effects of groundwater level on seismic response of soil foundation systems abstracta set of dynamic centrifuge experiments was performed to assess the effect of the depth of the groundwater table on the seismic site response and kinematic interaction of a foundation on un

analytical solution for groundwater flow in an anisotropic sloping aquifer with arbitrarily located multiwells this paper presents a new analytical solution to describe the hydraulic head distribution and flow system in an anisotropic unconfined aquifer with a sloping bed and arbitrarily located multiwells under transient recharge unlike the existing analytical solutions for delineating the capture zones the solution presented in this study is easy and convenient to calculate flow field in some complicated systems and it can provide useful information for the pump and treat design in addition the presented solution may have the possible application in evaluating the sensitivity of hydrogeological parameters or estimating the hydraulic parameters when coupled with an optimization approach to analyze the aquifer data

a delineation of regional hydraulic conductivity based on water table fluctuation summary the estimation of regional hydraulic conductivity is essential for the sustainable development and efficient management of groundwater this paper presents a new physical method of estimating hydraulic conductivity based on the water level fluctuation model developed by park and parker park e parker j c 2008 a simple model for water table fluctuations in response to precipitation j hydrol 356 344 349 the developed procedure was validated by comparison with the hypothetical numerical model for a variety of hydraulic conductivities aquifer inclinations and the heterogeneities the model was found to be highly reliable when using water level data far from the hydraulic boundaries the results show that the monitoring data obtained over a range of relative distances of an observation location x to the flow domain w x w 0 2 avoided the boundary effects a correction factor was also proposed based on the deviation analysis of the calibrated k and f n ratio of recharge to precipitation divided by porosity the results from the basal inclinations and the heterogeneities cases suggest that the estimated hydraulic conductivity is representing regional property rather than the local one to confirm the validity of the proposed procedure it was applied to the coastal aquifer of jeju island korea the calibrated hydraulic conductivities were consistent with the results from previous studies these results show that the proposed method is an effective and economical means to estimate hydraulic conductivity of large supporting volumes of subsurface aquifers with the convenient use of recharge and groundwater level data

hydraulic testing of low permeability formations a case study in the granite of cadalso de los vidrios spain abstract in recent years the study of low permeability geological formations has undergone considerable development this is mainly due to the use of natural geological barriers to confine waste disposals preventing leaking water from bringing contaminants into contact with the biosphere and the groundwater resources in that context the spanish geological survey igme spanish acronym supported by the national radioactive waste management agency enresa spanish acronym and with the technical advice of the swedish nuclear fuel and waste management company skb designed and built a mobile hydrogeological unit umh spanish acronym for low permeability formations characterization which has been operational since 1997 and has been used for different purposes among other possibilities the umh allows conducting constant transient state flow rate injection tests constant head transient state injection tests pseudo stationary state injection tests pressure fall off tests slug tests and pulse tests the main objectives of this article are to describe the hydraulic characterization methodology used by igme to carry out hydraulic tests in low permeability environment to compare different testing methods and to summarize the results that have been obtained when characterizing the leucogranites of cadalso de los vidrios in spain the study area presents an increasing interest for granite production inside the community of madrid the petrological and structural characteristics of the granite rocks and the core samples extracted from a 200 m deep borehole investigation are described the packer tests are conducted with the mobile hydrogeological unit the tests are interpreted with the help of analytical solutions the main software used is hytool an open source matlab toolbox that provides a library of analytical solutions and a set of routines to facilitate hydraulic tests interpretation the results allow the elaboration of a comparative analysis of the applied hydraulic tests and to define the hydraulic conductivity optimum application interval most suited for each of the used methods hydraulic conductivity values obtained varies from 3 20 10 7 m s for the upper weathered layer to 2 80 10 12 m s for the test section from 97 36 to 116 15 m depth finally the hydraulic conductivity values obtained in this area are compared with other case studies of granite formations around the world

