information content of slug tests for estimating hydraulic properties in realistic high conductivity aquifer scenarios summary a recently developed unified model for partially penetrating slug tests in unconfined aquifers malama et al in press provides a semi analytical solution for aquifer response at the wellbore in the presence of inertial effects and wellbore skin and is able to model the full range of responses from overdamped monotonic to underdamped oscillatory while the model provides a unifying framework for realistically analyzing slug tests in aquifers with the ultimate goal of determining aquifer properties such as hydraulic conductivity k and specific storage s s it is currently unclear whether parameters of this model can be well identified without significant prior information and thus what degree of information content can be expected from such slug tests in this paper we examine the information content of slug tests in realistic field scenarios with respect to estimating aquifer properties through analysis of both numerical experiments and field datasets first through numerical experiments using markov chain monte carlo methods for gauging parameter uncertainty and identifiability we find that 1 as noted by previous researchers estimation of aquifer storage parameters using slug test data is highly unreliable and subject to significant uncertainty 2 joint estimation of aquifer and skin parameters contributes to significant uncertainty in both unless prior knowledge is available and 3 similarly without prior information joint estimation of both aquifer radial and vertical conductivity may be unreliable these results have significant implications for the types of information that must be collected prior to slug test analysis in order to obtain reliable aquifer parameter estimates for example plausible estimates of aquifer anisotropy ratios and bounds on wellbore skin k should be obtained if possible a priori secondly through analysis of field data consisting of over 2500 records from partially penetrating slug tests in a heterogeneous highly conductive aquifer we present some general findings that have applicability to slug testing in particular we find that aquifer hydraulic conductivity estimates obtained from larger slug heights tend to be lower on average presumably due to non linear wellbore losses and tend to be less variable presumably due to averaging over larger support volumes supporting the notion that using the smallest slug heights possible to produce measurable water level changes is an important strategy when mapping aquifer heterogeneity finally we present results specific to characterization of the aquifer at the boise hydrogeophysical research site specifically we note that 1 k estimates obtained using a range of different slug heights give similar results generally within 20 2 correlations between estimated k profiles with depth at closely spaced wells suggest that k values obtained from slug tests are representative of actual aquifer heterogeneity and not overly affected by near well media disturbance i e skin 3 geostatistical analysis of k values obtained indicates reasonable correlation lengths for sediments of this type and 4 overall k values obtained do not appear to correlate well with porosity data from previous studies

reflectivity modeling of a ground penetrating radar profile of a saturated fluvial formation major horizons in radar reflection profiles may correlate with contacts between stratigraphic units or with structural breaks such as fault surfaces minor reflections may be caused by clutter or in some cases may indicate material properties or structure within stratigraphic units in this study we examine the physical basis for major and minor reflections observed in a shallow unconfined fluvial aquifer near boise idaho u s a we compare a 2d profile from a surface ground penetrating radar reflection transect with the 1d modeled reflection profiles at three wells adjacent to the surface reflection profile the 1d models are based on dielectric constant and electrical conductivity values from borehole logs and vertical radar profile data reflections at the water table capillary fringe at the base of a sand filled channel and at the base of two sand rich lenses in a cobble dominated unit are recognizable in the surfacereflection profile and in all 1d reflectivity models less prominent reflections in stratigraphic units occur in both the surface profile model and the reflectivity model although such minor reflections are not correlated easily general similarities in their presence and location indicate that sometimes the reflections may be useful for recognizing internal facies structure or character

a bayesian approach for inversion of hydraulic tomographic data 1 hydraulic tomography is a promising methodology that shows the potential to map subsurface hydraulic properties at an unprecedented level of detail by interpreting a suite of hydraulic tests in the present work we apply the hydraulic tomography concept to a multiple pulse multiple receiver mpmr cross well configuration which consists of two boreholes subdivided into intervals by packers a short pressure or flow pulse is applied sequentially to all the intervals and for each perturbation the transient heads are recorded at the remaining intervals the resulting tomograms are inverted within the bayesian framework by using the pilot point approach in addition to the values of the hydraulic conductivity at the pilot points we assume that the stochastic parameters of the spatial variability model the structural parameters are unknown using synthetic two dimensional and three dimensional examples we demonstrate the effectiveness of the mpmr configuration and the inversion procedure for characterizing the spatial variability of the hydraulic conductivity with limited or no prior information we observed that increasing the number of source points the locations at which the pulse is alternatively applied provides more details on the spatial variability and that the parameters of the hydrogeological model of spatial variability are inferred with an acceptable although variable level of accuracy in particular the theoretical variance of the log conductivity is estimated with large errors while the estimate of the anisotropic integral scales depends on the distance between the boreholes inversion preserves the overall spatial pattern of hydraulic conductivity although low conductivity values are less connected in the inferred than in the true conductivity fields

