gradient field and the vertical mixing of heat and momentum are essential elements of the model dynamics but the beta and horizontal mixing are not low order vertical modes n 6 tend toward a two dimensional balance they generate the transverse circulation pattern associated with coastal ekman pumping

numerical paleoceanographic study of the early jurassic transcontinental laurasian seaway the forces governing marine circulation of a meridional transcontinental seaway is explored with the princeton ocean model the jurassic laurasian seaway which connected the low latitude tethys ocean with the arctic sea is modeled quantitatively the global ocean is found to have a profound influence on seaway dynamics a north south density difference and hence sea level difference of the global ocean was probably the main factor in forcing the seaway flow when the tethys waters were the denser water the net seaway flow was southward and conversely it was northward for denser arctic waters marine bioprovincial boundaries and sediment data indicate that the seaway probably was dominated by boreal faunal groups and reduced salinities several times in the jurassic the model results suggest that this can be explained by southward flowing seaway currents which may have been related to an oceanic thermohaline circulation where no northern high latitude deep convection occurred

transition of the tsushima warm current path observed over toyama trough japan abstractmooring ctd and adcp observations were made in 2012 in and around the toyama trough tt cutting across a continental shelf along the japanese coast of the japan sea between noto peninsula np and sado island si to investigate spatiotemporal characteristics of path transition of the coastal branch of the tsushima warm current cbtwc around si downstream of the tt boundary a wavelike alongshore current perturbation accompanied by sea level rise was observed this perturbation occurred after the seasonal amplification of the cbtwc around the np on the upstream boundary of the tt this process was delineated by the results of numerical experiments performed with a two layer model using idealized topography the model showed that a current path of the cbtwc shifted from alongshore mode to offshore mode bridged over the tt in association with the lee eddy development behind the np toward the si over the tt this lee eddy is generated by positive vorticity induced over topographic discontinui

effect of the change of bottom depth on the penetration of kuroshio water onto the east china sea shelf 1 a theoretical problem of the penetration of a western boundary current driven by a cross stream sea level difference onto a shallow basin to the west of the current is put forth to account for the penetration of the kuroshio onto the east china sea ecs shelf and formation of the tsushima warm current different from previous studies this study assumes that the change of bottom depth is the primary factor determining the penetration for a given depth of the shallow basin the penetration depends on two external parameters speed of the western boundary current v0 and surface elevation of the current at the edge of the shallow basin z0 two penetration modes emerge depending on the magnitude of the inertia of penetration for sufficiently large inertia which is favored by large z0 and hindered by large v0 penetration occurs in the form of a free jet mode j otherwise it is in the form of a coastal current mode c volume transport of the penetration is maximized in mode j in general volume transport width and speed of the penetrating current increase with z0 although the latter two are slightly more dependent on v0 in mode c the model considered in this study predicts that the penetration of the kuroshio onto the ecs shelf is of mode j as indicated by observations the volume transport of the penetration is somewhat overestimated possibly because bottom friction is ignored in this model although this model is highly idealized it allows one to gain insight into the behavior of the kuroshio penetrating onto the shallow ecs shelf

soil containing rock fragments effects on infiltration abstract infiltration is a very complex process rock fragments affect infiltration by their presence in the soil matrix and on the soil surface procedures for quantifying soil and surface rock fragments are reviewed within the soil the physical properties and hydraulic properties that affect infiltration are shown to be influenced by rock fragments physical properties discussed are bulk density porosity and water content hydraulic properties that affect infiltration are water retention saturated conductivity and unsaturated conductivity rock fragments on the soil surface have been reported to both increase or decrease infiltration rates and amounts

medalus soil erosion models for global change abstract two novel soil erosion models have been developed within the medalus projects their principal innovation lies in the explicit treatment of long term interactions with the vegetation and soil with implications for the way in which the surface flow and infiltration are described and distributed areally the models are primarily targeted on and validated against mediterranean landscapes for uncultivated conditions but the conceptual principles have wider application both models contain four inter related submodels for the atmosphere vegetation soil and surface subsystems for a series of points down the length of a hillslope flow strip or catena in the medalus model processes are represented in detail and the model is designed to simulate outputs of water and sediment from the single catena and the changes in this catena over time a simplified version of the catena model is now being incorporated into the medrush model in which subcatchments of 1 20 km 2 each represented by a family of catenas are combined using water and sediment routing algorithms to provide forecasts for catchments of up to 5000 km 2 the paper emphasises three novel aspects of the models first the long term interactions and their scope for forecasting erosional soil degradation second the way in which microtopography is treated within the models and third the nesting of catenas and subcatchments within large catchments in medrush

application of field geophysics in geomorphology advances and limitations exemplified by case studies abstract during the last decade the use of geophysical techniques has become popular in many geomorphological studies however the correct handling of geophysical instruments and the subsequent processing of the data they yield are difficult tasks furthermore the description and interpretation of geomorphological settings to which they apply can significantly influence the data gathering and subsequent modelling procedure e g achieving a maximum depth of 30 m requires a certain profile length and geophone spacing or a particular frequency of antenna for more than three decades geophysical techniques have been successfully applied for example in permafrost studies however in many cases complex or more heterogeneous subsurface structures could not be adequately interpreted due to limited computer facilities and time consuming calculations as a result of recent technical improvements geophysical techniques have been applied to a wider spectrum of geomorphological and geological settings this paper aims to present some examples of geomorphological studies that demonstrate the powerful integration of geophysical techniques and highlight some of the limitations of these techniques a focus has been given to the three most frequently used techniques in geomorphology to date namely ground penetrating radar seismic refraction and dc resistivity promising applications are reported for a broad range of landforms and environments such as talus slopes block fields landslides complex valley fill deposits karst and loess covered landforms a qualitative assessment highlights suitable landforms and environments the techniques can help to answer yet unsolved questions in geomorphological research regarding for example sediment thickness and internal structures however based on case studies it can be shown that the use of a single geophysical technique or a single interpretation tool is not recommended for many geomorphological surface and subsurface conditions as this may lead to significant errors in interpretation because of changing physical properties of the subsurface material e g sediment water content in many cases only a combination of two or sometimes even three geophysical methods gives sufficient insight to avoid serious misinterpretation a good practice guide has been framed that provides recommendations to enable the successful application of three important geophysical methods in geomorphology and to help users avoid making serious mistakes

floodplain development based on selective preservation of sediments squamish river british columbia abstract in the conventional model of floodplain sediment accumulation mechanisms of floodplain growth are differentiated into lateral and vertical accretion processes in which within channel deposits are capped by overbank deposits in the high energy gravel based squamish river sediments laid down on bar surfaces are composed of trough and planar crossbedded coarse sands these sequences contrast incongruously with adjacent floodplain deposits which are composed in large part of vertically accreted fine sands atop coarse alluvial gravels using element analysis it is inferred that bar platform sediments are stripped away by chute channels which are subsequently infilled with lower energy deposits from this a model of floodplain growth based on selective preservation of bar platform sands and prefrential preservation of vertically accreted deposits is proposed this mechanism of sediment replacement occurs independent of channel planform type

the internal structure of scrolled floodplain deposits based on ground penetrating radar north thompson river british columbia abstract a study of floodplain deposits using ground penetrating radar gpr was conducted on a confined meander of the north thompson river near kamloops british columbia a survey grid consisting of 20 individual gpr profiles from 200 m to 900 m in length was constructed on a 0 9 km2 section of the floodplain all gpr profiles were collected using a pulse ekkotm iv gpr system with 100 or 200 mhz antennae dependent on the thickness of floodplain sediments floodplain sediments consist of sand and gravel deposits approximately 7 to 14 m thick that overlie silts and clays interpreted to be glaciolacustrine in origin vibracore and auger data obtained at nine locations in the gpr survey grid show that changes from medium sand to gravel do not produce distinct radar reflections in gpr profiles but that the water table may locally produce a distinct high amplitude radar reflection area well log data show that rapid signal attenuation at depth in all gpr profiles coincides with underlying silt and clay sediments gpr profiles were therefore useful in mapping 3 d variability in the thickness of floodplain deposits all gpr profiles were divided into macroscale 150 m2 in 2 d cross section radar facies delineated on the basis of the nature and orientation of reflections relative to surface scroll topography radar stratigraphy suggests that the floodplain is composed of a single complex lateral accretion deposit with periodic channel fills located between surface scroll ridges dip direction profiles normal to surface scroll ridges exhibit mainly inclined stratification is and or preserved ridge and swale ras deposits dipping in the direction of floodplain accretion well developed ras architecture in 200 mhz gpr profiles displays mainly wavy reflections conforming with surface topography and little inclined stratification these reflectors are interpreted to be the result of processes of vertical accretion associated with floodplain formation preserved scroll ridge deposits exhibit asymmetry at depth dipping more steeply in the direction of floodplain accretion profiles of strike direction parallel to surface scroll ridges show either parallel or slightly inclined 1 2 reflections dipping in the downstream direction