aquifer heterogeneity determination through the slope method in arid region wadis groundwater storage lies within shallow quaternary alluvium deposits which are connected with the present day hydrological cycle and therefore are replenished due to occasional runoff and flash flood occurrences the groundwater resources are precious in these environments therefore their potentiality must be assessed with care in the best manner the aquifer potentiality is calculated after the storativity and transmissivity parameter estimations which require rather long duration field tests with restrictive assumptions in the theoretical model developments such as the homogeneity and isotropy it is the main purpose of this paper to expose the fundamentals of the slope matching procedure smp and its application for short duration field tests in arid region aquifers in this manner the subsurface hydrogeological behaviours of the bored land pieces at and around the well locations are prospected in a detailed and refined manner it is shown that in many cases the classical techniques are appropriate inconvenient and inapplicable with conclusive reliable results and conclusions the application of the smp is presented for some aquifer tests from the central western part of the kingdom of saudi arabia copyright 2007 john wiley sons ltd

a new method for aquifer system identification and parameter estimation the standard practice for assessing aquifer parameters is to match groundwater drawdown data obtained during pumping tests against theoretical well function curves specific to the aquifer system being tested the shape of the curve derived from the logarithmic time derivative of the drawdown data is also very frequently used as a diagnostic tool to identify the aquifer system in which the pumping test is being conducted the present study investigates the incremental area method iam to serve as an alternative diagnostic tool for the aquifer system identification as well as a supplement to the aquifer parameter estimation procedure the iam based diagnostic curves for ideal confined leaky bounded and unconfined aquifers have been derived as part of this study and individual features of the plots have been identified these features were noted to be unique to each aquifer setting which could be used for rapid evaluation of the aquifer system the effectiveness of the iam methodology was investigated by analyzing field data for various aquifer settings including leaky unconfined bounded and heterogeneous conditions the results showed that the proposed approach is a viable method for use as a diagnostic tool to identify the aquifer system characteristics as well as to support the estimation of the hydraulic parameters obtained from standard curve matching procedures copyright 2012 john wiley sons ltd

hydraulic head response of a confined aquifer influenced by river stage fluctuations and mechanical loading summary the response to river stage fluctuation of a drilled well penetrating a confined aquifer was simulated using a stream aquifer interaction algorithm because the confined aquifer is overlaid by a water table aquifer the algorithm was coupled with formulae used to correct the heads for mechanical loading the coupling of stream aquifer interaction and mechanical loading models was tried for the first time in this study the test site was a drilled well installed on the montalto uffugo aquifer located at the calabria university groundwater test field calabria region south of italy this aquifer comprises a 44 m thick sand bank bounded on bottom and top by clay layers and covered by a 7 m thick sandy conglomerate being adjacent to the mavigliano river overall the head changes caused by a river stage raise represented a contribution of 49 3 57 8 to the total head while mechanical loading accounted for the remaining 50 7 32 2 the loading was triggered by a sequence of short spaced rainfall events lasting for a total of 167 days which caused recharge to the unconfined aquifer thickening the water column by some 3 1 m

a solution of the nonlinear boussinesq equation for phreatic flow using an integral balance approach abstract an analytical solution of the nonlinear boussinesq equation is presented using the integral balance method the solution obtained is the same as that obtained by basak 1979 following a different approach

a mathematical model of water table fluctuation in a semi infinite aquifer induced by localized transient recharge a mathematical model of the water table fluctuation in an unconfined aquifer subjected to a typical localized transient recharge is presented the aquifer is taken to be homogeneous isotropic underlain by a horizontal impermeable base and linked with a surface reservoir on one side sensitivity characteristics of the water table due to variations in the rate of recharge hydraulic conductivity and specific yield are illustrated with the help of a numerical example

from excess infiltration to aquifer recharge a derivation based on the theory of flow of water in unsaturated soils an approximate unit hydrograph of aquifer recharge due to effective percolation is derived from a theory describing flow of water in unsaturated soils the parameters appearing in the expression of the unit hydrograph have physical meaning comparison of the theory with field observations indicates that the theory works well a new tool for estimation of the temporal variation of aquifer recharge from that of excess infiltration is now available the tool is practical simple and physical and apparently works well as evidenced by comparisons with field observations

recharge to aquifers with mixed boundaries abstract the problem of localized groundwater recharge from a strip basin to an aquifer bounded by stream and impermeable boundaries was solved by the use of extended finite fourier transforms the solution was evaluated by comparison with the method of images and with numerical and experimental results the existing expression for the inverse of the extended finite fourier cosine transform was corrected