capacitive conductivity logging and electrical stratigraphy in a high resistivity aquifer boise hydrogeophysical research site we tested a prototype capacitive conductivity borehole tool in a shallow unconfined aquifer with coarse unconsolidated sediments and very low conductivity water at the boise hydrogeophysical research site bhrs examining suchahigh resistivitysystemprovidesagoodtestforthecapacitive conductivity tool because the conventional induction conductivity tool known to have limited effectiveness in high resistivity systems did not generate expressive well logs at the bhrs the capacitive conductivity tool demonstrated highly repeatable low noise behavior but poor correlation with the induction tool in the lower conductivity portions of the stratigraphy where the induction tool was relatively unresponsive singular spectrum analysis of capacitive conductivity logs reveals similar vertical length scales ofstructurestoporositylogsatthebhrs also majorstratigraphic units identified with porosity logs are evident in the capacitive conductivity logs however a previously unrecognized subdivision in the upper portion of one of the major stratigraphicunitscanbeidentifiedconsistentlyasarelatively low conductivity body i e an electrostratigraphic unit between the overlying stratigraphic unit and the relatively high conductivity lower portion despite similar porosity and lithology in adjacent units the high repeatability and resolutionandthewidedynamicrangeofthecapacitive conductivity tool are demonstrated here to extend to high resistivity unconsolidatedsedimentaryaquiferenvironments

aquifer heterogeneity characterization with oscillatory pumping sensitivity analysis and imaging potential 1 periodic pumping tests in which a fluid is extracted during half a period then reinjected have been used historically to estimate effective aquifer properties in this work we suggest a modified approach to periodic pumping test analysis in which one uses several periodic pumping signals of different frequencies as stimulation and responses are analyzed through inverse modeling using a steady periodic model formulation we refer to this strategy as multifrequency oscillatory hydraulic imaging oscillating pumping tests have several advantages that have been noted including no net water extraction during testing and robust signal measurement through signal processing through numerical experiments we demonstrate additional distinct advantages that multifrequency stimulations have including 1 drastically reduced computational cost through use of a steady periodic numerical model and 2 full utilization of the aquifer heterogeneity information provided by responses at different frequencies we first perform fully transient numerical modeling for heterogeneous aquifers and show that equivalent results are obtained using a faster steady periodic heterogeneous numerical model of the wave phasor the sensitivities of observed signal response to aquifer heterogeneities are derived using an adjoint state based approach which shows that different frequency stimulations provide complementary information finally we present an example 2 d application in which sinusoidal signals at multiple frequencies are used as a data source and are inverted to obtain estimates of aquifer heterogeneity these analyses show the different heterogeneity information that can be obtained from different stimulation frequencies and that data from several sinusoidal pumping tests can be rapidly inverted using the steady periodic framework

vsp traveltime inversion near surface issues p wave velocity information obtained from vertical seismic profiles vsps can be useful in imaging subsurface structure either by directly detecting changes in the subsurface or as an aid to the interpretation of seismic reflection data in the shallow subsurface p wave velocity can change by nearly an order of magnitude over a short distance so curved rays are needed to accurately model vsp traveltimes we used a curved ray inversion to estimate the velocity profile and the discrepancy principle to estimate the data noise level and to choose the optimum regularization parameter the curved ray routine performed better than a straight ray inversion for synthetic models containing high velocity contrasts the application of the inversion to field data produced a velocity model that agreed well with prior information these results show that curved ray inversion should be used to obtain velocity information from vsps in the shallow subsurface