effects of soil surface components on soil hydrological behaviour in a dry mediterranean environment southern spain abstract various researchers have studied the spatial pattern of soil surface components such as vegetation rock fragments bare soil litter and surface crusts as a key factor of hydrological behaviour in mediterranean settings with heterogeneous patches of vegetation cover and strong human impact the studies indicate that there is a mosaic of patches that generate run off or infiltrate overland flow distributed in various ways along hillslopes few of these studies however have looked at areas underlain by metamorphic rocks such as phyllites or schists this study analysed the temporal and spatial variability of the effects of soil surface components on hydrological processes in a small dry mediterranean catchment underlain by metamorphic rocks a systematic sampling of multiple sites throughout a hydrological year was carried out we related the hydrological behaviour of soil surface components to 1 their position along the hillslope 2 the distance of existing vegetation tussocks from the line of run off 3 rainfall intensity and 4 the main physical chemical soil properties affecting infiltration processes statistical analysis was used to check the validity of the relationships the results show that soil surface components have highly variable effects in both space and time on soil hydrological behaviour these effects particularly depend on the location along the line of maximum slope and the intensity of preceding rainfall whose interaction defines soil hydrological status these results are similar to those for other mediterranean settings with different lithology in that the succession of contributing patches are hydrologically interconnected along a hillslope the variables used and the grouping of explanatory variables through principal component analyses were found to be suitable for discussing the spatial distribution of soil surface components in the hydrologically dynamic environment of the study area

investigating lake sediments and peat deposits with geophysical methods a case study from a kettle hole at the late palaeolithic site of tyrsted denmark abstract kettle holes are common ice decay features in formerly glacial landscapes like those in southern scandinavia and northern germany here the kettle holes are represented either as dry depressions wetland areas or lakes however the majority of these features are silted and part of the present farmland we investigated a small kettle hole at tyrsted near the township of tyrsted south of horsens denmark with the aim to determine the extension and depth of this feature using geophysical methods a former excavation at tyrsted carried out from the horsens museum in 2017 at a neighboring site revealed late palaeolithic flint of the bromme type and worked reindeer antlers this connection in a late glacial horizon is unique not only in a danish context and it can help to improve and clarify the dating of the bromme culture we used ground penetrating radar gpr electromagnetic induction emi and electrical resistivity tomography ert to estimate the extension of the kettle hole 16 m 25 m shear wave reflection and refraction seismics sh seismics were able to detect the bottom sediment of the former lake at about 5 m depth furthermore a seismic event at about 1 30 m depth is visible which can be associated to the transition between the allerod and younger dryas sediment making the detection of the bromme horizon possible after the non invasive investigation a location for an open excavation has been chosen in a way to groundtruth the geophysical results allowing the direct comparison with the stratigraphy these results allow the archaeologists to identify key excavation areas focused on the investigation of the allerod and younger dryas layers in a way to improve the dating information about the bromme horizon collected so far furthermore geophysical investigations together with excavations will enable the archaeological and palaeoenvironmental research groups to search large scale palaeolandscapes for these very rare but highly important finds

long term coastal upwelling over a continental shelf slope abstract long term coastal upwelling over a continental shelf slope with emphasis on the planetary dispersion of rossby waves is studied with numerical models the ocean is forced by a wind stress with a limited longshore extent the thermocline intersects the shelf slope and the internal radius of deformation is smaller than the width of the shelf slope two case studies with and without the effect are studied lie early stage response within a week or so is similar between the two for an f plane case the whole stage response is accounted for by coastal trapped wave dynamics and only equatorward flow exists over the shelf slope at an advanced stage however inclusion of the effect leads to a significant change in the alongshore flow pattern at the advanced stage due to the westward rossby dispersion of the equatorward flow associated with the first and second coastal trapped mode responses the poleward undercurrent develops in the thermocline layer over the shelf the time for the undercurrent

linkages between surface and deep circulations in the southern japan sea during the last 27 000 years evidence from planktic foraminiferal assemblages and stable isotope records abstract we analyzed planktic foraminiferal assemblages oxygen and carbon isotope records and the presence or absence of laminations to reconstruct the paleoenvironments of the southern japan sea since the last glacial period data were collected from two well dated cores one core water depth 999 m included thinly laminated mud layers the other water depth 283 m contained nonlaminated sediments tephrochronology and accelerator mass spectrometry 14 c dating of 14 horizons revealed that the two cores contained continuous records of the last 27 cal kyr a total of 13 planktic foraminiferal species belonging to six genera were identified in down core samples the typical indicators of the tsushima current water globigerinoides ruber neogloboquadrina dutertrei pulleniatina obliquiloculata globigerinoides tenellus and globigerinita glutinata occurred since 9 3 cal kyr bp neogloboquadrina incompta which was the dominant species in the tsushima current region of the modern japan sea first occurred at 8 2 cal kyr bp and dominated the assemblage since 7 3 cal kyr bp these results clearly indicate that the warm tsushima current started to inflow into the japan sea at 9 3 cal kyr bp and the modern surface conditions in the southern japan sea were essentially established at 7 3 cal kyr bp our data and comparison of the presence or absence of laminated sediments in three locations from the southern japan sea suggest that deep circulation during the deglacial period was weaker than that at present in addition deep circulation in the modern japan sea which supplies oxygen rich water to the entire basin started probably in association with the first inflow of the tsushima current beginning at 9 3 cal kyr bp

formation and circulation processes of intermediate water in the japan sea abstract the formation and circulation processes of intermediate water in the japan sea have been investigated by study of the subduction of mixed layer water to simulate realistic seasonal variations in the velocity and hydrographic structures a numerical model with a nudging method for potential temperature and salinity which reproduced the general features in the japan sea is used close investigation of the subduction process reveals two major formation areas a and b of intermediate water area a 41 43 n west of 135 e corresponds to the region reported by recent observations whereas area b 40 43 n east of 136 e has not been reported so far the mixed layer water subducted in area a is advected southwestward and eventually its upper portion above 200 m reaches the eastern part of the japan basin whereas the lower branch below 200 m reaches the tsushima basin this indicates that the east sea intermediate water originates from the mixed layer in area a and suggests that the east sea

synoptic temperature structure of the east china and southeastern japan east seas abstract air deployed expendable bathythermograph axbt surveys are used to investigate the synoptic temperature structure of the east china sea ecs southern yellow sea and southeastern japan east sea jes from 1992 1995 in the depth range 0 400 m the main results of this study are as follows the regional winter mixed layer is shallow along the paths of the kuroshio and polar front due to strong advection of warm water which suppresses vertical mixing the region where mixing is to the bottom is generally northwest of the 100 m isobath in the ecs and in the tsushima strait two september surveys reveal two different kuroshio front positions in 1992 this front was far on shelf of its mean position preventing the formation of eddies at mien hwa canyon in 1993 the kuroshio front had migrated off shelf and eddies along the front had formed the kuroshio current branch west of kyushu is not seen in summer at 60 m depth only winter and spring however there is evidence of this branch current in all seasons at 100 m depth along the entire length of the ecs in all surveys except winter where wind mixing had homogenized the water column cross sections show that cold water

runoff and sediment yield from topsoils with different porosity as affected by rock fragment cover and position abstract interrill runoff and sediment yield from a topsoil having essentially textural pores and from another with structural pores were measured in the laboratory under simulated rain to investigate the effects of cover and positions of rock fragments the results reveal that the relation between the cover of rock fragments and interrill runoff or sediment yield can be negative as well as positive porosity in the soil near rock fragments determines both the type of relation and the degree to which the positions of rock fragments affect this relation rock fragments increase runoff and sediment yield when well embedded in a surface seal i e a top layer with essentially textural pore spaces a negative relation occurs either where rock fragments are partly embedded in a top layer with structural porosity or where the rock fragments rest on the surface of a soil having either textural or structural pore spaces the time at which macropores at the soil surface close is crucial for then the effect of the cover of rock fragments on the generation of runoff switches from reduction to an increase since cover can have an ambivalent effect on the hydrological and erosion response descriptions of topsoils containing rock fragments should include the type of soil porosity as well as the positions of rock fragments

ground penetrating radar antennae frequencies and transmitter powers compared for penetration depth resolution and reflection continuity1 twelve ground penetrating radar gpr experiments were conducted on the modern wave influenced william river delta on the southern shore of lake athabasca in northern saskatchewan canada the delta is a well sorted quartzoserich clean sand dominated water saturated geomorphic feature which provided an ideal site to test gpr penetration depths resolution and continuity of reflections were compared for different antennae frequencies 25 50 100 200 mhz and transmitter powers pulser voltage 400 v 1000 v the data show significant variations in vertical resolution from 0 15 m to 0 76 m 200 25 mhz depth of penetration from 14 m 28 m 200 25 mhz and continuity of reflections increasing the transmitter power from 400 v to 1000 v increases the depth of penetration by 5 to 14 and improves the continuity of reflections with little effect on the resolution

analysis of soil surface component patterns affecting runoff generation an example of methods applied to mediterranean hillslopes in alicante spain abstract spatial patterns of soil surface components vegetation rock fragments crusts bedrock outcrops etc are a key factor determining hydrological functioning of hillslopes a methodological approach to analyse the patterns of soil surface components at a detailed scale is proposed in this paper the methods proposed are applied to two contrasting semi arid mediterranean hillslopes and the influence of soil surface component patterns on the runoff response of the slopes was analysed a soil surface components map was derived from a high resolution photo mosaic obtained in the field by means of a digital camera rainfall simulation experimental data were used to characterise the hydrological behaviour of areas with a specific pattern of soil surface components by means of the parameters of the horton equation plot runoff data were extrapolated at the hillslope scale based on the soil surface component maps and their hydrological characterisation the results show that in both slopes runoff generation is concentrated up and downslope with a water accepting area in the centre of both slopes disrupting the hydrological connectivity at the slope scale this reinfiltration patch at the centre of the slope is related to the type of soil surface component and its spatial pattern herbaceous vegetation and on top rock fragments increase the infiltration capacity of soils at the centre of the slope in contrast embedded rock fragments rock outcrops as well as crusted surfaces located in the upper and lower slopes favour runoff generation in these areas in addition a general pattern of water contribution areas downslope is apparent on both slopes the south facing slope shows a higher hydrological connectivity and more runoff 55 of the surface of the south facing slope produces runoff at the end of a 1 hour rainfall event and 17 3 of the surface is covered by a runoff depth between 0 5 and 1 mm while on the north facing slope only 38 of the surface produces runoff under the same conditions longitudinal connectivity of runoff is higher at the south facing slope where more runoff generating surfaces appear and where the vegetation pattern favours the connectivity of bare areas

