downslope propagation of normal modes in a shallow water wedge experimental results are presented for the downslope propagation of acoustic normal modes in a shallow water wedge with a penetrable bottom and a slope of up to 9 a 7 element line source was used to generate individual low order normal modes to obtain single modes in a wedge it was necessary to align the line source to form an arc of a circle centered on the wedge apex the resulting normal modes propagate with wave fronts which are also curved into arcs of circles centered on the wedge apex these wedge modes propagate without coupling the amplitudes mode functions and group velocities of the wedge modes are described by simple adiabatic normal mode theory but the wave front curvature is not

relationship between deep diagenetic quartz cementation and sedimentary facies in a late ordovician glacial environment sbaa basin algeria abstract production of hydrocarbons from sandstone reservoirs is complicated by their diagenetic history although many aspects of sandstone diagenesis are well studied the character and processes of glacial associated diagenesis remain unknown to address this problem the origin conditions and timing of quartz cementation in glacial ordovician sandstones of the sbaa basin algeria were constrained on the basis of fluid inclusion microthermometry electron microprobe data and quantification by image analysis combined with optical and cathodoluminescence microscopic studies samples of the cambro ordovician formations in the sbaa basin were investigated from four wells at burial depths between 2 0 and 2 5 km and at ambient temperatures between 110 and 130 c quartz cements range in abundance from 1 to 27 of bulk rock volume in all wells three separate phases of quartz cementation are readily distinguished by cathodoluminescence microscopy the main silica sources are interpreted to be dissolution of feldspar grains intergranular quartz dissolution stylolitization and illitization of smectite fluid inclusion data depths indicate that quartz overgrowths precipitated between 100 to 160 c this range of temperature corresponds to the visean namurian burial phase according to the basin thermal history image analysis demonstrates intergranular quartz dissolution also called pressure dissolution in the presence of thin illite coatings around detrital quartz grains these clay coatings were mechanically emplaced below the ordovician ice sheet by pressurized meltwater circulation and subsequent fluid expulsion within sandy subglacial soft bedrock that was initially porous and permeable therefore the subglacial bedrock lithology directly influenced quartz diagenesis because an increase in the content of clay matrix or the presence of an argillaceous layer can block the circulation of fluids flowing below the ice sheet which prevents the formation of clay coatings quartz cements in this environment are favored in less compacted areas without clay coatings and with high porosity the results of this study clearly illustrate the relationships among sedimentary facies ice dynamics and diagenetic architecture of the formation these types of processes may control the porosity permeability distribution in other glacial sandstone successions through quartz cementation and chemical compaction

assessment of groundwater contamination around active dumpsite in ibadan southwestern nigeria using integrated electrical resistivity and hydrochemical methods investigation of groundwater contamination due to leachate migration in a solid waste disposal site was done using both geophysical and hydrochemical methods the main goals were to delineate groundwater contamination due to leachate percolation and thus assessment of quality of groundwater from nearby hand dug wells bordering the dumpsite for drinking purpose a total of ten resistivity traverses were acquired within and outside the dumpsite using wenner configuration with constant electrode separation ranging from 5 to 25 m the 2d resistivity data were processed and inverted using res2dinv and res3dinv softwares respectively geochemical assessment of groundwater samples were carried out according to apha standards while hydrochemical facies of the sampled groundwater was evaluated using piper trilinear software the inverse resistivity models of the subsurface from 2d and 3d imaging revealed low resistivity value less than 10 m suspected to be leachate while 3d inverse sections allowed delineation of leachate weathered layer bedrock and seepage path from the dumpsite the extent of migration was more pronounced in the southern part of the dumpsite hence possible contamination of shallow groundwater system as dumpsite ages the results of physico chemical analyses showed the groundwater samples to be within the limits of who nsdwq for drinking purpose however higher values of concentrations of most analyzed parameters were noticed in well 1 due to its nearness to dumpsite and well 10 due to agricultural activities respectively interpretation of piper diagram showed cahco3 to be dominant facie in the area while alkaline earth metals text ca 2 text mg 2 and weak acids hco3 co3 are dominant cations and anions during both climatic seasons groundwater in the study area is of hard fresh and alkaline in nature

evaluation of groundwater quality in coastal areas implications for sustainable agriculture seawater intrusion is a problem in the coastal areas of korea most productive agricultural fields are in the western and southern coastal areas of the country where irrigation predominantly relies on groundwater seawater intrusion has affected agricultural productivity to evaluate progressive encroachment of saline water the korean government established a seawater intrusion monitoring well network especially in the western and southern part of the peninsula automatic water levels and ec monitoring and periodic chemical analysis of groundwater help track salinization salinization of fresh groundwater is highly associated with groundwater withdrawal a large proportion of the groundwaters are classified as na cl and ca cl types the na cl types represent effects of seawater intrusion the highest ec level was over 1 6 km inland and high cl values were observed up to 1 2 km inland lower ratios of na cl and so4 cl than seawater values indicate the seawater encroachment a linear relation between na and cl represents simple mixing of the fresh groundwater with the seawater the saline na cl typed groundwaters showed br cl ratios similar to or less than seawater values the ca hco3 type groundwaters had the highest br cl ratios substantial proportions of the groundwaters showed potential for salinity and should be better managed for sustainable agriculture

