onset of recent rapid sea level rise in the western atlantic ocean a high resolution record of sea level change spanning the past 1000 years is derived from foraminiferal and chronological analyses of a 2 m thick salt marsh peat sequence at chezzetcook nova scotia canada former mean tide level positions are reconstructed with a precision of 0 055 m using a transfer function derived from distributions of modern salt marsh foraminifera our age model for the core section older than 300 years is based on 19 ams 14c ages and takes into account the individual probability distributions of calibrated radiocarbon ages the past 300 years is dated by pollen and the isotopes 206pb 207pb 210pb 137cs and 241am between ad 1000 and ad 1800 relative sea level rose at a mean rate of 17 cm per century apparent pre industrial rises of sea level dated at ad 1500 1550 and ad 1700 1800 cannot be clearly distinguished when radiocarbon age errors are taken into account furthermore they may be an artefact of fluctuations in atmospheric 14c production in the 19th century sea level rose at a mean rate of 1 6 mm yr between ad 1900 and ad 1920 sea level rise accelerated to the modern mean rate of 3 2 mm yr this acceleration corresponds in time with global temperature rise and may therefore be associated with recent global warming 2005 elsevier ltd all rights reserved

coupling instrumental and geological records of sea level change evidence from southern new england of an increase in the rate of sea level rise in the late 19th century 1 we construct a high resolution relative sea level record for the past 700 years by dating basal salt marsh peat samples above a glacial erratic in an eastern connecticut salt marsh to test whether or not the apparent recent acceleration in the rate of sea level rise slr is coeval with climate warming the data reveal an average slr rate of 1 0 0 2 mm year from about 1300 to 1850 a d coupling of the regional tide gauge data 1856 to present with this marsh based record indicates that the nearly three fold increase in the regional rate of slr to modern levels likely occurred in the later half of the 19th century thus the timing of the observed slr rate increase is coincident with the onset of climate warming indicating a possible link between historic slr increases and recent temperature increases

relative sea level rise and climate change over the last 1500 years we constructed a detailed relative sea level rise curve for the last 1500 years using a novel approach i e charting the rate of relative sea level rise using microfaunal and geochemical data from a coastal salt marsh sequence clinton ct usa the composition of benthic foraminiferal assemblages and the iron abundance in peats were used to describe shifts in marsh environment through time quantitatively the resulting sea level rise curve with age control from 14c dating and the onset of anthropogenic metal pollution shows strong increases in the rate of relative sea level rise during modern global warming since the late nineteenth century but not during the little climate optimum ad 1000 1300 there was virtually no rise in sea level during the little ice age ad 1400 1700 most of the relative sea level rise over the last 1200 years in clinton appears to have occurred during two warm episodes that jointly lasted less than 600 years changes from slow to fast rates of relative sea level rise apparently occurred over periods of only a few decades we suggest that changes in ocean circulation could contribute to the sudden increases in the rate of relative sea level rise along the northeastern usa seaboard relative sea level rise in that area is currently faster than the worldwide average which may result partially from an ocean surface effect caused by hydrodynamics our data show no unequivocal correlation between warm periods on a decaal to centennial time scale and accelerated sea level rise one period of acclerated sea level rise may have occurred between about ad 1200 and 1450 which was the transition for the little climate optimum to the little ice age i e a period of cooling at least in northwestern europe local changes in tidal range might also have contributed to this apparent increase in the rate of relative sea level however the second period of accelerated sea level rise occurred during the period of modern global warming that started at the end of the last century

joint inversion of seismic and magnetotelluric data in the parkfield region of california using the normalized cross gradient constraint we present jointly inverted models of p wave velocity vp and electrical resistivity for a two dimensional profile centered on the san andreas fault observatory at depth safod significant structural similarity between main features of the separately inverted vp and resistivity models is exploited by carrying out a joint inversion of the two datasets using the normalized cross gradient constraint this constraint favors structurally similar vp and resistivity images that adequately fit the seismic and magnetotelluric mt datasets the new inversion code tomoddmt merges the seismic inversion code tomodd and the forward modeling and sensitivity kernel subroutines of the mt inversion code occam2dmt tomoddmt is tested on a synthetic dataset and demonstrates the code s ability to more accurately resolve features of the input synthetic structure relative to the separately inverted resistivity and velocity models using tomoddmt we are able to resolve a number of key issues raised during drilling at safod we are able to infer the distribution of several geologic units including the salinian granitoids the great valley sequence and the franciscan formation the distribution and transport of fluids at both shallow and great depths is also examined low values of velocity resistivity attributed to a feature known as the eastern conductor ec can be explained in two ways the ec is a brine filled high porosity region or this region is composed largely of clay rich shales of the franciscan the eastern wall which lies immediately adjacent to the ec is unlikely to be a fluid pathway into the san andreas fault s seismogenic zone due to its observed higher resistivity and velocity values

drawdown and stream depletion induced by a nearby pumping well summary this study derives two dimensional analytical solutions for drawdown and stream depletion resulting from a pumping well near a stream the solutions were obtained for both line width and finite width streams in unconfined confined aquifers based on the principle of superposition these solutions are general enough to be used for different hydrogeological settings within both unconfined and confined aquifers results of analytical solutions for both drawdown and stream depletion were checked against results obtained using numerical models for confined unconfined aquifer it has been found that both line width and finite width stream depletion results are close to numerical results but the finite width stream solution has less error drawdown results show that the line width stream solution slightly over estimates the drawdown and the finite width stream solution has a good match with the numerical drawdown results the error in drawdown results is directly proportional to the increase in stream width but is higher in the case of a line width stream

stream depletion rate for a radial collector well in an unconfined aquifer near a fully penetrating river the stream depletion rate sdr is computed for a radial collector well installed in a semi infinite anisotropic homogeneous unconfined aquifer near a fully penetrating stream with a streambed with reduced conductivity for small pumping rates dimensional analysis and other arguments allow the sdr to be expressed as a function of eight parameters that describe the effect of properties of the aquifer and streambed as well as the configuration and placement of the well the calculations employ some results from huang et al 2012 j hydrol who expressed the sdr as a quintuple integral but by computing four of the integrals analytically the present solution requires less computational effort analytical calculation shows that the sdr in steady state does not depend on the streambed properties or any other parameters given enough time the flow through the streambed will equal the pumping rate of the well values of sdr are supported by comparing to previous solutions for special cases corresponding to appropriate limiting values of the parameters effects of the eight dimensionless parameters are studied systematically the properties of the streambed anisotropy of the aquifer and the position of the well affect the sdr more strongly than the orientation length and depth of the laterals

