leachate detection via statistical analysis of electrical resistivity and induced polarization data at a waste disposal site northern israel landfill site is an intensely heterogeneous medium in which application of 2 d geophysical techniques frequently does not enable its accurate examination due to the lack of correlation between different geophysical profiles the study was aimed to eliminate such difficulty hereafter the leachate detection methodology is presented including 2 d smoothness constrained inversion of geoelectrical raw data collected in situ the inverted data normalization and statistical examination to eradicate influence of high heterogeneity of the landfill body the generalized statistical model of the entire site was created including the likelihood analysis of the entire normalized data set three geoelectrical parameters were involved in the analysis inversed electrical resistivity inversed chargeability ip and the ratio of inversed chargeability to inversed electrical resistivity ip res the study was combined with the synthetic modeling the analysis of bulk versus fluid electrical resistivity relationship and test borehole drillings such generalized analysis ensures independency of the results from the locality of sampling measurements it was shown that leachate detection can be correctly performed utilizing the ip res ratio while the anomaly s likelihood is higher than 90

undersea longwall mining subsidence with special reference to geological and water occurrence criteria in the north east of england coalfield abstract to date the use of classical statistical techniques for the identification and analysis of parameters which control the occurrence of water on longwall panels has proved inconclusive an alternative and potentially more meaningful approach is to examine the interaction between the tensile strain induced by mining and the geological and hydrogeological environment surrounding the workings after a brief description of the geology and hydrogeology of the north east of england coalfield the paper examines in detail the water yield predicted tensile strain and geological strain water relationship occurring at four collieries with extensive undersea workings blackhall horden dawdon and westoe in each case water occurrences can be correlated with either faces worked in the vicinity of a major fault where aquifer horizons are displaced against coal measures strata overlying the working horizon or areas where the amount of cover to the base of the major aquifer horizon thins appreciably or a well developed potentially water bearing sandstone horizon exists within the intervening coal measures strata

chemostratigraphy a method to improve interwell correlation in barren sequences a case study using onshore duckmantian stephanian sequences west midlands u k abstract chemostratigraphy has been applied to onshore duckmantian stephanian successions encountered in outcrop and penetrated by two boreholes from the west midlands u k these successions represent the onshore equivalents of the barren red measures which are important hydrocarbon bearing sequences in the southern north sea much is known about the onshore successions in terms of sedimentology mineralogy and provenance and thus they provide the ideal test for the validity of chemostratigraphy as a stratigraphic tool reliable inorganic geochemical data have been acquired from geochemical analyses of core sidewall core and cuttings samples with 19 elements being determined stratigraphic variations in elemental concentrations are compared with known variations in the mineralogical data the established lithostratigraphic units of the duckmantian stephanian intervals can also be recognized from the geochemical data and by using these data can be subdivided further this results in an independent chemostratigraphic correlation being established for the two boreholes which has been assessed statistically by discriminant function analysis from the geochemical and mineralogical data distinct changes in provenance are identified within the upper carboniferous successions the sediments of the coal measures were derived from a north westerly and westerly source caledonian whereas the etruria formation sediments came from the wales brabant massif the sediments having mixed caledonian and cadomian characteristics eventually these sediments were replaced by sediments from a southern hercynian source halesowen and salop formations

saline tracer visualized with three dimensional electrical resistivity tomography field scale spatial moment analysis 1 cross well electrical resistivity tomography ert was used to monitor the migration of a saline tracer in a two well pumping injection experiment conducted at the massachusetts military reservation in cape cod massachusetts after injecting 2200 mg l of sodium chloride for 9 hours ert data sets were collected from four wells every 6 hours for 20 days more than 180 000 resistance measurements were collected during the tracer test each ert data set was inverted to produce a sequence of 3 d snapshot maps that track the plume in addition to the ert experiment a pumping test and an infiltration test were conducted to estimate horizontal and vertical hydraulic conductivity values using modified moment analysis of the electrical conductivity tomograms the mass center of mass and spatial variance of the imaged tracer plume were estimated although the tomograms provide valuable insights into field scale tracer migration behavior and aquifer heterogeneity standard tomographic inversion and application of archie s law to convert electrical conductivities to solute concentration results in underestimation of tracer mass such underestimation is attributed to 1 reduced measurement sensitivity to electrical conductivity values with distance from the electrodes and 2 spatial smoothing regularization from tomographic inversion the center of mass estimated from the ert inversions coincided with that given by migration of the tracer plume using 3 d advective dispersion simulation the 3 d plumes seen using ert exhibit greater apparent dispersion than the simulated plumes and greater temporal spreading than observed in field data of concentration breakthrough at the pumping well

uisge meinne mine water hydrogeology in the celtic lands from kernow cornwall uk to ceap breattain cape breton canada

overview of inert tracer experiments in key belgian soil types relation between transport and soil morphological and hydraulic properties to investigate relations between solute transport soil properties and experimental conditions we summarize results from leaching experiments that we carried out in a range of soils at different scales column 0 3 1 0 m id 1 0 m length and field plot scale and using different leaching rates 0 5 30 cm d 1 the lateral mixing regime and longitudinal dispersion were derived from time series of tracer concentrations at several depths in the soil field and column scale transport were similar in loam and silt loam soils the mixing regime was related to soil morphological features such as vertical tongues stratification macropores and a water repellent layer the dispersion increased in all soils more than linearly with increasing leaching rate implying that the dispersivity is not an intrinsic soil characteristic the change of dispersivity with leaching rate was linked to the unsaturated hydraulic conductivity using a multidomain conceptualization of the pore space

characterization of karst structures using quasi 3d electrical resistivity tomography karst is characteristically complex hydrogeologically due to a high degree of heterogeneity which is often typified by specific features for example cavities and sinkholes embedded in a landscape with significant spatial variability of weathering characterization of such heterogeneity is challenging with conventional hydrogeological methods however geophysical tools offer the potential to gain insight into key features that control the hydrological function of a karst aquifer electrical resistivity tomography ert is recognized as the most effective technique for mapping karstic features this method is typically carried out along transects to reveal 2d models of resistivity variability however karstic systems are rarely 2d in nature in this study ert is employed in valley and hillslope regions of a karst critical zone observatory chenqi watershed guizhou province china using a quasi 3d approach the results from the extensive geophysical surveys show that there is a strong association between resistivity anomalies and known karstic features they highlight the significance of a marlstone layer in channeling spring flow in the catchment and confining deeper groundwater flow evidenced by for example localized artesian conditions in observation wells our results highlight the need to analyze and interpret geophysical data in a three dimensional manner in such highly heterogeneous karstic environments and the value of combining geological and hydrogeological data with geophysical models to help improve our understanding of the hydrological function of a karst system

basement hydrogeology and fortification of the channel islands legacies of british and german military engineering the islands of jersey guernsey alderney and sark lie close to the normandy coast of france they expose a largely precambrian crystalline basement of metamorphic and igneous rocks jersey and alderney also expose some early palaeozoic clastic sediments and all have a thin but widespread quaternary sedimentary cover the three largest islands were progressively fortified by the british between the early 13th and mid 19th centuries and by german forces during occupation in world war ii a legacy illustrated by the castles forts and numerous german coastal fortifications that still adorn them a german military geologist based on jersey from mid 1941 to mid 1944 and a military geological team on guernsey and alderney during 1942 generated hydrogeological maps and reports that were then in advance of understanding of crystalline basement aquifers elsewhere in the british isles all the major documents have now been found in germany the usa and uk although none survived on the islands themselves geological mapping and hydrogeological studies postwar under the auspices of the british geological survey were completed without access to german data however german and british data together now facilitate an appraisal of the heavily stressed aquifers on these small hard rock islands over an unusually long 65 year timespan

hydrogeophysical tracking of three dimensional tracer migration the concept and application of apparent petrophysical relations 1 direct estimation of groundwater solute concentrations from geophysical tomograms has been only moderately successful because 1 reconstructed tomograms are often highly uncertain and subject to inversion artifacts 2 the range of subsurface conditions represented in data sets is incomplete because of the paucity of colocated well or core data and aquifer heterogeneity and 3 geophysical methods exhibit spatially variable sensitivity we show that electrical resistivity tomography ert can be used to estimate groundwater solute concentrations if a relation between concentration and inverted resistivity is used to deal quantitatively with these issues we use numerical simulation of solute transport and electrical current flow to develop these relations which we call apparent petrophysical relations they provide the connection between concentration or local resistivity and inverted resistivity which is measured at the field scale based on ert for media containing ionic solute the apparent petrophysical relations are applied to tomograms of electrical resistivity obtained from field measurements of resistance from cross well ert to create maps of tracer concentration on the basis of synthetic and field cases we demonstrate that tracer mass and concentration estimates obtained using these apparent petrophysical relations are far better than those obtained using direct application of archie s law applied to three dimensional tomograms from ert which gives severe underestimates