a multi isotope b sr o h and c and age dating 3h 3he and 14c study of groundwater from salinas valley california hydrochemistry dynamics and contamination processes 1 the chemical and isotope 11b 10b 87sr 86sr 18o 16o 2h h 13c 12c 14c and 3he 3h compositions of groundwater from the upper aquifer system of the salinas valley in coastal central california were investigated in order to delineate the origin and processes of groundwater contamination in this complex system the salinas valley has a relatively deep confined 400 foot aquifer overlain by a 180 foot aquifer and a shallower perched aquifer all made up of alluvial sand gravel and clay deposits groundwater from the aquifers have different 14c ages fossil 14c 21 3 percent modern carbon pmc for the 400 foot aquifer and modern 14c 72 2 98 2 pmc for the 180 foot aquifer fresh groundwater in all aquifers is recharged naturally and artificially through the salinas river the two modes of recharge can be distinguished chemically we identified several different saline components with distinguishable chemical and isotopic fingerprints 1 saltwater intrusion in the northern basin has c1 concentrations up to 1700 mg l a na cl ratio less than seawater a marine br cl ratio a ca cl ratio greater than seawater 11b between 17 and 38 and 87sr 86sr between 0 7088 and 0 7096 excess dissolved ca relative to the expected concentration for simple dilution of seawater correlates with 87sr 86sr ratios suggesting base exchange reaction with clay materials 2 agriculture return flow is high in no3 and so4 with a 87sr 86sr 0 7082 11b 19 and 13c between 23 and 17 the 3h 3he ages 5 17 years and 14c data suggest vertical infiltration rates of irrigation water of 3 10 m yr 3 nonmarine saline water in the southern part of the valley has high total dissolved solids up to 3800 mg l high so4 na cl ratio 1 11b between 24 and 30 and 87sr 86sr 0 70852 this groundwater may have acquired its geochemical signature from leaching of sedimentary rocks associated with the coast range marine deposits of mesozoic to early cenozoic age the combination of different geochemical and isotopic fingerprints enables us to delineate the impact of salt sources in different areas of the valley and to reconstruct the origin of the so4 enriched no3 depleted saline plume that is located west of the city of salinas we suggest that the latter is derived from a mixture of different natural saline waters rather than from anthropogenic contamination

empirical estimation of peak pressure level from sound exposure level part ii offshore impact pile driving noise numerical models of underwater sound propagation predict the energy of impulsive signals and its decay with range with a better accuracy than the peak pressure a semi empirical formula is suggested to predict the peak pressure of man made impulsive signals based on numerical predictions of their energy the approach discussed by galindo romero lippert and gavrilov j acoust soc am 138 in press 2015 for airgun signals is modified to predict the peak pressure from offshore pile driving which accounts for impact and pile parameters it is shown that using the modified empirical formula provides more accurate predictions of the peak pressure than direct numerical simulations of the signal waveform

hydrogeochemical processes in an arid region of europe almeria se spain abstract in the lower andarax river basin 3 aquifer units have been defined namely the carbonate aquifer the deep aquifer and the detrital aquifer which between them contain a wide variety of water types identification of hydrogeochemical processes has been performed by studying a series of ionic ratios comprising the principal constituents together with b and li cl vs so4 cl vs mg cl vs li b vs li among the processes detected the circulation of groundwaters with high concentrations of so4 was found to have significant effects moreover in the coastal region naturally occurring processes related to the flushing of saline waters from sediments of marine origin occur in conjunction with others clearly of human origin that are related to saltwater intrusion a further factor is the entry from overlying deposits of waters with a high saline content this salinity is related to the flushing of sediments of marine origin the use of b and li together enables waters in which salinity is related to seawater to be distinguished from others in which salinity is related to evaporitic layers or to thermal areas the concentration of li is directly related to water temperature while that of b is greater in the most saline sectors of gypsiferous and or seawater origin

demarcating saline water intrusion pathways using remote sensing gis and geophysical techniques in structurally controlled coastal aquifers in southern india application of remote sensing and geographical information system gis with the help of ground truth studies like vertical electrical soundings ves and water quality measurements gave a comprehensive picture on saline water intrusion pathways in the structural controlled aquifers of uppanar and cauvery river systems located in sirkazhi and mannanpandal coastal areas of southern india the detailed geomorphic units and lineaments were mapped using irs liss iii 1 50 000 scale and srtm elevation digital data under gis environment the area is mainly alluvial deposits of holocene age and classified into three major geomorphic units i e fluvial fluviomarine and marine geomorphic units the identified lineaments are mostly trending north northeast nne south southwest ssw northeast ne southwest sw northwest nw southeast se east west ew and east northeast ene west southwest wsw directions some of them are potential for fresh groundwater occurrence and movement the lineaments trending ne sw nne ssw and ene wsw act as pathways for saline water intrusion to the inland the lineament l1 nne ssw trending conformed as a sinisterly shifted fault played a significant role in saline water intrusion the area within the parallel lineaments l2 and l3 oriented ene wsw direction indicates low topography beach ridges paleo channel sinuosity large aerial extent of tidal flats and backwater inundation all the above geomorphic units gave indirect evidence of land subsidence which was confirmed with the help of sub surface geo electrical signals obtained through ves and in situ groundwater quality measurements integrating all the above results the saline water spread and fresh water pockets were identified

aquifer characterization using shallow geophysics in the keritis basin of western crete greece effective management of groundwater resources is a well known problem in several areas around the world it is especially important to areas suffering from an intrinsic lack of fresh water such as islands detailed study of available aquifers is of particular interest in the highly touristic greek island of crete the increasing water demand makes water resources management extremely important for sustainable development this is the case in the prefecture of chania in western crete where there has been a lack of success of many different groundwater management plans that have been produced over the years and submitted for application to water management authority the inefficiency of the management plans is verified by the continuous water shortage reported every year which forces the public authorities to transfer water from far away sources and wells until today there are only geological data as well as information from the borehole logs therefore the current work is focused to study in detail the tectonic and hydrogeological characteristics of the keritis watershed to make a correlation of the available geoenvironmental information with the geophysical data of the study aquifer transient electromagnetic soundings were conducted to obtain detailed information about the tectonic hydrogeological hydrolithological and geometrical characteristics of the aquifer under investigation in addition optimum areas of water well drilling were identified to minimize the uncertainty and the total cost economical managerial etc of future groundwater surveys

