a correction factor to account for mixing in ghyben herzberg and critical pumping rate approximations of seawater intrusion in coastal aquifers 1 the classic ghyben herzberg estimate of the depth of the freshwater saltwater interface together with the dupuit approximation is a useful tool for developing analytical solutions to many seawater intrusion problems on the basis of these assumptions strack 1976 developed a single potential theory to calculate critical pumping rates in a coastal pumping scenario the sharp interface assumption and in particular this analytical solution are widely used to study seawater intrusion and the sustainable management of groundwater resources in coastal aquifers the sharp interface assumption neglects mixing and implicitly assumes that salt water remains static consequently this approximation overestimates the penetration of the saltwater front and underestimates the critical pumping rates that ensure a freshwater supply we investigate the error introduced by adopting the sharp interface approximation and we include the effects of dispersion on the formulation of strack 1976 to this end we perform numerical three dimensional variable density flow simulations we find that strack s equations can be extended to the case of mixing zone if the density factor is multiplied by an empirically derived dispersion factor 1 t b 1 6 where t is transverse dispersivity and b is aquifer thickness we find that this factor can be used not only to estimate the critical pumping rate but also to correct the ghyben herzberg estimate of the interface depth its simplicity facilitates the generalization of sharp interface analytical solutions and good predictions of seawater penetration for a broad range of conditions

structure of the lunar crust at highland site apollo station 16 the seismic crustal structure of the moon is known in the region of oceanus procellarum from the analysis of artificial impact data to extend this knowledge we have used data from natural lunar seismic events to search for secondary seismic wave arrivals in the form of peg leg multiples caused by reflections at crustal interfaces and converted arrivals caused by refractions at crustal interfaces a polarization filter has been applied to the data to enhance the rectilinear particle motion expected for the onset of these body wave arrivals in the scattered coda of lunar seismograms the results of this work tentatively indicate that the highland site at station 16 has a 75 km thick crust with an intermediate 20 km interface compared to the 60 km crust and 20 km interface in oceanus procellarum a mare region since the 20 km upper crust appears to exist at both highland and mare sites it probably does not represent a mare basalt layer but rather a more general feature of the crust crustal thickness may partially control elevation by isostasy

tides in the strait of gibraltar the strait of gibraltar is where the transition occurs between two distinct tidal regimes the north atlantic where tidal ranges are in excess of 2 m and the western mediterranean where tidal ranges are less than 1 m within the strait the tide is principally semidiurnal observations indicate that on average 96 of the bottom pressure and 74 of the current variability are contained in the semidiurnal band 2 cpd the structure of the local cotidal chart of the m2 tidal constituent is complicated but can be explained in terms of the along and across strait momentum balances along the strait the pressure gradient is mainly balanced by the acceleration of the flow although friction can be of appreciable magnitude corresponding to a decay time scale of 3 16 hours across the strait the momentum balance appears mostly geostrophic but better observations would be required to explain residual terms available observations indicate that the m2 tide has no net energy flux through the strait at the sill the tidal transport in the upper layer exceeds that in the lower layer by nearly a factor of 2 at the eastern end of the strait between algeciras and ceuta the tidal transport is larger in the lower layer this apparent shift in the location of maximum tidal transport is explained in terms of the kinematics of the interface between atlantic and mediterranean waters a mean transport of 0 21 sv due to subinertial and tidal flows carries atlantic water through the strait compensated by an approximately equal return in the lower layer