water table shapes and drain flow rates in shallow drainage systems abstract a relationship between drain flow rate elevation and shape of the water table and recharge intensity in shallow drainage systems is developed from an analytical spatial integration of the boussinesq equation in transient conditions drain flow rates are shown to be the sum of three terms the first one is proportional to the maximum water table elevation and more generally to the steady state flow rate at the same water table elevation the second one is a fraction of the recharge rate of the water table depending on the water table shape the third one accounts for possible changes in water storage in the water table due to its shape changes drain flow rates in shallow drainage systems are shown to be fully predicted by one unique variable that is a function of a combination of the hydraulic conductivity k the drainable porosity f and the drain spacing 2l namely k f2l2 this variable also determines the dynamics of changes in the water table shape and in turn the respective parts of the three terms in the equation it is shown that drainage systems with values of 1 m 1 h 1 respond very fast to recharge events water table shape changes occur very quickly so that the third component of the drain flow can be neglected in that case the equation results in a simplified analytical relationship the reliability of the complete and simplified equations to predict drain flow rates in transient conditions is discussed in relation to in situ measurements

recharge from an ephemeral stream following wetting front arrival to water table after the infiltration wetting front from a river bed of an ephemeral stream in flood reaches the shallow water table the rate of recharge which is also that of infiltration is affected by the development of a groundwater mound the effect is practically immediate if the water content behind the wetting front is close to saturation an approximate analytical solution is developed in that case which predicts the time dependence of the recharge rate comparison with experimental results in the laboratory shows that the solution is excellent in spite of the assumptions necessary in the derivations as long as the ratio of river width over depth to water table exceeds 2 and as long as the ratio of initial saturated thickness over depth to the water table exceeds 2 5 the analytical solution is essentially exact under most field conditions these ratios are largely exceeded consequently the predictive equation for the time dependence of the recharge is both quite simple to use and adequately accurate for field applications

response of a sloping aquifer to constant replenishment and to stream varying water level the problem of seepage from a stream into an adjacent unconfined aquifer of semi infinite extent underlain by an impermeable sloping bed was considered in this study as a problem of one dimensional unsteady state groundwater flow it was assumed that the water level in the stream gradually rises to a certain height according to a known exponential function of time while the aquifer was assumed to be replenished at a constant rate from ground surface applying the laplace transformation method derived an analytical solution to an extended and linearized form of the nonhomogeneous boussinesq equation used to describe the phreatic surface in sloping aquifers the comparison of the analytical solution with a numerical solution obtained by applying the finite difference mac cormack explicit computational scheme to the nonlinear boussinesq equation illustrates the validity of the new analytical solution and the effectiveness of the linearization some nondimensional diagrams are also presented to show the variation of the water table height and the seepage rate as well as their sensitivity to various sets of parameter values

water table rise in a semiconfined aquifer due to surface infiltration and canal recharge abstract a general solution to the fluctuation of water table for unsteady state flow in a semiconfined and finite aquifer with recharge from canals and surface infiltration is presented the flow is assumed to be one dimensional in a horizontal direction with the recharging canals at different elevations the laplace transformation method is employed in the solution a numerical example is given for a flow situation in a hypothetical finite aquifer bounded by two recharging canals under vertical infiltration giving water table changes with respect to time

steady annual and monthly recharge implied by deep unconfined aquifer flow abstract we consider the response of a deep unconfined horizontal aquifer to steady annual and monthly recharge a groundwater divide and a zero head reservoir constrain the aquifer so that sinusoidal monthly and aperiodic annual recharge fluctuations create transient specific discharge near the reservoir and an unsteady water table elevation inland one existing and two new long term data sets from the plymouth carver aquifer in southeastern massachusetts calibrate and confirm hydraulic properties in a set of analytical models geohydrology and simulated groundwater flow 1992 data and a new power law for tritiugenic helium to tritium ratios calibrate the steady recharge that drives the classical parabolic model of steady hydraulics applied hydrogeology 2001 observed water table and gradient fluctuations calibrate the transient recharge models in the latter regard monitoring wells within 1 km of buttermilk bay exhibit appreciable specific discharge and reduced water table fluctuations we apply trans am geophys union 32 1951 238 periodic model to the monthly hydraulics and a recharge convolution integral j hydrol 126 1991 315 to annual flow an infiltration fraction of 0 79 and a consumptive use coefficient of 1 08 10 8 m s c relate recharge to precipitation and daylight weighted temperature across all three time scales errors associated with this recharge relation decrease with increasing time scale