testing and verification of a scale model acoustic propagation system this paper discusses the design and operation of a measurement apparatus used to conduct scale model underwater acoustic propagation experiments presents experimental results for an idealized waveguide and compares the measured results to data generated by two dimensional 2d and three dimensional 3d numerical models the main objective of this paper is to demonstrate the capability of the apparatus for a simple waveguide that primarily exhibits 2d acoustic propagation the apparatus contains a computer controlled positioning system that accurately moves a receiving transducer in the water layer above a scale model bathymetry while a stationary source transducer emits broadband pulsed waveforms experimental results are shown for a 2 133 m 1 219 m bathymetric part possessing a flat bottom bathymetry with a translationally invariant wedge of 10 slope along one edge beamformed results from a synthetic horizontal line array indicate the presence of strong in plane arrivals along with weaker diffracted and horizontally refracted arrivals a simulated annealing inversion method is applied to infer values for five waveguide parameters with the largest measurement uncertainty the inferred values are then used in a 2d method of images model and a 3d adiabatic normal mode model to simulate the measured acoustic data

delineating the fresh and brackish saline aquifer interface in neill island of andaman nicobar from india a prelude geoelectrical investigation for delineation of the interface between fresh and brackish saline aquifers 25 resistivity soundings using schlumberger configuration were made in neill island of andaman nicobar from india a fence diagram was prepared using the results obtained from the soundings interpretation together lithology of nearby well cross section and measurements made near out cropping materials groundwater levels and electrical conductivity this diagram displays various litho units down to conductive stratum saturated with brackish saline water and also clearly depicted the occurrence of fresh water aquifer the depth to interface between fresh and brackish saline water aquifers varies 1 9 to 9 3 meters below ground level in the neill island

closed system burial diagenesis in reservoir sandstones examples from the garn formation at haltenbanken area offshore mid norway abstract the middle jurassic garn formation of the haltenbanken area has been studied using mineralogical and geochemical data from 21 wells ranging in burial depths from 2 0 to 4 1 km relative to seafloor rsf k feldspar and plagioclase contents show variations on a regional scale both laterally and as a function of burial depth the content of pore filling authigenic illite increases sharply and the content of k feldspar and kaolinite decreases in garn sandstones presently at depths greater than 3 6 3 7 km rsf 120 130 c the depletion in k feldspar below 3 7 km rsf is not accompanied by lower potassium values in the bulk chemical composition wt k2o this suggests that the potassium released during k feldspar dissolution is retained in the sandstones and is precipitated as illite the variations in bulk contents of potassium and sodium are therefore considered to be related principally to primary variations in sandstone mineralogy the shallower sandstones 1 3 have a k feldspar kaolinite ratio greater than one the deeply buried 3 7 km rsf sandstones with similar potassium contents contain excess k feldspar and most of the kaolinite is illitized however deeply buried sandstones containing an average of 0 38 wt k2o k al molar ratio 1 4 contain a significant amount of kaolinite but negligible k feldspar this suggests that the k feldspar kaolinite ratio before the onset of illitization was less than one and hence that the kaolinite illite reaction has been restricted by an insufficient supply of potassium absence of k feldspar this illustrates how illitization of kaolinite depends upon k feldspar as a local source of potassium prediction of illitization in sandstones therefore must be based on integration of models for provenance facies and early diagenesis in addition to burial and thermal history the formation of pore filling authigenic illite in these sandstones is an important influence on the total reservoir quality

a computational method to predict and study underwater noise due to pile driving a hybrid modeling approach that uses the parabolic equation pe with an empirical source model is presented to study and predict the underwater noise due to pile driving in shallow inhomogeneous environments over long propagation ranges the empirical source model uses a phased point source array to simulate the time dependent pile source the pile source is coupled with a broadband application of a pe wave propagation model that includes range dependent geoacoustic properties and bathymetry simulation results are shown to be in good agreement with several acoustic observations of pile driving in the columbia river between portland or and vancouver wa the model is further applied to predict sound levels in the columbia river and study the effects of variable bathymetry and sediment configurations on underwater sound levels

case study a 3d resistivity and induced polarization imaging from downstream a waste disposal site in brazil a contaminated site from a downstream municipal solid waste disposal site in brazil was investigated by using a 3d resistivity and induced polarization ip imaging technique this investigation purpose was to detect and delineate contamination plume produced by wastes the area was selected based on previous geophysical investigations and chemical analyses carried out in the site indicating the presence of a contamination plume in the area resistivity model has successfully imaged waste presence 31 mv v water table depth and groundwater flow direction a higher chargeability zone m 31 mv v outside wastes placement and following conductive anomaly was interpreted as a contamination plume normalized chargeability mn m confirmed polarizable zone which could be an effect of a salinity increase contamination plume and the clay presence in the environment

an analytical model for the underwater sound pressure waveforms radiated when an offshore pile is drivena an analytical model has been developed for the pile vibration and consequent sound pressure and particle velocity radiated underwater when an offshore cylindrical pile is struck by a drop hammer the model which is based on the coupled equations of motion for axial and radial vibration of a thin cylindrical shell yields frequency dependent phase velocity and attenuation of these vibrations the amplitude of the pulse of axial and radial displacement that travels down a pile following an axial impact is described in terms of the hammer properties solutions are obtained for the radiated sound pressure and particle velocity using junger and feit s transform formulation of the pressure field of cylindrical radiators acoustical society of america new york 1993 p 216 the model is applied to published data on radiated noise from offshore driving of a steel pile the modeled pressure waveforms at 12 m horizontal range and at 9 hydrophone depths correlate significantly with the measured waveforms the modeled pressures of the initial positive peaks appropriately low pass filtered agree with data to within 1 db the initial negative peaks however exceed the data by up to 7 db and as hydrophone depth increases the model negative peaks have a maximum at 7 m whereas the data have a maximum at 9 m