relative sea level rise across the eastern border fault branford connecticut evidence against seismotectonic movements abstract basal peat age depth data from four salt marsh sites located 500 1500 m south of the eastern border fault ebf near branford connecticut document an error envelope for the lower limit of relative mean high water mhw rise during the past 3300 yr the long term rate of relative lower limit mhw rise during the past 3000 yr 1 1 mm yr 1 corresponds with late holocene rates of relative mhw rise found elsewhere in coastal connecticut 0 9 1 2 mm yr 1 this result invalidates repeated claims that multiple seismotectonic lowering of a crustal block towards the south has occurred along a segment of the ebf near branford shortly after 815 cal yr bc and during the past 1200 yr and calls for a non tectonic interpretation of biostratigraphic evidence of local short term sea level variations

magnetotelluric evidence for thick skinned tectonics in central taiwan taiwan is the type example of an arc continent collision numerous tectonic models have been proposed for this orogen and include both thin skinned and thick skinned lithospheric deformation these models predict very different structures at middle and lower crustal depths but insuffi cient geophysical data exist to unequivocally distinguish between them long period magnetotelluric mt data were collected in central taiwan in 2006 2007 to constrain the crustal resistivity structure a two dimensional inversion of these mt data revealed a prominent electrical conductor that extends across the decollement predicted by the thin skinned model this feature is interpreted to be due to 1 2 saline fl uids and is inconsistent with the thin skinned model in contrast the thick skinned model predicts this feature since fl uids are generated in the crustal root through metamorphism quantitative correlation of the resistivity and seismic velocity models supports small volume high salinity fl uids in a thickened crust as the cause of this conductor

the effects of pore fluid salinity on ultrasonic wave propagation in sandstones petrophysical interpretation of increasingly refined seismic data from subsurface formations requires a more fundamental understanding of seismic wave propagation in sedimentary rocks we consider the variation of ultrasonic wave velocity and attenuation in sandstones with pore fluid salinity and show that wave propagation is modified in proportion to the clay content of the rock and the salinity of the pore fluid using an ultrasonic pulse reflection technique 590 890 khz we have measured the p wave and s wave velocities and attenuations of 15 saturated sandstones with variable effective pressure 5 60 mpa and pore fluid salinity 0 0 3 4 m in clean sandstones there was close agreement between experimental and biot model values of dvp dm but they diverged progressively in rocks containing more than 5 clay however this effect is small vp changed by only 0 6 per molar change in salinity for a rock with a clay content of 29 the variation of vs with brine molarity exhibited biot behavior in so

north atlantic climate ocean variations and sea level in long island sound connecticut since 500 cal yr a d abstract a record of detrended mean high water mhw variations from hammock river marsh connecticut is extended from ca 850 to ca 500 cal yr a d and correlated with summer temperature reconstructions from northern fennoscandia and northern eurasia greenland ice sheet project 2 18 o and greenland ice core project borehole temperature variations from central greenland a sargasso sea sea surface temperature sst record and a proxy record for deep ocean flow south of iceland the records from northern fennoscandia eurasia and central greenland document century scale intervals of warming four and cooling three since ca a d 850 the mhw fluctuations lag behind these climate intervals by 0 100 yr with the two larger mhw rises corresponding to the two larger temperature increases this positive correlation suggests that surface air temperature sat is a dominant variable controlling sea level in the northwestern north atlantic since ca a d 850 the sst variations parallel the mhw fluctuations back to ca 950 cal yr a d a positive correlation is found also for sub century scale sat and mhw variations during the period a d 500 850 but this result is less firm mhw sst correlation over this time interval is not consistent

historical development of the saltmarsh at wells maine comparisons of maps and aerial photographs dating from the late 1700s to the present document the recent development of an 8 km2 saltmarsh that is situated behind a barrier spit in southern maine tidal channels that were relatively narrow in 1794 became wider by 1872 the reduction of marsh bordering tidal channels is interpreted as evidence that marsh accretion could not keep pace with rising sea level this suggests that the rate of sea level rise had increased although a change in discharge or sediment load caused by extensive settlement and land clearance may also have been involved meander patterns of the tidal streams changed considerably throughout the time period covered by the maps demonstrating that the streams of this marsh are more dynamic than some others that have been widely reported in the literature these differences in stream dynamics are probably related to the differences in sedimentological structure of the marshes between 1872 and 1956 the barrier spit eroded on its inside shoreward edge probably in response to the construction of riprapping and houses along the spit and the subsequent reduction of overwash and aeolian transport of sediment modification of the tidal inlet and adjacent marsh during the 1960s including jetty construction dredging and filling of portions of the marsh surface affected the marsh only locally one tidal stream has been migrating rapidly apparently in response to compaction of peat by dredge spoils and consequent local disruption of the marsh hydrology except for this migration erosion of the marsh edge occurred immediately after the inlet modifications planimetric changes in the marsh and its streams have been minor since then

sea level variability in the northwest atlantic during the past 1500 years a delayed response to solar forcing 1 numerical experiments with a coupled oceanatmosphere model ecbilt have shown that centennial variations in sea level sl in the northwest atlantic may be associated with deep ocean salinity anomalies generated by solar forced variations in the north atlantic overturning circulation here we compare simulated sl curves for the gulf stream region with reconstructed late holocene sl records from connecticut usa simulated sl variations lag the solar forcing record by ca 120 year this lag is found to be robust over a small number of different experiments the reconstructed sl curves visually match the solar forcing optimally when lagging it by ca 125 yr a quantitative test shows that the correlation is significant while this result is not sensitive to dating uncertainties the temporal response pattern of the simulated sl curves compares reasonably well with the reconstructions index terms 4556 oceanography physical sea level variations 1650 global change solar variability 4255 oceanography general numerical modeling 4267 oceanography general paleoceanography 3030 marine geology and geophysics micropaleontology citation van de plassche o g van der schrier s l weber w r gehrels and a j wright sea level variability in the northwest atlantic during the past 1500 years a delayed response to solar forcing geophys res lett 30 18 1921 doi 10 1029 2003gl017558 2003

the interaction between the unsaturated zone aquifer and stream during a period of groundwater withdrawal summary by combining laboratory and field experiments we study the release of water from above a falling water table and the implications this has on pumping test analysis and prediction of stream depletion undisturbed core samples from the field site were used in laboratory experiments to measure drainage responses to water table drawdown the responses can be sufficiently modeled by estimating the specific yield and five exponential time constants of a moench boulton type model of delayed drainage the average specific yield is thus estimated to 0 24 which is in agreement with previous small scale and large scale estimates in addition two pumping tests were conducted near the stream the drawdown analysis was made using a 3d numerical groundwater flow model facilitating use of the moench boulton type boundary condition at the water table the drawdown observations were fitted by calibrating two alternative models one simulating the release of water at the water table as instantaneous the other simulating the release of water as delayed comparing the calibration results for the two alternative models showed that they fit the drawdown observations nearly equally well and most estimated parameter values are realistic and nearly identical however estimation of the specific yield is found to be sensitive to whether drainage is modeled as instantaneous or as delayed in the first case the estimated specific yield is about half of the estimate from the core experiments and of the previous estimates in the second case the estimate 0 17 is in better agreement with core and previous estimates 0 24 the analysis indicates that relatively fast drainage and the existence of two drawdown dependent sources of groundwater recharge the storage and the stream complicates pumping test design to obtain unique parameter estimation the analysis supports that an essential factor in parameter estimation by pumping test analysis for at least some unconfined aquifers is the use of a model that accounts for time varying drainage from the vadose zone finally when predicting stream depletion beyond 1 day of pumping it is acceptable in the present case to use a model simulating drainage as instantaneous if unbiased parameter estimates are used

