glaciological applications with landsat 7 imagery early assessments enhanced thematic mapper plus etm data from landsat 7 are providing glaciologists with an ever expanding data set that makes a comprehensive monitoring of the global cryosphere feasible for the first time in history examples of etm data illustrate its ability to satisfy major scientific needs in the glaciological subdisciplines of sea ice glacier ice cap and ice sheet research with high resolution optical satellite imagery examples shown include use as proxy ground truth positioning glacier termini and snowlines and determining snow facies boundaries the additional etm panchromatic band at a higher spatial resolution of 15 m improves the spatial accuracy of these applications the glaciological aspects of the landsat 7 long term acquisition plan are discussed to show how the timing and location of the image acquisitions will generate a cryospheric data set of unprecedented utility for future research

active and passive microwave signatures of antarctic firn by means of field measurements and satellite data the angular dependence and polarization behaviour of back scattering and emission of polar firn at 5 2 ghz and 10 3 ghz were measured during an oversnow traverse in dronning maud land antarctica the signatures emphasize the importance of snow stratification in the interpretation of microwave remote sensing measurements highest backscattering coefficients and little angular variations were observed for refrozen firn near the coast in permanently dry snow areas with high accumulation rates and homogeneous snow morphology showed low backscattering coefficients and high emissivities pronounced layering and related density variations in low accumulation zones resulted in increased polarization differences of brightness temperatures and increased like polarized backscattering coefficients this behaviour is confirmed by the analysis of c band scatterometer measurements of the active microwave instrument aboard the european space agency s ers 1

evaluation of single well injection withdrawal tests in swedish crystalline rock using the lagrangian travel time approach a series of 10 single well injection withdrawal swiw tests are evaluated with two tracers each uranine and cesium cs an evaluation tool for swiw tests in crystalline rock is presented on the

the reflectance of rough snow surfaces in antarctica from polder adeos remote sensing data the polder polarization and directionality of the earth s reflectances sensor was launched onboard the japanese adeos satellite in august 1996 it measured the energy reflected by the earth in the solar spectrum at 8 wavelengths from this sensor an earth target could be seen up to 14 times along a single path providing a good characterization of the brdf bidirectional reflectance distribution function from space a set of one month of polder data over east antarctica was analyzed after cloud masking and atmospheric corrections mean brdfs were derived for different areas in some parts of the ice sheet the brdf is assymetric with a strong reflectance peak in the half space oriented towards the sun backscatter this peak is due to the anisotropic roughness of the surface sastrugi and its position depends on the sastrugi direction

effect of surface roughness on bidirectional reflectance of antarctic snow the angular pattern of sunlight reflected by snow is altered by surface roughness which in the interior of antarctica is usually in the form of meter scale longitudinal erosional features sastrugi whose axes align with the direction of strong winds the bidirectional reflectance distribution function brdf changes over the course of a day as the solar azimuth changes relative to the sastrugi axis the normalized brdf or anisotropic reflectance factor r was measured at south pole station from a 22 m tower at 600 660 and 900 nm wavelengths the r pattern was similar at the three wavelengths it probably varies little from 300 to 900 nm measurements were made at solar zenith angles 0 from 67 to 90 over the full range of viewing zenith angle r azimuth angle between sun and view and azimuth angle between sun and sastrugi sas variation of r with sas was notable sastrugi oriented perpendicular to the solar beam cause a reduction of the forward peak and sastrugi at an oblique angle cause r to lose its symmetry about the solar azimuth however the effects of sastrugi are mostly restricted to large viewing zenith angles so remote sensing of albedo and atmospheric properties can be carried out accurately without knowledge of sastrugi height and orientation if only near nadir views are used this recommendation is opposite that for observations of broken clouds over dark surfaces for which large r is preferred a parameterization of r is developed valid for viewing angles r 50 sastrugi can cause a reduction of the snow albedo by altering the angle of incidence and by trapping of photons for the small sastrugi of the antarctic plateau the albedo is unaffected at visible wavelengths but can be reduced by a few percent at near infrared wavelengths when the sun is low