application of ert and gpr for demarcating the saline water intrusion in coastal aquifers of southern india to investigate the pathways for saline water intrusion into fresh water aquifers the electrical resistivity tomography ert and ground penetrating radar gpr have been pooled for nagapattinam area of southern india the study area has two river sub basins uppanar river basin urb and cauvery river basin crb ert carried out in urb shows very low resistivity ranging from 0 003 to 1 5 m at shallow depth indicating saline water whereas the resistivity ranges away from the river stream are 1 7 5 0 m cauvery river basin shows resistivity range varying from 3 6 to 150 m indicating a salt fresh water mix similarly few gpr profiles were carried out along ert profiles to confirm the saline water intrusion and its pathway besides the hydrochemical study reveals the same signature of saline and fresh water zones in both river basins water samples collected during field investigation show high total dissolved solids tds content near urb and crb river course ert data was correlated with gpr data to distinguish fresh and saline water zones more accurately urb has more saline water zones at shallow depth nearer to river course and intermediate depth of saline water zones away from the river course while crb is having fresh water towards the inland

hydrogeochemical and isotopic evidence of groundwater salinization in a coastal aquifer a case study in jeju volcanic island korea abstract in order to identify the origin of saline groundwater in the eastern part of jeju volcanic island korea a hydrogeochemical and isotopic study has been carried out for 18 observation wells located in east and southeast coastal regions the total dissolved solid contents of groundwaters are highly variable 77 21 782 mg l oxygen hydrogen sulfur and strontium isotopic data clearly show that the saline water results from mixing of groundwater with seawater strontium isotopic compositions and br cl and i cl ratios strongly suggest that the source of salinity is modern seawater intrusion hydrogeochemical characteristics based on bivariate diagrams of major and minor ions show that changes in the chemical composition of groundwater are mainly controlled by the salinization process followed by cation exchange reactions the highly permeable aquifers at the east coastal region are characterized by low hydraulic gradient and discharge rate and high hydraulic conductivity as compared with other regions these properties enhance the salinization of groundwater observed in the study area based on the cl br and 18 o data seawater was determined to have intruded inland some 2 5 km from the coastline considering the poor correlation of sampling depth and cl concentrations observed the position of seawater freshwater interface is not uniformly distributed in the study area due to heterogeneities of the basaltic aquifers

petrography and geochemical indices of the lagos lagoon coastal sediments dahomey basin southwestern nigeria sea level change implications abstract the lagos lagoon part of the barrier lagoon geomorphic zone of the nigerian coastal system is underlain by quaternary coastal plain sands of the dahomey basin the study involves sedimentological and geochemical study of the three georeferenced wells to evaluate the lithotopes distribution provenance environment of deposition and the resulting marine transgression regression episodes from previous sea level changes a total of twenty nine core samples were used for this study eighteen of the samples sandstones were subjected to granulometric petrography analyses heavy mineral separation and inductively coupled plasma mass spectrometry icp ms analysis geochemical facies criteria were established based on diagnostic indices the quaternary lithosome indicates the presence of clay siltstone sandstone and conglomerate the sandstones are fine to coarse grained poorly sorted to moderately well sorted negatively to positively skewed and mesokurtic to leptokurtic the heavy mineral assemblage is characterized by zircon rutile tourmaline garnet staurolite sillimanite apatite epidote hornblende and kyanite this assemblage suggests sediments derived from both igneous and metamorphic provenance probably from the ibadan craton the average ztr index is 27 84 indicating mineralogically immature sediments petrographic analysis shows that the most abundant detrital minerals are quartz average of 88 7 feldspar average of 4 37 and rock fragments average of 7 3 the qfr ternary plots revealed that the sands are super mature quartz arenite derived from the uplifted continental block under a humid climatic setting which have undergone moderate transportation and have been subjected to moderate mechanical and chemical weathering the ratios of k 2 o na 2 o and sio 2 suggest passive and active continental margin settings linear discriminant analysis revealed that the sediments were deposited within fluvial to shallow marine lithosomes this corroborated the bivariate plots of the statistical parameter the results of the trace element and ratios considered with regard to their distribution in the diverse lithofacies showing the range of sr from 50 to 120 ppm ba 180 340 ppm ga 5 14 ppm b 25 48 ppm v 53 125 ppm sr ba 0 20 0 39 and ba ga 1 86 7 00 all indicating fluvial shallow and marginal marine lithosomes the lithofacies are derived from a mixed provenance have undergone chemical weathering during transportation and are deposited in the fluvio marine environment these indices indicate the occurrence of weak marine transgressions

salt water intrusion mapping by geoelectrical imaging surveys the geoelectrical imaging method is a tool for mapping the intrusion boundary between fresh water and saline water due to its inherent capability to delineate the lateral changes in pore water salinity a new field survey technique that can be used for environmental and geotechnical investigations has been developed this study evaluates the multiscale survey technique as a tool employed in electrical imaging to detect the salt water intrusion boundary in yan state of kedah northwest malaysia the technique was incorporated into these surveys and it has proved to be a robust method for accurately mapping the fresh water saline water boundary the resulting resistivity sections from these surveys were consistent with both the available geological and borehole information from the area and the previous resistivity surveys conducted by the geological survey of malaysia at those sites