3 d transient hydraulic tomography in unconfined aquifers with fast drainage response we investigate through numerical experiments the viability of three dimensional transient hydraulic tomography 3dtht for identifying the spatial distribution of groundwater flow parameters primarily hydraulic conductivity k in permeable unconfined aquifers to invert the large amount of transient data collected from 3dtht surveys we utilize an iterative geostatistical inversion strategy in which outer iterations progressively increase the number of data points fitted and inner iterations solve the quasilinear geostatistical formulas of kitanidis in order to base our numerical experiments around realistic scenarios we utilize pumping rates geometries and test lengths similar to those attainable during 3dtht field campaigns performed at the boise hydrogeophysical research site bhrs we also utilize hydrologic parameters that are similar to those observed at the bhrs and in other unconsolidated unconfined fluvial aquifers in addition to estimating k we test the ability of 3dtht to estimate both average storage values specific storage ss and specific yield sy as well as spatial variability in storage coefficients the effects of model conceptualization errors during unconfined 3dtht are investigated including 1 assuming constant storage coefficients during inversion and 2 assuming stationary geostatistical parameter variability overall our findings indicate that estimation of k is slightly degraded if storage parameters must bemore jointly estimated but that this effect is quite small compared with the degradation of estimates due to violation of structural geostatistical assumptions practically we find for our scenarios that assuming constant storage values during inversion does not appear to have a significant effect on k estimates or uncertainty bounds less

a field assessment of high resolution aquifer characterization based on hydraulic travel time and hydraulic attenuation tomography 1 in this study the potential of an inversion approach based on hydraulic travel time and hydraulic attenuation tomography was assessed both hydraulic travel time and hydraulic attenuation tomography are based on the transformation of the transient groundwater flow equation into the eikonal equation using an asymptotic approach the eikonal equation allows the calculation of pressure propagation and attenuation along trajectories which is computationally efficient the attenuation and travel time based inversion approaches are naturally complementary hydraulic travel times are determined by the hydraulic diffusivity a combination of hydraulic conductivity and specific storage whereas the attenuation is determined solely by specific storage the potential of our hydraulic tomographical approach was investigated at a well characterized sand and gravel aquifer located in the leine river valley near gottingen germany the database for the hydraulic inversion consists of 392 cross well slug interference tests performed between five wells in which the positions of the sources injection ports and the receivers observation ports isolated with double packer systems were varied between tests the results have shown that the combination of hydraulic travel time and hydraulic attenuation tomography allows the reconstruction of the diffusivity and storage distribution in two and three dimensions with a resolution and accuracy superior to that possible with type curve analysis

characterization of aquifer heterogeneity using transient hydraulic tomography 1 hydraulic tomography is a cost effective technique for characterizing the heterogeneity of hydraulic parameters in the subsurface during hydraulic tomography surveys a large number of hydraulic heads i e aquifer responses are collected from a series of pumping or injection tests in an aquifer these responses are then used to interpret the spatial distribution of hydraulic parameters of the aquifer using inverse modeling in this study we developed an efficient sequential successive linear estimator ssle for interpreting data from transient hydraulic tomography to estimate three dimensional hydraulic conductivity and specific storage fields of aquifers we first explored this estimator for transient hydraulic tomography in a hypothetical one dimensional aquifer results show that during a pumping test transient heads are highly correlated with specific storage at early time but with hydraulic conductivity at late time therefore reliable estimates of both hydraulic conductivity and specific storage must exploit the head data at both early and late times our study also shows that the transient heads are highly correlated over time implying only infrequent head measurements are needed during the estimation applying this sampling strategy to a well posed problem we show that our ssle can produce accurate estimates of both hydraulic conductivity and specific storage fields the benefit of hydraulic tomography for ill posed problems is then demonstrated finally to affirm the robustness of our ssle approach we apply the ssle approach to a hypothetical three dimensional heterogeneous aquifer

hydraulic conductivity imaging from 3 d transient hydraulic tomography at several pumping observation densities 1 3 d hydraulic tomography 3 d ht is a method for aquifer characterization whereby the 3 d spatial distribution of aquifer flow parameters primarily hydraulic conductivity k is estimated by joint inversion of head change data from multiple partially penetrating pumping tests while performance of 3 d ht has been studied extensively in numerical experiments few field studies have demonstrated the real world performance of 3 d ht here we report on a 3 d transient hydraulic tomography 3 d tht field experiment at the boise hydrogeophysical research site which is different from prior approaches in that it represents a baseline analysis of 3 d tht performance using only a single arrangement of a central pumping well and five observation wells with nearly complete pumping and observation coverage at 1 m intervals we jointly analyze all pumping tests using a geostatistical approach based on the quasi linear estimator of kitanidis 1995 we reanalyze the system after progressively removing pumping and or observation intervals significant progressive loss of information about heterogeneity is quantified as reduced variance of the k field overall reduced correlation with slug test k estimates at wells and reduced ability to accurately predict independent pumping tests we verify that imaging accuracy is strongly improved by pumping and observational densities comparable to the aquifer heterogeneity geostatistical correlation lengths discrepancies between k profiles at wells as obtained from ht and slug tests are greatest at the tops and bottoms of wells where ht observation coverage was lacking