distribution of modern salt marsh foraminifera in the albemarle pamlico estuarine system of north carolina usa implications for sea level research abstract we described the distributions of foraminifera from ten physiographically distinct salt marshes in the albemarle pamlico estuarine system north carolina using 193 surface samples we defined elevation dependent ecological zones at individual sites using cluster analysis and detrended correspondence analysis additionally seven principal biozones of salt marsh foraminifera were identified that have distinctive spatial distributions reflecting a pattern of salinity regimes caused by the current configuration of barrier island inlets high salinity sites along the southern outer banks are associated with sub tidal calcareous assemblages low marshes dominated by miliammina fusca and high marsh environments defined by haplophragmoides wilberti trochammina inflata and arenoparrella mexicana in contrast lower salinity marshes have ammobaculites spp in sub tidal settings miliammina fusca dominated low marshes and high marsh settings characterized by jadammina macrescens spatial variation of foraminiferal populations and the potential for biozones to migrate in response to changing inlet configuration and salinity suggests that datasets of modern salt marsh foraminifera from multiple environments would be appropriate for reconstructing holocene relative sea level in north carolina

effects of fluid viscosity on shear wave attenuation in saturated sandstones measurements of shear wave velocity and attenuation as a function of temperature were made in the kilohertz frequency range in sandstones saturated with various liquids for sandstones partially saturated with glycerol two attenuation peaks are observed between 80 c and 100 c they are attributed to viscous shear relaxation and squirt flow for fully water saturated berea sandstone the attenuation decreases as the crack density increases the displacement of the squirt peak caused by the increase of the central aspect ratio of cracks is at the origin of this decrease a simple viscoelastic model based on the model of o connell and budiansky using a cole cole distribution of cracks is proposed for calculation of the shear modulus of fluid saturated rocks this model interprets the experimental data satisfactorily the data suggest that the shear attenuation and velocity are controlled by the distribution of crack aspect ratios

sea level climate correlation during the past 1400 yr we present a new mean high water curve for hammock river marsh clinton connecticut obtained by improving the age model for an existing record of relative marsh elevation based on foraminiferal analysis of a 1 8 m long peat core unlike the earlier curve the new curve confirms trend changes in mean high water rise during the past 1400 yr as noted for salt marshes 15 km farther west suggesting a regional cause these trend changes and century scale mean high water variations in the clinton record correlate positively with large scale regional variations in sea surface and summer air temperature indicating a link between sea level and the climate ocean system on the basis of the clinton mean high water curve we conclude that real sea level oscillated centimeters to decimeters on a century time scale over the past 1400 yr was 25 25 cm higher ca a d 1050 medieval warm period than ca a d 1650 little ice age and rose at a mean rate of 1 mm yr 1 over the past 350 yr there was little or no rise during the cool 1800s

velocities and quality factors of sedimentary rocks at low and high effective pressures summary techniques for measuring acoustic velocities and quality factors q of sedimentary rocks in the laboratory are sufficiently accurate to establish closely fitting regression curves which represent the variation of these acoustic properties with pressure ultrasonic p and s wave measurements of velocity v v and q q q were made on 16 different water saturated sandstone samples at various effective pressures using an ultrasonic reflection technique and the data were fitted using a simple regression equation containing a constant plus linear and exponential pressure dependent terms the redundancy of the linear term in the regression of q data suggests that microcracks alone govern the pressure variation of q whereas velocities are additionally dependent on another mechanism consistent with the changes in elastic moduli caused by intergranular compression causing small reductions in porosity the implied rates of microcrack closure with increasing effective pressure in all samples were found to be comparable the regression equations describe the data closely enough to enable the extrapolation of acoustic properties to both low and high effective pressures this is of practical use since laboratory techniques can produce uncertain results at low pressures due to coupling problems and low signal strengths whilst high pressures require large confining vessels low pressure and high pressure data are applicable to shallow seismic surveys and hydrocarbon exploration respectively

stream depletion rate and volume from groundwater pumping in wedge shape aquifers in river basins with several tributaries wells in alluvial valleys are often located near the wedge shaped confluence of two tributaries therefore stream depletion characteristics namely stream depletion rate sdr and stream depletion volume sdv induced by the pumping wells are distributed between two tributaries upstream from the confluence existing methods for the evaluation of stream depletion characteristics are applicable only for a wedge shaped aquifer with special or uncommon wedge angles or for steady state conditions in water resources management temporal stream depletion characteristics are important for the adjudication of water rights a new and practically important method for analytical evaluation of transient sdr and sdv is developed for a wedge shaped aquifer with arbitrary wedge angles results are obtained for each of two tributaries or the tributary segment lengths a simple expression for the sdr fraction that originates from each tributary is presented for long period of pumping after which 100 of the pumping rate is supplied by stream depletion the sensitivity analyses for different parameters are performed to examine their affects on the influence period of the total sdr and the results indicated that the sdr is sensitive to the angles of wedge shaped aquifer and the pumping well the results and sensitivity analysis presented in this study may provide useful information in the assessment of water balance or exploitation of river basins

tide induced groundwater level fluctuation in a u shaped coastal aquifer summary the prediction of groundwater level fluctuation due to tidal waves propagation in coastal aquifers is important for the planning and management of water resources in coastal areas a two dimensional 2 d analytical solution is derived to describe the tidal groundwater fluctuation in an aquifer bounded by three water land boundaries that form a u shaped coastline two opposite sides represent estuary land boundaries on which the amplitude attenuation and phase shift of the tidal movement in the estuary are considered while the third side is an ocean land boundary the effects of wave interaction due to the propagation of oscillating oceanic tides in the cross shore direction inland and the transmission of the two opposite estuarine tides in the along shore direction are investigated three existing head fluctuation solutions can be considered as special cases of the present solution one is for one dimensional flow and the other two are for 2 d flow a transition distance ranging from 10 to 15 times of tidal propagation length along the shoreline can be estimated based on the solution this distance can be used to judge whether the interaction among tides is significant the influences of hydraulic properties on the tidal fluctuations within the aquifer can therefore be assessed quantitatively based on sensitivity analyses one can conclude that the tidal head is most sensitive to the transmissivity and storativity of the aquifer and least to the damping coefficient of tidal amplitude and wave number along the estuary the sensitivities of head fluctuation to the changes of transmissivity and storativity depend on the shoreline length and whether the interaction among waves is significant on the other hand the sensitivities of head fluctuation to the changes of damping coefficient and wave number increase with diagonal distance from the entry of estuary and reach the largest magnitude near the estuary far away seashore

