permafrost and climate in europe monitoring and modelling thermal geomorphological and geotechnical responses we present a review of the changing state of european permafrost within a spatial zone that includes the continuous high latitude arctic permafrost of svalbard and the discontinuous high altitude mountain permafrost of iceland fennoscandia and the alps the paper focuses on methodological developments and data collection over the last decade or so including research associated with the continent scale network of instrumented permafrost boreholes established between 1998 and 2001 under the european union pace project data indicate recent warming trends with greatest warming at higher latitudes equally important are the impacts of shorter term extreme climatic events most immediately reflected in changes in active layer thickness a large number of complex variables including altitude topography insolation and snow distribution determine permafrost temperatures the development of regionally calibrated empirical statistical models and physically based process oriented models is described and it is shown that though more complex and data dependent process oriented approaches are better suited to estimating transient effects of climate change in complex mountain topography mapping and characterisation of permafrost depth and distribution requires integrated multiple geophysical approaches and recent advances are discussed we report on recent research into ground ice formation including ice segregation within bedrock and vein ice formation within ice wedge systems the potential impacts of climate change on rock weathering permafrost creep landslides rock falls debris flows and slow mass movements are also discussed recent engineering responses to the potentially damaging effects of climate warming are outlined and risk assessment strategies to minimise geological hazards are described we conclude that forecasting changes in hazard occurrence magnitude and frequency is likely to depend on process based modelling demanding improved understanding of geomorphological process response systems and their impacts on human activity

crustal structure and earthquake focal depths beneath northeastern india and southern tibet summary we use broad band teleseismic data recorded at eight sites along a north south profile from karimganj 24 84 n 92 34 e south of the eastern shillong plateau to bomdilla 27 27 n 92 41 e in the eastern lesser himalaya to determine the seismic characteristics of the crust in northeastern india we also analyse data from the chinese digital seismic network station at lhasa and indepthii stations located on the southern tibetan plateau north of our profile to extend the seismic images of the crust further northwards although the northeastern indian stations and the tibetan stations do not lie along a linear profile across the himalaya the wellrecognized uniformity of the himalaya along strike make this comparison of the two profiles meaningful receiver functions calculated from these data show that the crust is thinnest 35 38 km beneath the shillong plateau receiver functions at cherrapunji on the southern edge of the shillong plateau have a strong azimuthal dependence those from northern backazimuth events show that the moho beneath the southernmost shillong plateau is at a depth of 38 km while receiver functions from southern backazimuth events indicate that the moho beneath the northernmost bengal basin is at a depth of 44 km receiver functions from sites on the brahmaputra valley demonstrate that the moho is deeper by 5 7 km than below the shillong plateau a result which agrees with the hypothesis that the shillong plateau is supported by shearing stress on two steep faults that cut through the crust further north of the eastern himalayan foredeep the moho dips gently northwards reaching a depth of 48 km beneath bomdilla in the lesser himalaya and 88 km below lhasa in tibet using the crustal velocity models obtained from receiver function inversions we redetermined focal depths of wellrecorded earthquakes across this part of the indo tibetan collision zone and find all of these to occur within the crust hence we find no evidence for bimodal depth distribution of earthquakes beneath this region of northeastern india

instruments and methods geophysical imaging of alpine rock glaciers slope instabilities caused by the disappearance of ice within alpine rock glaciers are an issue of increasing concern design of suitable counter measures requires detailed knowledge of the internal structures of rock glaciers which can be obtained using geophysical methods we examine benefits and limitations of diffusive electromagnetics geoelectrics seismics and ground penetrating radar georadar for determining the depth and lateral variability of the active layer the distributions of ice and water the occurrence of shear horizons and the bedrock topography in particular we highlight new developments in data acquisition and data analysis that allow 2 d or even 3 d structures within rock glaciers to be imaged after describing peculiarities associated with acquiring appropriate geophysical datasets across rock glaciers and emphasizing the importance of state of the art tomographic inversion algorithms we demonstrate the applicability of 2 d imaging techniques using two case studies of rock glaciers in the eastern swiss alps we present joint interpretations of geoelectric seismic and georadar data appropriately constrained by information extracted from boreholes a key conclusion of our study is that the different geophysical images are largely complementary with each image resolving a different suite of subsurface features based on our results we propose a general template for the cost effective and reliable geophysical characterization of mountain permafrost

mountain permafrost dynamics within a recently exposed glacier forefield inferred by a combined geomorphological geophysical and photogrammetrical approach geomorphological observations geoelectrical soundings and photogrammetric measurements of surface movement on the muragl glacier forefield were used to obtain an integrative analysis of a highly complex glacial and periglacial landform consisting of a push moraine creeping permafrost and permafrost free glacial till in close proximity electrical resistivity tomography is considered as an important multifunctional geophysical method for research in periglacial permafrost related environments joint application with measurements of surface displacements offers a promising tool for investigating periglacial landforms related to ice rich permafrost for a more comprehensive characterization of permafrost characteristics and geomorphological interpretation of periglacial morphodynamics the patchy permafrost distribution pattern described in this paper is determined by several factors including the sediment characteristics the snow cover distribution and duration the aspect and the former glacier distribution and thermal regime recent and modern permafrost dynamics within the glacier forefield comprise aggradation degradation and permafrost creep copyright 2007 john wiley sons ltd