field laboratory and modeling investigation of the skin effect at wells with slotted casing boise hydrogeophysical research site understanding and quantification of wellbore skin improves our ability to accurately measure or estimate hydrologic parameters with tests at wells such as pumping tests flowmeter tests and slug tests this paper presents observations and results from a series of field laboratory and modeling tests which together explain the source of wellbore skin at wells at a research wellfield and which support estimation of skin thickness ds and skin hydraulic conductivity ks positive wellbore skin effects were recognized at wells in the shallow unconfined coarse grained fluvial aquifer at the boise hydrogeophysical research site bhrs well development efforts at the bhrs removed residual drilling fines but only marginally reduced the skin effect likely causes for the remaining wellbore skin effect were examined partial clogging of screen slots with sand is consistent with field observations and can account for the magnitude of wellbore skin effect observed we then use the wtaq code barlow and moench 1999 with a redefinition of the term for delayed observation well response to include skin effects at observation wells in addition to pumping wells in order to analyze aquifer tests at the bhrs for average ks values at individual wells systematic differences in ks values are recognized in results at pumping ks q and observation ks obs wells larger values are seen at observation wells average ks obsz0 0023 cm s than pumping wells two possible causes are recognized for the occurrence of higher ks values at observation wells than pumping wells 1 flow diversion between aquifer layers on approach to a pumping well with positive skin and 2 larger portion offlow passing through lower k zones in the heterogeneous aquifer near the pumping well than the observation wells due to strongly radially convergent flow near the pumping well for the wellaquifer system at the bhrs modeling analyses of drawdown vs time at observation wells provide better ks estimates than those from pumping wells q 2005 elsevier b v all rights reserved

the impact of horizontal model grid resolution on the boundary layer structure over an idealized valley abstractthe role of horizontal model grid resolution on the development of the daytime boundary layer over mountainous terrain is studied a simple idealized valley topography with a cross valley width of 20 km a valley depth of 1 5 km and a constant surface heat flux forcing is used to generate upslope flows in a warming valley boundary layer the goal of this study is to investigate differences in the boundary layer structure of the valley when its topography is either fully resolved smoothed or not resolved by the numerical model this is done by performing both large eddy les and kilometer scale simulations with horizontal mesh sizes of 50 1000 2000 4000 5000 and 10 000 m in les mode a valley inversion layer develops which separates two vertically stacked circulation cells in an upper and lower boundary layer these structures weaken with decreasing horizontal model grid resolution and change to a convective boundary layer over an elevated plain when the valley is no longer resolved mean

investigating the stratigraphy of an alluvial aquifer using crosswell seismic traveltime tomography in this study we investigate the use of crosswell p wave seismic tomography to obtain spatially extensive information about subsurface sedimentary architecture and heterogeneity in alluvial aquifers our field site was a research wellfield in an unconfined aquifer near boise idaho the aquifer consists of a 20 m thick sequence of alluvial cobble and sand deposits which have been subdivided into five stratigraphic units based on neutron porosity logs grainsize analysis and radar reflection data we collected crosswell and borehole to surface seismic data in wells 17 1 m apart we carefully considered the impact of well deviation data quality control and the choice of inversion parameters our linearized inverse routine had a curved ray forward model and used different grids for forward modeling and inversion an analysis of the model covariance and resolution matrices showed that the velocity models had an uncertainty of 10 m s a vertical resolution of 1 m and a horizontal resolution of 5 m the velocity in the saturated zone varied between 2100 m s and 2700 m s inclusion of the borehole to surface data eliminated the xshaped pattern that is a common artifact in crosswell tomography and the increased angular coverage also improved the accuracy of the model near the top of the tomogram the final velocity model is consistent with previous stratigraphic analyses of the site although the locations of some of the unit boundaries differ by as much as 2 m in places the results of this study demonstrate that seismic tomography can be used to image the sedimentary architecture of unconsolidated alluvial aquifers even when the lithologic contrasts between units are subtle