tides in the black sea observations and numerical modelling longterm hourly data from 28 tide gauges were used to examine the main features of tides in the black sea the tides in this basin are directly caused by tide generating forces and the semidiurnal tides prevail over diurnal tides based on the princeton ocean model pom a numerical model of tides in the black sea and adjacent sea of azov was developed and found to be in good agreement with tide gauge observations detailed tidal charts for amplitudes and phase lags of the major tidal harmonics in these two seas were constructed the results of the numerical modelling and observations reveal for the semidiurnal tides the presence of an amphidromy with clockwise rotation and another one with counterclockwise rotation for the diurnal tides both located in the central part of the sea near the crimean peninsula therefore for this part of the sea the amplitudes of harmonics m2 and k1 are less than 0 1 cm relatively larger m2 amplitudes are observed on the east and west coasts of the sea 2 3 cm the maximum amplitude of the harmonic m2 was found at karkinit bay up to 4 5 cm while the maximum tidal range varies from 1 cm near the crimean peninsula to 18 19 cm in the dnieper bug estuary and karkinit bay radiational tides initiated mainly by sea breezes make an important contribution to the formation of tidal oscillations in the dnieper bug estuary

nodal variations and long term changes in the main tides on the coasts of china the long term changes in the main tidal constituents o1 k1 m2 n2 and s2 along the coasts of china and in adjacent seas are investigated based on 17 tide gauge records covering the period 1954 2012 the observed 18 61 year nodal modulations of the diurnal constituents o1 and k1 are in agreement with the equilibrium tidal theory except in the south china sea the observed modulations of the m2 and n2 amplitudes are smaller than theoretically predicted at the northern stations and larger at the southern stations the discrepancies between the theoretically predicted nodal variations and the observations are discussed the 8 85 year perigean cycle is identifiable in the n2 parameters at most stations except those in the south china sea the radiational component of s2 contributes on average 16 of the observed s2 except in the gulf of tonkin on the south coast where it accounts for up to 65 we confirmed the existence of nodal modulation in s2 which is stronger on the north coast the semidiurnal tidal parameters show significant secular trends in the bohai and yellow seas on the north coast and in the taiwan strait the largest increase is found for m2 for which the amplitude increases by 4 7 mm yr in the yellow sea the potential causes for the linear trends in tidal constants are discussed

tidal dynamics in the northern adriatic sea tides in the northern adriatic sea are investigated using two distinct numerical models first a two dimensional 2 d finite difference model is implemented with very high horizontal resolution 556 m to simulate the northern adriatic after calibration of open boundary conditions the model gives very satisfactory results the averaged vectorial difference between observed and simulated elevations is 1 3 cm for each of the seven major tidal constituents next a 3 d finite element model is applied to the entire sea in order to provide a better simulation of the tidal currents in the vicinity of the open boundary of the first model results show that the northern adriatic behaves like a narrow rotating channel in which the instantaneous sea surface elevation sse contours are aligned with the depth averaged velocity vectors and in which the sse is always higher to the right of the local current these features emphasize the rotational character that tides can exhibit in a relatively small basin wave fitting to the current elevation structure shows that semidiurnal tidal constituents are well represented with a system of two frictionless kelvin waves incident and reflected in contrast the diurnal constituents are best described as a topographic wave propagating across not along the basin from the croatian coast to the italian shore despite this obvious disparity the semidiurnal and diurnal tides can be understood as distinct members of a single family of linear waves which exist under the combined actions of gravity and topography

a comparison of deterministic and stochastic approaches for regional scale inverse modeling on the mar del plata aquifer summary inversion of the spatial variability of transmissivity t in groundwater models can be handled using either stochastic or deterministic i e geology based zonation approaches while stochastic methods predominate in scientific literature they have never been formally compared to deterministic approaches preferred by practitioners for regional aquifer models we use both approaches to model groundwater flow and solute transport in the mar del plata aquifer where seawater intrusion is a major threat to freshwater resources the relative performance of the two approaches is evaluated in terms of i model fits to head and concentration data available for nearly a century ii geological plausibility of the estimated t fields and iii their ability to predict transport we also address the impact of conditioning the estimated fields on t data coming from either pumping tests interpreted with the theis method or specific capacity values from step drawdown tests we find that stochastic models based upon conditional estimation and simulation techniques identify some of the geological features river deposit channels and low transmissivity regions associated to quartzite outcrops and yield better fits to calibration data than the much simpler geology based deterministic model which cannot properly address model structure uncertainty however the latter demonstrates much greater robustness for predicting sea water intrusion and for incorporating concentrations as calibration data we attribute the poor performance and underestimated uncertainty of the stochastic simulations to estimation bias introduced by model errors qualitative geological information is extremely rich in identifying large scale variability patterns which are identified by stochastic models only in data rich areas and should be explicitly included in the calibration process