constraints on hydraulic parameters and implications for groundwater flux across the upland estuary interface abstract analyses of independent laboratory and field scale measurements from two sites on sapelo island georgia reveal heterogeneity in hydraulic parameters across the upland estuary interface regardless of the method used short duration pumping tests amplitude attenuation of tidal pumping data sediment grain size distributions and falling head permeameter tests we obtain hydraulic conductivity of 10 4 m s 1 for the fine grained well sorted clean sands that make up the upland areas proximal to the upland estuary boundary the tidal pumping analyses and permeameter tests suggest that hydraulic conductivities decrease by more than two orders of magnitude a result consistent with the presence of a clogging layer such a clogging layer may arise due to a variety of physical chemical or biological processes the extent and orientation of the layers of reduced hydraulic conductivity near the upland estuary boundary influence the nature of the aquifer s response to tidal forcing where the lower conductivity layer forms a relatively flat creek bank tidal pumping produces a primarily mechanical response in the adjacent aquifer where the creek bank is nearly vertical there is a more direct hydraulic connection between the tidal creek and the adjacent aquifer the clogging layer likely contributes to the development of complicated flow pathways across the upland estuary boundary effective flow paths calculated from tidal pumping data terminate within the marsh beyond the boundary of the upland aquifer suggesting a diffuse regime of groundwater discharge in the marsh we postulate that in many settings submarsh flow may be as important as seepage faces for groundwater discharge into the marsh estuary complex

ground motion estimation at guwahati city for an mw 8 1 earthquake in the shillong plateau abstract in this paper the ground motion at guwahati city for an 8 1 magnitude earthquake on oldham fault in the shillong plateau has been estimated by stochastic finite fault simulation method the corresponding acceleration time histories on rock level at several sites in the epicentral region have been computed these results are validated by comparing them with the estimates obtained from medvedev sponheuer karnik msk intensity observations of 1897 shillong earthquake using the local soil parameters the simulated rock level acceleration time history at guwahati city is further amplified up to the ground surface by nonlinear site response analysis the results obtained are presented in the form of peak ground acceleration pga contour map the maximum amplification for pga over guwahati city is as high as 2 5 based on the simulated pga the liquefaction susceptibility at several locations in the city has been estimated the results are presented in the form of contours of factor of safety against liquefaction at different depths below the ground surface it is observed that over a large part of the guwahati city the factor of safety against liquefaction is less than one indicating that the city is highly vulnerable to liquefaction in the event of this earthquake the contour maps obtained can be used in identifying vulnerable areas and disaster mitigation

geophysical imaging of alpine rock glaciers slope instabilities caused by the disappearance of ice within alpine rock glaciers are an issue of increasing concern design of suitable counter measures requires detailed knowledge of the internal structures of rock glaciers which can be obtained using geophysical methods we examine benefits and limitations of diffusive electromagnetics geoelectrics seismics and ground penetrating radar georadar for determining the depth and lateral variability of the active layer the distributions of ice and water the occurrence of shear horizons and the bedrock topography in particular we highlight new developments in data acquisition and data analysis that allow 2 d or even 3 d structures within rock glaciers to be imaged after describing peculiarities associated with acquiring appropriate geophysical datasets across rock glaciers and emphasizing the importance of state of the art tomographic inversion algorithms we demonstrate the applicability of 2 d imaging techniques using two case studies of rock glaciers in the eastern swiss alps we present joint interpretations of geoelectric seismic and georadar data appropriately constrained by information extracted from boreholes a key conclusion of our study is that the different geophysical images are largely complementary with each image resolving a different suite of subsurface features based on our results we propose a general template for the cost effective and reliable geophysical characterization of mountain permafrost

the thickness and internal structure of fireweed rock glacier alaska u s a as determined by geophysical methods geophysical investigations on rock glaciers are often difficult because rock glaciers are covered by an unconsolidated debris mantle a few meters thick are typically 50 m thick and are composed of an ice rock mixture of unknown composition transient electromagnetics tem is a method that allows some of these difficulties to be minimized and data collection is relatively efficient tem with calibration from terminus exposure was used to determine the thickness 60 m of fireweed rock glacier alaska u s a under complex valley geometry a conductive layer beneath the rock glacier was identified and its distribution is consistent with a till like layer seismic refraction used to resolve the debris mantle thickness 2 4 m suggests the presence of a discontinuity at 18 28 m depth within the rock glacier the discontinuity is also indicated in the radio echo sounding and the tem data but to a lesser extent this discontinuity is important because the motion of the rock glacier may occur across this as a shear plane

tidal dynamics of the water table in beaches tidal motions of the water table height inside a sloping beach are investigated via field measurements and theoretical considerations only the movements forced by the tide are considered so a beach with negligible wave activity was chosen for the field measurements the data show that even in the absence of precipitation the time averaged inland water table stands considerably above the mean sea level also the water table at a fixed point inside the beach is far from sinusoidal even though its variation is forced by an essentially sinusoidal tide this latter effect is due to the boundary condition along the sloping beach face which acts as a highly nonlinear filter the observed behavior of the water table is explained in terms of perturbation extensions to the classical deep aquifer solution one extension deals with the nonlinearity in the interior the other with the boundary condition at the sloping beach face