comparisons between observations and numerical simulations of japan east sea flow and mass fields in 1999 through 2001 abstract the princeton ocean model pom as implemented for the japan east sea jes with mesoscale admitting resolution is driven by seasonal throughflow and synoptic atmospheric forcing for 1999 through 2001 temperature and salinity profiles from shipborne and palace float ctds and horizontal velocities at 800 m from palace float trajectories plus horizontal velocities at 15 m from woce surface drifters for 1988 through 2001 are used to assess the performance of the numerical simulations for a base case general agreement exists in the circulation at 15 and 800 m and the horizontal and vertical structure of the upper ocean temperature and salinity fields the mean observed flow at 15 m defines the two branches of the tsushima warm current and hints at the existence of a large cyclonic gyre over the japan basin which the simulations also produce the mean observed flow at 800 m defines a large cyclonic recirculation gyre over the japan basin that validates the simulated flow pattern variances of the observed and simulated flows at 15 and 800 m have similar patterns the main discrepancies are associated with the strength of the seasonal thermocline and halocline and the location of the subpolar front when smoother topography and smaller lateral friction are used in other cases the thermocline and halocline strengthen agreeing better with the observed values and when 80 of total outflow transport is forced to exit through soya strait the subpolar front extends along the coast to the north of tsugaru strait which is an observed feature absent in the base case

unstable holocene climate in the northeastern east sea sea of japan evidence from a diatom record abstract a total of 45 and 42 sediment subsamples from gravity cores gh98 1223 and gh98 1227 respectively were obtained in the northeastern east sea sea of japan and analyzed for diatom abundance a 14 c date for sediment organic carbon gh98 1223 along with probable and plausible correlation to the well established timeframe constrains the age to the mid to late holocene abundances of most species including neodenticulopsis seminae simonsen and kanaya simonsen and fragilariopsis doliolus wallich grunow were less than 20 in average relative to the most dominant species thalassionema nitzschioides grunow hustedt which ranged from 29 to 59 for core gh98 1223 and between 23 and 46 for core gh98 1227 frequencies of cold water species were generally higher than those of warm water species because of the high latitude cold water occupying dominantly in the basin the vertical distribution of cold water species was largely opposite to that of warm water species for example the frequency of a cold water species n seminae was inversely related to that of a warm water species f doliolus we conclude that changes in abundance of f doliolus and diatom temperature index t d value represent quasi periodic fluctuations demonstrating that the tsushima warm current and its branch of the soya warm current play a significant role in the transportation of diatom cells and heat the pulse like oscillations of this indicator species which are observed in basin wide and regional scales reflect that the strength or intensity of the dominant current is governed by a globally induced unstable climatic system during the holocene period

the role of discharge variability in the formation and preservation of alluvial sediment bodies abstract extant planform based facies models for alluvial deposits are not fully fit for purpose because they over emphasise plan form whereas there is little in the alluvial rock record that is distinctive of any particular planform and because the planform of individual rivers vary in both time and space accordingly existing facies models have limited predictive capability in this paper we explore the role of inter annual peak discharge variability as a possible control on the character of the preserved alluvial record data from a suite of modern rivers for which long term gauging records are available and for which there are published descriptions of subsurface sedimentary architecture are analysed the selected rivers are categorized according to their variance in peak discharge or the coefficient of variation cvqp standard deviation of the annual peak flood discharge over the mean annual peak flood discharge this parameter ranges over the rivers studied between 0 18 and 1 22 allowing classification of rivers as having very low 0 90 annual peak discharge variance deposits of rivers with very low and low peak discharge variability are dominated by cross bedding on various scales and preserve macroform bedding structure allowing the interpretation of bar construction processes rivers with moderate values preserve mostly cross bedding but records of macroform processes are in places muted and considerably modified by reworking rivers with high and very high values of annual peak discharge variability show a wide range of bedding structures commonly including critical and supercritical flow structures abundant in situ trees and transported large woody debris and their deposits contain pedogenically modified mud partings and generally lack macroform structure such a facies assemblage is distinctively different from the conventional fluvial style recorded in published facies models but is widely developed both in modern and ancient alluvial deposits this high peak variance style is also distinctive of rivers that are undergoing contraction in discharge over time because of the gradual annexation of the channel belt by the establishment of woody vegetation we propose that discharge variability both inter annual peak variation and flashiness may be a more reliable basis for classifying the alluvial rock record than planform and we provide some examples of three classes of alluvial sediment bodies representing low intermediate and high very high discharge variability from the rock record that illustrate this point

overland flow generation and continuity on stone covered soil surfaces the influence of stone cover on the generation and continuity of overland flow is a function of several variables primarily stone size distance spacing between stones and stone position on top of the soil surface or partially embedded the initial hypothesis of the present study were that stone size affects overland flow generation by inducing concentration overland flow and that the distance between stones affects overland flow continuity with respect to stone size and distance between stones opposing results have been found in the literature accordingly the present paper reports on laboratory experiments which were conducted to investigate systematically the effect on overland flow of stone size distance between stones and stone position the main conclusions were 1 stone cover tended to induce overland flow relative to bare soil small stones however especially in a low cover percentage setting and when resting on top of the soil surface produced less overland flow than bare soil 2 overland flow was positively related to stone size but inversely related to distance between stones 3 overland flow yield was always greater when stones were embedded than when on top of the soil surface 4 the effect of stone size on increasing the degree of overland flow was of greater significance than the effect of the distance between stones on reducing overland flow

observations of ice ocean eddy streets in the sea of okhotsk off the hokkaido coast using radar images abstract this study examines the features of fairly regular ocean wave motion in which some eddy streets or backward breaking waves are successfully visualized using sea ice floes as a tracer these examinations are made using the time sequence of radar imagery data collected during the past 20 years 1969 88 the correspondence of the radar images with the actual pattern is partially confirmed through aircraft observations the ice ocean eddy street or backward breaking wave pattern runs parallel to the coastline at a distance of about 20 km from the hokkaido coast the eddy street also corresponds to a boundary between the soya warm current and colder less saline offshore water the wave motion is characterized by wavelengths of 40 55 km phase velocities of 14 20 km day 1 and periods of 2 3 3 5 days the regular ice ocean wave motion pattern was observed when pack ice had a small ice concentration composed of uniform sized ice floes and weak winds the sea ice floes serve as a highly effective flow i

synoptic forcing of the korea strait transport abstract korea strait transport variations in the synoptic frequency band 2 20 days are examined using results of a numerical 3 d primitive equation model satellite observed sea level variations a linear barotropic adjoint dynamic model and observed transports the 3 d numerical model does not assimilate observations and the agreement with the observed transport implies that wind forcing is one of the main contributors to variations in the synoptic band the satellite observed and 3 d model sea level indicate a sea level response to wind stress along the east korean coast that propagates toward the korea strait and changes the sea level slope across the strait the adjoint results indicate that wind stress is most influential in the area east of korea along with secondarily important area along the east china sea shelf break south of japan the mechanism connecting wind stress to transport variations is a kelvin wave propagation that changes sea level slope across the strait leading to the altered geostrophic transport through the strait a strong southerly wind initially produces a sea level set down along the east korea coast and a sea level increase along the shelf break the set down propagates to the korea strait as a kelvin wave sea level across the strait changes and the transport through the strait increases similarly northerly wind stress produces a set up along the korea coast and subsequent decreased transport wind stresses across the yellow and east china seas are not a significant forcing mechanism since kelvin waves would propagate away from the strait barotropic transport response to wind stress is rapid on the order of 3 h but the relatively slow development of the atmospheric forcing on the order of 1 2 days modulates the response

the north pacific a global scale estuary abstract the atmospheric net flow of water from the atlantic to the pacific ocean is supposed to maintain the salinity difference between the two oceans assuming the existence of a subsurface level of no horizontal pressure gradient in the ocean the mean sea level in the northern pacific must be higher than in the arctic ocean this mean sea level difference is supposed to drive the observed mean flow through the bering strait the estimated flow of freshwater through the bering strait is approximately equal to the estimated atmospheric net flow of water from the north atlantic to the north pacific this justifies the formulation of a simple estuary model for the north pacific in which the brackish water exits through the bering strait the salinity difference between the two oceans is shown to be controlled by the topography of the bering strait the estuary model gives residence times for water in the upper layer 1000 m thick of approximately 1000 years and in the lower layer of approximately 400