parameter identification for axi symmetric density dependent groundwater flow based on drawdown and concentration data abstract a new tool for the simultaneous interpretation of a pumping and upconing test of saltwater is developed the forward model is verified and a synthetic example checks the functioning of the inverse model the new model interprets the movement of the transition zone between saltwater and freshwater towards the pumping well and the evolution of the drawdowns at different depths and different distances from the pumping well simultaneously the drawdown and concentration observations are considered in their logarithmic space during the definition of their residuals these two different types of data are interpreted by minimising a composite object function through a gauss newton algorithm with sensitivities calculated by the perturbation method the method is fast and relatively free of numerical dispersion because it uses an axi symmetric grid and particle tracking for the solute transport

management of coastal aquifers based on nonlinear optimization and evolutionary algorithms abstract a method of assessing the optimum pumping rates of coastal aquifers based on nonlinear optimization and evolutionary algorithms ea is developed the objective is to maximize the total pumping rate while protecting the wells from sea water intrusion the formulation of the constraints is based on numerical simulation of the freshwater flow equations the simulation model is based on the sharp interface and the ghyben herzberg approximation and is applicable to unconfined aquifers and steady state flow the single potential formulation of water resour res 12 1976 1165 is followed and the governing equations are solved numerically using finite differences the numerical model can handle aquifers of complex shapes nonuniform hydraulic conductivity nonuniform distribution of surface recharge etc the constraints are nonlinear with respect to the decision variables resulting in a nonlinear optimization problem two optimization methods are investigated specifically sequential quadratic programming sqp and evolutionary algorithms ea sqp requires less computer time than ea but can get stuck on local optimum solutions the simulation and optimization methodology is applied to a real unconfined coastal aquifer in the greek island of kalymnos for determining the optimal pumping rates while protecting the wells from sea water intrusion

vertical average for modeling seawater intrusion 1 seawater intrusion in coastal aquifers is a 3 d phenomenon however 3 d regional aquifer models are often limited by insufficient geological and hydrological data the large horizontal to vertical scales ratio and by numerical constraints we present an effective formulation for modeling seawater intrusion that relies on a dimensional reduction of the original density dependent flow and transport problem we carry out a vertical integration of the 3 d problem and arrive at a coupled set of 2 d equations for the mean flux and salt concentration which are essentially identical to those of 2 d groundwater flow however two new terms emerge from the integration 1 darcy s law needs not only the buoyancy term reflecting aquifer bottom slope but also another one reflecting variability of aquifer thickness and 2 transport requires a new term reflecting vertical variations of groundwater flux which are essential for density dependent flow and we approximate by means of a fickian dispersion term the proposed equations are verified by direct steady state numerical simulations of confined aquifers the results show that the effective formulation correctly reflects the effective dynamics in the 3 d system

lateral variations of lunar crustal thickness from the apollo seismic data set seismic waves generated by meteoroid impacts have been detected by the apollo lunar seismic network these waves are sensitive to the crustal structure beneath both the seismic stations and the impact sites we use a markov chain monte carlo algorithm in order to invert for lateral variations of crustal thickness on the moon the inversion uses travel times of seismic waves originating from multiple meteoroid impact locations previous seismic investigations constrained the crustal thickness solely for apollo stations 12 14 and 16 whereas our approach enables to estimate the crustal thickness at locations far from the apollo network and to build a first crustal thickness map based on seismic data here we compare our crustal thickness estimates based on seismic travel times to those based on inversions of the topography and gravity field both methods turn out to be coherent in the sense that highland sites possess a thicker crust than mare sites