a two dimensional analytical solution of groundwater response to tidal loading in an estuary a two dimensional transient groundwater flow equation for a confined nonleaky aquifer is solved analytically with an estuary tidal loading boundary condition the amplitude and phase of the tide varies with position and time respectively these variations called the damping coefficient for amplitude and separation constant for phase along the coastline are considered in the analysis the solution presented is more advanced than the traditional one dimensional analytical solution with a one dimensional tidal loading boundary condition the damping coefficient and separation constant in the application study are obtained from the harmonic analysis of the observed tidal level in apalachicola bay florida the analytical solution is compared to a two dimensional finite difference solution a numerical simulation illustrates the response of piezometric head to tidal loading the piezometric head and phase from both solutions match closely the analytical and numerical solutions show that a piezometric head along both sides of the estuary can be predicted given a tidal elevation at the entry of an estuary the fluctuation of piezometric head in response to tidal loading diminishes rapidly inland and diminishes slowly along the coastline of an estuary there are also obvious phase shifts associated with spatial variations as the wave propagates

tidal influence on behaviour of a coastal aquifer adjacent to a low relief estuary the tidal influence on groundwater hydrodynamics salt water intrusion and submarine groundwater discharge from coastal estuarine aquifers is poorly quantified for systems with a mildly sloping beach in contrast to the case where a vertical beach face is assumed we investigated the effect of beach slope for a coastal aquifer adjacent to a low relief estuary where industrial waste was emplaced over the aquifer the waste was suspected to discharge leachate towards the estuary field observations at various locations showed that tidally induced groundwater head fluctuations were skewed temporally frequency analysis suggested that the fluctuation amplitudes decreased exponentially and the phase lags increased linearly for the primary tidal signals as they propagated inland salinisation zones were observed in the bottom part of the estuary and near the beach surface flow and transport processes in a cross section perpendicular to the estuary were simulated using seawat 2000 which is capable of depicting density dependent flow and multi species transport the simulations showed that the modelled water table fluctuations were in good agreement with the monitored data further simulations were conducted to gain insight into the effects of beach slope in particular the limiting case of a vertical beach face was considered the simulations showed that density difference and tidal forcing drive a more complex hydrodynamic pattern for the mildly sloping beach than the vertical beach as well as a profound asymmetry in tidally induced water table fluctuations and enhanced salt water intrusion the simulation results also indicated that contaminant transport from the aquifer to the estuary was affected by the tide where for the mildly sloping beach the tide tended to intensify the vertical mass exchange in the vicinity of the shoreline

determination of aquifer transmissivity from earth tide analysis the water level in an open well tapping an artesian aquifer responds to pressure head disturbance caused by earth tide dilatation of the aquifer because a finite amount of time is needed for water to flow into and out of the well there exists a phase shift or time lag between the tidal dilatation of the aquifer and the water level response in the well we derive an analytical solution that expresses the phase shift as a function of the aquifer transmissivity storage coefficient well radius and the period of the harmonic disturbance this solution is rather insensitive to the storage coefficient thus if the phase shift is known for a harmonic disturbance the transmissivity can be calculated given a rough estimate of the storage coefficient theoretical analysis shows that a significant phase shift may be present even if the disturbance is slowly varying as in the case of earth tides this opens the possibility of estimating aquifer transmissivity from water level records that show earth tide fluctuations a case study using data from a site near parkfield california is presented to illustrate application of the theory phase shifts of the o1 25 82 hour period and m2 12 42 hour period tidal constituents are chosen for analysis because they are free of systematic contamination by fluctuations in barometric pressure a brief error analysis suggests that the computed o1 phase shift is subject to large uncertainty while the computed m2 phase shift is substantially more accurate based on an assumed storage coefficient range of 10 4 to 10 6 the estimated transmissivity range is 8 10 6 to 2 10 5 m2 s while hydraulic tests have not been performed to validate these estimates the range is consistent with the transmissivity value determined by other investigators from analysis of the water level response to an earthquake

the flow of fireweed rock glacier alaska u s a fireweed rock glacier is a large rock glacier in south central alaska u s a it flows relatively fast with velocities up to 3 5 ma 1 and exhibits both seasonal and annual velocity variations some of which are related to periodic terminus calving and increased rainfall our analysis reveals that motion is likely concentrated in a pseudo rectangular channel within the larger parabolic channel with a shear plane at 27 m depth there is likely motion along the shear plane as well as internal deformation above it we estimate that the ice rock mixture is up to seven times softer than clean glacier ice with a temperature of 2 c calving at the terminus is an important component of the mass balance of this rock glacier