the confluence zone of the intense katabatic winds at terra nova bay antarctica as derived from airborne sastrugi surveys and mesoscale numerical modeling the surface wind field inland of the intense coastal kataba c wind regime at terra nova bay antarctica has been studied both observationally and numerically airborne surveys of windinduced features on the snow surface have been used to construct the time averaged winter surface airflow pattern the surface motion field has also been simulated by a mesoscale primitive equation model using terrain slopes with a horizontal resolution of 32 km both methods of analys s demonstrate that the intense katabatic airstream at terra nova bay is forced by converging air currents in the continental interior the broadscale confluence zone becomes organized into two regions within about 180 km of the coast the primary route for katabatic mass transport into the terra nova bay area is reeves glacier valley but an important secondary source is provided by airflow down david glacier the former is generated by the coriolis induced concentration of mass transport on the left side looking downwind of the broadscale confluence zone as well as by the near coastal mountain deflection of airflow into the valley head the confluence zone feeding into david glacier valley stretches over 100 km into the interior and is forced by the broadscale terrain configuration of the ice sheet source areas for the two airstreams differ with reeves glacier valley being fed by cold air formed well into the interior whereas the airflow down david glacier is sustained by radiative cooling over lower parts of the ice sheet which are much closer to the ross sea evaluation of the observational and modeling results reveals both the strengths and weaknesses of each approach airborne surveys of sastrugi orientations are a highly successful method for establishing the detailed pattern of surface airflow however a systematic examination of sastrugi dimensions suggests that such work could also be carried out using spot type satellite observations which is a more cost effective approach than aircraft surveying the double jet structure of katabatic airflow into the terra nova bay area is well represented by the primitive equation modeling but much finer grids are needed to resolve the near coastal drainage details

a particle based conditional sampling scheme for the simulation of transport in fractured rock with diffusion into stagnant water and rock matrix in situ experiments and field scale characterization studies have pointed out that in fractured crystalline media groundwater flow is highly channelized this implies that at the scale of a sing

models for the assessment of transport of naturally occurring nuclides in fractured media abstract in fractured media naturally occurring nuclides are produced by the decay of the natural uranium and thorium present in the rock matrix back diffusion from the matrix into the water bearing fractures and advection along these fractures leads to nuclide concentration values that are representative of groundwater flow and transport processes hence interpretation of measured levels of naturally occurring nuclides might provide valuable information about these underlying processes here we have provided mathematical models for the simulation of generation and transport of naturally occurring nuclides in fractured media the proposed analytical solutions have been applied to study 4 he generation and migration in realistic transport pathways the results of these simulations have shown that in fractured crystalline media steady state conditions are attained after thousands to tens of thousands of years one of the developed analytical solution have also been used to infer typical values of transport resistance i e the ratio between the groundwater residence time and the fracture half aperture in the shallow bedrock at olkiluoto finland the results of this analysis have pointed out the very strong retention capacity of the considered fractured system

integrated method of rs and gpr for monitoring the changes in the soil moisture and groundwater environment due to underground coal mining mining affects the environment in different ways depending on the physical context in which the mining occurs in mining areas with an arid environment mining affects plants growth by changing the amount of available water this paper discusses the effects of mining on two important determinants of plant growth soil moisture and groundwater table gwt which were investigated using an integrated approach involving a field sampling investigation with remote sensing rs and ground penetrating radar gpr to calculate and map the distribution of soil moisture for a target area we initially analyzed four models for regression analysis between soil moisture and apparent thermal inertia and finally selected a linear model for modeling the soil moisture at a depth 10 cm the relative error of the modeled soil moisture was about 6 3 and correlation coefficient 0 7794 a comparison of mined and unmined areas based on the results of limited field sampling tests or rs monitoring of landsat 5 thermatic mapping tm data indicated that soil moisture did not undergo remarkable changes following mining this result indicates that mining does not have an effect on soil moisture in the shendong coal mining area the coverage of vegetation in 2005 was compared with that in 1995 by means of the normalized difference vegetation index ndvi deduced from tm data and the results showed that the coverage of vegetation in shendong coal mining area has improved greatly since 1995 because of policy input rmb 0 4 per ton coal production by shendong coal mining company the factor most affected by coal mining was gwt which dropped from a depth of 35 41 m before mining to a depth of 43 38 m after mining at the bulianta coal mine based on water well measurements ground penetrating radar at frequencies of 25 and 50 mhz revealed that the deepest gwt was at about 43 4 m there was a weak water linkage between the unsaturated zone and groundwater and the decline of water table primarily resulted from the well pumping for mining safety rather than the movement of cracking strata this result is in agreement with the measurements of the water wells the roots of nine typical plants in the study area were investigated populus was found to have the deepest root system with a depth of about 26 m based on an assessment of plant growth demands and the effect of mining on environmental factors we concluded that mining will have less of an effect on plant growth at those sites where the primary gwt depth before mining was deep enough to be unavailable to plants if the primary gwt was available for plant growth before mining especially to those plants with deeper roots mining will have a significant effect on the growth of plants and the mechanism of this effect will include the loss of water to roots and damage to the root system