applications of geochemical data to modelling sediment dispersal patterns in distal turbidites late quaternary of the madeira abyssal plain abstract an extensive geochemical database has been used to constrain depositional processes sediment dispersal patterns and palaeoflow pathways of late quaternary distal turbidites deposited on the madeira abyssal plain map turbidites are meter thick mud dominated units with distinctive litho bio and chemostratigraphic characteristics which have enabled the correlation of individual beds over 67 000 km2 geochemical profiles for si ti al mg fe ca and zr have been constructed for a representative 5 meter bed turbidite b at 18 core localities distributed across the central part of the map these profiles combined with grain size and mineralogical data demonstrate that turbidites consist of a 1 120 cm laminated sand silt basal layer rich in volcanic gla s basalt clasts heavy minerals and foraminifera unit 1 overlain by 1 5 m of poorly graded silty muds geochemical data additionally indicate the presence of a central layer which is relatively enriched in heavy mineral and flocculated clay aggregate muds and is typified by high ti fe mg and zr contents unit 2 this unit is overlain by sediments containing increasing proportions of calcareous nannofossils and clay minerals unit 3 and characterized by enhanced ca and al concentrations unit 1 thins and fines whereas units 2 and 3 thicken and fine toward the deepest part of the basin and into local depressions and cul de sacs it is argued that the majority of the turbidites were deposited from evolving highly concentrated flows which prevented significant grain size segregatio and enabled the rapid deposition of meter thick poorly graded muds the sorted and graded basal silts unit 1 were deposited primarily by an initially turbulent flow which decelerated and matured into a highly concentrated fluid mud turbidity current shear at the flow base was responsible for the grading in the upper part of unit i and in the silty muds of unit 2 fluid entrained under the current head which migrated up through the flow carried light carbonate and clay minerals toward the turbidite top leaving a central plug of dense muds overlying sheared sands silts and silty muds isocon maps produced by joining points of equal chemical concentration based on mean values for ca ti mg and zr in unit 2 are used to reconstruct sediment dispersal patterns and palaeoflow pathway these maps confirm that turbidite b was deposited by turbidity currents which flowed axially southwestward across the central part of the map implying that the canary islands and madeira offer a potential source of sediment for map turbidites

radar frequency dielectric dispersion in sandstone implications for determination of moisture and clay content 1 the relationship between dielectric permittivity water saturation and clay content for the sherwood sandstone from ne england was characterized as part of a wider study of the vadose zone moisture dynamics and pollution vulnerability of this aquifer dielectric permittivity was measured over the full range of saturation levels for various lithologies ranging from clean medium grained sandstone to fine grained sandstone containing up to 5 clay using a specially constructed dielectric cell dielectric constant kr is largely independent of frequency between 350 mhz and 1000 mhz below 350 mhz kr of fine grained clay rich sandstone shows frequency dispersion tests on physical models of the sandstone consisting of a fine fraction of ottawa sand and montmorillonite clay indicate that the clay minerals within the sandstone are responsible for its frequency dispersive behavior these tests also show that increasing pore fluid salinity increases dielectric dispersion at the lower end of the frequency range which indicates that this arises from the interfacial maxwell wagner mechanism associated with platy clay particles water saturated sand clay mixtures show very low dielectric constants at high frequencies over 650 mhz this effect is independent of salinity and probably results from the layered geometric arrangement of solids bound and free water within the swelling clay the complex refractive index method crim with a mineral dielectric constant of about 5 provides a good match to the water saturation versus dielectric constant data for all sherwood sandstone lithologies at frequencies between 350 and 1000 mhz and for clay poor sandstone at lower frequencies below 350 mhz the presence of a few percent of clay in some sherwood sandstone lithologies raises their crim best fit mineral dielectric constant substantially

joint inversion of seismic refraction and resistivity data using layered models applications to groundwater investigation we developed a method for joint inversion of seismic refraction and resistivity data using sharp boundary models with few layers typically three we demonstrated the usefulness of the approach v

nature of surface electrical conductivity in natural sands sandstones and clays the electrical conductivity of rocks results from conduction through the bulk solution occupying the pores and from surface conduction occurring at the fluid grain interface the nature of the surface electrical conductivity of shaly and clean sands and sandstones is examined surface conduction is characterized by the specific surface conductance which is the sum of three contributions i conduction within the electrical diffuse layer which makes a negligible contribution to the total specific surface conductance ii conduction in the stern layer which is shown to vary significantly with the salinity of the pore fluid at low salinities 10 6 to 10 3 mol 1 1 but becomes independent of salinity at higher salinities iii a mechanism operating directly on the mineral surface independent of salinity and perhaps associated with proton transfer at salinities higher than 10 3 mol 1 1 and at 25 c the specific surface conductance of quartz and clays is equal to 8 9 10 9 s and 2 5 10 9 s respectively equations describing the influence of surface conductivity and microstructure upon the macroscopic electrical conductivity of sands sandstones and shales are also developed

resistivity and percolation study of preferential flow in vadose zone at bokhorst germany traditional nondestructive resistivity techniques have been applied in combination with tracer displacement and conventional soil moisture recording methods i e buried tensiometer and time domain reflectometry tdr for studying flow processes at an arable site in bokhorst germany three water infiltration experiments were carried out using tap water spiked with a nonreactive tracer at different concentrations the study aimed at exploring the capabilities of these combined techniques for tracing the preferential movement of water in the uppermost 1 5 m of the highly heterogeneous vadose zone the results illustrate that the applied tensiometer and tdr techniques can detect the relatively fast flow process at their position points and thus only tentatively trace the preferential flow the additional application of the resistivity method can trace the preferential flow paths continuously along the plane of measurements the results of the individual applied methods complement and confirm each other

the hydrogeologic information in cross borehole complex conductivity data from an unconsolidated conglomeratic sedimentary aquifer abstractaccurate estimation of the hydrological properties of near surface aquifers is important because these properties strongly influence groundwater flow and solute transport laboratory based investigations have indicated that induced polarization ip properties of porous media may be linked through either semiempirical or fully mechanistic models to hydrological properties including hydraulic conductivity therefore there is a need for field assessments of the value of ip measurements in providing insights into the hydrological properties of aquifers a cross borehole ip survey was carried out at the boise hydrogeophysical research site bhrs an unconsolidated fluvial aquifer that has previously been well studied with a variety of geophysical and hydrogeologic techniques high quality ip measurements were inverted with careful consideration of the data error structure to provide a 3d distribution of complex electrical conductivity values the inverted distribution was further simplified usin

three dimensional resistivity tomography in extreme coastal terrain amidst dense cultural signals application to cliff stability assessment at the historic d day site summary pointe du hoc overlooking the english channel in normandy france was host to one of the most important military engagements of world war ii but is vulnerable to cliff collapses that threaten important german fortifications including the forward observation post op and rudder s command post the objective of this study is to apply advanced 3 d resistivity tomography towards a detailed site stability assessment with special attention to the two at risk buildings 3 d resistivity tomography data sets at pointe du hoc in the presence of extreme topography and dense cultural clutter have been successfully acquired inverted and interpreted a cliff stability hazard assessment scheme has been designed in which regions of high resistivity are interpreted as zones of open dry fractures with a moderate mass movement potential regions of low resistivity are zones of wet clay filled fractures with a high mass movement potential the op tomography results indicate that the highest mass movement hazard appears to be associated with the marine caverns at the base of the cliff that are positioned at the point of strongest wave attack these caverns likely occupy the future site of development of a sea arch that will threaten the op building the mass movement potential at the rudder s command post area is low to moderate the greatest risk there is associated with soil wedge failures at the top of the cliffs

lithology stratigraphy chemostratigraphy and depositional environment of the mississippian sycamore rock in the scoop and stack area oklahoma usa field lab and machine learning studies on outcrops and subsurface wells abstract this paper presents an interpreted depositional environment developed 2nd order sequence stratigraphy framework and detailed lithofacies identification from two mississippian sycamore outcrops i 35 sycamore and speake ranch and subsurface wells in the scoop south central oklahoma oil province then these rocks calibrate the rock properties with wireline log responses to identify the best landing zones qualitative and quantitative techniques of field laboratory and machine learning studies were conducted for the field studies we measured the complete 450 ft of the outcrop stratigraphic section another separate 50 ft outcrop examined the underlying woodford shale and overlying caney shale boundary contacts documented sedimentary structures constructed an outcrop gamma ray profile and developed a sequence stratigraphic framework laboratory studies included petrographic analyses detailed x ray fluorescence xrf scanning electron microscopy sem and x ray diffraction xrd for machine learning studies a principal component analysis pca elbow method and self organizing map som were used to analyze the electrofacies and chemofacies from the outcrop and a subsurface uncored well the outcrop hand held gamma ray profile was obtained and correlated with subsurface wells five major outcrop lithofacies and chemofacies within six stratigraphic units of alternating siltstone and shale strata were identified from the wireline logs a maximum flooding surface mfs and two major 2nd order sequence boundaries sb were recognized at the outcrop and a nearby subsurface well bouma sequences and repetitive cycles of sedimentary structures indicated sediment gravity flow deposition on a marine slope setting this study provides geologic insights to better understanding the depositional environment and the lithology of the sycamore rocks the bioturbated siliceous shale and or the sandy siltstone can be potential target zones due to their reservoir quality lithology bed continuity and brittleness this information can be of direct benefit to the exploration and development programs of many companies in the scoop area particularly in the anadarko and ardmore basins in oklahoma