a general analytical solution for groundwater fluctuations due to dual tide in long but narrow islands 1 this paper develops a general mathematical model for describing head fluctuations in an aquifer of long but narrow islands subject to a dual tide effect the upper boundary condition of the aquifer is represented by an equation combining the simplified free surface equation with a leakage term such an equation is considered as a general expression representing the upper boundary condition of a confined unconfined or leaky confined aquifer the closed form solution of the model represented by two series terms is developed by the direct fourier method and finite fourier sine transform one of the series can reduce to a closed form expression by means of contour integral and residue theorem if the width of the island is very large this solution gives the predicted head almost the same as that of the solution for an aquifer subject to a single tide effect it is found that the presence of an upper aquitard produces significant vertical flow in the lower leaky confined aquifer even if the aquitard permeability is low neglecting such vertical flow may result in an overestimate of hydraulic head in the leaky confined aquifer the attenuation factor and phase lag predicted from the present solution subject to the dual tide effect agree well with those estimated from 57 day head fluctuation data observed at garden island australia

tidal influence on self potential measurements long term surface and borehole self potential sp monitoring was conducted in the uk chalk aquifer at two sites the coastal site is c 1 7 km from the coast and the inland site is c 80 km from the coast at both sites power spectral density analysis revealed that sp data contain the main ocean tidal periodic components however the principal lunar component m2 the dominant ocean tidal component was most significant at the coastal site the m2 signal in surface referenced sp data at the inland site was partly due to telluric currents caused by the geomagnetic ocean dynamo earth and or atmospheric tides also contributed as the sp power spectrum was not typical of a telluric electric field the m2 component in borehole referenced data at the inland site was below the significance level of the analysis method and was two orders of magnitude smaller than the m2 signal in borehole referenced sp data at the coastal site the tidal response of the sp data in the coastal borehole is therefore primarily driven by ocean tides these cause changes in fluid pressure and chemical concentration gradients within the coastal aquifer leading to time varying electrokinetic and exclusion diffusion potentials borehole referenced sp measurements could be used to characterize and monitor tidal processes in coastal aquifers such as the intrusion of seawater

structural characterization of an island aquifer via tidal methods 1 a set of water level time series collected along a transect through a sedimentary island aquifer was used to test the utility of various simple models of ocean tidal propagation in bounded one dimensional aquifers fourier spectra were calculated for the ocean tidal modes and compared with spectra measured in wells along the island transect other sources of fluctuation could be neglected an observed spatial bias in the well responses attenuations and lags could not be modeled by a homogeneous aquifer theory a theory involving composite heterogeneity accounted well for the spatial bias yielding estimates of aquifer transmissivities and storage coefficients indicating a fivefold difference in hydraulic diffusivity along the transect a lack of well locations toward one end of the transect reduced the statistical significance of this result with correlations between regression parameters evident at the same time a second bias was seen involving the ratio of signal amplitude and lag with penetration distance into the aquifer as observed in prior tidal studies a brief set of numerical experiments showed that horizontal layering in aquifer properties was the most probable cause of this propagation bias application of these results to the island data set supported a conceptual stratigraphic model of a highly conductive sloping stratum underlying a less conductive superficial sand layer this model is inconsistent with well logs along the island transect but is supported by additional off transect well logs it was concluded that one dimensional tidal propagation models may be useful in inverse characterization of aquifers with macroscale hydrogeological structures and that the analysis of measured propagation bias has the potential to yield extra information on aquifer properties in the vertical direction

groundwater flow to a general well configuration in an unconfined aquifer overlying a fractured bedrock abstract unconfined aquifers sometimes overlie fractured bedrocks consisting of unconfined fractured aquifer systems pumping induced hydrodynamics in such aquifer systems has not received much attention as in other types of aquifer systems this paper aims to obtain semi analytical solutions of flow to a general well configuration in such an unconfined fractured two layer aquifer system the examples of general well configuration specifically discussed here include 1 a horizontal well 2 a vertical well 3 a vertical well with one horizontal collector and 4 a vertical well with two horizontal collectors which are perpendicular with each other the methodology is general and can be extended to other types of wells with minor modifications of solutions developed in this study the point sink source solution is first obtained using double infinite fourier and laplace transformations where sink is for pumping and source is for injection the line sink source solution is then obtained via integrating the point sink source along the desired direction and following the principle of superposition the de hoog numerical inverse laplace transform and gaussian quadrature are used to obtain time domain dimensionless drawdown solutions the instantaneous drainage of water table and the inter porosity flow of the underlying fractured aquifer are taken into account the effects of the length of horizontal well on dimensionless drawdown and dimensionless drawdown derivative and scaled sensitivity of the hydraulic parameters of the underlying fractured aquifer are explored the dimensionless drawdowns and drawdown derivatives of a vertical pumping well a vertical well with a single horizontal collector and a vertical well with two perpendicular horizontal collectors are also compared the scaled sensitivity of dimensionless drawdown to the hydraulic parameters of the underlying fractured aquifer of these different pumping well structures is explored the results of this study can be used to evaluate the hydraulic parameters using the drawdown data collected during a pumping test performed in a general well configuration in a unconfined fractured two layer aquifer system furthermore the presented solutions can be utilized to design the pumping well to minimize drawdown in low permeability or thin aquifers by eliminating the inter porosity flow term from the underlying fractured aquifer the solutions are applicable to groundwater flow to a pumping well in leaky aquifers