aquifer boundaries explored by geoelectrical measurements in the coastal plain of yemen a case of equivalence until 216 vertical electrical schlumberger soundings were made little was known about the subsurface geology at the wadi surdud area in the coastal plain of the yemen arab republic these soundings provide information on the distribution of aquifers aquitards and impermeable rocks and the salinity of the groundwater a first qualitative interpretation of the geoelectrical sounding curves gives a general impression of the hydrogeologic setting and the aquifer boundaries however a more detailed quantitative interpretation shows that no single resistivity model completely satisfies all the hydrogeologic and geologic facts and theories basically two different models are possible in one the thickness of the aquifer is fixed in the other its resistivity is fixed several geologic and hydrogeologic hypotheses may be put forward to support each model varying from relying upon tectonic events and sedimentary depositional environments to influences of agriculture and water abstraction both models are

sound radiation from impact driven raked piles sound emissions from impact pile driving of raked piles present a significant azimuthal dependence in the radiated sound field due to the non axisymmetric orientation of the pile in this work the sound radiation from raked piles is modeled using a finite element method fem model of the pile and near field region the near field model of the sound field is then used as input into a normal mode model to predict the sound radiation in the far field the azimuthal dependence of the radiated sound field is shown to be accurately predicted using an equivalent axisymmetric fem model of the pile configuration thus negating the need to construct a fully three dimensional model 3d of the raked pile this is achieved by matching the radiated field from the equivalent axisymmetric pile model to a vertical array of phased point sources and then horizontally offsetting the source locations to match the incline of the raked pile the resulting sound field closely matches the numerical predictions from a fully 3d fem model of the raked pile the results of numerical modeling are compared to corresponding acoustic measurements taken on the north west shelf of western australia

application and evaluation of electromagnetic methods for imaging saltwater intrusion in coastal aquifers seaside groundwater basin california developing effective resource management strategies to limit or prevent saltwater intrusion as a result of increasing demands on coastal groundwater resources requires reliable information about the geologic structure and hydrologic state of an aquifer system a common strategy for acquiring such information is to drill sentinel wells near the coast to monitor changes in water salinity with time however installation and operation of sentinel wells is costly and provides limited spatial coverage we studied the use of noninvasive electromagnetic em geophysical methods as an alternative to installation of monitoring wells for characterizing coastal aquifers we tested the feasibility of using em methods at a field site in northern california to identify the potential for and or presence of hydraulic communication between an unconfined saline aquifer and a confined freshwater aquifer one dimensional soundings were acquired using the time domain electromagnetic tdem and audiomagnetotelluric amt methods we compared inverted resistivity models of tdem and amt data obtained from several inversion algorithms we found that multiple interpretations of inverted models can be supported by the same data set but that there were consistencies between all data sets and inversion algorithms results from all collected data sets suggested that em methods are capable of reliably identifying a saltwater saturated zone in the unconfined aquifer geophysical data indicated that the impermeable clay between aquifers may be more continuous than is supported by current models

postdepositional chemical alteration of ouachita shales shales belonging to the carboniferous flysch exposed in the ouachita mountains of west central arkansas and southeastern oklahoma have undergone postdepositional alteration that has significantly affected their whole rock chemistry alteration is particularly pronounced in the northeastern ouachitas and along the benton broken bow uplift altered rocks have lost ca mg k na fe and si relative to the conservative elements al ti zr cr and ni some evidence exists for slight loss of al and ti relative to cr ni and zr pyrophyllite and chloritoid bearing samples are enriched in 18 o relative to less altered samples and this enrichment is not due to changes in the 18 o of quartz mineralogical and textural evidence support a postdepositional alteration model rather than mixing of sediment from different sources or sedimentary sorting to account for the variations in whole rock chemistry development of microscopic foliation parallel zones enriched in phyllosilicates and in ti and al is related to slaty cleavage development and suggests that chemical alteration is coeval with deformation and very low grade metamorphism volume loss calculations based on conservation of immobile elements and on deformation of detrital mica grains give minimum estimates of 30 50 volume loss in the most altered shales the postdepositional changes recorded in whole rock chemistry of these shales may be unique to the ouachita flysch but suggest a need for greater caution in the uncritical use of shale chemistry in studies of crustal evolution and provenance

application of gis and hydrogeochemistry of groundwater pollution status of nagapattinam district of tamil nadu india this study evaluated groundwater quality of the coastal aquifer in nagapattinam district with intensive agricultural activities in the southern part of india chemical components such as ph ec tds major cations and anions were used to identify seawater intrusion fifty two groundwater samples were collected from dug and bore wells in this region during summer and monsoon seasons 2011 ec tds na and cl were higher in summer than in monsoon the correlation and two way joining cluster analyses clearly show that groundwater quality is mainly controlled by seawater intrusion and other anthropogenic sources modified hill piper exhibits that most of the samples belong to water contaminated with gypsum sector the interpretation of gibbs plot represents the groundwater samples that fall in evaporation and rock weathering zone and other samples are affiliated to various anthropogenic activities based on na sar chloride hardness and wilcox classification the groundwater is moderately suitable for agriculture this region is vulnerable to seawater intrusion during summer due to the severe pumping of groundwater in groundwater quality maps produced by inverse distance weighting of arcgis some good and medium patches could be used for agriculture to a certain extent the northern southern and central parts of the study area fell in poor quality regions because of seawater intrusion and infiltration of irrigation water contaminated with pesticides and fertilizers

imaging of contaminant plumes using ert in qinhuai river water and its bed caused by urban effluents at nanjing china this paper presents the imaging of contaminant plumes in qinhuai river and its bed for the remediation strategies of the river qinhuai meets with yangtze river at nanjing area via inner and outer channels coursing through urban districts of the city the discharge of urban effluents has badly affected the water quality of the river generally contamination assessment is carried out through traditional point based sampling methods however these methods are often inadequate to estimate accurately the spatial distribution of contaminants and their extension therefore electrical resistivity tomography ert is applied because of its high quality imaging to investigate contamination and its extension in qinhuai river and its bed eight sites were selected at outer and inner channels of the river a 2 d inversion of the perceived data was carried out and the obtained resistivity values were converted into salinity after temperature correction the acquired images of resistivity and salinity show that in low streaming conditions the river has large zones of low resistivity in the water body which are extending toward underlying bed corresponding to high contamination conversely in high streaming conditions the low resistivity zone shrinks significantly at almost all the studied sites except xishan bridge site e which still showed high plume of contamination this phenomenon reveals that in low streaming conditions the contamination level is high while in high streaming conditions salts are flushed out from the river this study further demonstrates that ert method can be a useful technique for the environmental studies of rivers canals and surface water environments