a new approach for time lapse data weighting in electrical resistivity tomography abstractapplications of time lapse inversion of electrical resistivity tomography allow monitoring variations in the subsurface that play a key role in a variety of contexts the inversion of time lapse data provides successive images of the subsurface properties showing the medium evolution image quality is highly dependent on the data weighting determined from the data error estimates however the quantification of errors in the inversion of time lapse data has not yet been addressed we have developed a methodology for the quantification of time lapse data error based on the analysis of the discrepancy between normal and reciprocal readings acquired at different times we applied the method to field monitoring data sets collected during the injection of heated water in a shallow aquifer we tested different error models to indicate that the use of an appropriate time lapse data error estimate yielded significant improvements in terms of imaging an adapted inversion weighting for time lapse data impl

lithologic imaging using complex conductivity lessons learned from the hanford 300 area abstractfield scale lithologic applications of complex conductivity imaging have been hindered by the challenges of 1 acquiring reliable induced polarization ip measurements and 2 obtaining reliable images from the measurements we performed a series of 2d time domain resistivity ip surveys at the hanford 300 area richland washington where the challenge was to image the spatial distribution of two lithologic units that control the exchange between groundwater and surface water of the columbia river exploiting the equivalence between time domain and frequency domain measurements of polarization a 2d inversion real conductivity imaginary conductivity and phase angle was used to image the spatial distribution of across the site synthetic studies were carried out to investigate the effects of noise on the resolution of images and to add confidence on the interpretation of possible paleochannels observed in the field data sets the synthetic studies show that with inc

sulfur isotopic trends and pathways of iron sulfide formation in upper holocene sediments of the anoxic black sea down core trends for extents of iron sulfidation in upper holocene microlaminated deposits of the black sea abyssal plain imply that most of the pyrite in these sediments is formed in the sulfidic water column and or very close to the sediment water interface sulfur isotopic data for pyrite within microlaminated muds from two localities in the deep basin show striking uniformity between sites and down core with a mean 34scdt value of 37 2 0 9 1 n 18 these isotopic trends support the hypothesis of early pyrite formation isotopic compositions of pyrite sulfur in the microlaminated bottom sediments are similar to those reported for particulate reduced sulfur collected in middepth sediment traps and to 34s values for water column dissolved sulfide within a narrow zone immediately below the o2 h2s interface these three sulfur reservoirs are distinctly different from the isotopic composition of ambient dissolved sulfide of the deep water column 175 m with 34s values for the deep dissolved sulfide reservoir being consistently lower by 2 to 4 these isotopic relationships suggest that iron sulfidation is occurring dominantly within a narrow shallow region at the top of the sulfidic water mass isotopic data from a fine grained turbidite collected in the deep basin and from rapidly accumulating iron monosulfide rich muds on the anoxic upper slope are enriched in34s relative to the microlaminated deposits the enrichments on the basin margin reflect a large component of iron sulfide formed during rapid burial a broad suite of geochemical data including sulfur isotopic results are consistent with an upper slope sediment source for the ubiquitous muddy turbidites of the deep basin the collective effects of reworking transport and redeposition result in a complete conversion of avs to pyrite with little additional iron sulfidation this conclusion is supported by a detailed isotopic mass balance the present isotopic study also highlights fundamental differences in the reactivities of the iron reservoirs distributed throughout the anoxic basin sediments of the upper slope and the genetically linked turbidites of the deep basin show similar extents of iron sulfidation that are significantly lower than those of the microlaminated deposits of the deep basin floor suggesting dramatically shorter timescales of iron reactivity for the microlaminated sediments of the deep basin importantly isotopic patterns from the modern black sea should assist greatly in the recognition and interpretation of ancient anoxia in the stratigraphic record

a geological assessment method of floor water inrush risk and its application abstract the risk assessment of floor water inrush is essential to assure the safe production in a coal pit floor aquifuge is the key factor controlling water inrush both the impermeability and the resistance to water pressure of an aquifuge vary with its lithology and structure features with the increase of mudstone content the permeability and resistance to water pressure of the floor drops the dense tectonic fissures in floor will transform intact blocky structure into very blocky or blocky disturbed structure lower the resistance to water pressure increase the permeability of floor aquifuge and thereby will raise the risk of water inrush considering the lithology and structure features and based on a conventional water inrush coefficient a coal floor water inrush risk assessment method is put forward with fangezhuang coal mine of china as a case study the implementation of this method is elaborated

groundwater in the celtic regions this book covers a diverse range of hydrogeological environments that occur in the celtic regions of britain and ireland these include hard rock aquifers of lower palaeozoic and precambrian age generally dominated by fracture flow within a shallow zone of weathering carboniferous limestone aquifers often characterized by conduit flows in karstic systems dual porosity permo triassic sandstone aquifers and quaternary deposits many of which form shallow granular aquifers the papers presented here address a number of current issues common to the celtic regions including groundwater protection policies groundwater management in karst aquifers groundwater development in quaternary aquifers groundwater evaluation in data scarce aquifers and groundwater supplies to small island communities

the trace metal content of recent organic carbon rich sediments implications for cretaceous black shale formation organic carbon rich sediments are enriched in several redox sensitive and stable sulfide forming trace metals tm and form an important sink in global tm cycles in today s ocean such sediments are deposited in coastal upwelling areas like those in the gulf of california off peru or off the namibian coast and euxinic basins like the black sea in an attempt to distinguish both environments by their specific tm patterns some important conclusions may be drawn 1 the tm enrichment seen in both environments broadly is rather similar 2 upwelling sediments are often enriched in cd and p and depleted in co and mn 3 sapropels have a tendency towards higher enrichments in ba and mo s re as cu ni sb and fe reflecting the strong sulfidation in an anoxic water column 4 upwelling systems cover a broad range of environmental settings where the steepness of the slope the proximity of h2s to the sediment seawater interface and the intensity of bio accumulation and regeneration play an important role for tm accumulation 5 the tm content of anoxic basins is mainly controlled by tm availability in the water column and sedimentation rate 6 enhanced bio productivity is the main switch turning an oxygenated into an anoxic environment cretaceous black shales oae 2 exhibit tm signatures of both coastal upwelling areas and sapropels the strong enrichments in cd mo tl v cu ni bi and sb demonstrate that bio accumulation and presence of h2s in the water column and associated sulfidation processes persisted during this time interval in large parts of the proto atlantic the usefulness of ba as a paleoproductivity proxy is obscured by diagenesis the extreme accumulation in ag and zn requires either an additional tm source for instance hydrothermal input or a different tm seawater composition during the cretaceous the geochemical data suggest that the major driving force for the widespread occurrence of c t black shales seems to be the increase in volcanic activity and associated co2 input throughout the cretaceous the ocean atmosphere system operated in a mode different from today during this time interval after conversion of the nutrient co2 into organic matter the system switched back into the normal operational mode

characterization of water content dynamics and tracer breakthrough by 3 d electrical resistivity tomography ert under transient unsaturated conditions characterization of preferential flow and transport is still a major challenge but may be improved employing noninvasive tomographic methods in this study 3 d time lapse electrical resistivity tomography ert was employed during infiltration on an undisturbed unsaturated soil core in a laboratory lysimeter a tracer breakthrough was conducted during transient conditions by applying a series of short term infiltrations simulating natural precipitation events the electrical response was quantitatively validated using data from a multicompartment suction sampler water content probes were also installed for ground truthing of ert responses water content variations associated with an infiltration front dominated the electrical response observed during individual short term infiltration events permitting analysis of water content dynamics from ert data we found that instead of the application of an uncertain petrophysical function shape measures of the electrical conductivity response might be used for constraining hydrological models considering tracer breakthroughs the ert observed voxel responses from time lapse tomograms at constant water contents in between infiltration events were used to quantitatively characterize the breakthrough curve shape parameters of the breakthrough derived from ert such as average velocity were highly correlated with the shape parameters derived from local tracer breakthrough curves observed in the compartments of the suction plate the study demonstrates that ert can provide reliable quantitative information on both tracer breakthroughs and water content variations under the challenging conditions of variable background electrical conductivity of the pore solution and non steady state infiltration