application of genetic algorithm technique to inverse modeling of tide aquifer interaction modeling of tide aquifer interaction plays a vital role in the management of coastal aquifer systems a novel and robust methodology is presented in this paper for estimating aquifer parameters of coastal aquifers from tide aquifer interaction data using tide aquifer interaction model and genetic algorithm ga two stand alone computer programs were developed to optimize hydraulic diffusivities of unconfined and confined coastal aquifers at multiple sites using ga technique and tide aquifer interaction model and considering two approaches lumped tidal component approach and multi tidal component approach five sets of real world tide aquifer interaction data at two sites of an unconfined aquifer and one set of tide aquifer interaction data at three sites of a confined aquifer were used to demonstrate the efficacy of the methodology the analysis of the ga based inverse modeling results indicated that the multi tidal component approach yields more accurate and reliable hydraulic diffusivities for the unconfined aquifer rmse 0 0129 0 0521 m nse 0 70 0 97 and d1 0 91 0 99 as well as for the confined aquifer rmse 0 0204 0 0545 m nse 0 95 0 97 and d1 0 99 compared with the lumped tidal component approach a comparative evaluation of data size revealed that the short duration datasets of the unconfined aquifer provide more reliable estimate of hydraulic diffusivity than the long duration datasets further it was found that the spring and neap tidal data yield unreasonable values of hydraulic diffusivity with considerably high values of rmse and very low values of r 2 nse and d1 thereby suggesting that spring and neap tidal data are not suitable for aquifer parameter estimation overall it is concluded that the ga based tide aquifer interaction model following multi tidal component approach is the most efficient tool for estimating aquifer parameters of unconfined and confined aquifers from tide aquifer interaction data the developed methodology is also applicable to other coastal basins of the world irrespective of hydrogeological settings

plateau pop up in the great 1897 assam earthquake the great assam earthquake of 12 june 1897 reduced to rubble all masonry buildings within a region of northeastern india roughly the size of england and was felt over an area exceeding that of the great 1755 lisbon earthquake1 hitherto it was believed that rupture occurred on a north dipping himalayan thrust fault propagating south of bhutan2 3 4 5 but here we show that the northern edge of the shillong plateau rose violently by at least 11 m during the assam earthquake and that this was due to the rupture of a buried reverse fault approximately 110 km in length and dipping steeply away from the himalaya the stress drop implied by the rupture geometry and the prodigious fault slip of 18 7 m explains epicentral accelerations observed to exceed 1g vertically and surface velocities exceeding 3 m s 1 ref 1 this quantitative observation of active deformation of a pop up structure confirms that faults bounding such structures can penetrate the whole crust plateau uplift in the past 2 5 million years has caused the indian plate to contract locally by 4 2 mm yr 1 reducing seismic risk in bhutan but increasing the risk in northern bangladesh

evaluation of seismic soil liquefaction at guwahati city great earthquakes in the past e g 1869 cachar earthquake 1897 great assam earthquake have caused large scale damage and ground liquefaction in the guwahati city moreover seismologists are of opinion that a great earthquake might occur in the unruptured segment of the north east himalaya that is near to guwahati city in this paper the liquefaction hazard due to these events have been simulated the obtained results are in general agreement with the reported damages due to the past earthquakes the central part of the city i e dispur gs road that has large thickness of soft soil deposit and shallow ground water table is highly vulnerable to liquefaction

an analytical solution and case study of groundwater head response to dual tide in an island leaky confined aquifer 1 this paper presents an analytical solution of groundwater head response to dual tide fluctuation in the transect of an island leaky aquifer system comprising a confined aquifer and its overlying semipermeable confining layer both layers terminate at the coastlines on two sides of the island solution analysis indicates that the tidal waves from the two sides of the island transect interfere at the middle of the island and the interference decreases to zero as the horizontal length of the aquifer increases to infinity the leakage of the overlying confining layer enhances the landward attenuation of the tidal head fluctuation and shortens the time lag between the head and tide fluctuations the solution agreed well with the observations in eight piezometers in garden island on the continental shelf of western australia reported by trefry and bekele 2004

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

groundwater response to tidal fluctuation in a two zone aquifer summary a coastal aquifer may consist of two zones of distinctly different hydraulic properties with the coastal zone of limited width and the inland zone of infinite width the analytical solutions for groundwater level response to tidal fluctuation in such a two zone aquifer are derived and the underlying physical meanings are discussed a dimensionless zone contrast parameter r is introduced which is controlled by ratio between the product of the transmissivity and storativity of the inland zone and that of the coastal zone in the coastal zone the amplitude of groundwater head fluctuation attenuates more quickly when r becomes greater the amplitude declines exponentially with distance from the coastline and the phase lag increases linearly only when r 1 in the inland zone however the head fluctuation always exhibits an exponential attenuation of the amplitude and a linear increase of the phase lag for any value of r thus the diffusivity of the inland zone can be readily assessed with measurements of fluctuation amplitudes or lags as are frequently used when estimating aquifer parameters in homogeneous aquifers compared with jacob 1950 solution for a semi infinite homogeneous aquifer the existence of the coastal zone reduces the amplitude in the inland zone by a spatially constant coefficient and increases the phase lag by a spatially constant shift inverse estimation of aquifer parameters are discussed based on the analytical solutions the analytical solutions are used to estimate the aquifer parameters in a coastal two zone aquifer located in the west part of dongzhai harbor hainan province china