circulation and haline structure of a microtidal bay in the sea of japan influenced by the winter monsoon and the tsushima warm current mooring and hydrographic surveys were conducted in tango bay a microtidal region of freshwater influence rofi in the sea of japan in order to clarify the circulation pattern in the bay and its driving forces monthly mean velocity records at four stations revealed an inflow and outflow at the eastern and northern openings of the bay respectively indicating an anticyclonic circulation across the bay mouth the circulation was significantly intensified in winter in accordance with the prevailing nw wind component of the winter monsoon the anticyclonic circulation at the bay mouth was connected to an estuarine circulation that was evident near the mouth of the yura river at the bay head surface salinity just offshore of the river mouth was closely related to the yura river discharge whereas in lower layers the offshore water had a stronger influence on salinity prior to a seasonal increase in the yura river discharge summer salinity decreased markedly through the water column in tango bay possibly reflecting intrusion of the changjiang diluted water transported by the tsushima warm current in contrast with the traditional assumption that estuarine circulation is controlled mainly by river discharge and tidal forcing the circulation in tango bay is strongly influenced by seasonal wind and the tsushima warm current the narrow shelf may be responsible for the strong influence of the tsushima warm current on circulation and water exchange processes in tango bay

subinertial to interannual transport variations in the korea strait and their possible mechanisms 1 the voltage derived transport in the korea strait from march 1998 to april 2002 reveals various temporal variations such as subinertial monthly seasonal and interannual variations the driving mechanisms of these temporal variations in the flows through the straits and the mean sea level of the east sea sea of japan are investigated using a simple analytical barotropic model the east sea is simplified as a flat bottomed semienclosed basin and it is forced by the atmospheric pressure the along strait wind stress and the sea level differences along the straits despite its simplicity this model explains most variations and helps us understand dominant driving forces on each timescale at the subinertial periods of 2 10 days the atmospheric pressure dominantly drives the flows into or out of the east sea due to a helmholtz resonance whose period is about 3 days and the mean sea level cannot respond isostatically the effects of the atmospheric pressure on the transport variations become weak at long periods because there is enough time for the east sea to be drained or filled through the strait flows as its mean sea level responds isostatically on the other hand the changes in the adjusted sea levels outside the straits of the east sea cause the pressure gradient forces along the straits and induce most of variations in the strait flows and the mean sea level at the monthly to interannual periods

interannual to interdecadal variability in the japan sea based on a new gridded upper water temperature dataset a new gridded water temperature dataset of upper 400 m depths 0 50 100 200 300 and 400 m for the japan sea or east sea is produced by using an optimal interpolation technique from 1930 to 1996 based on oceanographic observations collected in the world ocean database 1998 the temperature data are analyzed by a complex empirical orthogonal function ceof with six levels combined using the data for a period from 1957 to 1996 during which most of gridded data are available before calculating the ceofs low pass or highpass filters cutoff period at 7 yr are applied to separate interannual and decadal temperature changes respectively one interannual and two decadal ceof modes are identified the interannual first ceof mode is characterized by the energetic variability around and south of the subpolar front in the western japan sea accompanied by northward and northeastward phase propagations emanating from the tsushima strait the decadal first ceof mode exhibits a broad structure prevailing over the whole japan sea but large amplitudes are trapped by the subpolar front with 608 908 phase lags between the northeastern and southwestern japan sea the decadal second ceof mode has a localized structure with strong correlations in the yamato basin the relation between the atmosphere and ocean is analyzed by a correlation analysis of wintertime sea level pressures slps onto the temporal coefficients of the ceof modes the interannual first ceof mode is accompanied by the slp anomalies over the western north pacific ocean with steep slp gradients over the japan sea suggesting that this mode is forced by local wind anomalies associated with the slp changes over the western north pacific the decadal first ceof mode is likely to be caused by changes of the east asian winter monsoon due to the slp variability of the northern part of the siberian high which is closely associated with the decadal fluctuations of the arctic oscillation and the north atlantic oscillation the second decadal ceof mode is accompanied by high slp correlations over the central north pacific associated with strength changes of aleutian lows suggestive of remote forcing from the central north pacific

rapid thermohaline transition in the pacific western subarctic and oyashio fresh core eddies seven years of conductivity temperature depth data enable direct computations of volume transport and a description of the temporal changes of water properties in the western subarctic pacific the cooling of the western subarctic surface layer is shown through the observation of the thermohaline transition which occured in the western subarctic during 1990 1997 its main consequences were changes of the oyashio path and restratification of the western subarctic water the example presented here uses data obtained during the canada russia international north pacific ocean climate study as well as the russian project subarctic to show that a warming and ventilation of the midlayers of the western subarctic 200 1000 dbar occurred because of the influx of warm subtropical waters to the oyashio and sea of okhotsk and to the weak coastal oyashio before the transition this influx appears to have reversed in the early 1990s now subarctic intermediate waters displace the remnants of subtropical waters that penetrated to the sea of okhotsk through the soya strait and create strong stratification in the oyashio area this transition appears to have begun during the reinforcement in the coastal oyashio

coastal trapped wave scattering into and out of straits and bays abstract a theory for the generation of coastal trapped waves ctws by an oscillatory coastal flux through a strait is extended so as to make velocity pressure and energy flux everywhere continuous this development is achieved through the inclusion of kelvin and poineare wave modes in a match for pressure leading to a system of linear equations for the unknown amplitudes a kelvin wave incident on the eastern mouth of bass strait for example is shown to preferentially scatter energy into ctw modes 2 and 1 on the shelf as well as driving a poincare wave field that results in a velocity jet trapped to the victorian coast such coastal velocity jets are also a feature of the scattering of ctws incident on a strait for a mode n incident ctw the fraction of net energy flux that enters the strait is also shown to be well approximated by h0bn2 where h0 is the strait depth and bn coupling coefficient the scattering of the remaining energy among other ctw modes is detailed and shown to become larger as the

a near uniform basin wide sea level fluctuation over the japan east sea a semienclosed sea with multiple straits 1 sea level of the japan east sea observed by the topex poseidon t p satellite altimeter is analyzed using a 1 4 resolution ocean general circulation model a significant fraction of the japan east sea sea level variability is found to be spatially uniform with periods ranging from 20 d to a year the model simulation is consistent with t p records in terms of the basin wide sea level fluctuation s spectral energy and coherence the simulation indicates that the changes are barotropic in nature and controlled notably at high frequencies by the net mass transport through the straits of the japan east sea driven by winds in the vicinity of the korea tsushima and soya straits a series of barotropic simulations suggest that the sea level fluctuations are the result of a dynamic balance at the straits among near strait winds friction and geostrophic control the basin wide sea level response is a linear superposition of changes due to winds near the individual straits in particular a basin wide sea level response can be established by winds near either one of the straits alone for the specific geometry and winds winds near the soya strait have a larger impact on the japan east sea mean sea level than those near the korea tsushima strait

interannual to decadal variability in the southern okhotsk sea based on a new gridded upper water temperature data set 1 a new gridded water temperature data set of upper 200 m depths 0 50 100 200 m depths for the okhotsk sea was produced using an optimal interpolation technique from 1950 to 1996 using oceanographic observations in the world ocean database 1998 temperature variability at 50 100 and 200 m depths in the southern okhotsk sea south of 52 n in the warm season may october was investigated by an empirical orthogonal function eof analysis from 1958 to 1994 for which sufficient data exist for an eof analysis the first eof mode has a monopole structure with the maximal amplitude in the kuril basin and the corresponding principal component pc exhibits prominent quasi decadal variability the first eof mode is closely related with the wintertime december february sea surface temperature anomalies over the subarctic front or oyashio front in the north pacific and with wintertime sea level pressure slp differences between northern eurasia and the northern north pacific this suggests that the temperature changes in the okhotsk sea are caused by changes in the strength of the asian winter monsoon which are associated with the slp difference a quasi decadal oscillation similar to that of the pc 1 is observed in the slp difference since the 1960s and shared by the polar eurasian pol pattern arctic oscillation ao and north atlantic oscillation nao some hints of the relating variability are observed in coastal sea level difference between wakkanai and abashiri which was used as a proxy for transport in the soya warm current also some features of sea ice extents co vary with the pc 1

three dimensional sedimentary architecture of a large mid channel sand braid bar jamuna river bangladesh the three dimensional subsurface alluvial architecture of a large approximately 3 km long 1 km wide 12 m high mid channel sand braid bar in the jamuna river bangladesh is described evolution of the bar and its depositional characteristics are assessed from a unique combination of ground penetrating radar surveys vibracoring and trenching that are allied to a series of bathymetric surveys taken during growth of the bar over a 29 month period this methodology permits identification of the formative processes of different packages of braid bar sedimentation and provides a facies model for deposition within the entire bar mid channel bar growth occurred in a region of flow expansion and was probably initiated by the stalling and amalgamation of large dunes these dunes created a bar core that grew by i propagation of a downstream accreting slipface ii vertical accretion through stacking of dunes on both bar stoss and top and iii lateral accretion on the bar margins during recession of the flood hydrograph braid bar sedimentation is dominated by four radar facies 1 large scale predominantly planar dipping reflections interpreted as cross stratification up to 8 m in height and greater than 100 m in width that is produced by the cross channel migration of bar margins 2 medium scale trough shaped and planar discontinuous reflections interpreted as cross stratification up to 4 m in height and 300 m wide that is deposited from large sinuous crested sand dunes 3 discontinuous reflections up to 2 m high and 30 m wide interpreted as small scale trough cross stratification that is the product of smaller sinuous crested dunes and 4 high amplitude undulating reflections interpreted as mud drapes deposited in regions of slow flow often in the bar tail region at low stage dune size decreases vertically within the bar in response to the progressively shallower flows on the emerging bar top later evolution of the bar as one anabranch channel became dominant created a 1 5 km extension to the bar tail with an 8 m high angle of repose bar margin slipface formed by flow transverse to the long axis of the bar seven styles of deposition can be defined that constitute the alluvial architecture bar margin slipface vertical accretion in channel bar top vertical accretion upstream accretion lateral accretion downstream accretion and low stage mud drapes a model of braid bar sedimentation is presented that shares many similarities with previous studies of smaller sand bed braid bars with the dominance of dune scale cross stratification the presence of large scale bar margin cross stratification and the occurrence of lateral vertical upstream and downstream accretion however the contribution of the bar margin facies to the preserved stratigraphy highlighted herein may have been underestimated in previous models of braided rivers in which the braid bars were migrating slowly this study suggests a scale invariance in several aspects of mid channel bar sedimentation in sand bed rivers and proposes a model of braid bar sedimentation that may be applied widely within studies of braided alluvial architecture