mountain permafrost development and challenges of a young research field an overview is given of the relatively short history important issues and primary challenges of research on permafrost in cold mountain regions the systematic application of diverse approaches and technologies contributes to a rapidly growing knowledge base about the existence characteristics and evolution in time of perennially frozen ground at high altitudes and on steep slopes these approaches and technologies include 1 drilling borehole measurement geophysical sounding photogrammetry laser altimetry gps sar surveying and miniature temperature data logging in remote areas that are often difficult to access 2 laboratory investigations e g rheology and stability of ice rock mixtures 3 analyses of digital terrain information 4 numerical simulations e g subsurface thermal conditions under complex topography and 5 spatial models e g distribution of permafrost where surface and microclimatic conditions are highly variable spatially a sound knowledge base and improved understanding of governing processes are urgently needed to deal effectively with the consequences of climate change on the evolution of mountain landscapes and especially of steep mountain slope hazards as the stabilizing permafrost warms and degrades interactions between glaciers and permafrost in cold mountain regions have so far received comparatively little attention and need more systematic investigation

joint inversion of steady state hydrologic and self potential data for 3d hydraulic conductivity distribution at the boise hydrogeophysical research site we combine sedimentological hydraulic and geophysical information to characterize the 3d distribution of transport properties of an heterogeneous aquifer we focus on the joint inversion of hydraulic head and self potential measurements collected during an extensive experimental campaign performed at the boise hydrogeophysical research site bhrs boise idaho and involving a series of dipole tests while hydraulic head data obtained from piezometric readings in open wells represent a depth averaged value self potential signals provide an estimate of the water table location the aquifer is conceptualized as a multiple continuum where the volumetric fraction of a geo material within a cell of the numerical flow model is calculated by multiple indicator kriging the latter is implemented on the basis of available sedimentological information the functional format of the indicator variograms and associated parameters are estimated on the basis of formal model identification criteria self potential and hydraulic head data have been embedded jointly within a three dimensional inverse model of groundwater flow at the site each identified geo material category is assumed to be characterized by a constant hydraulic conductivity the latter constitute the set of model parameters the hydraulic conductivity associated with a numerical block is then calculated as a weighted average of the conductivities of the geo materials which are collocated in the block by means of multiple indicator kriging model parameters are estimated by a maximum likelihood fit between measured and modeled state variables resulting in a spatially heterogeneous distribution of hydraulic conductivity the latter is effectively constrained on the sedimentological data and conditioned on both self potential and borehole hydraulic head readings minimization of the maximum likelihood objective function allows estimating the relative weight of measurement errors associated with self potential and borehole based head data the procedure adopted allowed a reconstruction of the heterogeneity of the site with a level of details which was not obtained in previous studies and with relatively modest computational efforts further validation against dipole tests which were not used in the inversion procedure supports the robustness of the results

hydrological response of weathered clay shale slopes water infiltration monitoring with time lapse electrical resistivity tomography this work presents an attempt to monitor water infiltration and subsurface flow within a clay shale landslide using time lapse electrical resistivity tomography ert a rainfall experiment was carried out on a plot of 100 m2 at the laval landslide in the draix experimental catchments ore draix south french alps in order to characterize the spatial and temporal development of water circulation in the soil and to identify when steady state flow conditions are reached the experiment was conducted during 67 h with initial unsaturated conditions in the slope the apparent electrical resistivity values were inverted with a time lapse approach using several cross models the results indicate a significant decrease in resistivity 18 compared to the initial state in the rain plot downslope progression of negative resistivity anomalies is imaged suggesting that vertical and subsurface lateral flows have developed about 21 h after the start of the rain experiment a constant level of resistivity values is observed indicating that the hydrological system reached steady state flow conditions this observation is consistent with ground water level observations and chemical tracer analysis computed differences in time of steady state conditions highlight possible preferential flows near the landslide toe a hydrological concept of functioning of the slope is proposed and apparent saturated hydraulic conductivity ks of 1 7 10 4 m s 1 is computed from the steady state times this study demonstrates the potentiality of ert monitoring to monitor water infiltration in clay shale slopes and the high water transfer capacity of reworked clay shale material

electrical resistivity imaging for long term autonomous monitoring of hydrocarbon degradation lessons from the deepwater horizon oil spill abstractconceptual models for the geophysical responses associated with hydrocarbon degradation suggest that the long term evolution of an oil plume will result in a more conductive anomaly than the initial contamination in response to the deepwater horizon dh oil spill into the gulf of mexico in 2010 an autonomous resistivity monitoring system was deployed on grand terre louisiana in an attempt to monitor natural degradation processes in hydrocarbon impacted beach sediments of this island a 48 electrode surface array with a 0 5 m spacing was installed to obtain twice daily images of the resistivity structure of the shallow subsurface impacted by oil over the course of approximately 18 months we observed a progressive decrease in the resistivity of the dh spill impacted region detailed analysis of pixel point resistivity variation within the imaged area showed that long term decreases in resistivity were largely associated with the dh impacted sediments a microbial diversity survey revealed the

subsurface fluid distribution and possible seismic precursory signal at the salse di nirano mud volcanic field italy mud volcanoes are geological systems often characterized by elevated fluid pressures at depth deviating from hydrostatic conditions this near critical state makes mud volcanoes particularly sensitive to external forcing induced by natural or man made perturbations we used the nirano mud volcanic field as a natural laboratory to test pre and post seismic effects generated by distant earthquakes we first characterized the subsurface structure of the nirano mud volcanic field with a geoelectrical study next we deployed a broad band seismic station in the area to understand the typical seismic signal generated by the mud volcano seismic records show a background noise below 2 s sometimes interrupted by pulses of drumbeat like high frequency signals lasting from several minutes to hours to date this is the first observation of drumbeat signal observed in mud volcanoes in 2013 june we recorded a m4 7 earthquake that occurred approximately 60 km far from our seismic station according to empirical estimations the nirano mud volcanic field should not have been affected by the m4 7 earthquake yet before the seismic event we recorded an increasing amplitude of the signal in the 10 20 hz frequency band the signal emerged approximately two hours before the earthquake and lasted for about three hours our statistical analysis suggests the presence of a possible precursory signal about 10 min before the earthquake

combining fiber optic dts cross hole ert and time lapse induction logging to characterize and monitor a coastal aquifer the characterization of saline water intrusion swi and its hydrodynamics is a key issue to understand submarine groundwater discharge sgd and manage groundwater resources in coastal areas to test and compare different methods of characterization and monitoring a new experimental site has been constructed in a coastal alluvial aquifer north of barcelona city catalonia spain the site is located between 30 and 90 m from the seashore and comprises 16 shallow piezometers organized in nests of three with depths ranging between 15 and 25 m and 4 solitary piezometers the objective of this paper is to combine different recently developed monitoring techniques to evaluate temporal variations in the aquifer hydrodynamics of the site at different spatial scales before and after the dry season of 2015 at the site scale fibre optic distributed temperature sensing fo dts for the first time applied to study swi and cross hole electrical resistivity tomography chert has been applied at the meter borehole scale electrical conductivity of the formation has been applied not only in a repeated manner time lapse but also for the first time at relatively high frequency 1 sample every 10 min chert has provided a better characterization of the seawater intrusion than electrical conductivity data obtained from piezometers the combination of techniques has allowed improving the understanding of the system by 1 characterizing the extent and shape of swi 2 differentiating two different dynamics in the aquifer and 3 identifying preferential flow paths over different time and spatial intervals future challenges and the application of these techniques in other areas are also discussed

quantitative imaging of solute transport in an unsaturated and undisturbed soil monolith with 3 d ert and tdr electrical resistivity tomography ert has proved to be a valuable tool for imaging solute transport processes in the subsurface however a quantitative interpretation of corresponding ert results is constrained by a number of factors one such factor is the nonuniqueness of the ert inverse problem if no additional constraints are imposed in the vadose zone further problems arise from the general ambiguity of the imaged bulk electrical conductivity in terms of water content and solute concentration in this study we address these issues in detail for a solute tracer experiment conducted in an undisturbed unsaturated soil monolith where the tracer transport was monitored by means of 3 d smoothness constrained ert and time domain reflectometry tdr measurements the experimental design allowed the determination of solute tracer concentrations directly from imaged bulk electrical conductivity independent tdr data and effluent tracer concentrations provided a ground truth for the ert derived apparent convection dispersion equation transport parameters the apparent transport velocity calculated from the ert results was consistent with that based on tdr data and the sampled effluent independent of the degree of smoothness imposed in the ert inversion on the other hand the apparent dispersivity calculated from the ert results was larger than that estimated from tdr data but smaller than that estimated from the sampled effluent with the magnitude of deviations dependent on the degree of smoothing importantly no mass balance problems were observed in the ert results we believe that this is largely a consequence of the uniform application of the tracer as a front and of the configuration of the electrode array with respect to the main transport direction in conclusion the study demonstrates that ert can yield unprecedented quantitative information about local and column scale solute transport characteristics in natural soils