field study of dispersion in a heterogeneous aquifer 3 geostatistical analysis of hydraulic conductivity observations of the spatial variability of hydraulic conductivity at a tracer test site located at columbus air force base in mississippi are presented direct measurements of hydraulic conductivity of the heterogeneous alluvial aquifer at the site were made using borehole flowmeter logging slug tests and a laboratory permeameter to test undisturbed soil cores indirect methods estimating hydraulic conductivity were also evaluated including soil grain size analyses surface geophysical surveys and mapping of sediment facies the spatial covariance of the 2187 hydraulic conductivity values obtained with the borehole flowmeter method was examined the log hydraulic conductivity variance ln2k and the horizontal and vertical correlation scales h and v of 4 5 12 8 m and 1 6 m respectively were estimated assuming second order stationarity of the conductivity field the covariance parameters are uncertain with bounding values that are 24 76 above or below the estimate covariance parameters estimated with more limited nonflowmeter data were within the same magnitude as those obtained using the extensive flowmeter data suggesting that data from a variety of methods may be used to provide approximate values of the autocovariance parameters nonstationarity of the ln k field was examined by removing three dimensional polynomial trend surfaces and calculating variograms of the residuals significantly lower estimates for ln2k h and v of 2 7 4 8 m and 0 8 m respectively were obtained from the third order log conductivity residuals after trend removal the bounding parameter values differ 15 44 from the estimated values accounting for unsteady flow and the uncertainty in the covariance parameters of the third order log conductivity residuals the calculated longitudinal and horizontal transverse macrodispersivities ranged from 1 5 m to 1 8 m and 0 3 m to 0 6 m respectively

traveltime inversion of vertical radar profiles traveltimes of direct arrivals in vertical radar profiles vrps are tomographically inverted to estimate the earth s electromagnetic em velocity between a surface transmitter and a downhole receiver we determine the 1d interval velocity model that best fits the first arrival traveltimes by using a weighted damped least squares inversion scheme we assess the accuracy of the velocity model using synthetic traveltimes from a known velocity distribution model simulating an unconfined aquifer the inverted velocity profile closely matched the velocity profile of the input model in the synthetic examples using vertical radar profile data from an unconfined aquifer near boise idaho we inverted traveltimes to obtain velocity estimates at the well location the velocity change at a depth of 2 0 m corresponds well with the measured depth to the water table of 1 95 m and at depths between 2 and 18 m the velocities ranged between 0 06 and 0 1 m ns our estimates approximately match the velocity distribution determined from neutron derived porosity logs at depths greater than about 2 m an important function of inverse methods is to assess quantitatively and qualitatively the uncertainty of inverted velocity estimates we note that the velocity values in the upper and lower parts of the inverted model are not as well constrained compared to those between the depths of 4 and 13 m from the model resolution and model covariance matrices of the real data inversion we determine theuncertainty in ourvelocity model leading to more reliable interpretations of the subsurface

improving crosshole radar velocity tomograms a new approach to incorporating high angle traveltime data to obtain the highest resolution ray based tomographic images from crosshole ground penetrating radar gpr data wide angular ray coverage of the region between the two boreholes is required unfortunately at borehole spacings on the order of a few meters high angle traveltime data i e traveltime data corresponding to transmitter receiver angles greater than approximately 50 from the horizontal are notoriously difficult to incorporate into crosshole gpr inversions this is because 1 low signal to noise ratios make the accurate picking of first arrival times at high angles extremely difficult and 2 significant tomographic artifacts commonly appear when high and low angle ray data are inverted together we address and overcome thesetwo issues for a crosshole gpr data example collected at the boise hydrogeophysical research site bhrs to estimate first arrival times on noisy high angle gathers we develop a robust and automatic picking strategy based on crosscorrelations where reference wav

application of a new 2d time domain full waveform inversion scheme to crosshole radar data crosshole radar tomography is a useful tool in diverse investigations in geology hydrogeology and engineering conventional tomograms provided by standard ray based techniques have limited resolution primarily because only a fraction of the information contained in the radar data i e thefirst arrivaltimesandmaximumfirst cycleamplitudesis included in the inversion to increase the resolution of radar tomograms wehavedevelopedaversatilefull waveforminversion scheme that is based on a finite difference time domain solution of maxwell s equations this scheme largely accountsforthe3dnatureofradar wavepropagationandincludes an efficient method for extracting the source wavelet from the radar data after demonstrating the potential of the newschemeontworealisticsyntheticdatasets weapplyitto two crosshole field data sets acquired in very different geologic hydrogeologic environments these are the first applications of full waveform tomography to observed crosshole radar data the resolution of all full waveform tomograms is showntobemarkedlysuperiortothatoftheassociatedraytomograms small subsurface features a fraction of the dominant radar wavelength and boundaries between distinct geological hydrological units are sharply imaged in the fullwaveformtomograms