two dimensional flow response to tidal fluctuation in a heterogeneous aquifer aquitard system in alluvial coastal aquifers finer sediments are preferentially deposited along the downstream direction so the hydraulic conductivity is generally heterogeneous and changes with distance from the coastline to investigate the influence of aquifer heterogeneity on seawater groundwater interaction a new two dimensional model characterising groundwater flow in an aquifer aquitard system was developed assuming that the hydraulic conductivity of the aquifer linearly increases with the distance from the coastline along the inland direction a closed form analytical solution was derived using the separation of variables method comparing the new solution with the numerical solution by comsol multiphysics sweden based on the finite element method one can see that the new solution agreed with the numerical solution very well except at the early time we found that both aquitard leakance and the heterogeneity factor b could result in the propagation bias the propagation bias represents the inconsistency between the theoretical calculation and the observed strong attenuation and small time lag between the head and tide fluctuations the attenuation decreased with perpendicular distance from the coastline x axis whereas the time lag increased with distance along the x axis the relationship between the time lag and the distance along the x axis seemed to be linear when b was 0 001 m 1 whereas it obeyed a power function when b was greater than 0 01 m 1 copyright 2014 john wiley sons ltd

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

estimating hydraulic properties of coastal aquifers using wave setup summary wave setup is the elevated mean water table at the coast associated with the momentum transfer of wave breaking which occurs generally over several days groundwater responses to wave setup were observed as far as 5 km inland in central maui hawaii the analysis showed that at times of energetic swell events wave driven water table overheights dominate low frequency groundwater fluctuations associated with barometric pressure effects matching peak frequencies at 1 7 10 6 hz and 3 7 10 6 hz were identified in setup and observed head using spectral decomposition similar to tides the setup propagation through the aquifer shows exponentially decreasing amplitudes and linearly increasing time lags due to the longer periods of setup oscillations the signal propagates deeper into the aquifer 10 km in central maui than diurnal tides 5 km and can therefore provide information on greater length scales hydraulic diffusivity was estimated based on the setup propagation an effective diffusivity of 2 3 107 m2 d is consistent with aquifer parameters based on aquifer tests and tides a one dimensional numerical model supports the results of the analytical solution and strengthens the suitability to estimate hydraulic parameters from setup propagation the methodology is expected to be beneficial to high permeability coastal environments such as on volcanic islands and atolls

response of the water level in a well to earth tides and atmospheric loading under unconfined conditions the response of the water level in a well to earth tides and atmospheric loading under unconfined conditions can be explained if the water level is controlled by the aquifer response averaged over the saturated depth of the well because vertical averaging tends to diminish the influence of the water table the response is qualitatively similar to the response of a well under partially confined conditions when the influence of well bore storage can be ignored the response to earth tides is strongly governed by a dimensionless aquifer frequency q u the response to atmospheric loading is strongly governed by two dimensionless vertical fluid flow parameters a dimensionless unsaturated zone frequency r and a dimensionless aquifer frequency qu the differences between q u and qu are generally small for aquifers which are highly sensitive to earth tides when q u and qu are large the response of the well to earth tides and atmospheric loading approaches the static response of the aquifer under confined conditions at small values of q u and qu well response to earth tides and atmospheric loading is strongly influenced by water table drainage when r is large relative to qu the response to atmospheric loading is strongly influenced by attenuation and phase shift of the pneumatic pressure signal in the unsaturated zone the presence of partial penetration retards phase advance in well response to earth tides and atmospheric loading when the theoretical response of a phreatic well to earth tides and atmospheric loading is fit to the well response inferred from cross spectral estimation it is possible to obtain estimates of the pneumatic diffusivity of the unsaturated zone and the vertical hydraulic conductivity of the aquifer

determination of fluid flow properties from the response of water levels in wells to atmospheric loading the water level in a well that taps a partially confined aquifer is often sensitive to atmospheric loading the magnitude and character of this response is partly governed by the well radius the lateral hydraulic diffusivity of the aquifer the thickness and vertical pneumatic diffusivity of the unsaturated zone and the thickness and vertical hydraulic diffusivity of the saturated zone overlying the aquifer these key elements can be combined into five dimensionless parameters that partly govern the phase and attenuation of the response in many cases the response of a well to atmospheric loading can be broken up into a high intermediate and low frequency response the high frequency response is governed largely by the well radius and lateral diffusivity of the aquifer the intermediate frequency response is governed by the loading efficiency of the aquifer the low frequency response is governed by the vertical pneumatic diffusivity and thickness of the unsaturated zone and the vertical hydraulic diffusivity and thickness of the saturated material above the aquifer cross spectral estimation is used to fit the response to atmospheric loading of three water wells to the theoretical curves in order to yield estimates of three of the key dimensionless parameters these estimates then are used to make estimates or place bounds on the vertical pneumatic diffusivity of the unsaturated zone the lateral permeability of the aquifer and the composite vertical hydraulic diffusivity of the overlying saturated materials

the nature and dynamics of frozen ground in alpine and subarctic periglacial environments a spatial assessment of the complex discontinuous and sporadic permafrost distribution and characteristics in high altitude alpine and high latitude subarctic permafrost environments was achieved u