on the resonance and influence of the tides in ungava bay and hudson strait 1 the tides of leaf basin in ungava bay may be the world s highest an analysis of the frequency dependence of the response to outside forcing a normal mode analysis and a study of the damped oscillation of an initial disturbance suggest that the ungava bay hudson strait region has a natural period of about 12 7 hours and so is close to resonance with the tidal forcing the implications for regional and global tides in the present past and future are explored

discussion about the validity of sharp interface models to deal with seawater intrusion in coastal aquifers analytical models have been exhaustively used to study simple seawater intrusion problems and the sustainable management of groundwater resources in coastal aquifers because of its simplicity easy implementation and low computational cost most of these models are based on the sharp interface approximation and the ghyben herzberg relation and their governing equations are expressed in terms of a single potential theory to calculate critical pumping rates in a coastal pumping scenario the ghyben herzberg approach neglects mixing of fresh water and seawater and implicitly assumes that salt water remains static therefore the results of the analytical solutions may be inaccurate and unacceptable for some real complex case studies this paper provides insight into the validity of sharp interface models to deal with seawater intrusion in coastal aquifers i e when they can be applied to obtain accurate enough results for that purpose this work compares sharp interface solutions based on the ghyben herzberg approach with numerical three dimensional variable density flow simulations for a set of heterogeneous groundwater flow and mass transport parameters and different scenarios of spatially distributed recharge values and spatial wells placement the numerical experiment has been carried out in a 3d unconfined synthetic aquifer using the finite difference numerical code seawat for solving the coupled partial differential equations of flow and density dependent transport this paper finds under which situations the sharp interface solution gives good predictions in terms of seawater penetration transition zone width and critical pumping rates additionally the simulation runs indicate to which parameters and scenarios the results are more sensitive copyright 2013 john wiley sons ltd

tidal resonance in juan de fuca strait and the strait of georgia abstract the resonant period and quality factor q are determined for the semienclosed sea comprising juan de fuca strait puget sound and the strait of georgia the observed tidal elevation gain and phase change from the pacific ocean to this inland sea are fitted to the predictions of simple analytic models which give a resonant period of 17 21 h and a q of about 2 the low q value indicative of a highly dissipative system is consistent with the need for numerical models for the area to employ large bottom friction coefficients these include the effects of form drag

measurement and analysis of lunar basin depths from clementine altimetry altimetric profiles from the clementine lidar are used to calculate the depths of 29 large craters and basins on the moon plotting the depths of the best preserved structures together with values for simple and complex craters measured in pre clementine studies reveals an inflection in the depth diameter d d curve in addition to the one revealed by pre clementine data this inflection occurs in the diameter range that corresponds to the morphologic transition from complex crater to basin the best empirical power law fit for basin depths is log10 d 0 41 log10 d 0 57 this relationship is characterized by a lower slope than that for complex craters demonstrating that this morphologic transition corresponds to a further decrease in the depth of an impact structure relative to its diameter with increasing size qualitative consideration of possible causes for the second inflection leads to the conclusion that it is most likely a consequence of a short term modification mechanism that influences fundamental crater morphology such as the increasing influence of gravity with diameter thicknesses of maria in the major basins are calculated by assuming that their unfilled depths would follow thed drelation results are compared with previous estimates and yield thicknesses that are generally greater than those determined by studies of flooded craters and less than those obtained from analysis of gravity

a two dimensional tidal model for the mediterranean sea the tidal propagation in the mediterranean sea is described through a high resolution two dimensional hydrodynamic model forced by the equilibrium tide and the incoming tide at the strait of gibraltar the four most significant constituents m2 s2 k1 and o1 are included in the model good agreement with a set of 63 coastal gauges is achieved the significance of the equilibrium tide and the forcing at the open boundary is investigated the incoming wave from the strait of gibraltar is important in tuning the tides in the whole of the mediterranean for the north aegean sea the solution without the forcing at gibraltar results in a doubling of the amplitudes of the semidiurnal tides the estimated energy dissipation due to bottom friction is 8 8 108 w the major area of dissipation is the gulf of gabes energy fluxes through the major straits are calculated