hierarchical geostatistics and multifacies systems boise hydrogeophysical research site boise idaho 1 the geostatistical structure of a heterogeneous coarse fluvial aquifer is investigated with porosity data derived from neutron logs at a research well field boise hydrogeophysical research site or bhrs that was designed in part to support three dimensional geostatistical analysis of hydrologic and geophysical parameters recognizing that the coarse fluvial deposits include subdivisions units between bounding surfaces we adopt a hierarchical approach and examine the porosity geostatistics of the aquifer at three scales at the bhrs the saturated fluvial deposits as a whole maximum interwell spacing 80 m thickness 16 18 m are at hierarchical level 1 five subhorizontal units within these deposits four cobble dominated units and a channel sand can be traced across the central area of the bhrs and are at hierarchical level 2 and subunits patches or lenses in one of the level 2 units unit 4 are at hierarchical level 3 we use variography and porosity statistics to recognize nonstationarity at hierarchical level 1 and in one of the level 2 units unit 4 where the means and variances of porosity differences as a function of lag are not constant between distinct units and subunits respectively the geostatistical structure at level 1 is modeled with different horizontal and vertical structures that have different sills vertical sill greater than horizontal sill the difference in sills can be explained quantitatively by the summing of weighted sills from all individual units and combined units i e a given pair of different units where the weights are the proportions of data pairs contributing to the sills at each lag from the individual and combined units extension of this analysis leads to a weighted multistructure form of the variogram function whereby a global experimental variogram in a hierarchical system can be decomposed quantitatively into weighted component individual and combined unit or facies structures for any number of units or hierarchical levels such decomposition of the global horizontal variogram from the bhrs indicates that short range periodicity in that structure is due to both 1 combined unit structures associated with patches or lenses at hierarchical level 3 in unit 4 and 2 variations in thickness of unit 2 for hierarchical multifacies systems structure models fit to global horizontal and vertical experimental variograms may not be useful for subsequent stochastic modeling if the system on which the structure models are based is nonstationary

transport modeling in heterogeneous aquifers 1 statistical description and numerical generation of gravel deposits transport of solutes in groundwater is decisively influenced by the heterogeneity of the aquifer the goal of the present work is the numerical generation of synthetic heterogeneous aquifer models based on a statistical description of heterogeneities in gravel aquifers large unweathered outcrops in several gravel pits in northeastern switzerland were investigated in this context on the basis of sedimentological observations it was possible to specify distinct sedimentary structures appearing as lenses or layers all structures have been identified in each of the investigated outcrops by inspecting and analyzing photographs of the outcrops it was possible to estimate the probability density functions pdf of the geometrical attributes of the sedimentary structures disturbed and undisturbed samples were taken from these structures to estimate the pdf of their hydraulic properties that is the hydraulic conductivity and the porosity the information obtained is used to generate distinct numerical realizations by unconditional stochastic simulation of synthetic aquifers having the same statistical properties with respect to hydraulic conductivity and porosity as the investigated deposits

estimating porosity with ground penetrating radar reflection tomography a controlled 3 d experiment at the boise hydrogeophysical research site 1 to evaluate the uncertainty of water saturated sediment velocity and porosity estimates derived from surface based ground penetrating radar reflection tomography we conducted a controlled field experiment at the boise hydrogeophysical research site bhrs the bhrs is an experimental well field located near boise idaho the experimental data set consisted of 3 d multioffset radar acquired on an orthogonal 20 30 m surface grid that encompassed a set of 13 boreholes experimental control included 1 1 d vertical velocity functions determined from traveltime inversion of vertical radar profiles vrp and 2 neutron porosity logs we estimated the porosity distribution in the saturated zone using both the topp and complex refractive index method crim equations and found the crim estimates in better agreement with the neutron logs we found that when averaged over the length of the borehole surface derived velocity measurements were within 5 of the vrp velocities and that the porosity differed from the neutron log by less than 0 05 the uncertainty however is scale dependent we found that the standard deviation of differences between ground penetrating radar derived and neutron log derived porosity values was as high as 0 06 at an averaging length of 0 25 m but decreased to less than 0 02 at length scale of 11 m additionally we used the 3 d porosity distribution to identify a relatively high porosity anomaly i e local sedimentary body within a lower porosity unit and verified the presence of the anomaly using the neutron porosity logs since the reflection tomography approach requires only surface data it can provide rapid assessment of bulk hydrologic properties identify meter scale anomalies of hydrologic significance and may provide input for other higher resolution measurement methods