rapid sea level rise in the gulf of maine usa since ad 1800 two sea level records from salt marshes in coastal maine are derived from foraminiferal analyses and ams 14 c 210 pb 137 cs and pollen chronology both records cover the period from ad 800 until the present and show corresponding patterns of sea level change when corrected for trends which could accommodate millennial scale isostatic adjustments the records provide a detailed sea level chronology for the last few centuries and thus link the instrumental tide gauge record with the long term geological record of sea level change results show that sea level was relatively stable between ad 800 and 1300 and reached a lowstand around ad 1800 which was preceded by an oscillation in the eighteenth century since ad 1800 sea levels in the gulf of maine have risen by 0 3 0 4 m the onset of this rise corresponds with regional climatic warming and could be interpreted as thermal expansion of the gulf of maine and north atlantic sea surface sea level rise possibly slowed temporarily during the mid nineteenth century but twentieth century rates are unprecedented in the last millennium and correspond with hemispheric warming

magnetotelluric imaging beneath the taiwan orogen an arc continent collision 1 the taiwan orogen has formed since the late miocene by oblique collision between the luzon volcanic arc on the philippine sea plate and the eurasian continental margin this oblique collision has produced an orogen that decreases in age from north to south and permits study of the temporal evolution of an arc continent collision these factors make taiwan a favorable location to study the process of arc continent collision the first long period magnetotelluric mt measurements were recorded in taiwan as part of the taiwan integrated geodynamics research taiger project in 2006 7 measurements were made at 82 sites on three transects across south central and north taiwan that span the breadth of the orogen and cross all major tectonic boundaries robust remote reference processing of the mt time series data resulted in high quality soundings that were modeled in both 2 and 3 dimensions these mt models support predictions of lithospheric deformation i e thick skinned tectonics beneath the central ranges in south and central taiwan but are inconsistent with predictions of orogen scale thin skinned models the mt resistivity model for northern taiwan is consistent with dewatering of the subducting philippine slab and with deformation described by the subducting indenter tectonic model modeling the taiger mt data has definitively shown that conductive and seismically active crustal structures exist to 30 km beneath the orogen these conductive regions interpreted as interconnected fluid map pervasive zones of collisional deformation that are lithospheric in scale

variation in dynamic elastic shear modulus of sandstone upon fluid saturation and substitution experimental acoustic measurements on sandstone rocks at both sonic and ultrasonic frequencies show that fluid saturation can cause a noticeable change in both the dynamic bulk and shear elastic moduli of sandstones we observed that the change in dynamic shear modulus upon fluid saturation is highly dependent on the type of saturant its viscosity rock microstructure and applied pressures frequency dispersion has some influence on dynamic elastic moduli too but its effect is limited to the ultrasonic frequency ranges and above we propose that viscous coupling reduction in free surface energy and to a limited extent frequency dispersion due to both local and global flow are the main mechanisms responsible for the change in dynamic shear elastic modulus upon fluid saturation and substitution and we quantify influences

the process of sedimentation on the surface of a salt marsh abstract an unditched salt marsh creek drainage basin holland glade marsh lewes delaware has a sedimentation rate of 0 5 cm year 1 during normal storm free conditions the creek carries negligible amounts of sand and coarse silt of the material in the waters flooding the marsh surface over 80 disappears from the floodwaters within 12 m of the creek about one half of the lost material is theoretically too fine to settle even if flow were not turbulent however sediment found on spartina stems can account for the loss the quantity of suspended sediment that does reach the back marsh during these normal tides is inadequate to maintain the marsh surface against local sea level rise this suspended sediment is also much finer than the deposited sediments additionally remote sections of low marsh sections flooded by only the highest spring tides have 15 30 cm of highly inorganic marsh muds this evidence indicates that normal tidal flooding does not produce sedimentation in holland glade study of the effects of two severe storms of a frequency of once per year suggests that such storms can deposit sufficient sediment to maintain the marsh the actual deposition of fine grained sediments fine silt and clay appears to result primarily from biological trapping rather than from settling in addition this study proposes that the total sedimentation on mature marshes results from a balance between tidal and storm sedimentation storms will control sediment supply and movement on micro and meso tidal marshes and will have less influence on macro tidal marshes

stream depletion predictions using pumping test data from a heterogeneous stream aquifer system a case study from the great plains usa abstract this uniquely designed study investigates a fundamental issue the feasibility of predicting stream depletion rates using linear uniform two dimensional models required input for these models includes the hydraulic parameter estimates of the aquifer and the stream aquifer interface which may be obtainable through pumping test data analysis this study utilizes pumping test data collected near the naturally meandering prairie creek platte river watershed nebraska usa drawdown data were obtained in eight piezometer clusters located on both sides of the stream each containing three piezometers screened at different aquifer depths parameter estimates and thus stream depletion predictions varied over a wide range large parameter variance and a low degree of goodness of fit between the calculated and measured data encountered during the analysis suggest deficiencies of the uniform aquifer models in describing significant physical processes this was also shown by additional field experiments that indicate lateral and vertical aquifer heterogeneity hydrogeological and sedimentological considerations of the meandering stream architecture point bar versus cut bank and the application of a linear piecewise homogeneous model yielded a higher degree of goodness of fit and higher confidence in stream depletion predictions aquifer heterogeneity appears to be the major reason for uncertainty in stream depletion predictions though other possible sources of uncertainty should be considered these include the model linearity the dupuit assumption the simplified representation of the stream aquifer interface the approximation of the stream as a straight line or a strip and the impact of regional groundwater flow

palaeoenvironment palaeoclimate and sea level changes in the shuaiba lagoon during the late holocene last 3 6 ka eastern red sea coast saudi arabia multi proxy investigations of sediment lithology geochemistry benthic foraminifera and 18o and 13c of elphidium striatopunctatum were carried out on a sediment core shua3 2 2 m long spanning

centennial scale cycles in middle holocene sea level along the southeastern swedish baltic coast submerged sea grasses and stoneworts growing in the immediate nearshore of the baltic sea are sensitive indicators of sea level the alternating changes in concentrations of sea grass and stonewort macrofossils obtained from an ancient lagoon of the baltic sea are ascribed to middle holocene sea level fluctuations along the southeastern swedish coast abundances of stonewort and sea grass macrofossils between 7500 and 6000 cal calibrated yr b p were lower and less variable indicating high and relatively stable sea level low frequency fluctuations of sea level with a 1470 yr period during this time may have been forced by tidal action in the millennial band after 6000 cal yr b p sea level was lower and exhibited strong fluctuations at centennial time scales as evident in the stonewort and sea grass macrofossil records such a high frequency oscillatory mode of sea level may have been regulated by centennial scale solar activities or tidal actions or both the modest variation in solar irradiance is unlikely to have resulted in large scale oscillations of sea level by directly changing the steric component instead it governed sea level fluctuations by changing the regional storminess through a north atlantic oscillation nao like system storms embedded in the nao induced southwesterly winds played a major role in the centennial scale fluctuations of the baltic sea level by pushing saltwater from the north sea into the baltic basin less