analytical solution of water table fluctuations above an inclined leaky layer due to ditch recharge ditch recharge is a method used for raising a water table however if the aquifer lies above a leaky layer then the leaky bed will have an effect on the height of the water table this paper attempts to provide an analytical solution of the transient state to the linearized boussinesq equation the solution proposed in this paper is intended for a generalized form of the leaky layer with the boundary condition of the water level moving according to an exponential form the results of theoretical analysis and experimental studies can provide a much better explanation of ditch recharge on an inclined leaky layer copyright 2006 john wiley sons ltd

water table fluctuation owing to time varying recharge pumping and leakage this paper presents an analytical solution of a 2 d linearized boussinesq equation to predict water table variation in a horizontal aquifer induced by time varying recharge and or withdrawal from any number of recharge basins pumping wells and leakage sites of different dimensions the rate of time varying recharge or withdrawal is approximated by series of line elements of different lengths and slopes depending on the nature of variation of recharge or withdrawal rate advantage of this approximation scheme is that any complex nature of recharge and or withdrawal rates for any number of recharge basins pumping wells and leakage sites and for any number of these operations can be approximated with more accuracy application of the solution in the prediction of water table variation in the presence of time varying recharging pumping and leakage is demonstrated with the help of an example problem the present analytical solution is validated by comparing its results with the corresponding numerical results obtained from modflow for the same example problem

water table rise due to infiltration from canals abstract analytical solutions are presented for transient water table profiles in finite unconfined aquifers due to infiltration occurring from a single canal or more than one canal the aquifer boundaries are assumed to be parallel to the alignment of the canal s and the lower impervious bottom is horizontal further the aquifer is assumed to be homogeneous and isotropic losses such as evapotranspiration are ignored likewise replenishment from other sources for example rainfall is also neglected

recharge from rectangular areas to finite aquifers abstract a generalized analytical solution is derived for the growth of groundwater mound in finite aquifers bounded by open water bodies in response to recharge from rectangular areas finite fourier transforms are used to solve the linearized differential equation of groundwater flow unlike earlier solutions the method presented here does not require the use of tables for evaluation of complicated functions the solution is evaluated by comparison with existing numerical and analytical results in stream aquifer systems similar to those described above application of the proposed solution is more realistic than using solutions available for infinite aquifers

water table fluctuation in soils overlying semi confined aquifers in response to time varying replenishment abstract the water table height in drained agricultural land depends on time varying replenishment that is due to the vertical downward recharge from irrigation or rainfall and in some cases to the upward vertical leakage from a semi confined aquifer the downward recharge may be assumed to vary exponentially with time whereas the upward leakage may be expressed as a function of the unknown water table height furthermore the rising of the water level in the field drainage system that may cause an inverse flow from the drains towards the soil is introduced through a properly defined boundary condition a non homogeneous form of the boussinesq equation that is used to describe this particular drainage problem is solved for three different initial conditions the same drainage problems were solved numerically by using the finite element method comparison between analytical and numerical solutions shows satisfactory agreement from the analytical solutions we obtain the non dimensional water table height at the midpoint between the drains and the non dimensional discharge of the drains per unit drained area as functions of non dimensional time and constants describing the aforementioned drainage conditions variation of these functions has also been illustrated graphically in non dimensional diagrams these can be used to show the sensitivity to various sets of parameter values and to calculate easily the water table height and the drain discharge in practical problems

groundwater flow in sloping aquifer under localized transient recharge analytical study abstractthis paper analyzes the groundwater flow system in an unconfined downward sloping aquifer of semi infinite extent in response to localized transient recharge the aquifer is in contact with a water body of constant water level at one end and receives localized transient recharge from a recharge basin of finite width the mathematical model is based on the boussinesq equation with dupuit forchheimer assumption in which the spatial coordinate of the recharge basin is treated as an additional parameter analytical solutions of the linearized boussinesq equation are obtained using the laplace transform technique by dividing the aquifer in a three zone system containing both dirichlet and neumann boundary conditions at the hypothetical interfaces upward and zero sloping cases are deduced from the main results by appropriately adjusting the slope parameter to assess the validity and efficiency of the linearization method the nonlinear boussinesq equation is also solved using a fully explicit predic

analytical models of slug tests in the present paper attempts are made to develop solutions to various models of slug tests that may be applicable in analyzing the results of such tests where existing solutions are inadequate various geometries that may be encountered in heterogeneous systems such as fractured rocks are considered solutions are presented for linear flow radial flow with boundaries two layer and concentric composite models with different flow geometries between the inner and outer region solutions are obtained in laplace space and inverted back to real space numerically type curves are presented for each solution analyses of the type curves and derivative response curves reveal that many curves have unique shapes only for certain combination of the flow parameters and the distance other sets of type curves are similar in shape although log log plots and derivative plots may emphasize some features that may not be apparent in semilog plots these results show that slug tests suffer problems of nonuniqueness to a greater extent than other well tests