low frequency current observations in the korea tsushima strait abstract high resolution continuous current measurements made in the korea tsushima strait between may 1999 and march 2000 are used to examine current variations having time periods longer than 2 days twelve bottom mounted acoustic doppler current profilers provide velocity profiles along two sections one section at the strait entrance southwest of tsushima island and the second section at the strait exit northeast of tsushima island additional measurements are provided by single moorings located between korea and tsushima island and just north of cheju island in cheju strait the two sections contain markedly different mean flow regimes a high velocity current core exists at the southwestern section along the western slope of the strait for the entire recording period the flow directly downstream of tsushima island contains large variability and the flow is disrupted to such an extent by the island that a countercurrent commonly exists in the lee of the island the northeastern section is marked b

the annual cycle of the japan sea throughflow abstractthe mechanism responsible for the annual cycle of the flow through the straits of the japan sea is investigated using a two layer model observations show maximum throughflow from summer to fall and minimum in winter occurring synchronously at the three major straits tsushima tsugaru and soya straits this study finds the subpolar winds located to the north of japan as the leading forcing agent which first affects the soya strait rather than the tsushima or tsugaru straits the subpolar winds generate baroclinic kelvin waves along the coastlines of the subpolar gyre affect the sea surface height at the soya strait and modify the flow through the strait this causes barotropic adjustment to occur inside the japan sea and thus affect the flow at the tsugaru and tsushima straits almost synchronously the barotropic adjustment mechanism explains well why the observations show a similar annual cycle at the three straits the annual cycle at the tsugaru strait is further shown to be weaker than t

significance of shallow seismic reflection ssr and ground penetrating radar gpr profiling on the modern coast line history of the bedre area egirdir lake isparta turkey abstract lake level changes and settlement places constitute the main problems in controlling the coastal environment along the egirdir lake sw turkey the quaternary geology in the bedre coast was studied based on shallow seismic reflection ssr survey ground penetrating radar gpr profiles and the data derived from boreholes and investigations in the field thus six seismic and five radar facies were determined respectively the geological units from the basement rock to the holocene deposits were imaged by the ssr technique gpr technique is used for the shallower part ranging from the ancient to the modern lacustrin sediments the quaternary lake level changes borehole seismic and radar data indicate that a pond with a connected to the lake around the bedre area existed in the last century sand barriers climate topographical elevation and erosions of the basement rocks control the sedimentation of the back barrier of the coastal line marsh muddies and ancient beach sands are the main sediments of the pond area from the profiles ancient buried sand barriers were also seen in the lake side in our view as the previous lake level dropped from the highstand the ancient sand barrier was formed which divided the lake and the pond and isolated a small inland lake which lies 4 m below the level of the coastal barrier for agricultural purposes artificial man made constructions were done on the barrier and channels thus dry agricultural land appeared in the last 50 years on the pond side

modern distribution of dinocysts from the north pacific ocean 37 64 n 144 e 148 w in relation to hydrographic conditions sea ice and productivity abstract palynological analyses were performed on 53 surface sediment samples from the north pacific ocean including the bering and okhotsk seas 37 64 n 144 e 148 w in order to document the relationships between the dinocyst distribution and sea surface conditions temperatures salinities primary productivity and sea ice cover samples are characterized by concentrations ranging from 18 to 143 816 cysts cm3 and the occurrence of 32 species a canonical correspondence analysis cca was carried out to determine the relationship between environmental variables and the distribution of dinocyst taxa the first and second axes represent respectively 47 and 17 8 of the canonical variance axis 1 is positively correlated with all parameters except to the sea ice and primary productivity in august which are on the negative side results indicate that the composition of dinocyst assemblages is mostly controlled by temperature and that all environmental variables are correlated together the cca distinguishes 3 groups of dinocysts the heterotrophic taxa the genera impagidinium and spiniferites as well as the cyst of pentapharsodinium dalei and operculodinium centrocarpum five assemblage zones can be distinguished 1 the okhotsk sea zone which is associated to temperate and eutrophic conditions seasonal upwellings and amur river discharges it is characterized by the dominance of o centrocarpum brigantedinium spp and islandinium minutum 2 the western subarctic gyre zone with subpolar and mesotrophic conditions due to the kamchatka current and alaska stream inflows assemblages are dominated by nematosphaeropsis labyrinthus pyxidinopsis reticulata and brigantedinium spp 3 the bering sea zone depicting a subpolar environment influenced by seasonal upwellings and inputs from the anadyr and yukon rivers it is characterized by the dominance of i minutum and brigantedinium spp 4 the alaska gyre zone with temperate conditions and nutrient enriched surface waters which is dominated by n labyrinthus and brigantedinium spp and 5 the kuroshio extension north pacific subarctic current zone characterized by a subtropical and oligotrophic environment which is dominated by o centrocarpum n labyrinthus and warm taxa of the genus impagidinium transfer functions were tested using the modern analog technique mat on the north pacific ocean 359 sites and the entire northern hemisphere databases 1419 sites results confirm that the updated northern hemisphere database is suitable for further paleoenvironmental reconstructions and the best results are obtained for temperatures with an accuracy of 1 7 c

coherent sea level variation in and around the sea of okhotsk abstract we investigated the seasonal and interannual variations of the sea level in and around the sea of okhotsk and their causes based on tide gauge and satellite altimeter data the sea level all along the coastal region of the sea of okhotsk is found to be dominated by the seasonal variation with a maximum in winter and a minimum in summer which cannot be explained by the annual cycle of atmospheric heat flux and pressure this sea level variation appears to reflect ocean current variations both the arrested topographic waves atws caused by alongshore wind stress and the sverdrup transport by wind stress curl show corresponding seasonal variations seasonal amplitude of the sea level is relatively large along sakhalin island with a tendency of a larger amplitude toward the south this meridional dependence is consistent with the atws but not with the sverdrup transport in the sea of okhotsk seasonal variation of the geostrophic current velocity expected from the sea level variation is comparable to that of the observed nearshore current and is consistent with the theoretical atw transport it is also revealed that on an interannual timescale the wintertime sea level fluctuates quite coherently all around the sea of okhotsk and further along the east kamchatka and oyashio coasts in the north pacific the altimeter data clearly show that this coherent sea level variation is trapped over the coastal and continental shelf regions with depths shallower than 1000 m the wintertime sea levels have a higher correlation with the atw transport than with the sverdrup transport in the sea of okhotsk and the upstream east kamchatka coast all these suggest that the interannual sea level variation along the coastal and shelf regions in winter as well as the seasonal variation is mainly caused by the atws coastal trapped current forced by the alongshore wind stress the wintertime sverdrup transport raised by the previous studies is the secondary contributor to these variations

the formation of an anabranching planform in a sandy floodplain by increased flows and sediment load anabranching rivers evolve in various geomorphic settings and various river planforms are present within these multi channel systems in some cases anabranches develop meandering patterns such river courses existed in europe prior to intensive hydro technical works carried out during the last 250 years proglacial stream valleys inherited from the last glaciation provided a suitable environment for the development of anabranching rivers wide valleys floors with abundant sand deposits the main objective of the present study is to reconstruct the formation of an anabranching river planform characterized by meandering anabranches based on geophysical and geological data obtained from field research and a reconstruction of palaeodischarges a model of the evolution of an anabranching river formed in a sandy floodplain is proposed it is demonstrated that such a river system evolves from a meandering to an anabranching planform in periods of high flows that contribute to the formation of crevasse splays the splay channels evolve then into new meandering flow paths that form second order crevasses avulsions and cutoffs the efficiency of the flow is maintained by the formation of cutoffs and avulsions preventing the development of high sinuosity channels and redirecting the flow to newly formed channels during maximum flow events a comparison with other anabranching systems revealed that increased discharges and sediment loads are capable of forming anabranching planforms both in dryland and temperate climate zones the sediment type available for transport often inherited from older sedimentary environments is an important variable determining whether the channel planform is anabranching with actively migrating channels or anastomosing with stable straight or sinuous branches

a numerical study of barotropic instability associated with the soya warm current in the sea of okhotsk abstract numerical model experiments have been carried out in an attempt to elucidate the generation mechanism of the eddy or wave street in the soya warm current we use a barotropic model incorporating bottom topography under realistic conditions the model produces waves whose properties are within range of the observed ones the generation mechanism of the waves proposed in this experiment is as follows when the current is driven by the mean water level difference between the japan sea and the sea of okhotsk the flow separates from the cape in the soya strait in the region of the flow separation strong positive vorticity is produced by the frictional torques occurring as the water flows through the strait and by vortex stretching as the water is pushed out to deeper depths this strong vorticity or horizontal shear induces barotropic instability in which the waves are generated in brief the system of the soya warm current accompanied by an eddy street is interpreted as a good geophysical ex