application of refraction seismics in alpine permafrost studies a review abstract refraction seismics is a common geophysical application to investigate permafrost in alpine studies this study reviews the physical basis of the use of refractions seismics and introduces the history of its application in alpine environments seismic properties are influenced by rock or soil properties and fluid or ice effects in laboratory measurements these influences are determined and linked to mechanical properties or used for calibration of field studies in field conditions supplementary environmental factors influence the seismic properties of landforms in this paper laboratory studies of rocks from different lithologies and with different properties as well as case studies on rock glaciers moraines talus slopes and debris covered slopes are collected and influencing factors quantitatively analyzed the data demonstrate how lithology porosity and anisotropy influence p wave velocity environmental factors result in a high variation of p wave velocities in landforms however p wave velocities enable the differentiation of active layer and permafrost in rock glaciers and moraines in talus slopes and debris covered slopes p wave velocity contrasts between active layer and permafrost layer might be insufficient and require the application of additional methods for a final differentiation

hypoaigic influences on groundwater flux to a seasonally saline river hypoaigic zones are aquifer volumes close to and beneath the shores of saline surface water bodies and are characterized by the presence of time dependent natural convection and chemical stratification when transient and cyclic processes are involved there is significant potential for complex flow and reaction in the near shore aquifer presenting a unique challenge to pollutant risk assessment methodologies this work considers the nature of some hypoaigic processes generated by the seasonally saline canning river of western australia near a site contaminated by petroleum hydrocarbons a dissolved hydrocarbon plume migrates within the shallow superficial aquifer to the nearby bank of the canning river beneath the river bank a zone of complex fluid mixing is established by seasonal and tidal influences understanding this complexity and the subsequent ramifications for local biogeochemical conditions is critical to inferring the potential for degradation of advecting contaminants a range of modelling approaches throws light on the overall topographic controls of discharge to the river on the saline convection processes operating under the river bank on the potential for fluid mixing and on the various important time scales in the system saline distributions simulated within the aquifer hypoaigic zone are in at least qualitative agreement with previous field measurements at the site and are strongly affected by seasonal influences groundwater seepage velocities at the shoreline are found to be positively correlated with river salinity calculations of fluid age distributions throughout the system show sensitivity to dispersivity values however maximum fluid ages under the river appear to be diffusion limited to a few decades the saline convection cell in the aquifer defines a zone of strong dispersive dilution of aged many decades deep aquifer fluids with relatively young several months riverine fluids seasonal recharge and river salinity cycles induce regular perturbations to the convection cell yielding intra annual variations of 50 in seepage velocity and almost 30 in wedge penetration distance at the plume location

analysis of tide and offshore storm induced water table fluctuations for structural characterization of a coastal island aquifer analysis of water table fluctuations can provide important insight into the hydraulic properties and structure of a coastal aquifer system including the connectivity between the aquifer and ocean this study presents an improved approach for characterizing a permeable heterogeneous coastal aquifer system through analysis of the propagation of the tidal signal as well as offshore storm pulse signals through a coastal aquifer offshore storms produce high wave activity but are not necessarily linked to significant onshore precipitation in this study we focused on offshore storm events during which no onshore precipitation occurred extensive groundwater level data collected on a sand barrier island sable island ns canada show nonuniform discontinuous propagation of the tide and offshore storm pulse signals through the aquifer with isolated inland areas showing enhanced response to both oceanic forcing signals propagation analysis suggests that isolated inland water table fluctuations may be caused by localized leakage from a confined aquifer that is connected to the ocean offshore but within the wave setup zone two dimensional groundwater flow simulations were conducted to test the leaky confined unconfined aquifer conceptualization and to identify the effect of key parameters on tidal signal propagation in leaky confined unconfined coastal aquifers this study illustrates that analysis of offshore storm signal propagation in addition to tidal signal propagation provides a valuable and low resource approach for large scale characterization of permeable heterogeneous coastal aquifers such an approach is needed for the effective management of coastal environments where water resources are threatened by human activities and the changing climate

locating and characterising groundwater storage areas within an alpine watershed using time lapse gravity gpr and seismic refraction methods unconsolidated sediments in alpine watersheds can store glacier melt and snowmelt as groundwater which helps sustain flow in mountain rivers during dry periods however the amount and distribution of groundwater storage in rugged alpine terrain is not well understood hindering our ability to predict the rate and timing of groundwater discharge into alpine streams we show how non invasive time lapse microgravity surveys can be used to gauge the spatial distribution of groundwater storage changes within a large ca 1500 1000 m moraine talus field of the lake o hara alpine watershed of the canadian rockies additional ground penetrating radar gpr and seismic refraction surveys provide complementary information on subsurface bedrock topography and reveal the location of a major northwest southeast trending depression that likely controls groundwater flow to an alpine lake contiguous with the moraine talus field repeat relative gravity measurements made on a network of 80 gravity stations over and around the moraine talus field during the summers of 2009 and 2010 reveal gravity changes of up to 25 gal although the small gravity changes associated with groundwater flowing out of storage areas are noisy significant changes are evident on the eastern side of the moraine talus field her majesty the queen in right of canada 2012