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

modelling of water table variation in response to time varying recharge from multiple basins using the linearised boussinesq equation a mathematical model is presented to describe the variations of the water table in an unconfined aquifer due to time varying recharge applied from four rectangular basins the model is developed by solving the linearised boussinesq equation using the extended finite fourier cosine transform the time varying recharge rate is approximated by a number of piecewise linear elements of different lengths and slopes depending on the nature of the variation in recharge rate application of this model for the prediction of water table fluctuations and in the sensitivity analysis of various controlling parameters on the aquifer response is demonstrated in an example

pumping tests in non uniform aquifers the linear strip case abstract many pumping tests are performed in geologic settings that can be conceptualized as a linear infinite strip of one material embedded in a matrix of differing flow properties a semi analytical solution is presented to aid the analysis of drawdown data obtained from pumping tests performed in settings that can be represented by such a conceptual model integral transform techniques are employed to obtain a solution in transform space that can be numerically inverted to real space examination of the numerically transformed solution reveals several interesting features of flow in this configuration if the transmissivity of the strip is much higher than that of the matrix linear and bilinear flow are the primary flow regimes during a pumping test if the contrast between matrix and strip properties is not as extreme then radial flow should be the primary flow mechanism sensitivity analysis is employed to develop insight into the controls on drawdown in this conceptual model and to demonstrate the importance of temporal and spatial placement of observations changes in drawdown are sensitive to the transmissivity of the strip for a limited time duration after that time only the total drawdown remains a function of strip transmissivity in the case of storativity both the total drawdown and changes in drawdown are sensitive to the storativity of the strip for a time of quite limited duration after that time essentially no information can be gained about the storage properties of the strip from drawdown data an example analysis is performed using data previously presented in the literature to demonstrate the viability of the semi analytical solution and to illustrate a general procedure for analysis of drawdown data in complex geologic settings this example reinforces the importance of observation well placement and the time of data collection in constraining parameter correlation a major source of the uncertainty that arises in the parameter estimation procedure

aquifer parameter estimation using an incremental area method theoretical well functions have been derived over the years to predict ground water level behaviour in aquifer systems under stress owing to groundwater extraction the drawdown data collected during pump tests are typically analysed using graphical curve matching procedures to estimate aquifer parameters based on these well functions difficulty in aquifer characteristic identification and parameter estimation may arise when the field data do not perfectly match the drawdown curves obtained from the well functions the present study provides a new method for the interpretation of aquifer pump tests which supplements the existing curve matching procedures in case ideal conditions do not exist the proposed method provides a greater degree of flexibility in the data analysis for diagnostic tool purposes the method referred to as the incremental area method iam is based on integrating the logarithmic based drawdown curves within a discrete time and matching the results with a corresponding time integral of the theis 1935 well function which governs ideal confined aquifers the application of the proposed method to synthetically generated data and field data showed that iam represents a viable method which yields information on potential non idealness of the aquifer and provides aquifer parameter estimates thus potentially overcoming drawdown data curve matching difficulties copyright 2011 john wiley sons ltd

a new parameter estimation procedure for pumping test analysis using a radial basis function collocation method theoretical well function formulations in confined aquifer leaky or unconfined aquifer types were originally developed to analyze the transient response of the ideal aquifer settings i e homogeneous isotropic medium constant withdrawal rate negligible well bore storage and skin effects etc any deviations from the idealization of the aquifer settings inversely affect the estimation performance which may result in an unrealistic interpretation of pump test analysis a radial basis function collocation method rbfcm based estimation procedure was proposed to elaborate the aquifer parameters in homogeneous and heterogeneous porous medium in the present work the potential drawbacks of the classical curve matching techniques and the derivative based estimation methods have been evaded without dense computation efforts using rbfcm the proposed method as a default application procedure requires no additional parameter no initial guess no interpolation or any complicated derivative calculation to assess the aquifer parameters the suggested approach therefore provides a greater degree of flexibility in the estimation and the same level of accuracy when compared to the existing methods used in hydrology practice this study also reveals the use of proposed method as a diagnostic tool to identify aquifer character by tracking the aquifer parameter variation in time as well as the potential use of rbfcm as an inverse solution technique in the hydrogeology problems