effects of tidal fluctuations and spatial heterogeneity on mixing and spreading in spatially heterogeneous coastal aquifers we study the combined effect of heterogeneity in the hydraulic conductivity field and tidal oscillations on the three dimensional dynamics of seawater intrusion in coastal aquifers we focus on the quantification of its impact on solute mixing and spreading of the freshwater seawater interface three dimensional monte carlo realizations of log normally distributed permeability fields were performed and for each realization numerical variable density flow and solute transport simulations were conducted mixing is characterized by the spatial moments of concentration the enhanced solute mixing is quantified by an effective dispersion coefficient the simulations show that heterogeneity produces an inland movement of the toe location along with a significant widening of the transition zone which is linearly proportional to the product of the arithmetic mean of the correlation lengths in the three spatial dimensions a and the permeability field variance lnk2 we find that once tidal oscillations are included as the degree of heterogeneity increases the combined effect of heterogeneity and tidal oscillations on mixing and spreading of the interface reduces this is explained by the fact that an increase in the log permeability variance induces an increase in both the effective permeability and the spatial connectivity which implies a more uniform hydraulic response to tidal forcing and as a result the degree of mixing decreases this study also identifies that the mixing behavior induced by tidal oscillations in heterogeneous coastal aquifers is controlled by the effective tidal mixing number ntme which depends on the amplitude the period the storativity and the effective horizontal permeability

first seismic receiver functions on the moon we applied the s receiver function technique farra and vinnik 2000 to the recordings of deep moon quakes at seismograph station apollo 12 in order to detect phases converted sp and reflected beneath the station we detected sp phases from the base of the surficial low velocity zone and from the mantle crust boundary the average p velocity in the surficial layer 1 km thick should be a few times higher than in reference model toksoz et al 1974 the observed time amplitude and waveform of sp phase from the mantle crust boundary are close to those predicted by the reference model but with a modified surficial layer the s wavetrains within the first 10 s may contain waves scattered in the mantle this scattering is stronger than in the earth at comparable depths the polarized component in the coda waves that we observe is another previously unknown phenomenon

inverse modelling for freshwater lens in small islands kish island persian gulf a number of challenges including instability nonconvergence nonuniqueness nonoptimality and lack of a general guideline for inverse modelling have limited the application of automatic calibration by generic inversion codes in solving the saltwater intrusion problem in real world cases a systematic parameter selection procedure for the selection of a small number of independent parameters is applied to a real case of saltwater intrusion in a small island aquifer system in the semiarid region of the persian gulf the methodology aims at reducing parameter nonuniqueness and uncertainty and the time spent on inverse modelling computations subsequent to the automatic calibration of the numerical model uncertainty is analysed by constrained nonlinear optimization of the inverse model the results define the percentage of uncertainty in the parameter estimation that will maintain the model inside a user defined neighbourhood of the best possible calibrated model sensitivity maps of both pressure and concentration for the small island aquifer system are also developed these sensitivity maps indicate higher sensitivity of pressure to model parameters compared with concentration these sensitivity maps serve as a benchmark for correlation analysis and also assist in the selection of observations points of pressure and concentration in the calibration process copyright 2012 john wiley sons ltd

the adriatic sea m2 and k1 tides by 3d model and data assimilation in the present work we explore the impact of assimilating local tide gauge and altimetric data on the quality of predicting the major adriatic tides m2 and k1 to that end we compute optimal tidal open boundary conditions for a 3d high resolution finiteelement model by using an incremental assimilation formalism the essence of the method is the use of two dynamical models where the solution in the complex 3d high resolution model is sought via assimilation of prediction errors into the simpler 2d model with explicit inverse in the central numerical experiment harmonic constants from 12 tide gauges are assimilated and the results are analysed at 31 locations hence 19 independent ones the data assimilation contributes to the reduction of maximum amplitude error from 5 6 to 0 5 cm for m2 and from 3 9 to 0 1 cm for k1 the assimilation procedure is repeated by assimilating suitably processed topex poseidon altimeter data again validating the outcome at 31 tide gauge locations the result was very similar to the gauge data assimilation outcome the model output is also validated with the current data not used in the assimilation at two locations and at three depths the model was able to reproduce the major and the minor semi axes of tidal ellipses as well as their orientations very well 2003 elsevier ltd all rights reserved