flow to a well in an unconfined fractured and leaky wedge shaped aquifer system abstract wedge shaped aquifers are usually formed where two linear boundaries intersect these types of aquifers are commonly seen in river basins and alluvial fans but have received much less attention in the hydrological sciences community fundamental understanding of the effects of lateral boundaries on the hydrodynamic process in such aquifers is quite poor particularly for unconfined fractured and leaky wedge shaped aquifer systems which will be the concern of this study solutions of flow to a well in an unconfined fractured wedge shaped two aquifer system are obtained using laplace hankel and fourier transforms an infinitesimal radius pumping well partially penetrates the overlying unconfined aquifer both aquifer layers are homogeneous and anisotropic bounded by two intersecting linear lateral boundaries of constant head or barrier types and the aquifer system is semi infinite in radial direction the time domain drawdowns are obtained via the stehfest algorithm and gaussian quadrature the inter porosity flow in the underlying fracture aquifer the instantaneous water table drainage the horizontal and vertical hydraulic conductivity anisotropy and the wedge angle are taken into account eliminating the inter porosity flow in the underlying fractured aquifer the presented solution reduces to a leaky wedge shaped aquifer case the influences of the underlying fractured aquifer hydraulic parameters on the overlying unconfined aquifer for different wedge angles and linear lateral boundaries types are explored using dimensionless drawdown and scaled sensitivity curves the results of this study can be utilized to obtain hydraulic parameters of an alluvial and river basin unconfined fractured wedge shaped aquifer systems the presented solution can also be used for water budget assessment of river basin aquifers

middle and late holocene sea level changes in eastern maine reconstructed from foraminiferal saltmarsh stratigraphy and ams 14c dates on basal peat abstract a relative sea level history is reconstructed for machiasport maine spanning the past 6000 calendar years and combining two different methods the first method establishes the long term 10 3 yr trend of sea level rise by dating the base of the holocene saltmarsh peat overlying a pleistocene substrate the second method uses detailed analyses of the foraminiferal stratigraphy of two saltmarsh peat cores to quantify fluctuations superimposed on the long term trend the indicative meaning of the peat the height at which the peat was deposited relative to mean tide level is calculated by a transfer function based on vertical distributions of modern foraminiferal assemblages the chronology is determined from ams 14 c dates on saltmarsh plant fragments embedded in the peat the combination of the two different approaches produces a high resolution replicable sea level record which takes into account the autocompaction of the peat sequence long term mean rates of sea level rise corrected for changes in tidal range are 0 75 mm yr between 6000 and 1500 cal yr b p and 0 43 mm yr during the past 1500 years the foraminiferal stratigraphy reveals several low amplitude fluctuations during a relatively stable period between 1100 and 400 cal yr b p and a sea level rise of 0 5 m during the past 300 years

solution for flow rates across the wellbore in a two zone confined aquifer a closed form solution for transient flow rates across the wellbore in a confined aquifer is derived from a two zone radial ground water flow equation subject to the boundary condition of keeping a constant head at the well radius an aquifer may be considered as a two zone system if the formation properties near the wellbore are significantly changed due to the well construction and or well development an efficient numerical approach is used to evaluate this newly derived solution values of the transient flow rate are provided in a tabular form and compared with those obtained by numerical inversion for the laplace domain solution the results show that the two solutions are in good agreement this newly derived solution can be used not only for predicting the transient flow rate across the wellbore but also for identifying the effects of a skin with a finite thickness on the estimation of transient flow rates in a ground water system with two different formation properties

analytical solution for two dimensional groundwater flow in presence of two isopotential lines 1 the groundwater flow pattern is examined in an idealized situation which is an approximation for situations as found at the confluence of rivers or where streams flow into or out of a lake or at peninsulas or bays two isopotential lines meet at an angle it is assumed that the aquifer is well connected to all surface water bodies moreover groundwater flow is determined by a base flow component and recharge or pumping wells the flow field is constructed using superposition of analytical solutions and conformal mapping classical results for concerning the onset of bank filtration and the length of the infiltration zone are extended for the general case finally an outlook is given on general problem setups for which the proposed methodology can be applied too

groundwater dynamics due to general stream fluctuations in an unconfined single or dual porosity aquifer subjected to general areal recharge abstract analytical solutions of groundwater dynamics in an elongated aquifer subjected to general time dependent recharge are presented the lateral boundaries are specified heads with the head variations governed by general time dependent functions general recharge function was not considered in previous works of this kind both single and double porosity aquifers are considered the solution is obtained using fourier sine and laplace transformations followed by an inverse fourier laplace transform involving residue theorem and convolutional integral for the unconfined single porosity aquifer case the exact time domain solution is obtained using the residue theorem for the unconfined double porosity aquifer case the time domain head is calculated using the de hoog inverse laplace algorithm the presented solution can be used to estimate the hydraulic parameters of 1 groundwater head variation of a river basin aquifer subjected to general lateral head variation and recharge 2 groundwater head variation in a double porosity elongated fractured anticline 3 groundwater depletion of an elongated fractured anticline subjected to recharge due to rainfall or snowmelt to its adjacent alluvial aquifer in addition the presented solution can be utilized to optimize the irrigation pattern in a cropland between two trench drains to control the groundwater mound

steady state response of annular wedge shaped aquifers to arbitrarily located multiwells with regional flow abstract wedge shaped aquifers are sometimes cut by crossing streams so that the areal geometry can be delineated by an annular wedge of infinite radial extent despite their worldwide spread the problem of groundwater flow in such geometrical entities has not received much attention in analytical studies this paper presents a closed form analytical solution for the aquifer head distribution in response to a system of multiwells superimposed on a background regional flow the aquifer is isotropic homogeneous and in prefect hydraulic connection with the surrounding streams a steady state green s function is constructed for this laterally bounded aquifer system the formulation is general in the sense that the aquifer vertex angle as well as number of wells and their positions can be arbitrary chosen closed form expression for the stream function is obtained by integration of the cauchy riemann equations three types of hydrogeological boundary conditions are considered combining streams of constant and linearly varying head and no flow barrier the results are applicable to both confined and unconfined flows extremely simple expressions are derived to quantify the amount of water exchange across stream aquifer interfaces flow nets are given for a number of hypothetical test cases demonstrating different aspects of the generated flow field sensitivity maps are prepared for the stream depletion rates due to a single pumping well and the role of aquifer vertex angle on the model response is investigated multiple stagnation points in the flow field are identified on a semi analytical basis this helps to assess how the position of a single stagnation point is affected by changes in the gradient of regional flow for relatively high gradients it is observed that the radial position of the stagnation point coincides with that of the well itself finally the formulation is extended to account for rainfall recharge over an unconfined aquifer having the same areal extent the aquifer response is found to agree well with other analytical and numerical results