some analytical solutions of the linearized boussinesq equation with recharge for a sloping aquifer subsurface flow from a hillslope can be described by the hydraulic groundwater theory as formulated by the boussinesq equation several attempts have been made to solve this partial differential equation and exact solutions have been found for specific situations in the case of a sloping aquifer brutsaert 1994 suggested linearizing the equation to calculate the unit response of the hillslope in this paper we first apply the work of brutsaert by assuming a constant recharge to the groundwater table the solution describes the groundwater table levels and the outflow in function of time then an analytical expression is derived for the steady state solution by allowing time to approach infinity this steady state water table is used as an initial condition to derive another analytical solution of the boussinesq equation this can then be used in a quasi steady state approach to compute outflow under changing recharge conditions subsurface flow from a hillslope can be described by the hydraulic groundwater theory as formulated by the boussinesq equation several attempts have been made to solve this partial differential equation and exact solutions have been found for specific situations in the case of a sloping aquifer brutsaert 1994 suggested linearizing the equation to calculate the unit response of the hillslope in this paper we first apply the work of brutsaert by assuming a constant recharge to the groundwater table the solution describes the groundwater table levels and the outflow in function of time then an analytical expression is derived for the steady state solution by allowing time to approach infinity this steady state water table is used as an initial condition to derive another analytical solution of the boussinesq equation this can then be used in a quasi steady state approach to compute outflow under changing recharge conditions

water table fluctuation in aquifers overlying a semi impervious layer due to transient recharge from a circular basin summary an analytical solution of a linearised form of boussinesq equation is presented in this paper to describe the water table fluctuation in unconfined aquifers overlying a semi impervious layer in response to transient recharge this solution does not require the common assumption of an impervious formation underlain the unconfined aquifer on the contrary it shows that even when the hydraulic conductivity of the semi impervious layer is several orders of magnitude less than the aquifer hydraulic conductivity downward leakage can be important and can lead to large overestimations of water table heights if it is ignored the rate of recharge is considered to decrease exponentially with time during a single cycle of recharge while two cycles of time varying recharge are approximated by continuous elements described by nth degree polynomials numerical solution of the non linear boussinesq equation was implemented to validate the applied linearisation

40ar 39ar thermochronology of epidote blueschists from the north d aguilar block queensland australia timing and kinematics of subduction complex unroofing mechanisms proposed for exhumation of blueschists include whole crust uplift and erosion denudation by crustal scale extensional faulting or ductile strain and transport of blocks entrained in rising diapiric masses insight into the unroofing process and the role of granitic plutonism can be gleaned from study of north d9aguilar block in the new england orogen of southeastern queensland australia epidote blueschist facies rocks occur as structurally coherent schists and as blocks in serpentinite matrix melange these subduction underplated rocks formed at depths 18 km and occur in the lower plate of a metamorphic core complex a slate from the upper plate has a whole rock total gas age of 315 ma interpreted as a minimum age for subduction along this part of the paleo pacific margin exhumation of lower plate schists was coeval with overprinting of early high pressure m 1 metamorphic fabrics by a greenschist facies fabric m 2 and was accomplished in part by ductile stretching and normal faulting phengites from most lower plate schists yield 40 ar 39 ar plateau ages of ca 299 296 ma recording the time elapsed since the schists cooled below 350 50 c following m 2 plateau shaped age spectra and small structural depth related age gradients indicate rapid cooling of schists in the footwall of a present day low angle normal fault samples from deeper levels of the lower plate remained at 350 c for 35 m y longer than the other samples and contain extraneous ar possibly absorbed from fluids originating at depth at ca 307 ma a granodiorite pluton was intruded into the lower plate near the peak of m 2 a synkinematically intruded in part mylonitic pluton increased the regional m 2 fabric to amphibolite facies in its aureole heat from the granitic pluton and perhaps others like it at depth may have played a strain softening role in formation of the core complex similar 40 ar 39 ar cooling ages for different blueschist and greenschist blocks in serpentinite matrix melange support the view that the australian melange was uplifted by extensional tectonic processes unrelated to serpentinite diapirism