identifying seawater intrusion in coastal areas by means of 1d and quasi 2d joint inversion of tdem and ves data abstract seawater intrusion is an increasingly widespread problem in coastal aquifers caused by climate changes sea level rise extreme phenomena like flooding and droughts and groundwater depletion near to the coastline to evaluate and mitigate the environmental risks of this phenomenon it is necessary to characterize the coastal aquifer and the salt intrusion geophysical methods are the most appropriate tool to address these researches among all geophysical techniques electrical methods are able to detect seawater intrusions due to the high resistivity contrast between saltwater freshwater and geological layers the combination of two or more geophysical methods is recommended and they are more efficient when both data are inverted jointly because the final model encompasses the physical properties measured for each methods in this investigation joint inversion of vertical electric and time domain soundings has been performed to examine seawater intrusion in an area within the ferragudo albufeira aquifer system algarve south of portugal for this purpose two profiles combining electrical resistivity tomography ert and time domain electromagnetic tdem methods were measured and the results were compared with the information obtained from exploration drilling three different inversions have been carried out single inversion of the ert and tdem data 1d joint inversion and quasi 2d joint inversion single inversion results identify seawater intrusion although the sedimentary layers detected in exploration drilling were not well differentiated the models obtained with 1d joint inversion improve the previous inversion due to better detection of sedimentary layer and the seawater intrusion appear to be better defined finally the quasi 2d joint inversion reveals a more realistic shape of the seawater intrusion and it is able to distinguish more sedimentary layers recognised in the exploration drilling this study demonstrates that the quasi 2d joint inversion improves the previous inversions methods making it a powerful tool applicable to different research areas

underwater mach wave radiation from impact pile driving theory and observation the underwater noise from impact pile driving is studied using a finite element model for the sound generation and parabolic equation model for propagation results are compared with measurements using a vertical line array deployed at a marine construction site in puget sound it is shown that the dominant underwater noise from impact driving is from the mach wave associated with the radial expansion of the pile that propagates down the pile after impact at supersonic speed the predictions of vertical arrival angle associated with the mach cone peak pressure level as function of depth and dominant features of the pressure time series compare well with corresponding field observations

beam forming of the underwater sound field from impact pile driving observations of underwater noise from impact pile driving were made with a vertical line array previous studies reinhall and dahl j acoust soc am 130 1209 1216 2011 show that the dominant underwater noise from impact driving is from the mach wave associated with the radial expansion of the pile that propagates down the pile at supersonic speed after impact here precise estimates of the vertical arrival angles associated with the down and up going mach wave are made via beam forming and the energy budget of the arrival structure is quantified

evaluating freshwater lens morphology affected by seawater intrusion using chemistry resistivity integrated technique a case study of two different land covers in carey island malaysia freshwater lenses are vital to small island communities but are susceptible to seawater intrusion due to the physical changes in the shoreline land cover the effect of seawater intrusion and irrigation water on a coastal unconfined aquifer beneath naturally preserved mangrove and deforested mangrove barren belt was investigated in carey island analysis of the total dissolved solids tds and earth resistivity er using a geochemistry electrical integrated technique gave a tds er relationship capable of predicting freshwater lens morphology affected by sea irrigation water the study result shows freshwater was fourfold thicker in close proximity of the mangrove forest than the mangrove barren area the further the shoreline from the mangrove thickest section the less vulnerable was the seawater intrusion and the more fresh the irrigation water and hence the greater the freshwater availability potential

review of electromagnetic induction for mapping barrier island framework geology abstract the geologic framework controls on modern barrier island transgression and the relationship of these controls to subsurface structure hydrology and island geomorphology are not well understood recent evidence suggests that alongshore variations in pre holocene geology of barrier islands modify nearshore hydrodynamic processes and sediment transport ultimately affecting how barrier islands will respond to relative sea level rise explorations of holocene barrier island geology are usually based on cores to supplement bathymetric onshore offshore seismic and or ground penetrating radar gpr surveys the advantages and limitations of these methods with respect to barrier island investigations are briefly described in this review alternative near surface geophysical methods including electromagnetic induction emi sensors are increasingly being used for coastal research because they are non invasive provide continuous subsurface information across a variety of sub environments and are capable of characterizing large areas in a short time although these emi sensors have shown promise in coastal applications a number of issues primarily related to subsurface hydrology need to be addressed to fully assess the limitations of this technique this paper reviews the theory methodology and applications of emi in support of geologic framework studies with particular reference to barrier islands resolution of these issues will allow emi sensors to complement and offer significant advantages over traditional methods in support of an improved understanding of large scale barrier island evolution

assessment of the state of soils shallow sediments and groundwater salinity in abi cross river state nigeria abi area in nigeria borders the salinity enriched lower benue trough lbt and plans are currently underway to extend large scale irrigation facilities under construction in the lbt to abi area in order to generate baseline soil and water salinity information about abi area under non irrigation condition integrated information from constrained analyses of vertical electrical sounding data two dimensional electrical resistivity tomographies and laboratory analyses of soil and water samples were used to assess and map the spatial salinity distribution existence of widespread heterogeneities in the distribution of soil and water salinity between the shaly and sandy materials that dominate the shallow geology of the area was observed minimum values of water electrical conductivity wec and total dissolved solids tds were observed to be 19 2 s cm and 13 mg l respectively in the sandstone dominated areas maximum values of wec and tds were observed to be 931 0 s cm and 624 mg l respectively within the shale dominated areas soil electrical conductivity was observed to vary from 5 0 s cm in the sandstone areas to 14 0 s cm in the shale dominated areas minimum and maximum soil ph observations were 4 53 in the shale dominated area and 6 55 in the sandstone dominated area respectively these results show that the water and soil resources in the area vary from fresh to slightly saline and non saline to high salinity levels respectively consequently both resources are still good for agricultural purposes