a salt tracer test monitored with surface ert to detect preferential flow and transport paths in fractured karstified limestones in hard rock aquifers fractured zones constitute adequate drinking water exploitation areas but also potential contamination paths one critical issue in hydrogeological research is to identify characterize and monitor such fractured zones at a representative scale a tracer test monitored with surface electrical resistivity tomography ert could help by delineating such preferential flow paths and estimating dynamic properties of the aquifer however multiple challenges exist including the lower resolution of surface ert compared with crosshole ert the finite time that is needed to complete an entire data acquisition and the strong dilution effects we conducted a natural gradient salt tracer test in fractured limestones to account for the high transport velocity we injected the salt tracer continuously for four hours at a depth of 18 m we monitored its propagation with two parallel ert profiles perpendicular to the groundwater flow direction concerning the data acquisition we always focused

free phase gas processes in a northern peatland inferred from autonomous field scale resistivity imaging the mechanisms that control free phase gas fpg dynamics within peatlands and therefore estimates of past present and future gas fluxes to the atmosphere remain unclear electrical resistivity imaging eri is capable of autonomously collecting three dimensional data on the centimeter to tens of meter scale and thus provides a unique opportunity to observe fpg dynamics in situ we collected 127 3 d eri data sets as well as water level soil temperature atmospheric pressure and limited methane flux data at a site in a northern peatland over the period july august 2013 to improve the understanding of mechanisms controlling gas releases at a hitherto uncaptured field scale our results show the ability of eri to image the spatial distribution of gas accumulation and infer dynamics of gas migration through the peat column at high i e hourly temporal resolution furthermore the method provides insights into the role of certain mechanisms previously associated with the triggering of fpg releases such as drops in atmospheric pressure during these events buoyancy driven gas release primarily occurs in shallow peat as proposed by the shallow peat model releases from the deeper peat are impeded by confining layers and we observed a large loss of fpg in deep peat that may likely represent a rupture event where accumulated fpg escaped the confining layer as suggested by the deep peat model negative linear correlations between water table elevation and resistivity result from hydrostatic pressure regulating bubble volume although these variations did not appear to trigger fpg transfer or release

stochastic inversion of tracer test and electrical geophysical data to estimate hydraulic conductivities 1 quantifying the spatial configuration of hydraulic conductivity k in heterogeneous geological environments is essential for accurate predictions of contaminant transport but is difficult because of the inherent limitations in resolution and coverage associated with traditional hydrological measurements to address this issue we consider crosshole and surface based electrical resistivity geophysical measurements collected in time during a saline tracer experiment we use a bayesian markov chain monte carlo mcmc methodology to jointly invert the dynamic resistivity data together with borehole tracer concentration data to generate multiple posterior realizations of k that are consistent with all available information we do this within a coupled inversion framework whereby the geophysical and hydrological forward models are linked through an uncertain relationship between electrical resistivity and concentration to minimize computational expense a facies based subsurface parameterization is developed the bayesian mcmc methodology allows us to explore the potential benefits of including the geophysical data into the inverse problem by examining their effect on our ability to identify fast flowpaths in the subsurface and their impact on hydrological prediction uncertainty using a complex geostatistically generated two dimensional numerical example representative of a fluvial environment we demonstrate that flow model calibration is improved and prediction error is decreased when the electrical resistivity data are included the worth of the geophysical data is found to be greatest for long spatial correlation lengths of subsurface heterogeneity with respect to wellbore separation where flow and transport are largely controlled by highly connected flowpaths

monitoring snowmelt induced unsaturated flow and transport using electrical resistivity tomography the flow and transport of a non reactive tracer and melt water was monitored in a heterogeneous coarse sandy unsaturated zone in southeastern norway during the snowmelt of 2001 electrical resistivity tomography ert as well as conventional suction cup techniques was employed a frozen solution of nabr in water was supplied as a line source on the ground surface above two parallel vertical profiles monitored by the two measurement systems prior to the onset of snowmelt the two monitored vertical profiles were separated by approximately 1 m the results were analysed by visual comparison of images and by the use of spatial moments analysis the two measurement approaches showed that the system was affected by the presence of preferential flow paths during the early stages of the snowmelt perhaps due to ice near the surface but the major part of the plume moves uniformly later in the snow melting period after most of the tracer plume has reached the depth monitored by both systems i e below 0 4 m depth there is a good consistency between the two datasets spatial moment calculations on the basis of ert cannot be used to describe the movement of tracer alone as the resistivity is affected by changes in both saturation levels and tracer concentration nevertheless ert appears to be an appropriate method to characterise regions of localised high infiltration in this type of soil the method therefore constitutes a possible alternative and supplement to suction cups in a monitoring system

halite karst geohazards natural and man made in the united kingdom in the united kingdom permian and triassic halite rock salt deposits have been affected by natural and artificial dissolution producing karstic landforms and subsidence brine springs from the triassic salt have been exploited since roman times or possibly earlier indicating prolonged natural dissolution medieval salt extraction in england is indicated by the names of places ending in wich indicating brine spring exploitation at northwich middlewich nantwich and droitwich later victorian brine extraction in these areas accentuated salt karst development causing severe subsidence problems which remain a legacy the salt was also mined but the mines flooded and consequent brine extraction caused the workings to collapse resulting in catastrophic surface subsidence legislation was enacted to pay for the damage and a levy is still charged for salt extraction some salt mines are still collapsing and the re establishment of the post brine extraction hydrogeological regimes means that salt springs may again flow causing further dissolution and potential collapse

imaging and characterisation of subsurface solute transport using electrical resistivity tomography ert and equivalent transport models abstract we assess the usefulness of electrical resistivity tomography ert in imaging and characterising subsurface solute transport in heterogeneous unconfined aquifers a field tracer experiment was conducted at the krauthausen test site germany the spatial and temporal evolution of the injected nabr solute plume was monitored in a 2d ert image plane located downstream of the injection well for 90 days since ert maps changes in bulk electrical conductivity the reconstructed images at selected time intervals are first converted to solute concentration maps by postulating a linear relation the concentration maps are then analysed using an equivalent convection dispersion model cdm which conceptualises the aquifer as a homogeneous medium with a uniform mean flow velocity as demonstrated by associated synthetic model studies ert resolution in terms of recovered equivalent dispersivities is limited due to spatial smoothing inherent to the imaging algorithm since for heterogeneous media local concentrations within the plume deviate from those predicted by the equivalent cdm we also interpret the ert derived pixel breakthrough curves in terms of an equivalent stream tube model stm the stm represents transport in the aquifer by a set of 1d convection dispersion processes allowing the degree of mixing and the heterogeneity of transport within the plume to be quantified we believe that the observed tracer plume is satisfactorily described by the equivalent cdm probably because the tracer plume was small relative to the heterogeneity scale of the aquifer even though application of the stm revealed some deviation from the ideal homogeneous case the equivalent dispersivity in the stm matches the longitudinal dispersivity of the cdm closely consistent with predominantly homogeneous mixing however the stm analysis illustrates how ert results can be used to quantify the variability of parameters relevant to flow and transport in heterogeneous aquifers

hydrogeochemical and isotopic characterization of groundwater salinization in the bangkok aquifer system thailand the deterioration of groundwater quality particularly due to salinization because of the overexploitation of groundwater in the lower central plain of thailand remains a major concern with increasing demand for water there is a growing need for sustainable management of the resource which would benefit from an improved understanding of the sources of chloride contamination thus a hydrochemical and isotopic study was carried out to chemically characterize groundwater and to investigate possible sources of salinization and in particular of chloride contamination in the multi layered bangkok aquifer system groundwater samples were taken from four topmost aquifers bangkok phra pradaeng nakhon luang and nonthaburi additionally short term rainwater sampling as well as river and seawater sampling was performed and later analyzed for ionic composition and stable water isotopes ionic and isotopic data indicate at least three different recharge sources for groundwater the major recharge source is rainwater the influence of seawater is limited to the coastal region and tidally influenced areas of the two main rivers chao phraya and tha chin bromide data also suggest the influence of saline water in deeper aquifers due to trapped water most importantly although the influence of seawater on groundwater is recognizable the surrounding geology contributes a significant number of dissolved ions detected in the groundwater

hydrochemical characteristics of groundwater movement and evolution in the xinli deposit of the sanshandao gold mine using fcm and pca methods the objective of this study is to characterize the physicochemical properties of groundwater in the sanshandao gold deposit analyze the laws of motion and evolution of the groundwater system and provide evidence for the design of undersea mining and safety warnings using combined fuzzy c means fcm and principal component analysis pca methods thirteen physicochemical indicators and two isotopic indicators were surveyed from 100 fissure water samples and 13 typical water samples from xinli a deposit of the sanshandao gold mine in china first pca was used to extract four pcs with explained variances 48 25 10 and 7 and the characteristics of the hydrochemistry indicators of each pc were examined the four pcs are identified as the processes of concentration and dilution sericite rock orientation and carbonatization potash feldspathization and dissolution of carbon dioxide next using the four pcs developed from pca 100 fissure water samples were grouped into four spatially continuous clusters using the fcm cluster method with the aid of graphic technology the four fuzzy clusters were determined as deep saline water shallow saline water bedrock brine and mixed wastewater following careful analysis of the hydrochemical characteristics of each cluster combined with a related hydrogeological report finally further analysis of the pca and fcm results determined factors constituting the groundwater system including sources of water flow path mixing zone local fissure zone and impact of mining on the groundwater system this study shows that the combination of pca and fcm is important for understanding hydrochemical characteristics of a groundwater system