ground penetrating radar investigation of a lake bonneville deita provo level brigham city utah field experiments carried out in the brigham sand and gravel company pit near brigham city utah show an impressive similarity between observed gravelly deltaic foreset facies in highwall exposures and inclined reflections detected by ground penetrating radar gpr beneath the pit floor the radar indicates additional inclined strata more than 30 m deep in a test to compare different antenna frequencies 50 100 and 200 mhz using a 400 v transmitter 50 mhz antennas are capable of detecting gravel facies in excess of 30 m whereas signal loss for the 100 and 200 mhz antennas occurs below 23 and 17 m respectively though providing higher resolution

is history of rivers important in restoration projects the example of human impact on a lowland river valley the obra river poland abstract palaeoenvironmental and palaeohydrological reconstructions can provide important guidance for river restoration projects this paper reconstructs the trajectory of river pattern changes of a lowland river the obra river western poland as a basis to inform realistic restoration activities the history of river changes is reconstructed for the last 12 700 radiocarbon years bp the sequence and timing of change differ from widely recognized conventional assessments of transitions from braided to meandering planforms in the polish lowlands traces of a laterally migrating anabranching system were found in the middle obra valley in its lower course a transition from a braided to meandering planform took place later than in other rivers of the polish lowlands sediment delivery from parts of the catchment situated downstream of lakes in the river course could have been the main reason for maintenance of the braided pattern restoration scenarios that take into account the trajectory of river planform changes are hypothesized in relation to variations of sediment supply and degree of anthropogenic impact

ground penetrating radar of northern lacustrine deltas ground penetrating radar gpr was used in several selected deltaic sedimentary environments to better understand subsurface stratigraphy and reconstruct former depositional environments the profiles provide high resolution continuous subsurface data on facies thickness and depths orientation of major sedimentary structures postdepositional failure planes and depth of peat deposits field experiments were carried out on six river deltas records from four of the deltas exhibit sedimentary facies a record from one delta shows a possible slump and records from another delta reveal the thickness and stratigraphic relationships of peat deposits the delta types are i sandy wave influenced ii sandy immature wave influenced steeper middle and lower shoreface iii sandy braided and iv gravelly fan foreset in areas of limited subsurface control stratigraphic logs from drill core cutbank exposure or geophysical logs radar profiles can provide big picture perspectives of the subsurface

millennial scale variability of holocene hydrography in the southwestern okhotsk sea diatom evidence diatom analysis of two submarine cores off eastern hokkaido island northern japan provides insights into the holocene palaeoenvironmental history of the southwestern okhotsk sea diatom flora was

rapid lake infill following major rockfall bergsturz events revealed by ground penetrating radar gpr measurements reintal german alps the capability of gpr ground penetrating radar measurements to decipher the sedimentary history of young alluvial plains is investigated the sediment basins result from the infill of two lakes which were dammed by high magnitude rockfalls 400 600 and 200 years ago in an alpine trough valley the thickness and structure of the dammed sediments was derived from a series of longitudinal and cross profiles in order to take advantage of both high penetration and high resolution measurements we applied 25 50 100 and 200 mhz antennas the radargrams allow for a detailed analysis of the history of the alluvial fill the pre existing valley bottom is clearly visible under one of the basins the profiles display the former clayey lake bottom and illustrate several stages of lake infill small scale sedimentary structures such as topset beds or foreset beds are discernible and provide proxy information on water level sediment supply and phases of infill activity at the second basin discordant structures

using ground penetrating radar and capacitively coupled resistivity to investigate 3 d fluvial architecture and grain size distribution of a gravel floodplain in northeast british columbia canada abstract this study combines ground penetrating radar gpr and capacitively coupled resistivity ccr for geophysical architecture analysis of a bar platform and channel bend on the floodplain of a poorly organized wandering gravel bed river an important objective of fluvial architectural analysis is linking fluvial style with preserved subsurface sedimentology however architectural analysis relies on opportunistic outcrops with locations or orientations that may not provide appropriate data gpr is a well established geophysical method that images reflections interpreted to represent bed geometry and bounding surfaces and is therefore ideal for imaging fluvial architecture unfortunately grain size information which is integral to architectural classification is more elusive using gpr resistivity data can be used as a proxy for sediment grain size when gpr and ccr are combined they offer an effective tool for geophysical fluvial architectural analysis five trenches provided direct observation of the subsurface sedimentology and are used to calibrate the two geophysical methods eight radar facies and one radar element are classified from the gpr survey and grouped into four categories horizontal and subhorizontal laterally continuous reflections group 1 clinoform reflections group 2 discontinuous reflections group 3 and concave up elements group 4 the 2 d resistivity data are combined in a gis to establish a 3 d resistivity model for the upper 5 m of the floodplain resistivity values correlate well with grain size and are categorized into fine grained 800 ohm m sediments in general resistivity values indicate coarse sediment in the bar platform and sand to fine grained material in the main channel and subordinate depressions resistivity profiles were extracted from the 3 d model along the gpr lines so that resistivity values could be directly compared to radar facies the shape and spread of the resistivity distributions provide dominant grain size as well as an indication of sediment sorting for individual radar facies in some cases the same radar facies is associated with markedly different grain sizes indicating different architectural elements i e horizontally bedded gravel verses horizontally bedded sand or fine grained sediment this demonstrates the utility of combining gpr and ccr insomuch as radar architecture alone is not diagnostic of fluvial architectural elements in this case study the bar platform and channel have a planform that might suggest a meandering fluvial style however gpr ccr results indicate that the dominant depositional process across the bar platform was vertical accretion of gravel sheets an architecture more consistent with a wandering gravel bed fluvial style lateral migration was limited to the outer downstream margin of the platform a location dominated by a mix of sand and gravel coarse gravel likely occupies the base of the main channel with fine grained sediment contributing to the remainder of the channel fill a four phase history is presented where the initial phase of development involves vertical accretion and migration of stacked gravel sheets during floods forming the core of the bar platform after flooding subsides and the interior bar emerges the channel becomes established and lateral migration becomes the dominant depositional process the evolution concludes with avulsion and eventual abandonment of the channel

morphology and evolution of bars in a wandering gravel bed river lower fraser river british columbia canada a hierarchical typology for the channels and bars within aggradational wandering gravel bed rivers is developed from an examination of a 50 km reach of lower fraser river british columbia canada unit bars built by stacking of gravelly bedload sheets are the key dynamic element of the sediment transfer system linking sediment transport during individual freshets to the creation development and remoulding of compound bar platforms that have either a lateral or medial style primary and secondary unit bars are identified respectively as those that deliver sediment to compound bars from the principal channel and those that redistribute sediment across the compound bar via seasonal anabranches and smaller channels the record of bar accretion evident in ground penetrating radar sequences is consistent with the long term development of bar complexes derived from historical aerial photographs for two compound bars inter annual changes associated with individual sediment transport episodes are measured using detailed topographic surveys and longer term changes are quantified using sediment budgets derived for individual bars from periodic channel surveys annual sediment turnover on the bars is comparable with the bed material transfer rate along the channel indicating that relatively little bed material bypasses the bars bar construction and change are mainly accomplished by lateral accretion since the river has limited capacity to raise bed load onto higher surfaces styles of accretion and erosion and therefore the major bar form morphologies on fraser river are familiar and consistent with those in gravelly braided channels but the wandering style does exhibit some distinctive features for example 65 year histories reveal the potential for long sequences of uninterrupted accretion in relatively stable wandering rivers that are unlikely in braided rivers

architectural element analysis within the kayenta formation lower jurassic using ground probing radar and sedimentological profiling southwestern colorado abstract a well exposed outcrop in the kayenta formation lower jurassic in southwestern colorado was examined in order to delineate the stratigraphy in the subsurface and test the usefulness of ground probing radar gpr in three dimensional architectural studies two fluvial styles are present within the kayenta formation sandbodies within the lower third of the outcrop are characterized by parallel laminations that can be followed in the cliff face for well over 300 m these sandbodies are sheet like in appearance and represent high energy flood deposits that most likely resulted from episodic floods the remainder of the outcrop is characterized by concave up channel deposits with bank attached and mid channel macroforms their presence suggests a multiple channel river system the gpr data collected on the cliff top together with sedimentological data provided a partial three dimensional picture of the paleo river system within the kayenta formation the 3 d picture consists of stacked channel bar lenses approximately 50 m in diameter the gpr technique offers a very effective means of delineating the subsurface stratigraphy its high resolution capabilities easy mobility and rapid rate of data collection make it a useful tool its shallow penetration depth and limitation to low conductivity environments are its only drawbacks

ground penetrating radar stratigraphy and dynamics of megaflood gravel dunes ground penetrating radar was used to elucidate the stratigraphy of late pleistocene gravel dunes in the altai mountains of southern siberia that formed when a lake emptied as a result of ice dam failure survey lines across dunes had a resolution of decimetres with depth penetration of 20 m the reflections identify bounding surfaces and radar facies two classes of unconformities are identified 1 an erosional unconformity at the base of the dunes 2 steeply inclined unconformities that truncate underlying inclined reflections and are downlapped by overlying inclined reflections within the dunes unconformities define six radar facies rf rf 1 basal subhorizontal discordant reflections rf 2 poorly defined discordant reflections rf 3 planar inclined reflections rf 4 sigmoidal inclined reflections rf 5 trough fills rf 6 low angle inclined reflections the basal unconformity represents the flood cut surface across which the dunes migrated the inclined unconformities may be interpreted in two ways 1 erosional surfaces induced by unsteady flow within one flood or 2 erosional surfaces developed by a series of floods reactivating dunes left stranded by previous floods the evidence favours the latter model which is consistent with the occurrence of several dune forming events within the basin the broader implications of the study are considered with respect to investigations of megaflood bedforms worldwide