mixing behavior in quaternary garnet solid solution and an extended ellis and green garnet clinopyroxene geothermometer applications of the different formulations of garnet clinopyroxene geothermometers to crustal granulites and particularly to metamorphosed manganese formations show a wide scatter of estimates this is primarily related to the uncertainty associated with the formulation of the activity composition relationship in garnet solid solution besides that in the clinopyroxene solid solution the largest uncertainty appears to have resulted from the adopted mg mn interaction parameter in garnet which is yet to be experimentally determined a fresh statistical regression of eleven pairs of garnet and clinopyroxene equilibrated at identical p t conditions from a manganese formation in india yields wmg mngt wmn mg value of 1600 500 cal mols an extension of the ellis and green 1979 geothermometer known to work well in normal granulites incorporating terms associated with the activity coefficients of the exchangeable cations now yields consistent temperature estimation from normal granulites as well as from metamorphosed manganese formations the geothermometer however will not work well for garnet having xfe 0 65 and clinopyroxenes containing appreciable na al and or fe3

significance of porosity for stratigraphy and textural composition in subsurface coarse fluvial deposits boise hydrogeophysical research site recognition and quantitative characterization of subsurface stratigraphic units in coarse unconsolidated fluvial deposits are difficult because large grain size and the large scale of sedimentary structures make direct interpretation from core difficult or impossible in this paper we use porosity data from well logs and grain size distribution gsd data from core to investigate four pebble and cobble dominated units that have been identified in porosity logs in deposits at a research well field boise hydrogeophysical research site lacking direct observation at an appropriate scale questions about distribution of parameters and textural composition in these units are analyzed with statistical tests the four pebble and cobble dominated porosity stratigraphic units may be grouped into two types 1 units 1 and 3 have low porosity mean 0 17 0 18 and low porosity variance and 2 units 2 and 4 have higher porosity mean 0 23 0 24 and higher porosity variance based on gsd data core samples are subdivided into five lithotypes the five lithotypes occur in different proportions and have different vertical transition probability characteristics in the two types of units 1 units 1 and 3 have only framework gravel dominated lithotypes and have random vertical transition probability between these two lithotypes and 2 units 2 and 4 consist of both framework gravel dominated and sand or matrix dominated lithotypes and have structured vertical transition probability the two framework gravel dominated lithotypes occur in all four stratigraphic units but have distinctly lower porosity in units 1 and 3 i e tighter packing than in units 2 and 4 looser packing considering the repeated stratigraphic occurrence of and the statistical significance of differences between the two types of units both the individual unit distinctions and the two unit groupings appear to be valid it is reasonable to interpret that the observed packing differences associated with units 1 and 3 compared with units 2 and 4 are related to different sedimentary processes that produce different bedforms or grain fabrics perhaps under different bedload transport rates

large scale natural gradient tracer test in sand and gravel cape cod massachusetts 3 hydraulic conductivity variability and calculated macrodispersivities hydraulic conductivity k variability in a sand and gravel aquifer on cape cod massachusetts was measured and subsequently used in stochastic transport theories to estimate macrodispersivities nearly 1500 k measurements were obtained by borehole flowmeter tests and permeameter analyses of cores the geometric mean for the flowmeter tests 0 11 cm s is similar to that estimated from other field tests the mean for the permeameter tests 0 035 cm s is significantly lower possibly because of compaction of the cores the variance for the flowmeter 0 24 is also greater than that for the permeameter 0 14 geostatistical analyses applying negative exponential models with and without nuggets reveal similar spatial correlation structures for the two data sets estimated correlation scales range from 2 9 to 8 m in the horizontal and from 0 18 to 0 38 m in the vertical estimates of asymptotic longitudinal dispersivity b 35 0 78 m are similar in magnitude to that observed in the natural gradient tracer test 0 96 m previously conducted at this site