reconstructing holocene sea level change from coastal freshwater peat a combined empirical and model based approach this paper presents a novel method to reconstruct sea level change in coastal freshwater back barrier marshes freshwater environments have long been considered to be unsuitable for the reconstruction of holocene sea level changes as they provide limiting rather than precise sea level index points we recorded the stratigraphy of a small beach and back barrier coastal phragmites reed marsh at hallsands south devon southwest england using hand drilled cores and ground penetrating radar and collected five new sea level index points from the base of a holocene peat sequence to refine the regional holocene relative sea level curve we demonstrate that the samples despite their freshwater origin yield accurate sea level index points as determined from the quantifiable relationship between tide levels and groundwater by means of water table monitoring and groundwater modelling we show that the primary controls on the water table in the marsh are 1 stratigraphy 2 peat permeability and 3 recharge rates in the back barrier marsh the five index points document relative sea level positions between 7200 and 2400 cal yr bp three points are in good agreement with previously collected regional data from inter tidal deposits and two points usefully fill gaps in the existing reconstruction an amended holocene relative sea level curve for south devon based on 30 data points is presented we conclude that the combined approach of data collection and modelling used in this paper can be applied to similar coastal settings around the world and allows the collection of sea level index points from locations not previously thought suitable for this purpose

rupture mechanism and seismotectonics of the ms6 5 ludian earthquake inferred from three dimensional magnetotelluric imaging a three dimensional 3 d resistivity model around the 2014 ms6 5 ludian earthquake was obtained the model shows that the aftershocks were mainly distributed in a shallow inverse l shaped conductive angular region surrounded by resistive structures the presences of this shallow conductive zone may be the key factor leading to the severe damage and surface rupture of the ludian earthquake a northwest trending local resistive belt along the baogunao xiaohe fault interrupts the northeast trending conductive zone at the zhaotong lianfeng fault zone in the middle crust which may be the seismogenic structure of the main shock based on the 3 d electrical model combining with gps thermal structure and seismic survey results a geodynamic model is proposed to interpret the seismotectonics deep seismogenic background and deformation characterized by a sinistral strike slip with a tensile component of the ludian earthquake

sea level changes since the last glacial maximum an appraisal of the ipcc fourth assessment report the ipcc fourth assessment report ar4 stated that global sea level rose by about 120 m between the last glacial maximum lgm and 3 2 ka and did not rise again until the late 19th century a review of relevant literature demonstrates that the rise may have been larger by 10 15 m that the timing of stabilisation is poorly constrained within the last 7 ka bp and that the onset of modern rates of sea level rise is not synchronous and uniform across the globe the lgm lowstand as defined in the ar4 is based on the classic barbados sea level history but the sea level curve from this island may not be an accurate eustatic approximation if glacial isostatic adjustment gia processes were significant as suggested by various authors the barbados sea level curve revealed the existence of meltwater pulse mwp 1a at around 14 000 cal a bp questions about the source and causal mechanism of mwp 1a are still being explored by field scientists and gia modellers these problems have direct relevance for contemporary measurements of ice mass changes because space geodetic measurements rely on information provided by gia models to separate land motion from ice mass changes global patterns of holocene sea level change are controlled by regional sea level variability not only through isostatic and tectonic processes but also through steric effects longer wavelength gravitational changes produced by changing ice ocean mass flux and hemispheric scale perturbations in the earth s rotation eustasy is therefore merely a concept not a measurable quantity constraining the late holocene ice melt contribution to global sea level rise and determining regional sea level rise patterns in the 18th and 19th centuries are important future tasks for sea level scientists these will establish the baseline contributions to 20th and 21st century sea level rise and will help to determine the causes of modern rates of sea level rise constraining historical sea level accelerations and short term ice mass flux will aid models of ice sheet dynamics and help to reduce current uncertainties in future sea level predictions the ar4 shows that regional sea level variability is clearly present in sea level change patterns for the past 50 a and an important challenge for the next ipcc assessment is to incorporate this variability into regional future sea level rise scenarios copyright 2009 john wiley sons ltd

integrated high precision analyses of holocene relative sea level changes lessons from the coast of maine a suite of salt marsh peat samples from four sites along the coast of maine wells phippsburg gouldsboro and machiasport has been analyzed using high precision techniques to determine local relative sea level trends and to evaluate proposed along coast warping a spatially variable set of relative sea level records in maine would have important implications for geophysical models that predict the response of the lithosphere during deglaciation and postglacial isostatic relaxation the amplification of m sub 2 tidal range in the gulf of maine and the bay of fundy during the holocene is modeled and applied to the mean high water data yielding best estimate envelopes of mean tide level change for each location average long term thousands of years mean tide level rise did not exceed approx 2 mm yr at any time during the late holocene at wells phippsburg and machiasport between 4 5 and 3 ka calibrated cal the apparent rate of rise at gouldsboro was higher than at any other site studied this along coast variation in the rate of mean tide level rise may reflect time of deglaciation neotectonics or differential isostatic adjustments a slight acceleration of mean tide level rise has occurred during the past millennium in gouldsboro and machiasport if 12 m downwarping inmore easternmost maine occurred as suggested in other publications it must have happened prior to 5 7 ka cal 84 refs 13 figs 8 tabs less

use of insolation as a proxy for high frequency eustasy in forward modeling of platform carbonate cyclostratigraphy a promising approach abstract eustatic oscillations driven by milankovitchian astronomical forcing have been interpreted as sea level drivers for high frequency carbonate depositional cycles in studies dating from the mid 1960s forward modeling of these oscillations with respect to their recorded effects on cyclical stacking patterns has only been attempted using generalized parameters for milankovitchian forcing the development of increasingly advanced forward modeling software coupled with the availability of formulas quantifying insolation incoming solar radiation as a function of composite orbital variations allows for the testing of milankovitchian insolation against measured stratigraphy in this case a series of milankovitchian insolation curves were calculated and used to generate proxy sea level curves for use in the carb3d forward modeling package in order to synthesize a series of stacked carbonate strata these synthetic successions are compared against that of the latemar platform middletriassic northern italy which has been interpreted to contain a record of orbital forcing within its stratigraphy while the timing and nature of periodic drivers that affected latemar stratigraphy have stirred a vigorous debate results from this study indicate that use of milankovitchian insolation as a proxy for high frequency sea level oscillations was successful in modeling latemar like stratigraphy with both pure milankovitchian and mixed milankovitchian sub milankovitchian temporal frameworks