intrusion of a branch of the oyashio current into the japan sea during the holocene 1 the holocene history of the japan sea was reconstructed using foraminiferal assemblages and stable isotope records from two piston cores recovered from west of the tsugaru strait with the overall goal to resolve a controversy regarding flow in and out of the japan sea during the holocene in the northern core the planktonic foraminifer n pachyderma changed from left coiling to right coiling at 8 3 ka however in the southern core the left coiling form remained dominant until 4 8 ka some indices of the stable isotopic records also changed at 8 3 and 4 8 ka these results suggest that the tsushima current started to inflow into the japan sea at 8 3 ka but a branch of the oyashio current continued to inflow until 4 8 ka we attribute the coexistence of the two currents between 8 3 and 4 8 ka to the opposite direction flows between the shallow and the deep portions of the tsugaru strait driven by baroclinic components

rotating stratified barotropic flow over topography mechanisms of the cold belt formation off the soya warm current along the northeastern coast of hokkaido abstractthe soya warm current swc flows through a shallow strait between the japan sea and the sea of okhotsk the swc has a jet structure downstream of the strait along the northern coast of hokkaido with a maximum speed exceeding 1 m s 1 at its axis in summer and fall a surface cold belt with a subsurface doming structure forms offshore of the swc axis mechanisms of the cold belt formation are discussed from a point of view of resonant interaction between a barotropic stratified flow and a shallow sill and subsequent baroclinic adjustment along the swc when a stratified current rides a slope upstream the thermocline displaces upward greatly and outcrops owing to resonant generation of internal kelvin waves if the upper layer is thinner than the lower layer the control section where a froude number is unity occurs upstream from the sill crest when the ambient inflow has a barotropic flow component these upwelling features closely resemble those along the southwestern coast of sakhalin islan

geostrophic control of fluctuating barotropic flow through straits abstract a simple model in which the cross strait sea surface slope is geostrophically balanced and the along strait slope is balanced by acceleration and friction is shown to be supported by the results of buchwald and miles for fluctuating flow through a gap between two semi infinite oceans for a narrow gap compared with the rossby radius and the scale of the motion in the far field the transport through it is exactly the same as that predicted by the model provided that the gap is regarded as having an elective length as determined in this paper the importance of the models is that they demonstrate that at low frequency the flow may be geostrophically controlled and the transport limited to a value much less than that which would arise in a nonrotating system the neglect of nonlinear advective terms in the models is justified by a comparison or the bernoulli set down in the strait with the driving head and the mean water depth the formula for the flux through a strait may be applied in stu

channel planform as a non controlling factor in fluvial sedimentology the case of the squamish river floodplain british columbia abstract channel planform styles demonstrate a continuum of variability whereas end member situations may exhibit diagnostic sedimentologic characteristics non end member situations may be exceedingly difficult to reliably differentiate the relevance of channel planform based sedimentologic differentiation of fluvial depositional units has been questioned for some time e g jackson 1978 bridge 1985 brierley 1989a despite reservations outlined in these papers facies models and interpretations of depositional suites in the rock record continue to be applied in terms of channel planform style this paper describes a test of this principle in one particular depositional setting the squamish river in southwestern british columbia is a high energy gravel based river in a fjord setting in a 20 km reach this river displays a distinct downstream gradation in channel planform type from braided through wandering gravel bed to meandering assemblages of bedform scale facies units on bar surfaces in this river do not differ by planform type brierley 1989a rather facies associations relate directly to the pattern of morphostratigraphic units on bar surfaces brierley 1991a when analysed in floodplain exposures sediment sequences which are equivalent to morphostratigraphic units are termed elements these elements are defined in terms of their geometry bounding surface and sediment characteristics detailed analysis of floodplain deposits in the braided wandering gravel bed and meandering reaches of the squamish river demonstrates that just as assemblages of bedform scale facies cannot be differentiated by planform style neither can assemblages of floodplain elements indeed for the squamish river the type character and spatial association of these elements cannot be differentiated reliably at the channel planform scale this indicates the limited relevance of planform differentiation of sedimentary environments under transitional planform situations such as those of high energy gravel bed rivers in confined valleys in such situations sediment inventory at the element scale provides greater insight into mechanisms of floodplain evolution than can be provided by interpretation at either the channel bedform or channel planform scales

ground penetrating radar evaluation of the internal structure of fluvial tufa deposits devanos anavieja system ne spain an approach to different scales of heterogeneity

recent variability in the pacific western subarctic boundary currents and sea of okhotsk abstract the objective of this research is to describe physical processes which are the cause of the recent variability of the pacific western subarctic waters rapid thermohaline changes have occurred within the oyashio and kamchatka current during the last decade this variability has included a warming of the kamchatka current warm intermediate layer but a cooling and freshening of the upper layer in the oyashio and sea of okhotsk the example presented here uses data obtained during the canada russia inpoc and woce projects as well as the new russian studies with high resolution station grid the possible physical mechanism that generated the upper layer freshening during the thermohaline transition is examined major components of the fresh water budget of the okhotsk sea are considered in order to describe the dramatic changes in salinity which have recently occurred in the pacific subarctic significant changes in precipitation and other fresh water inputs are demonstrated it is suggested that upper layer of the oyashio and kamchatka current became cooler and fresher because of the export of cold fresher waters from the bering and okhotsk seas these waters from the marginal seas have cooled the bottom of the halocline reducing evaporation and acting as a feedback that has kept the upper layer of the western subarctic boundary currents fresh it is also shown that the outflow of the cold sea of okhotsk water has changed its path during this recent thermohaline transition

the flow system in the japan sea caused by a sea level difference through shallow straits we investigate how the current system through the japan sea is driven and what determines the volume transport we suppose that a part of the difference in geopotential anomaly between the subtropical and subpolar gyre is converted into a barotropic sea level difference across the three shallow straits which connect the japan sea with the pacific and that this difference is the primary driving force of the current system then we examine the flow under the condition that there is a constant sea level difference between two oceans connected through a shallow strait we found that the strait acts as a source of arrested shelf waves or steady coastal flows for the timescale beyond the inertial period in the northern hemisphere steady flows are established along the shelves with the coast to the right left in the ocean of low high sea level we apply this notion to the current system through the japan sea the tsushima nearshore branch the tsugaru coastal mode and the soya current can all be interpreted as a coastally trapped flow whose source is the upstream strait further a series of northeastward flows along the south and east china seas shelves should be interpreted as coastally trapped flows whose source is the downstream tsushima strait numerical model experiments incorporating the realistic topography also simulate the observed flow fields the volume flux through each strait being limited geostrophically relations between the sea level difference and volume transport can be represented by simple formulas

gpr and aerial imageries to identify the recent historical course of the obra river and spatial extent of obrzanskie lake altered by hydro technical works ground penetrating radar gpr measurements have been conducted to retrace the natural course of the obra river and changes of spatial extent of obrzanskie lake western poland the obra river valley was subjected to intensive anthropogenic transformation three artificial canals were constructed here in the beginning of the nineteenth century the gpr surveys were done using a georadar mala proex equipped with 250 mhz antenna the measurement was verified by coring and analyses of historical maps aerial photographs and satellite images the research has shown that there are at least three elongated depressions preserved in the modern land surface near the village of solec situated in the middle course of the valley several structures suggesting functioning of a multi channel pattern in the past have been detected inside and in the vicinity of the depressions filling the channels with silts and peats might have been the effect of flow deceleration caused by the construction of the obra canals moreover situation of two of the retraced depressions suggests that the landforms might be the remains of a river bed disappearing in wetlands further studies including groundwater flux measurements in the area between the depressions are needed to confirm such hypothesis furthermore the study allowed retracing the spatial extent of obrzanskie lake the sediment structures detected by the gpr measurements and calibrated with coring were interpreted to be the traces of the lake shoreline the interpretation was supported by the findings inferred from aerial and satellite images it was shown that obrzanskie lake had had at least three islands and had been directly connected with a network of braided channels before the anthropogenic intervention the spatial extent of the lake was significantly altered by the construction of the north obra canal disconnecting the lake from the canal resulted in more than 50 decrease of the lake surface

northward flow in the bering and chukchi seas the ocean circulation on the bering and chukchi sea shelves is investigated using a barotropic numerical model in the presence of the winter seasonal wind stress from the northeast observed northward transport through bering strait of 0 6 sv for the 8 month winter season 1981 1982 can be driven by a sea level difference of 0 4 m between the pacific and arctic oceans this sea level difference between basins is in agreement with hydrographic estimates in the absence of wind stress a 0 4 m sea level difference drives a northward transport through bering strait of 1 1 sv maximum transport through bering strait is geostrophically limited not frictionally or inertially limited major qualitative circulation features of the region are evident in the simulations westward intensification of the northward transport across the bering sea shelf is confirmed with the major transport occurring in the relatively deep gulf of anadyr in the absence of wind anadyr strait contributes 72 of the northward transport through bering strait with northeasterly winds there is a net clockwise circulation around saint lawrence island within the 20 m isobath norton and kotzebue sounds are little influenced by the general circulation northward transport in the chukchi sea bifurcates in the vicinity of point hope the predominant branch is directed toward the northwest in a broad canyon feature south of herald shoal and the balance becomes the alaskan coastal current between cape lisburne and point barrow