the underwater sound field from vibratory pile driving underwater noise from vibratory pile driving was observed using a vertical line array placed at range 16 m from the pile source water depth 7 5 m and using single hydrophones at range 417 m on one transect and range 207 and 436 m on another transect running approximately parallel to a sloping shoreline the dominant spectral features of the underwater noise are related to the frequency of the vibratory pile driving hammer typically 15 35 hz producing spectral lines at intervals of this frequency the mean square pressure versus depth is subsequently studied in third octave bands depth and frequency variations of this quantity observed at the vertical line array are well modeled by a field consisting of an incoherent sum of sources distributed over the water column adiabatic mode theory is used to propagate this field to greater ranges and model the observations made along the two depth varying transects the effect of shear in the seabed although small is also included bathymetric refraction on the transect parallel to the shoreline reduced mean square pressure levels at the 436 m measurement site

a model for underwater sound levels generated by marine impact pile driving marine impact pile driving generates very high underwater sound pressures which can harm aquatic life environmental assessments for pile driving projects typically require acoustic impact zones for marine mammals and fish to be estimated in advance a computer model that predicts the radiated acoustic field from impact driving of cylindrical piles has been developed a lumped mass model of the hammer which predicts the force generated at the top of the pile is coupled to a 1 d finite difference model of radial and axial stress waves in a cylindrical pile the radiated pressure is computed by matching the velocity boundary condition at the pile wall using a superposition of monopole sources distributed over the length of the pile in a layered 2 d fluid medium the transfer function for the monopoles is computed using the near field hankel transform for radial particle velocity at the pile wall standard ocean acoustic modeling techniques are used to compute the mach wave propagating away from the pile the model considers the physical characteristics of the pile hammer system such as the hammer energy pile dimensions sediment properties and pile hammer impedance ratio the model s predictions are compared to field measurements obtained in a riverine environment

the importance of diffusion advection and host rock lithology on vein formation a stable isotope study from the paleozoic ouachita orogenic belt arkansas and oklahoma more than 600 stable isotope analyses from veins and their metasedimentary host rocks from the ouachita orogenic belt of arkansas and oklahoma provide an opportunity to study fluid rock interaction processes associated with vein formation during deformation and low grade regional metamorphism the 18o values of vein quartz vary from 16 0 to 26 4 whereas coexisting host rocks have a greater range from 12 9 to 27 4 the oxygen isotopic compositions of quartz vein versus those of the coexisting host rocks follow an array described by 18ovein quartz 18owhole rock e where e 8 0 3 18owhole rock this relationship emphasizes the dependence of 18o values of vein quartz on host rock oxygen isotopic composition the e term empirically monitors the difference between the quartz water fractionation factor and the compositional dependence of the bulk rock water fractionation factor vein quartz host rock 18o fractionations are 0 in chert novaculite quartzite and siliceous shale and typically between 1 and 4 in sandstones and shales in quartzite and sandstone units that are bounded by shales and associated with significant quartz crystal deposits vein quartz host rock fractionations are often unusually large near 7 quartz calcite oxygen isotope geothermometry indicates that veins from the ouachita mountains formed over a temperature interval of 100 c consistent with fluid inclusion temperatures previously obtained from quartz crystals individual quartz veins are homogeneous with 0 4 variation for all vein orientations at all scales even though vein formation occurred over a temperature interval in which quartz water fractionation varies by 5 this homogeneity highlights the insensitivity of vein quartz 18o values to temperature when veins form under rock buffered conditions the similarity between vein and host rock 18o values in quartz rich lithologies and between vein and host rock 13c values in calcite bearing rocks indicates that diffusion was an important mass transport mechanism the variability in 18o values between calcite bearing veins and host rocks and large vein quartz whole rock fractionations in some sandstones and quartzites indicates that advection also played a major role in mass transport associated with vein formation this inference leads to the interpretation that veins from the ouachita mountains formed by a combined diffusion advection process whereby 18o and 13c from the host rock was transported into the veins with the assistance of a rock buffered fluid on outcrop scales of 10 100 m

towards a complete physically based forecast model for underwater noise related to impact pile driving an approach for the prediction of underwater noise caused by impact pile driving is described and validated based on in situ measurements the model is divided into three sub models the first sub model based on the finite element method is used to describe the vibration of the pile and the resulting acoustic radiation into the surrounding water and soil column the mechanical excitation of the pile by the piling hammer is estimated by the second sub model using an analytical approach which takes the large vertical dimension of the ram into account the third sub model is based on the split step pade solution of the parabolic equation and targets the long range propagation up to 20 km in order to presume realistic environmental properties for the validation a geoacoustic model is derived from spatially averaged geological information about the investigation area although it can be concluded from the validation that the model and the underlying assumptions are appropriate there are some deviations between modeled and measured results possible explanations for the observed errors are discussed