analytical solutions for strip basin recharge to aquifers with cauchy boundary conditions abstract analytical solutions for groundwater recharge from strip basins to finite aquifers are presented the problem concerns the impact of either continuous or periodic seasonal recharge schemes on aquifers with a boundary condition of the third kind cauchy the solutions can be useful for assessing aquifer response as well as for calibrating numerical computer models

paleomagnetic data from the new england orogen eastern australia and implications for oroclinal bending orogenic curvatures oroclines are common in modern and ancient orogens but the geodynamic driving forces of many oroclines remain controversial here we focus on the new england oroclines of eastern australia the formation of which had been previously broadly constrained to the early middle permian this time interval encompasses periods of both back arc extension at 300 280 ma and subsequent contractional deformation hunter bowen orogeny that commenced at 270 ma along the paleo pacific and gondwanan subduction plate boundary we present new paleomagnetic data from volcanic rocks that were extruded during the transition from extension to contraction at 272 ma and we show that the oroclinal structure must have formed prior to the emplacement of the volcanic rocks our results thus indicate that oroclinal bending in the southernmost new england orogen has been completed prior to the onset of middle permian contractional deformation it is therefore concluded that the oroclines have likely formed during back arc extension and that a major contribution to the orogenic curvature was driven by trench retreat

water table fluctuation in a sloping aquifer with transient recharge abstract an analytical solution of the linearized boussinesq equation with a complex transient recharge function is presented to describe the water table fluctuation in a sloping aquifer of finite width the solution is obtained by using an eigenvalue eigenfunction expansion method some previously known solutions for different recharge functions have been shown to be special cases of the present general solution applications of the solutions in prediction of the spatio temporal distribution of the water table in a ditch drainage system are illustrated with the help of synthetic examples

ecoulement sature et non sature de l eau souterraine vers des drains en aquifere a nappe libre the drainage of sports fields highways farm lands and covers for wastes corresponds to the drainage of a shallow unconfined aquifer resting on a horizontal or sloping impervious substratum the seepage partly saturated and partly unsaturated is thus described by nonlinear equations that are not easy to solve a few analytical solutions exist they were obtained after several simplifying assumptions are they realistic in this paper comparisons are made between predictions from analytical solutions and those from numerical resolutions for saturated and unsaturated seepage under steady and transient states the analytical solutions predict a water table and flow rates that differ significantly from those of the numerical resolutions and are sometimes unrealistic corrections to the analytical solutions have already been proposed to account for the vadose zone despite such corrections the published solutions to drainage problems may be inaccurate in engineering projects where the duration of dra

recharge to finite aquifers from strip basins abstract the problem of groundwater recharge from strip basins to finite aquifers is solved analytically by the method of finite fourier transforms both impermeable and recharge boundaries are considered the analytical solutions are evaluated by comparison with experimental results in sand tank models reported in the literature

analytical and experimental solutions for drainage of sloping lands with time varying recharge m j boussinesq s 1904 nonlinear partial differential equation for unsteady state flow of water through a phreatic aquifer resting on a sloping impervious barrier and receiving time varying recharge has been solved two patterns of recharge rates i e linearly increasing and exponentially declining with time were considered the initial conditions of the water table were taken at the drain level transformations were devised to transform the resulting approximate linearized boussinesq equation to the form of a one dimensional heat flow equation for each case of recharge pattern and analytical solutions for the height of the water table between parallel drains were obtained in the form of a convergent series the analytical solutions were experimentally verified with a hele shaw model a reasonably close agreement was found in the computed and observed phreatic surfaces the results showed that the analytical solutions presented herein can be used with reasonable accuracy for designing subsurface drainage in sloping phreatic aquifers