on the field estimation of moisture content using electrical geophysics the impact of petrophysical model uncertainty the spatiotemporal distribution of pore water in the vadose zone can have a critical control on many processes in the near surface earth such as the onset of landslides crop yield groundwater recharge and runoff generation electrical geophysics has been widely used to monitor the moisture content distribution in the vadose zone at field sites and often resistivity or conductivity is converted to moisture contents through petrophysical relationships e g archie s law though both the petrophysical relationships i e choices of appropriate model and parameterization and the derived moisture content are known to be subject to uncertainty they are commonly treated as exact and error free this study examines the impact of uncertain petrophysical relationships on the moisture content estimates derived from electrical geophysics we show from a collection of data from multiple core samples that significant variability in the relationship can exist using rules of error propagation we demonstrate the combined effect of inversion and uncertain petrophysical parameterization on moisture content estimates and derive their uncertainty bounds through investigation of a water injection experiment we observe that the petrophysical uncertainty yields a large range of estimated total moisture volume within the water plume the estimates of changes in water volume however generally agree within large uncertainty bounds our results caution against solely relying on electrical geophysics to estimate moisture content in the field the uncertainty propagation approach is transferrable to other field studies of moisture content estimation

study of tracer movement through unsaturated sand abstract a column of 100 cm length and 15 4 cm diameter was filled with sand a solute displacement experiment using tritium as a tracer was conducted under saturated water flow conditions analysis of the observed effluent concentration resulted in an estimated dispersivity of 0 094 cm solute displacement experiments under unsaturated water flow conditions were conducted by leaching the column intermittently on a daily basis with constant amounts of water as soon as the amount drained from the column was equal to the daily input tritium was added to the infiltrating water for some period three such experiments were conducted with different amounts of water infiltrated daily these amounts were small enough for the water flow to remain unsaturated the parameters of the hydrodynamic dispersion equation were fitted to the observed effluent concentrations very large dispersion coefficients were obtained with a dispersivity of about 7 3 cm a possible explanation of this phenomenon is the presence of immobile water pockets during unsaturated flow for all experiments it was found that about 36 of the water in the unsaturated column could be considered as immobile the exchange of solute between the mobile and immobile phases explains very well the large dispersion observed in the experiments conducted under unsaturated conditions

potential of electrical resistivity tomography to infer aquifer transport characteristics from tracer studies a synthetic case study 1 with time lapse electrical resistivity tomography ert transport processes in the subsurface can be imaged and monitored the information content of obtained spatiotemporal data sets opens new ways to characterize subsurface spatial variability difficulties regarding a quantitative interpretation of the imaged transport may arise from the fact that data inversion used in ert is generally underdetermined and that ert data acquisition is often limited to two dimensional 2 d image planes to address this problem we conducted a numerical tracer experiment in a synthetic heterogeneous aquifer with preset variability and spatial correlation of the hydraulic conductivity and monitored the tracer breakthrough in a 2 d image plane perpendicular to the mean flow direction using time lapse ert the tracer breakthrough patterns in the image plane were interpreted using equivalent transport models an equivalent convection dispersion equation to characterize the spatially averaged breakthrough and a stream tube model to characterize local breakthrough curves equivalent parameters derived from simulated and from ert inverted concentrations showed a good agreement which demonstrates the potential of ert to characterize subsurface transport using first order approximate solutions of stochastic flow and transport equations equivalent model parameters and their spatial variability were interpreted in terms of the local scale dispersion and the spatial variability of the hydraulic conductivity the spatial correlations of the stream tube velocity and of the hydraulic conductivity were found to be closely related consequently the hydraulic conductivity spatial correlation may be inferred from stream tube velocity distributions which can be observed with sufficiently high spatial resolution using ert

temperature calibrated imaging of seasonal changes in permafrost rock walls by quantitative electrical resistivity tomography zugspitze german austrian alps 1 changes of rock and ice temperature inside permafrost rock walls crucially affect their stability permafrost rocks at the zugspitze were involved in a 0 3 0 4 km3 rockfall at 3 7 ka b p whose deposits are now inhabited by several thousands of people a 107 year climate record at the summit 2962 m asl shows a sharp temperature increase in 1991 2007 this article applies electrical resistivity tomography ert to gain insight into spatial thaw and refreezing behavior of permafrost rocks and presents the first approach to calibrating ert with frozen rock temperature high resolution ert was conducted in the north face adjacent to the zugspitze rockfall scarp in february and monthly from may to october 2007 a smoothness constrained inversion is employed with an incorporated data error model calibrated on the basis of normal reciprocal measurement discrepancy laboratory analysis of zugspitze limestone indicates a bilinear temperature resistivity relationship divided by a 0 5 0 1 c and 30 3 k m equilibrium freezing point and a twentyfold increase of the frozen temperature resistivity gradient 19 3 2 1 k m c temperature dominates resistivity changes in rock below 0 5 c while in this case geological parameters are less important ert shows recession and readvance of frozen conditions in rock correspondingly to temperature data maximum resistivity changes in depths up to 27 m coincide with maximum measured water flow in fractures in may here we show that laboratory calibrated ert does not only identify frozen and unfrozen rock but provides quantitative information on frozen rock temperature relevant for stability considerations

using complex resistivity imaging to infer biogeochemical processes associated with bioremediation of an uranium contaminated aquifer 1 experiments at the department of energy s integrated field research challenge ifrc site near rifle colorado have demonstrated the ability to remove uranium from groundwater by stimulating the growth and activity of geobacter species through acetate amendment prolonging the activity of these strains in order to optimize uranium bioremediation has prompted the development of minimally invasive and spatially extensive monitoring methods diagnostic of their in situ activity and the end products of their metabolism here we demonstrate the use of complex resistivity imaging for monitoring biogeochemical changes accompanying stimulation of indigenous aquifer microorganisms during and after a prolonged period 100 days of acetate injection a thorough raw data statistical analysis of discrepancies between normal and reciprocal measurements and incorporation of a new power law phase error model in the inversion were used to significantly improve the quality of the resistivity phase images over those obtained during previous monitoring experiments at the rifle ifrc site the imaging results reveal spatiotemporal changes in the phase response of aquifer sediments which correlate with increases in fe ii and precipitation of metal sulfides e g fes following the iterative stimulation of iron and sulfate reducing microorganisms only modest changes in resistivity magnitude were observed over the monitoring period the largest phase anomalies 40 mrad were observed hundreds of days after halting acetate injection in conjunction with accumulation of fe ii in the presence of residual fes minerals reflecting preservation of geochemically reduced conditions in the aquifer a prerequisite for ensuring the long term stability of immobilized redox sensitive contaminants such as uranium

electrical monitoring of saline tracers to reveal subsurface flow pathways in a flat ditch drained field abstract time lapse electrical resistivity imaging eri combined with salt tracers can enhance our understanding of subsurface flow and transport in ditch drained agroecosystems in a nearly level field adjacent to a drainage ditch we installed 192 electrodes in a 72 m2 plot along with five hydrometric stations to enable time lapse eri monitoring during storms immediately prior to a wintertime rainstorm we applied 5 kg of kbr to a shallow trench located roughly 11 m upgradient from the ditch antecedent conditions prior to the storm were wet assuring a hydrologically connected state that favored tracer dissolution and movement in the subsurface we monitored the evolution of the tracer plume with eri over a seven day period four dimensional 4d delineation of precipitation and tracer transport using time lapse eri showed that the tracer plume moved preferentially downward through a discontinuity in the argillic horizon within the first 57 hrs over the following 79 hrs the tracer plume exhibited steady lateral movement towards the drainage ditch within a more permeable sandy horizon situated just below the argillic a spatial moment analysis of logarithmic changes in conductivity in the sand layer revealed seepage velocities ranging from 0 0027 to 0 0482 m d 1 these values were positively correlated with hydraulic gradients suggesting laminar flow processes typical of sandy aquifers increasing groundwater velocities with hydraulic gradients suggest that solute transfers from groundwater to ditch are likely to be faster in storms especially during wet periods even so predominantly slow lateral transport within the sandy horizon even during storms indicates that critical source areas of pollutant loss are likely within a few meters of the ditch

a brief discussion on the mean oceanic residence time of elements abstract the mean oceanic residence times of elements obtained from deposition rates in deep sea sediments are more representative than those obtained from river input rates the average concentration data of dissolved s au ag se as hg sb zn sn cu and pb in rivers contain large pollution and or contamination components