interpreting sea level rise and rates of vertical marsh accretion in a southern new england tidal salt marsh an investigation of marsh accretion rates on a new england type high marsh barn island wildlife management area stonington connecticut reveals that this system is sensitive to changes in sea level and storm activity and the peat can accurately record rates of relative submergence as determined by tide gauge records over intervals of 2 5 decades the results also suggest that the relationship between the accretion deficit and plant community structure is important when utilizing peat records to reconstruct historic sea level curves within stablespartina patenshigh marsh communities in systems where major vegetation changes are prominent over short periods of time 50 years interpretations of sea level rise should be limited to the system in which they are developed unless careful vertical controls can be maintained on the data and multiple datable horizons can be identified within the substrate the results of this investigation further show that in a stablespartina patenscommunity within this particular system there is little vertical translocation of137cs making this isotope a powerful tool for assessing rates of vertical marsh development since 1954

stratigraphy pollen history and geochronology of tidal marshes in a gulf of maine estuarine system climatic and relative sea level impacts abstract sedimentologic and stratigraphic characteristics of five tidal marshes in great bay estuary new hampshire which is located on the western boundary of the gulf of maine were assessed from 20 vibracores detailed descriptions of surficial environments pollen analyses and radiocarbon dating modern marsh sequences in great bay estuary initiated with a time transgressive basal peat that formed at the upland brackish marsh boundary the oldest basal peat deposit sampled during this study was dated at 4560 cal yr b p based on an age of 4060 40 14 c yr b p the original tidal marshes that formed in great bay estuary apparently were unable to accrete at a high enough rate to allow seaward expansion resulting in a transgressive sequence of low marsh or mudflat sediments overlying the basal peat the transgressive tidal marsh sequence is capped by high marsh sediments that corresponded to a slowing of relative sea level rsl rise in the region and regressive seaward expansion of the tidal marshes however significant variations from these transgressive regressive sequences occur in the great bay tidal marshes as a result of more recent marsh expansion and tidal channel migrations detailed pollen analyses of a vibracore taken in a tidal marsh along squamscott river with a sedimentary record spanning the last 3900 cal yr b p exhibit five well documented marker horizons including 1 an increase of tsuga hemlock 2 the appearance of picea spruce 3 tsuga and fagus beech declines 4 an increase in ambrosia ragweed coupled with a sudden decrease in quercus oak and 5 the castanea chestnut decline using published ages for these pollen horizons and a calibrated 14 c age obtained during this study for a basal peat accretion rates for this marsh system over five time intervals were calculated 1 0 4 to 0 5 mm yr 1 from 3900 to 2850 cal yr b p 2 0 6 mm yr 1 from 2850 to 1960 cal yr b p 3 0 8 mm yr 1 from 1960 to 580 cal yr b p 4 0 7 to 0 8 mm yr 1 from 580 to 210 cal yr b p and 5 0 8 to 0 9 mm yr 1 over the last 210 years the long term accretion rate for the entire sequence based on the calibrated 14 c age of the basal peat was 0 6 to 0 7 mm yr 1 this result agrees with accretion rates determined from calibrated 14 c ages from two other tidal marsh systems in great bay estuary with accretion rates between 0 6 to 0 8 mm yr 1 higher accretion rates were obtained at a nearby tidal marsh with 1 2 mm yr 1 for just the marsh and 1 3 mm yr 1 for the marsh and underlying subtidal sediment the results of this study indicate that the sedimentology and stratigraphy of moderate size tidal marshes in rocky glaciated coasts are highly variable and are strongly influenced by complex interactions among rsl climatic variations and anthropogenic influences for instance the early development of many of the marshes in the great bay estuary area were likely driven by changes in rates of rsl resulting in transgressive onlap boundaries subsequently overlain by regressive intertidal marsh sequences however more recent changes in tidal marsh sediment composition deposited during a relatively slow steady rsl rise likely result from other forcings such as changes in minerogenic and orogenic sediment inputs due to anthropogenic effects tidal channel migrations major storms causing erosion of the marsh or climatic changes causing shifts in sediment delivery or vegetation

late holocene sea level change around newfoundland differential sea level change in formerly glaciated areas is predicted owing to variability in extent and timing of glacial coverage newfoundland is situated close to the margin of the former laurentide ice sheet and the orientation of the shoreline affords the opportunity to investigate variable rates and magnitudes of sea level change analysis of salt marsh records at four sites around the island yields late holocene sea level trends these trends indicate differential sea level change in recent millennia a north south geographic trend reflects submergence in the south very slow sea level rise in the northeast and a recent transition from falling to rising sea level at the base of the northern peninsula this variability is best explained as a continued isostatic response to deglaciation

reinterpretation of past sea level variation of the bay of fundy reports of shifts in rates of aggradation in a salt marsh deposit at amherst point nova scotia have been linked with fluctuations in eustatic sea level crustal subsidence and possibly changes in tidal amplitude however evidence for the most recent fluctuation is an artifact of early acadian land reclamation that occurred in the seventeenth century at amherst point acadian settlers had constructed dikes to prevent regular tidal flooding but probably allowed occasional flooding of the surface by tidal waters thus maintaining the salt marsh signature of the deposit statistical analysis of the pollen assemblage from the uppermost deposit inter preted as a regressive sequence aligns critical depths with pollen assemblages retrieved from modern soils of diked and drained marshes inspection of historical aerial photographs confirms that the dikes persisted on the site until at least 1939 interpretations of earlier fluctuations recorded in deposits below this regressive sequence remain valid it is possible that the bay of fundy experienced a regressive period just prior to acadian diking but future research on unexamined salt marsh deposits here or elsewhere must include an exhaustive search of historical documents to avoid misinterpretation of anthropogenic modifications

transient solution for stream unconfined aquifer interaction due to time varying stream head and in the presence of leakage summary this paper presents new analytical solutions of a linearized boussinesq equation characterizing groundwater flow in a stream unconfined aquifer system due to transient seepage the aquifer is underlain by a horizontal leaky bed and interacts with an adjoining stream of varying water level through a semipervious vertical stream bank close form analytical expressions are derived to predict water head distribution flow rate and volumetric exchange of water in response to time dependent rise or drop in the stream water level comparison between analytical and numerical results shows satisfactory agreement the effects of the finite and semi infinite lengths of the domain are considered in detail certain asymptotic situations such as sudden rise or drop in the stream water level no flow condition at the aquifer s base and absence of vertical stream bank can be dealt with as limiting cases of main results an illustration of the new analytical approach is used to quantify the accretion recession of the bank storage due to variation in various aquifer parameters

sea level in time and space revolutions and inconvenient truths in this paper we identify four revolutions that in our view have shaped the study of sea level changes in recent decades i the search for eustasy one of the most hotly debated issues in the 1960s is still relevant as models of glacial isostatic adjustment gia require input of the amount of meltwater transferred to the world s oceans following the demise of the large pleistocene ice sheets ii resolution of sea level archives all sea level archives have limitations in their resolving power but are we willing to define these from studies of salt marsh deposits and corals it is highly likely that climate driven metre scale sea level fluctuations have not occurred during the middle and late holocene iii rapid sea level changes improved coring technology has resulted in the suggestion of meltwater pulses during the last deglaciation low frequency high magnitude events have been documented along seismically active shorelines and provide information on seismic hazards and storm impacts iv merging of empirical sea level investigations and models much sea level research in the past two decades has embraced the integration of models and field derived data providing testable hypotheses and insights into processes we conclude with some reminders about the inconvenient truths that keep the sea level scientist honest