tidal fluctuations in a leaky confined aquifer localised effects of an overlying phreatic aquifer damping of tidal head fluctuations in a leaky confined coastal aquifer is enhanced by leakage into an overlying phreatic aquifer we show that the phreatic aquifer is however resistant to the leakage flow and in particular a deep phreatic aquifer can reduce the leakage effects significantly an analytical solution based on a vertical flow model for the phreatic aquifer is derived for quantifying the role of this upper free water body in tidal propagation in the lower semi confined aquifer

applicability of analytical solutions to tidal propagation in circular islands abstract the propagation of tides into coastal aquifers is an important phenomenon in the migration of coastal contaminants for the representation of shoreline boundary conditions in regional scale groundwater models and for the estimation of aquifer properties based on tidal amplitude attenuation and or phase increase in this study an analytical solution to the propagation of tidal fluctuations in a radial flow field applicable to circular islands is compared to the existing straight coastline ferris solution the analytical solution is compared to numerical simulation using seawat of a simple harmonic ocean tide and its propagation within a circular island this represents the first attempt to combine a previous correction that allows seawat to simulate axisymmetric flow and a modification to seawat to create tidal boundary conditions bench testing the analytical solution against the numerical model confirms the numerical approach the circular island solution is compared to the ferris solution in terms of tidal amplitude decay and phase shift whereas amplitude decay from the ferris solution is valid only for near shore locations within circular islands the ferris solution produces reasonable phase lag estimates for typical aquifer diffusivities and for most locations within circular islands by comparing the ferris and circular island solutions we propose a correction factor to the ferris solution that allows it to be applied in circular boundary settings this extends the application of the widely applied ferris solution to a broader range of situations

the estimation of fluid flow properties from the response of water levels in wells to the combined atmospheric and earth tide forces the water level in an open well tapping a confined formation is influenced by natural forces including the solid earth tide set and atmospheric pressure variation apv the spectral method is used to analytically derive a model for well response to both random and periodic components of the combined set and apv forcings csa an inverse theory and algorithm are developed in order to provide improved results when using the model to estimate the hydraulic parameters associated with a given formation an examination of the response surface of the estimation criterion reveals a uniqueness problem in estimating storativity s since there is little correlation between the transmissivity t and s estimators a good estimate for t is still possible independent of having accurate knowledge of s an estimate of t is possible only if the data contain sufficient information so that the analysis occurs within an identifiability window the csa estimation methodology is compared to individual set and apv schemes the csa scheme gives the greatest probability that sufficient information is contained in a data record so that t is indeed identifiable the results of applications to synthetic data indicate that the csa scheme gives a t estimate with the most precision and also that it requires collecting fewer observations these results are discussed in light of practical considerations when designing data collection procedures

saltwater wedge variation in a non anthropogenic coastal karst aquifer influenced by a strong tidal range burren ireland summary spatial and temporal changes in saltwater wedges in coastal karst aquifers are still poorly understood largely due to complex mixing processes in these heterogeneous environments but also due to anthropogenic forcing such as pumping which commonly affect natural variations in wedges the purpose of this study was first to characterize the hydrodynamic functioning of a karst aquifer in an oceanic temperate climate with little anthropogenic pressure but strongly influenced by a high tidal range and second to evaluate the extent and movements of a saltwater wedge influenced by both the tide and the natural recharge of the aquifer variations in specific conductivity combined with water chemistry results from six boreholes and two lakes located in the bell harbour catchment western ireland enabled us to assess the extent of the intrusion of the saltwater wedge into the aquifer as a function of both karst recharge and tidal movements at high low and neap spring tidal cycles the marked spatial disparity of the saltwater wedge was analysed as a function of both the hydrodynamic and the structural properties of the karst aquifer results showed that the extent of the saltwater wedge depended not only on the intrinsic properties of the aquifer but also on the relative influence of the recharge and the tide on groundwater levels which have opposite effects recharge in the burren area throughout the year is large enough to prevent saltwater intruding more than about one kilometre from the shore a strong tidal amplitude seems to be the motor of sudden saltwater intrusion observed in the aquifer near the shore while the position of the groundwater level seems to influence the intensity of the salinity increase competition between recharge and the tide thus controls the seawater inputs hence explaining temporal and spatial changes in the saltwater wedge in this coastal karst aquifer

fast deformation of perennially frozen debris in a warm rock glacier in the swiss alps an effect of liquid water 1 surface movement internal deformation and temperature were monitored over 5 years on buz north rock glacier a small rock glacier located at the lower limit of the permafrost belt in the swiss alps the permafrost in the rock glacier mainly consists of pebbles and cobbles filled with interstitial ice two inclinometers installed at 4 and 5 m depths showed fast deformation with large seasonal and interannual variations while the permafrost temperatures remained almost at the melting point the movement of the inclinometers coincided with changes in the surface velocities the deformation rapidly accelerated during snowmelt periods whereas it gradually decelerated below a dry snow cover in winter the frozen debris was more deformable than typical glacier ice at the melting point these phenomena suggest that the frozen debris is permeable to snowmelt water the fast deformation should result from significant annual relocation of debris particles which probably creates a network of air voids in the frozen debris that eventually allows water infiltration the meltwater infiltration accelerates the deformation by reducing effective stress resulting in the reduced strength of the frozen debris the refreezing of the pore water which depends on the cooling intensity in winter decelerates the deformation the combination of these processes controls the temporal variations in the deformation