seawater inrush assessment based on hydrochemical analysis enhanced by hierarchy clustering in an undersea goldmine pit china seawater inrush is deadly to undersea mine and it is very important to accurately assess the connectivity between seawater and the mine pit with xinli gold mine area as a case study following the analysis of geological setting a detailed hydrogeological survey and sampling were conducted and conservative ions test of mine water samples was carried out in the laboratory furthermore the physical significances of ion concentration and ion ratios such as cl so42 cl and na cl were checked the test data analysis enhanced by the physical significance check and hierarchy clustering analysis was used to assess the overlying seawater inrush into the mine pit it was determined that the undersea rock masses in the xinli mine area bear high mineralization brine water the ore controlling fault gouge and a thin layer of clay in quaternary block the seepage of overlying seawater into the undersea mine pit to a great extent the mine water from surrounding rock of the northeast gopher drift is closer to seawater in hydrogeochemical features which indicates that the connectivity between the northeast of footwall of the ore controlling fault and seawater is relatively good and should be closely monitored in future production the mine water from the southwest gopher drift and crosscuts is similar to the brine salty water in chemical features drains the net reserves of brine salty water in bedrock fissures and will impose few impacts on production in the near future this approach is feasible and cost effective

investigating the characteristics of mine water in a subsea mine using groundwater geochemistry and stable isotopes investigation were conducted in the xinli subsea mine from 2006 to 2011 which is the largest subsea mine in china and threatened by the overlying quaternary aquifer and seawater hydrochemical and stable isotopic 2h and 18o analyses were used to study the relationships between various waters hydrochemical results indicated that the seepage water in the mine tunnels had higher ec tds and concentrations of most elements than the seawater and saline groundwater water analyses indicated the mine discharge was a mixture of the seawater brine and atmospheric precipitation the proportions of the three different sources were calculated based on hydrochemical and isotopic analyses the seepage water were more isotopically enriched than the seawater but less than the brine in addition the isotope mixing calculation indicated that the average proportions of mine water from seawater brine and atmospheric precipitation were about 38 5 46 and 15 5 respectively for the entire mine in 2006 however the concentrations of these analyses decreased and the proportion of the seawater increased 21 1 after 5 years of exploitation in 2011 these changes demonstrated that the surrounding rock mass underwent a certain extent of deformation and failure because of the mining disturbance which enhanced the permeability of the surrounding rock mass

assessment of the impact of anthropogenic activities on the groundwater hydrology and chemistry in tarsus coastal plain mersin se turkey using fuzzy clustering multivariate statistics and gis techniques summary tarsus coastal plain tcp is an economically and ecologically important area situated in between the fertile fluvio deltaic plains of two rivers delicay and tarsus mersin se turkey where anthropogenic activities agricultural industrial and domestic are very intense twenty four water quality parameters were surveyed at 193 groundwater and 10 surface water sites during august 2008 the objective was to characterize the physico chemical properties of groundwaters in tcp assess the impact of anthropogenic activities on the groundwater hydrology and chemistry and identify the major hydrogeochemical processes occurring in the area groundwater samples were grouped into hydrochemically distinct and spatially continuous four water classes i e c1 c2 c3 and c4 using the fuzzy c means fcm clustering method where membership values were interpolated using the ordinary kriging technique principal components analysis pca was used to decipher various underlying natural and anthropogenic processes creating these distinct water classes four principal components pcs were extracted in pca which explained more than 73 of the total variance in water quality major factors responsible for the variations in chemistries of water classes are identified as 1 water rock interaction and nitrate contamination 2 salinization by seawater intrusion and evaporite dissolution 3 geogenic anthropogenic cr fe and mn and 4 anthropogenic zn pollution overexploitation of the aquifer is clearly evident especially at settlements located near the coastal zone where the water table is lowered 2 5 m below the sea level salinization is well known in the area and is attributed not only to seawater intrusion but also to dissolution of evaporitic series from the handere formation hydrochemical evidence also suggest that in the area subsurface paleo river channels and the deposits infilling the ancient lagoon area within quaternary recent alluvial deposits act as significant hydrological features where preferential groundwater flow occurs along them

hydrogeochemical processes affecting groundwater in an irrigated land in central tunisia detailed hydrogeochemical investigation has provided new information concerning the major factors and mechanisms controlling the groundwater chemistry of chougafiya basin the hydrogeochemical characteristics of groundwaters comprise three main types cl so4 ca cl so4 na and cl na hydrochemical characteristics based on the bivariate diagrams of major cl so42 no3 hco3 na mg2 k and ca2 and some trace br and sr2 ions mineral saturation indices and hierarchical cluster analysis indicate different origins of groundwater mineralization the water rock interaction dissolution of evaporitic minerals followed by cation exchange reactions with clay minerals constitute the main processes that control groundwater salinization however the chemical composition of brackish groundwater in the central and southern parts of the study area is influenced by a mixing process with sabkhas salt groundwater the mixing proportions inferred from chloride mass balance prove that the contribution of sabkhas groundwater to quaternary aquifer ranges between 2 7 and 9 1 these intrusion rates reflect the progress of the saltwater freshwater interface which is mainly controlled by the piezometric level variation and the distance to the sabkhas

imaging and characterization of solute transport during two tracer tests in a shallow aquifer using electrical resistivity tomography and multilevel groundwater samplers 1 the relevance of aquifer heterogeneity for flow and transport is recognized broadly however its characterization is hampered by the inaccessibility of the subsurface time lapse electrical resistivity tomography ert offers the possibility of imaging noninvasively subsurface transport we present results of two tracer tests that were carried out successively in a shallow aquifer at the krauthausen test site germany the breakthroughs of an electrically conductive and a resistive tracer were monitored with ert and local multilevel groundwater samplers mls along two cross sections perpendicular to the mean flow direction sinking of the conductive salt tracer due to density effects was observed with ert we applied a stream tube model to characterize the spatially variable transport ert derived stream tube parameters showed similar patterns for the two tracer experiments reflecting the effect of aquifer heterogeneity on transport mls data did not show similar spatial patterns which indicates that these measurements may be prone to subtle changes of the flow field in the small sampling volume and mixing within screened wells between 50 and 10 of the tracer was recovered in the ert derived breakthrough curves compared with transport simulations in a homogeneous aquifer ert derived time integrated changes in electrical conductivity were locally larger but focused in a smaller area mls data indicated that in this area ert did not underestimate the tracer recovery the relatively low tracer recovery was attributed to undetected tracer breakthrough in regions with low ert sensitivity and in regions where the length of the tracer plume and the electrical conductivity contrast were small

statistical analysis of resistivity anomalies caused by underground caves geophysical prospecting of underground caves being performed on a construction site is often still a challenging procedure estimation of a likelihood level of an anomaly found is frequently a mandatory requirement of a project principal due to necessity of risk safety assessment however the methodology of such estimation is not hitherto developed aiming to put forward such a methodology the present study being performed as a part of an underground caves mapping prior to the land development on the site area consisted of application of electrical resistivity tomography ert together with statistical analysis utilized for the likelihood assessment of underground anomalies located the methodology was first verified via a synthetic modeling technique and applied to the in situ collected ert data and then crossed referenced with intrusive investigations excavation and drilling for the data verification the drilling excavation results showed that the proper discovering of underground caves can be done if anomaly probability level is not lower than 90 such a probability value was shown to be consistent with the modeling results more than 30 underground cavities were discovered on the site utilizing the methodology

the quantification and application of handheld energy dispersive x ray fluorescence ed xrf in mudrock chemostratigraphy and geochemistry abstract traditionally analytical techniques such as wavelength dispersive x ray fluorescence wd xrf inductively coupled plasma icp and mass spectrometry icp ms instrumental neutron activation analysis inaa or stationary bench top energy dispersive x ray fluorescence ed xrf have been used to generate quantitative geochemical results however a more efficient means of data collection using portable ed xrf instrumentation now allows the investigator to acquire rapid non destructive quantitative measurements on drill core and clean flat rock surfaces in addition to pressed powder pellets typically used in wd xrf analysis similar to traditional xrf methods quantification using the handheld ed xrf requires a matrix specific calibration unfortunately very few internationally accepted mudrock or shale reference materials exist and their elemental ranges provide inadequate coverage for the geochemical diversity of mudrocks in order to return reliable calibrated results a unique set of reference materials has been developed that incorporates a wide range of mudrock elemental compositions the current method provides elemental calibrations for major elements heavier than sodium and the following trace elements ba v cr ni cu zn rb sr y zr nb mo th and u a comparison of handheld energy dispersive and wavelength dispersive x ray fluorescence ed xrf and wd xrf results from pressed powder pellets of mississippian age barnett shale of north central texas usa is presented in order to evaluate the reliability of the reference calibration and the quantification of unknown samples using two different instrument platforms it will be demonstrated that calibrated results from the handheld ed xrf effectively define chemostratigraphic changes in real time as a consequence quantified results can be used immediately to assess changes in bulk mineralogy paleo redox conditions and to link down core geochemical changes to stratigraphic sedimentological and paleoenvironmental observations