on the underwater sound field from impact pile driving arrival structure precursor arrivals and energy streamlines underwater noise from impact pile driving is studied through measurements using a vertical line array vla placed at range 120 m from the pile source water depth 7 5 m over which bathymetry varied gradually increasing to depth 12 5 m at the vla the data were modeled assuming the pile impact produces a radial expansion that acts as sound source and propagates along the pile at supersonic speed this leads to the conceptualization of the pile as a discrete vertical line source for which frequency and source depth dependent complex phasing is applied dominant features of the pressure time series versus measurement depth are reproduced in modeled counterparts that are linearly related these observations include precursor arrivals for which arrival timing depends on hydrophone depth and influence of a sediment sound speed gradient on precursor amplitude spatial gradients of model results are taken to obtain estimates of acoustic particle velocity and vector intensity for which active intensity is studied in the time domain evaluation of energy streamlines based on time integrated active intensity and energy path lines based on instantaneous or very short time integrated active intensity reveal interesting structure in the acoustic field including an inference as to the source depth of the precursor

delineation of saltwater intrusion into the freshwater aquifer of lekki peninsula lagos nigeria recently the deterioration of water quality in the coastal zones of lekki peninsula area of lagos due to saltwater infiltration into the freshwater aquifer has become a major concern with the aim of providing valuable information on the hydrogeologic system of the aquifers the subsurface lithology and delineating the groundwater salinity vertical electrical resistivity ves sounding survey was carried out utilizing surface schlumberger electrode arrays and electrode spacing varying between 1 and 150m the dc resistivity surveys revealed significant variations in subsurface resistivity also the ves resistivity curves showed a dominant trend of decreasing resistivity with depth thus increasing salinity in general the presence of four distinct resistivity zones were delineated viz the unconsolidated dry sand a having resistivity values ranging between 125 and 1 028 m represent the first layer the fresh water saturated soil zone b having resistivity values which correspond to 32 256 m is the second layer the third layer zone c is interpreted as the mixing transition zone of fresh with brackish groundwater the resistivity of this layer ranges from 4 to 32 m while layer four zone d is characterized with resistivities values generally below 4 m reflecting an aquifer possibly containing brine the rock matrix salinity and water saturation are the major factors controlling the resistivity of the formation moreover this investigation shows that saline water intrusion into the aquifers can be accurately mapped using surface dc resistivity method

validation of finite element computations for the quantitative prediction of underwater noise from impact pile driving the acoustic radiation from a pile being driven into the sediment by a sequence of hammer strikes is studied with a linear axisymmetric structural acoustic frequency domain finite element model each hammer strike results in an impulsive sound that is emitted from the pile and then propagated in the shallow water waveguide measurements from accelerometers mounted on the head of a test pile and from hydrophones deployed in the water are used to validate the model results transfer functions between the force input at the top of the anvil and field quantities such as acceleration components in the structure or pressure in the fluid are computed with the model these transfer functions are validated using accelerometer or hydrophone measurements to infer the structural forcing a modeled hammer forcing pulse is used in the successive step to produce quantitative predictions of sound exposure at the hydrophones the comparison between the model and the measurements shows that although several simplifying assumptions were made useful predictions of noise levels based on linear structural acoustic models are possible in the final part of the paper the model is used to characterize the pile as an acoustic radiator by analyzing the flow of acoustic energy 2013 acoustical society of america

global basin classification system a proposed system classifies sedimentary basins worldwide into specific as well as general categories the geologic history of each basin may be subdivided into cycles using three parameters basin forming tectonics depositional sequences and basin modifying tectonics sedimentary basins may be simple with one or two tectonic sedimentary cycles or they may be complex polyhistory basins with many different cycles and events there are eight simple cycle types in this classification which cover continental continental margin and oceanic areas the eight basic cycle types their depositional fills and tectonic modifiers have been given letter and number symbols so that the specific geologic history of each basin may be written as a formula these formulas may then e compared and similarities or differences between basins noted

seawater intrusion and associated processes in a small coastal complex aquifer castell de ferro spain an attempt to identify the hydrogeochemical processes that accompany current or past intrusion of seawater in the castell de ferro coastal aquifer se spain was made using ionic deltas ionic ratios and saturation indices alluvial and coastal quaternary sediments and triassic marbles constitute this complex aquifer cation exchange dolomitization and calcite dissolution were identified as operating in the aquifer the cation exchange processes in the detrital materials are different from those in the marbles in addition it was determined that while the processes of marine intrusion associated with periods of low groundwater levels still persist in the detrital aquifer in the carbonate sector the flushing process characteristic of wetter conditions has begun

electrical methods ves and ert for identifying mapping and monitoring different saline domains in a coastal plain region alt emporda northern spain summary the spatial variability through time of the degree of salinity of soils and groundwater is a major issue concerning the sustainable management of water resources the problem is accentuated in coastal plain areas where saline bodies of different origin coexist we present an extensive geoelectrical resistivity dataset collected in the alt emporda clastic coastal aquifer system ne spain integrating the results of field campaigns undertaken within a period of more than two decades the dataset is unique in the literature and comprises highly valuable information for the investigation of saline domains the joint application of vertical electrical sounding ves and electrical resistivity tomography ert methods allowed the identification of saline domains and monitoring their evolution through time geophysical data gathered during field campaigns in 1982 2002 and 2010 were calibrated and interpreted on the basis of soil and groundwater physico chemical analyses and hydrogeological stratigraphic and geomorphological data the results illustrate the potential of electrical resistivity methods at differentiating saline domains in coastal aquifer areas and at modelling their configuration and evolution although the ves data processing allows solving the one dimensional resistivity structure of the subsurface the inversion imposes a 1d layered model thus interpretation of two dimensional structures is subject to the interpolation between discrete measures in contrast ert data offer a continuous 2d image of the resistivity distribution both laterally and in depth given that the bulk resistivity of the medium is extremely sensitive to salt content the ert profiles permitted identifying and determining the geometry of hyper saline areas characterized by resistivities of less than 5 m the study demonstrates the efficiency of the electrical methods to map subsurface conductive zones and illustrates how the accurate knowledge of the hydrogeological pattern results critical to meet this objective