calibration of seawater intrusion models inverse parameter estimation using surface electrical resistivity tomography and borehole data electrical resistivity tomography ert can be used to constrain seawater intrusion models because of its high sensitivity to total dissolved solid contents tds in groundwater and its relatively high lateral coverage however the spatial variability of resolution in electrical imaging may prevent the correct recovery of the desired hydrochemical properties such as salt mass fraction this paper presents a sequential approach to evaluate the feasibility of identifying hydraulic conductivity and dispersivity in density dependent flow and transport models from surface ert derived mass fraction in the course of this study geophysical inversion was performed by using a smoothness constraint tikhonov approach whereas the hydrological inversion was performed using a gradient based levenberg marquardt algorithm two synthetic benchmarks were tested they represent a pumping experiment in a homogeneous and heterogeneous coastal aquifer respectively these simulations demonstrated that only the lower salt mass fraction of the seawater freshwater transition zone can be recovered for different times this ability has here been quantified in terms of cumulative sensitivity and our study has further demonstrated that the mismatch between the targeted and the recovered salt mass fraction occurs from a certain threshold we were additionally able to explore the capability of sensitivity filtered ert images using ground surface data only to recover in both synthetic cases the hydraulic conductivity while the dispersivity is more difficult to estimate we attribute the latter mainly to the lack of ert derived data at depth where resolution is poorer as well as to the smoothing effect of the ert inversion

tidal dynamics in the gulf of maine and new england shelf an application of fvcom 1 the unstructured grid finite volume community ocean model fvcom was used to simulate the tides in the gulf of maine gom and new england shelf nes for homogeneous and summer stratified conditions fvcom captures the near resonant nature of the semidiurnal tide and energy flux in the gom and the complex dynamics governing the tide in the nes stratification has limited impact on tidal elevation but can significantly modify the tidal current profile internal tides are energetic in the stratified regions over steep bottom topography but their contribution to the total tidal energy flux is only significant over the northeast flank of georges bank the model suggests that the tidal flushing induced eddy east of monomoy island is the dynamic basis for the locally observed phase lead of the m2 tide the southward propagating tidal wave east of cape cod encounters the northeastward propagating tidal wave from the nes south of nantucket island forming a zone of minimum sea level along a southeast oriented line from nantucket island these two waves are characterized by linear dynamics in which bottom friction and advection are negligible in the momentum balance but their superposition leads to a strong nonlinear current interaction and large bottom stress in the zone of lowest sea elevation

a coupled stochastic inverse sharp interface seawater intrusion approach for coastal aquifers under groundwater parameter uncertainty abstract this paper presents an alternative approach to deal with seawater intrusion problems that overcomes some of the limitations of previous works by coupling the well known swi2 package for modflow with a stochastic inverse model named gc method on the one hand the swi2 allows a vertically integrated variable density groundwater flow and seawater intrusion in coastal multi aquifer systems and a reduction in number of required model cells and the elimination of the need to solve the advective dispersive transport equation which leads to substantial model run time savings on the other hand the gc method allows dealing with groundwater parameter uncertainty by constraining stochastic simulations to flow and mass transport data i e hydraulic conductivity freshwater heads saltwater concentrations and travel times and also to secondary information obtained from expert judgment or geophysical surveys thus reducing uncertainty and increasing reliability in meeting the environmental standards the methodology has been successfully applied to a transient movement of the freshwater seawater interface in response to changing freshwater inflow in a two aquifer coastal aquifer system where an uncertainty assessment has been carried out by means of monte carlo simulation techniques the approach also allows partially overcoming the neglected diffusion and dispersion processes after the conditioning process since the uncertainty is reduced and results are closer to available data