an analytical solution for groundwater flow to a vertical well in a triangle shaped aquifer the problem of drawdown and determination of velocity field near a fully penetrating pumping well which is located in a confined aquifer is investigated an isosceles triangular domain defining the geometry of the aquifer is considered in this paper the combination of streams with without impervious layer forms the boundaries of the domain of interest the concept of image well is employed to formulate the problem the method of green s function together with two dimensional fourier series expansion is used to obtain the closed form solution for the problem the isopotential lines and corresponding velocity field are presented for a particular position of pumping well also the water depletion from interfacing streams is analytically calculated for different positions of pumping well and the results are plotted the plots can be effectively used in water resources management and environmental engineering

a concept of maximum stream depletion rate for leaky aquifers in alluvial valleys 1 existing analytical models for evaluating stream depletion by wells in alluvial aquifers are based on the assumption that stream depletion supplies 100 of groundwater withdrawals analysis of specific hydrostratigraphic conditions in leaky aquifers indicates that stream depletion may range from 0 to 100 a new concept of maximum stream depletion rate msdr is introduced and defined as a maximum fraction of the pumping rate contributed by the stream depletion several new analytical solutions indicate that the msdr is determined by aquifer hydrostratigraphic conditions geometry of recharge and discharge zones and locations of pumping wells

relationships among compressional wave attenuation porosity clay content and permeability in sandstones anelastic attenuation is the process by which rocks convert compressional waves into heat and thereby modify the amplitude and phase of the waves understanding the causes of compressional wave attenuation is important in the acquisition processing and interpretation of high resolution seismic data and in deducing the physical properties of rocks from seismic data we have measured the attenuation coefficients of compressional waves in 42 sandstones at a confining pressure of 40 mpa equivalent to a depth of burial of about 1 5 km in a frequency range from 0 5 to 1 5 mhz the compressional wave measurements were made using a pulse echo method in which the sample 5 cm diameter 1 8 cm to 3 5 cm long was sandwiched between perspex lucite buffer rods inside the high pressure rig the attenuation of the sample was estimated from the logarithmic spectral ratio of the signals corrected for beam spreading reflected from the top and base of the sample the results show that for these samples compressio

acoustic and petrophysical relationships in low shale sandstone reservoir rocks this paper describes the measurements of the acoustic and petrophysical properties of two suites of low shale sandstone samples from north sea hydrocarbon reservoirs under simulated reservoir conditions the acoustic velocities and quality factors of the samples saturated with different pore fluids brine dead oil and kerosene were measured at a frequency of about 0 8 mhz and over a range of pressures from 5 mpa to 40 mpa the compressional wave velocity is strongly correlated with the shear wave velocity in this suite of rocks the ratio v p v s varies significantly with change of both pore fluid type and differential pressure confirming the usefulness of this parameter for seismic monitoring of producing reservoirs the results of quality factor measurements were compared with predictions from biot flow and squirt flow loss mechanisms the results suggested that the dominating loss in these samples is due to squirt flow of fluid between the pores of various geometries the contribution of the biot flow loss mechanism to the total loss is negligible the compressional wave quality factor was shown to be inversely correlated with rock permeability suggesting the possibility of using attenuation as a permeability indicator tool in low shale high porosity sandstone reservoirs

steady state groundwater recharge in trapezoidal shaped aquifers a semi analytical approach based on variational calculus summary this study presents a semi analytical solution for steady groundwater flow in trapezoidal shaped aquifers in response to an areal diffusive recharge the aquifer is homogeneous anisotropic and interacts with four surrounding streams of constant head flow field in this laterally bounded aquifer system is efficiently constructed by means of variational calculus this is accomplished by minimizing a properly defined penalty function for the associated boundary value problem simple yet demonstrative scenarios are defined to investigate anisotropy effects on the water table variation qualitative examination of the resulting equipotential contour maps and velocity vector field illustrates the validity of the method especially in the vicinity of boundary lines extension to the case of triangular shaped aquifer with or without an impervious boundary line is also demonstrated through a hypothetical example problem the present solution benefits from an extremely simple mathematical expression and exhibits strictly close agreement with the numerical results obtained from modflow overall the solution may be used to conduct sensitivity analysis on various hydrogeological parameters that affect water table variation in aquifers defined in trapezoidal or triangular shaped domains

boundary depletion rate and drawdown in leaky wedge shaped aquifers this study presents analytical solutions of the three dimensional groundwater flow to a well in leaky confined and leaky water table wedge shaped aquifers leaky wedge shaped aquifers with and without storage in the aquitard are considered and both transient and steady state drawdown solutions are derived unlike the previous solutions of the wedge shaped aquifers the leakages from aquitard are considered in these solutions and unlike similar previous work for leaky aquifers leakage from aquitards and from the water table are treated as the lower and upper boundary conditions a special form of finite fourier transforms is used to transform the z coordinate in deriving the solutions the leakage induced by a partially penetrating pumping well in a wedge shaped aquifer depends on aquitard hydraulic parameters the wedge shaped aquifer parameters as well as the pumping well parameters we calculate lateral boundary dimensionless flux at a representative line and investigate its sensitivity to the aquitard hydraulic parameters we also investigate the effects of wedge angle partial penetration screen location and piezometer location on the steady state dimensionless drawdown for different leakage parameters results of our study are presented in the form of dimensionless flux dimensionless time and dimensionless drawdown leakage parameter type curves the results are useful for evaluating the relative role of lateral wedge boundaries and leakage source on flow in wedge shaped aquifers this is very useful for water management problems and for assessing groundwater pollution the presented analytical solutions can also be used in parameter identification and in calculating stream depletion rate and volume copyright 2011 john wiley sons ltd

using foraminiferal transfer functions to produce high resolution sea level records from salt marsh deposits maine usa quantitative analyses of foraminiferal distributions along the coast of maine are used to provide transfer functions for reconstruction of sea level changes from fossil foraminiferal assemblages the indicative meaning of fossil assemblages is most accurately predicted by a training set that incorporates live and dead foraminifera and that uses flooding duration not height as the predictor variable sea level records are produced for two sites in maine usa a middle marsh site in scarboro and a high marsh site in machiasport these records offer temporal resolution of five to seven years and span the past century they are compared with instrumental data from a nearby tidal station to assess their accuracy strong correlations are found between the geologic records and the observational data in particular between the foraminiferal record from machiasport and the tide gauge record from eastport r2 0 83 p 0 005 thus a foraminifera based transfer function approach offers great potential for reso