long shelf waves generated by a coastal flux solutions are presented for the shelf response of barotropic and stratified oceans to an oscillatory coastal flux through a strait the flux is modeled as the return interior flow due to an ekman transport that arises from a fictitious square wave longshore wind stress the width 2 d of the square wave stress is taken to be that of the strait and the response due to the coastal flux determined from longwave wind forced solutions that exist in the literature the net longshore energy flux for the nth strait forced shelf wave mode wave number kn is shown to be proportional to u2 bnsin knd knd 2 where u2 is the coastal flux spectrum and bn the modal wind coupling coefficients results compare favorably with existing barotropic theories and estimates of net longshore energy flux obtained for the australian coastal experiment region are shown to be in reasonable agreement with observations at periods of 9 days when forcing by bass strait is assumed greatest

a 9000 year record of vertical and lateral accretion on the floodplain of the lower thames river southwestern ontario canada and implications for archaeological research abstract results of ground penetrating radar and grain size analysis of sediments from three 5 7 m long cores generally support a classic fining up point bar model of floodplain development on a reach of the lower thames river a single thread meandering channel that flows southwest into lake st clair bankfull discharge 411 m3 s 1 four radiocarbon dates on organic material recovered from cores indicate that floodplain development in this reach occurred over at least the past 9000 years these results are not typical for southern ontario channels previous studies have shown that some other large rivers in southern ontario have low energy cohesive bank channels with floodplains strongly dominated by vertical accretion the distribution of culturally diagnostic archaeological artifacts on the floodplain surface dating back to the middle archaic period but mostly confined to the early woodland period or later suggests that human settlement of the floodplain was restricted to the later holocene the observation that a middle archaic site component is located in what should be a younger part of the floodplain challenges the notion that a simple lateral channel migration occurred with orderly channelward emplacement of sediment by the river there is a possibility that the channel was anabranching in this reach of the river

ground penetrating radar for high resolution mapping of soil and rock stratigraphy ground penetrating radar is a technique which offers a new way of viewing shallow soil and rock conditions the need to better understanding overburden conditions for activities such as geochemical sampling geotechnical investigations and placer exploration as well as the factors controlling groundwater flow has generated an increasing demand for techniques which can image the subsurface with higher resolution than previously possible the areas of application for ground penetrating radar are diverse the method has been used successfully to map ice thickness water depth in lakes bedrock depth soil stratigraphy and water table depth it is also used to delineate rock fabric detect voids and identify karst features the effective application of the radar for the high resolution definition of soil stratigraphy and fractures in bedrock is highlighted the basic principles and practices involved in acquiring high quality radar data in the field are illustrated by selected case histories one example demonstrates how radar has been used to map the bedrock and delineate soil horizons to a depth of more than 20 m two case histories show how radar has been used to map fractures and changes of rock type to 40 m range from inside a mine another case history demonstrates how radar has also been used to detect and map the extent of groundwater contamination the corroboration of the radar results by borehole investigations demonstrates the power and utility of the high resolution radar method as an aid for interpolation and extrapolation of the information obtained with conventional coring programmes with the advent of new instrumentation and field procedures the routine application of the radar method is becoming economically viable and the method will see expanded use in the future

a multiscale radar stratigraphic analysis of fluvial aquifer heterogeneity the objective of this study is to use an integrated and multiscale exploration approach to quantify the geometrical parameters that are needed to predict block hydraulic conductivity tensors within fluvial deposits we use 3 d ground penetrating radar gpr data electromagnetic em surveys resistivity soundings and hand augered borings to characterize the 3 d architecture of fluvial deposits on a floodplain of the piscatiquis river near south sebec maine field scale surveys made across the entire floodplain were used to map the depth to the glacially eroded bedrock surface and the thickness of the overlying sediments which consist of glaciomarine clay fluvial sands and silts and overbank deposits an em conductivity anomaly in the center of the floodplain defines the position of a ridge in the glaciomarine clay deposit this ridge separates horizontally bedded sand and silt deposits in the northern half of the floodplain from inclined point bar sand and silt deposits in the southern half of the

high resolution subsurface gpr imaging and sedimentology of coastal ponds maine u s a implications for holocene back barrier evolution ground penetrating radar gpr transects and sediment cores have been used to examine the basement morphology stratig raphy and environmental history of maritime ponds along the pen insular coast of maine silver lake lily pond and north pond are shallow 3 m water bodies bordered by steep bedrock ridges in the north east and west and sandy barriers to the south the bedrock basins of the ponds are formed in metasedimentary rocks surrounded by resistant pegmatitic intrusions a dense network of gpr traverses obtained over the ice covered silver lake reveals a series of prominent wavy parallel and basin fill reflector geometries terminating against the bedrock or grading into the barrier sediments and interpreted as organic lake bottom facies the transparent units represent sand rich horizons mostly eolian in origin convex up structures found both on the surface and within the basin fill sequence are interpreted as pre served parts of coastal dunes the present study indicates that fresh water conditions prevailed since at least 4 6 ka with an initial sedi mentation rate of 1 7 mm yr the position of this unit below the con temporary sea level suggests presence of a welded barrier by that time radar profiles taken along the shores of lily pond a small water body behind the sand dune barrier indicate a significantly larger areal extent of the pond in the past a succession of organic deposits over lying a pleistocene glaciomarine unit indicates progressive inundation of the paleo lagoon by rising sea level saltwater peat seaward of lily pond was buried by washover sands about 1 2 ka and a narrow pond existed here prior to dredging and artificial infilling of its eastern part in the 1950s 60s the organic and eolian units are absent in the north pond where sedimentary fill consists of glaciomarine clay overlain by marine sands a proposed three stage model of pond evolution along an embayed coastline consists of 1 organic accumulation in an up land depression during lower sea level 2 predominantly washover or tidal deposition in a lagoon stage 2a or blocked coastal pond stage 2b during initial transgression and 3 mainly eolian and organic de position behind a prograded or aggraded barrier future accelerated rise in relative sea level and inadequate sediment supply will cause many back barrier ponds to reenter stage 2 of the proposed model

the hydrological response of soil surfaces to rainfall as affected by cover and position of rock fragments in the top layer rainfall experiments have been conducted in the laboratory in order to assess the hydrological response of top soils very susceptible to surface sealing and containing rock fragments in different positions with respect to the soil surface for a given cover level rock fragment position in the top soil has an ambivalent effect on water intake and runoff generation compared to a bare soil surface rock fragments increase water intake rates as well as time of runoff concentration and decrease runoff volume if they rest on the soil surface for the same cover level rock fragments reduce infiltration rate and enhance runoff generation if they are well embedded in the top layer the effects of rock fragment position on infiltration rate and runoff generation are proportional to cover percentage micromorphological analysis and measurements of the saturated hydraulic conductivity of bare top soils and of the top layer underneath rock fragments resting on the soil surface reveal significant differences supporting the mechanism proposed by poesen 1986 i e runoff generated as rock flow or as horton overland flow can partly infiltrate into the unsealed soil surface under the rock fragments provided that they are not completely embedded in the top layer hence rock fragment position beside other rock fragment properties should be taken into account when assessing the hydrological response of soils susceptible to surface sealing and containing rock fragments in their surface layers a simple model based on the proportions of bare soil surface soil surface occupied by embedded rock fragments and soil surface covered with rock fragments resting on the soil surface describes the runoff coefficient data relatively well

architecture of the lower terraces and evolution of the dordogne river at bergerac southwest france during the last glacial interglacial cycle the lower terraces of the dordogne river at bergerac south west france were studied in detail using cores trenches ground penetrating radar profiles and 14 c optically stimulated luminescence and infrared stimulated luminescence dating this study shows that the lowest terrace fx is made up of two major lithostratigraphic units i dominantly horizontal gravel strata interpreted as compound bar deposits in a braided river which pre date 18 17 ka and ii thick lateral accretion gravel units point bars formed in an anabranching river during the late pleniglacial and lateglacial most of the anabranching channels were abandoned at ca 11 10 ka following shrinkage of the river bed into a single meandering channel and were partially filled by gyttjas during the boreal chronozone finally the channels were plugged by overbank fines until about 5 ka floods seldom reached the fx terrace during the late holocene and accretion became negligible the main phase of bedrock incision spanned the holocene whereas the period of channel adjustment to change in river regime during late marine isotope stage mis 2 only led to a redistribution of the pleniglacial gravels the higher terrace fw3 formed before the eemian and was covered by colluvial fans mainly during mis 2 and 3

pycnobathic currents over the upper continental slope abstract the dynamic interaction of a sloping seafloor with along isobath density variation is calculated for cases involving a sharp pycnocline and a surface to bottom front pycnocline depth is supposed to vary in the alongshore direction only over a sloping plane seafloor the bottom trace of the surface to bottom front is supposed to cut across isobaths the calculations are diagnostic and make use of linearized equations with a linear bottom friction term the results illustrate the manner in which cross isobath baroclinic flow is converted at the slope into a barotropic flow field with velocities nearly parallel to the isobaths the forward portion of the slope that which lies in the direction of kelvin wave propagation only is affected if there is only one inflow or outflow region however for equal and opposite inflow and outflow a closed circulation pattern arises connecting these two regions accompanied by a secondary closed circulation cell forward of both the inflow and outflow legs