orogenesis without collision stabilizing the terra australis accretionary orogen eastern australia the neoproterozoic to end paleozoic terra australis orogen extended along the gondwana margin of the paleo pacific ocean and it now provides a detailed record of orogenic activity and continental stabilization within an ongoing convergent accretionary plate margin new geochronological data from end paleozoic plutonic and volcanic rocks associated with the gondwanide orogeny in the new england region of eastern australia integrated with information on the nature and timing of associated sedimentation deformation and metamorphism allow resolution of a high fidelity record of orogenesis at the end of the carboniferous around 305 ma convergent margin magmatism which had been active along the western margin of the new england region terminated and was followed by a short pulse of regional compressional deformation and metamorphism marking the commencement of the tablelands phase of gondwanide orogenesis deformation was almost immediately followed by the onset of clastic sedimentation and local calc alkaline volcanism dated at 293 ma in the extensional barnard basin emplacement of the two new england s type granitic suites the bundarra and the hillgrove suites along with localized high temperature low pressure metamorphism was essentially contemporaneous ranging in age from 296 to 288 ma and overlapped in time with i type magmatism and the switch from regional compression to extension and barnard basin rifting the hunter bowen phase of the gondwanide orogeny commenced with contractional deformation resulting in termination of sedimentation in the barnard basin and regional deformation and metamorphism across new england and into the sydney and gunnedah basins to the west at around 265 260 ma contractional loading of the sydney and gunnedah basins resulted in their conversion from extensional to foreland basins which received ongoing pulses of sediment from the new england orogenic welt until 230 ma the hunter bowen phase was associated with widespread i type plutonism and volcanic activity in new england that ceased around 230 ma marking the termination of gondwanide orogenesis orogenesis occurred in an evolving convergent plate margin setting s and i type magmatic activity ranging in age from ca 300 to 230 ma represents a stepping out of arc magmatism from the western margin of new england prior to 305 ma into the preexisting arc trench gap there is no evidence that deformation was related to the collision of the convergent margin with a major lithospheric mass and the widespread development of extensional basins in the eastern third of australia in the early permian indicates control by phenomena acting on a continental scale probably changing plate kinematics associated with the amalgamation of pangea

two dimensional modelling of water table fluctuation in response to localised transient recharge abstract an analytical solution of the linearised boussinesq equation is presented and used to predict the spatio temporal variation of the water table in a finite aquifer system in response to a transient recharge from an overlying rectangular basin the boundary conditions of the finite aquifer are taken as fixed heads which would apply when the aquifer system is surrounded by open water bodies application of the solution is illustrated with the help of a numerical example the results would also have applications in studying stream aquifer interaction in the presence of transient recharge

water table fluctuations in an aquifer system owing to time varying surface infiltration and canal recharge a solution of the linearized boussinesq equation for predicting the transient position of the water table in an unconfined aquifer system which lies between two recharging canals at different elevations above the aquifer s base and receives time varying recharge from the overlying soils is presented the solution for the constant rate of recharge is shown as a special case of the present solution the effect of variation in the rate of recharge on the water table fluctuation is investigated with the help of an example

contrasting modes of eclogite and blueschist exhumation in a retreating subduction system the tasmanides australia abstract blueschists and eclogites located in the tasmanides of eastern australia preserve evidence of contrasting modes of exhumation a review of structural metamorphic geochronological and geochemical data indicates that these hp metamorphic rocks can be sub divided into three main groups i eclogite blueschists with calc alkaline and tholeiitic affinities contained within thick sedimentary sequences called continental hp rocks ii moderate pressure thermobarometric and geochronological data from eclogites and blueschists in the peel manning fault system new england orogen also provide evidence for discontinuous exhumation of subducted oceanic rocks these data indicate that eclogites were exhumed from depths of 70 km to 30 km during the ordovician 490 470 ma with terminal exhumation and exposure along the peel manning fault system probably occurring during the permian based on these timing constraints we suggest a model where hp rocks reside between depth dependant exhumation circuits for considerable lengths of time

flow to a well of finite diameter in a homogeneous anisotropic water table aquifer a laplace transform solution is presented for the problem of flow to a partially penetrating well of finite diameter in a slightly compressible water table aquifer the solution which allows for evaluation of both pumped well and observation piezometer data accounts for effects of well bore storage and skin and allows for the noninstantaneous release of water from the unsaturated zone for instantaneous release of water from the unsaturated zone the solution approaches the line source solution derived by neuman as the diameter of the pumped well approaches zero delayed piezometer response which is significant during times of rapidly changing hydraulic head is included in the theoretical treatment and shown to be an important factor in accurate evaluation of specific storage by means of a hypothetical field example it is demonstrated that evaluations of specific storage ss using classical line source solutions may yield values of ss that are overestimated by a factor of 100 or more depending upon the location of the observation piezometers and whether effects of delayed piezometer response are included in the analysis theoretical responses obtained with the proposed model are used to suggest methods for evaluating specific storage