homogenization and effective parameters for the henry problem in heterogeneous formations 1 general upscaling of density dependent flow is investigated for the classical two dimensional henry problem of saltwater intrusion in coastal aquifers combined theoretical and numerical results are here presented effective flow and transport parameters for saline intrusions could be derived for statistically isotropic and anisotropic heterogeneous permeability fields by use of homogenization theory applying also to the preasymptotic regime our numerical results indicate that heterogeneities in permeability affect foremost the transient evolution of saltwater intrusion whereas the steady state saltwater distribution is less sensitive to spatially varying permeabilities and longitudinal dispersion for the isotropic media the effective permeability is found to correspond to the geometric mean as under conditions without fluid density contrast the extension of results to anisotropic media requires nontrivial corrections for the effective permeability which include the variance of log k and the directional correlation lengths the appropriate dispersion coefficients for the problem correspond to the local dispersion coefficients rather than macrodispersion coefficients these results are discussed in light of the specific flow configuration posed in the henry problem

anticipating the effects of groundwater withdrawal on seawater intrusion and soil settlement in urban coastal areas intensive pumping in urban coastal areas is a common threat to water resource quality due to seawater intrusion in those areas where subsurface water resources are not usually used for human consumption or irrigation intensive pumping is associated with other activities like the lowering of the water table necessary to support underground structures and building foundations this activity also increases the likelihood of soil settlement that affects building stability and the corrosion of concrete structures due to groundwater salinity under these circumstances the awareness of a certain municipality calonge ne spain of the potential effects of groundwater withdrawal upon foundations has led to an integrated approach to anticipate seawater intrusion related to urban development geological mapping and correlation of borehole logs electrical resistivity tomography and hydrochemical data provide comprehensive knowledge of the geology and hydrogeology of the area and act as screening tools necessary to discern the influence of hydrological processes in coastal areas developing strack s analytical solution new comprehensive dimensionless expressions are herein derived to determine the critical pumping rate necessary to prevent seawater intrusion as well as to reproduce the evolution of the wedge toe and the water table stagnation point under different withdrawal rates furthermore the dupuit forchheimer well discharge formula allows the estimation of the effects of the water table lowering due to such critical pumping in the surrounding building foundations field data from the calonge coastal plain illustrate this approach and provide assessment criteria for future urban development and planning copyright 2012 john wiley sons ltd

seismic velocity structure of the lunar mantle i have inverted the recently completed set of seismic arrival times from the apollo lunar seismic network to estimate the average seismic velocities in three sections of the lunar mantle two for the upper mantle and one for the middle mantle the method used is a variation of the linearized least squares inversion where the inversion is accomplished in steps the estimated average velocities in the upper mantle decrease from vp 7 74 km s and vs 4 49 km s in the section above 270 km depth to vp 7 46 km s and vs 4 25 km s in the section between 270 and 500 km depth confirming the earlier finding of negative gradients based on seismic amplitude variations the average velocities in the middle mantle between the depths of 500 km and 1000 km of vp 8 26 km s and vs 4 65 km s are significantly higher than those in the upper mantle contradicting earlier estimates based on more limited data the higher velocities may suggest initial melting of the moon down to at least 1000 km depth

inverse modelling of seawater intrusion in the llobregat delta deep aquifer abstract a flow and mass transport mathematical model has been calibrated to simulate piezometric head and chloride evolution in the llobregat delta confined aquifer a twenty year period 1965 1985 is simulated with monthly time steps automatic estimation of flow and transport parameters are obtained by means of a code that simulates flow and mass transport of constant density fluids in this case density differences owing to groundwater salinity changes by marine intrusion can be neglected because the aquifer thickness is relatively small and because both the horizontal density gradient and the aquifer dip are small calibration of the flow problem leads to an excellent fit between measured and computed heads which however can be obtained with different transmissivity patterns when switching to the transport problem best results in terms of concentration fits are obtained by associating the seawater intrusion plumes with high transmissivity zones that can be attributed to palaeochannels in short transient head and concentration data have been used jointly for automatic calibration of a regional model which has proven advantageous both because it facilitates model selection and because it has led to a model with an improved conceptual basis