engineering geology ground surface movement and fissures induced by underground mining in the jinchuan nickel mine the jinchuan nickel mine is the largest underground mine with cut and fill mining in china in 1999 there appeared evident ground surface movement and many ground fissures in jinchuan no 2 mine following an introduction to the engineering geology and mechanical properties of the rock mass in the jinchuan mine areas this paper reveals the features of the measured in situ stresses and puts emphasis on an analysis of the mechanism of surface movement and ground fissures induced by the underground mining with backfill it is indicated that both the fault structures and the alteration contact zones are well developed as the dominant engineering geological characteristics in the jinchuan mine areas the stress redistribution in surrounding rocks resulting from the mining the low stiffness of the filling body the existence of the void space and the influence of on going mining activities is the main reason for the occurrence of surface movement and ground fissures

seasonal variation of moisture content in unsaturated sandstone inferred from borehole radar and resistivity profiles understanding the processes controlling recharge to aquifers is critical if accurate predictions are to be made on the fate of contaminants in the subsurface environment in order to understand fully the hydrochemical mechanisms in the vadose zone it is essential that the dynamics of the hydrology can be suitably characterised the correlation between moisture content and both bulk dielectric and resistivity properties of porous media is well established using suitably placed sensors in boreholes detailed depth profiles of dielectric and resistivity behaviour have been monitored over a period of two years at a triassic sherwood sandstone aquifer field site at hatfield england the borehole borehole transmission radar and borehole resistivity profiles show a significant correlation through appropriate petrophysical relationships derived from core samples seasonal dynamics of the vadose zone are seen to illustrate the migration of wetting and drying fronts over the monitoring period at a second field site in eggborough located 17 km from hatfield similar temporal changes in moisture content in the sandstone were observed using borehole radar profiles travel times of seasonal wetting fronts through the sandstone at both sites appear to be approximately 2 m per month the retardation of this front propagation in the top 3 m is also common to both sites suggesting that pollutant transport may be principally controlled by near surface sediments the results have important consequences to existing groundwater modelling programmes that are being utilised to predict transfer of agricultural chemicals through the vadose zone

quartz types authigenic and detrital in the upper cretaceous eagle ford formation south texas usa abstract lithologic heterogeneity of the eagle ford formation in south texas arises from mixing of extrabasinal grains of siliciclastic composition with intrabasinal grain assemblages composed dominantly of marine carbonate with a lesser component of biosiliceous debris detrital quartz in particular is derived from both extrabasinal and intrabasinal sources posing a challenge for the use of bulk compositional data for mudrock classification extrabasinal detrital quartz supplied along a major axis of siliciclastic influx the woodbine depositional system of east texas is reduced to a minor part of the grain assemblage in south texas petrographic evidence and point count results indicate that around 85 percent of total quartz in these rocks equal to about 12 6 volume percent is authigenic thus significant quantities of authigenic silica are not restricted to siliceous mudrocks but can be found in carbonate rich mudrocks as well formerly opaline skeletons of radiolaria the dominant source of silica for authigenic quartz precipitation are only poorly preserved by replacements including calcite dolomite pyrite and quartz dissolved silica released by dissolution of radiolarians and perhaps also by volcanic glass dissolution is re precipitated in a variety of forms including matrix dispersed microquartz cement fillings within primary intragranular pores and grain replacement of both calcareous and siliceous allochems the mass balance of dissolved silica mobilized from radiolarians and other reactive silicates and the precipitation of authigenic quartz is uncertain because the initial volumes of now dissolved detrital material versus the final volume of authigenic material quartz and other authigenic silicates cannot be determined with accuracy

study of the hydrogeological characteristics and permeability of the xinli seabed gold mine in laizhou bay jiaodong peninsula china this paper presents a case study investigation into the hydrogeological characteristics and permeability of rock mass in a seabed mine following an introduction to the geology and hydrogeological conditions in the xinli mine area we reveal the features of the preferred structural planes dynamic characteristics of mine water seepage and the permeability of the fractured rock mass in the pit the permeability of the pit rock mass shows varied characteristics at different geotectonic locations because of the different degrees to which the structural planes developed the fractured rock mass generally shows low permeability and the main composition of water seepage is high salinity brine future large scale undersea mining may induce rock mass movement destroy water resistant layers and enhance water transmissibility and the probability of water gushing into the pit thus strengthening the quality of the filling mass protecting the stope roof and the water resistant layers as well as regular monitoring of water seepage discharge and identification of water sources are critical to work safety and the prevention of seawater gushing in the mine

characterization of the mississippian chat in south central kansas to understand production from low resistivity high porosity mississippian chat reservoirs in south central kansas it is necessary to understand the nature of deposition and diagenesis how tectonics is a factor the lithofacies controls on petrophysical properties and log response to these properties the initial mudstones to sponge spicule wacke packstones were deposited in transgressive regressive t r cycles on a shelf to shelf margin setting resulting in a series of shallowing upward cycles sponge spicule content appears to increase upward with increasing cycle thickness after early silicification inter and post mississippian subaerial exposure resulted in further diagenesis including sponge spicule dissolution vuggy porosity development in moldic rich rocks and autobrecciation meteoric water infiltration is limited in depth below the exposure surface and in distance downdip into unaltered cherty cowley formation facies areas of thicker preserved chat and increased diagenesis can be correlated with structural lineaments and in some areas with recurrent basement block movement combination of folding or block fault movement prior to or during development of the basal pennsylvanian unconformity sponge spicule concentration and possibly thickness of overlying bioclastic wacke grainstones resulted in variable reservoir properties and the creation of pods of production separated by nonproductive cherty dolomite mudstones these events also resulted in alteration of the depositional cycles to produce a series of lithofacies that exhibit unique petrophysical properties from bottom to top in a complete cycle seven lithofacies are present 1 argillaceous dolomite mudstone 2 argillaceous dolomite mudstone that has chert nodules 3 clean dolomite mudstone that has nodular chert 4 nodular to bedded chert 5 autoclastic chert 6 autoclastic chert that has clay infill and 7 bioclastic wacke grainstone the uppermost cycle was terminated by another lithofacies a chert conglomerate of mississippian and or pennsylvanian age the chert facies exhibit porosities ranging from 25 to 50 and permeabilities greater than 5 md the begin page 86 cherty dolomite mudstones argillaceous dolomite mudstones and bioclastic wacke grainstones exhibit nonreservoir properties reservoir production numerical simulation and whole core data indicate fracturing can be present in chat reservoirs and can enhance permeability by as much as an order of magnitude capillary pressure data indicate the presence of microporosity and can explain high water saturations and low resistivity observed in wire line logs relative permeabilities to oil decrease rapidly for saturations greater than 60 and may be influenced by dual pore systems archie cementation exponents increase from 1 8 for mudstones to more than 2 5 in the cherts that have increasing sponge spicule mold and vug content detailed modified pickett plot analysis of logs reveals critical aspects of chat character and can provide reliable indices of reservoir properties and pay delineation models developed provide additional insight into the chat of south central kansas and understanding of the nature of controls on shallow shelf chert reservoir properties

challenges and opportunities for fractured rock imaging using 3d cross borehole electrical resistivity abstractthere is an increasing need to characterize discrete fractures away from boreholes to better define fracture distributions and monitor solute transport we performed a 3d evaluation of static and time lapse cross borehole electrical resistivity tomography ert data sets from a limestone quarry in which flow and transport are controlled by a bedding plane feature ten boreholes were discretized using an unstructured tetrahedral mesh and 2d panel measurements were inverted for a 3d distribution of conductivity we evaluated the benefits of 3d versus 2 5d inversion of ert data in fractured rock while including the use of borehole regularization disconnects brds and borehole conductivity constraints high conductivity halos inversion artifacts surrounding boreholes were removed in static images when brds and borehole conductivity constraints were implemented furthermore applying these constraints focused transient changes in conductivity resulting from solute transport on the bedding plane pr

study of shallow groundwater quality evolution under saline intrusion with environmental isotopes and geochemistry evolution of the shallow groundwater quality under saline intrusion in porous aquifer system has been studied with environmental isotopes and geochemistry in the laizhou bay area china two campaigns of water sampling from various sources were carried out in spring and winter for environmental isotopic and chemical analyses the origin of groundwater salinity from intrusion of both modern seawater and deep brine water was identified by analysing the correlations between 18o d t cl so 4 2 and electrical conductivity the results indicate that the brine is originated from evaporating and concentrating of intruded seawater and its d and 18o are different from modern seawater but similar to those of mixture of seawater with fresh groundwater it is hard to distinguish the salinity origin in this area by the d 18o relationship alone the relations between 18o and conductivity cl and so 4 2 have been used to identify the salinity origin due to the distinct difference in salinity between the brine and seawater conjunctively with use of t a threshold of t 12 tu was adopted to identify the origin of saline groundwater