monitoring ice sheet behavior from space satellite remote sensing has revolutionized ice sheet research a variety of instruments sensitive to different parts of the electromagnetic spectrum take what the human eye detects as a flat white desert and provide data sets rich in scientific information image based maps of ice sheets are becoming commonplace and have become an integral component of field work more than a pretty picture the digital character of the satellite data from these instruments has become fundamental to the production of elevation motion accumulation and reflectance data sets visible imagery shows the scientist a wealth of features that offer clues to the history and current behavior of the ice sheet radar and microwave imagery provide information from beneath the surface and have been used to estimate snow accumulation rates interferometry principles have recently been applied to measure surface topography and ice motion with unparalleled precision nonimaging instruments also keep a watchful eye monitoring the ice sheet for indications of growth or shrinkage further expansion of the uses of satellite data is anticipated in the future

investigations into the factors influencing long range matrix diffusion rates and pore space accessibility at depth in granite abstract investigations in granite systems have been conducted on 1 diffusion through fissure surfaces 2 the effect of confining pressures on diffusion rates 3 the extent of pore interconnectivity over metre distances and 4 the accessiblity of the pore space to colloidal particles in the size range 0 3 0 09 m diffusion rates through fissure surfaces were found to be greater than or equal to those measured on samples taken well away from such surfaces no evidence for pore blocking by alteration products was found confining pressures of up to 16 mpa reduced diffusion rates at the highest pressures reductions by factors of between 2 and 2 5 compared with diffusion rates measured at ambient pressure were recorded pore connectivity over distances of up to 125 cm on granite cores saturated with 3 m nacl was demonstrated by the measurement of formation factors as a function of core length using a conductivity technique increases in the formation factor for short core lengths 1 cm were ascribed to sample size and pore geometry effects which converted some of the dead end porosity into transport porosity colloidal particles in the size range investigated neither entered the pore structure nor blocked pore apertures to any significant extent

sorbing tracer experiments in a crystalline rock fracture at aspo sweden 3 effect of microscale heterogeneity we study the impact of microscale 10 3 10 2 m heterogeneity in material and structural properties on sorbing tracer transport in a single crystalline fracture of the true 1 tests mesoscale

sorbing tracer experiments in a crystalline rock fracture at aspo sweden 2 transport model and effective parameter estimation 1 transport and retention of sorbing tracers in a single altered crystalline rock fracture on a 5 m scale is investigated we evaluate the results of a comprehensive field study referred to as

joint application of satellite remote sensing ground penetrating radar gpr and resistivity techniques for targeting ground water in fractured ophiolites of south andaman island india the ophiolitic complex of the study area oriented in n s direction having moderate to steep slopes of the topography and characterized by strong heterogeneity repetitive deformations and multiple intrusions ophiolites of the study area encompass the major groundwater bearing zones generally these formations have shallower fractured aquifers of a thickness 30 45 m and sometimes due to deep tensile fractures the thickness of aquifer exceeds more than 60 m with a considerable groundwater yield a joint venture of satellite remote sensing geoelectrical resistivity and ground penetrating radar gpr techniques has been used to assess the groundwater potential of the fractured ophiolites the interpreted resistivity inversion model and gpr results were incorporated with borehole lithologs for their subsurface properties and structural variations the integration of using multiple techniques has increased the accuracy of interpretation and thus conflated results significantly rendered the existence of weathered and fractured zone having hydrogeological importance based on the parameters viz geoelectrical properties of layers reflection configuration thickness of weathered and fractured aquifer zone a typical aquifer model for the study area that contains various layers and subtle structural variation has been developed further the derived integrated geophysical data also detail on various lithological characteristics and advances the understanding about aquifer systems of fractured ophiolites and the distribution of groundwater in fractures

clear sky albedo measurements on a sloping glacier surface a case study in the bolivian andes an important potential source of error in snow albedo measurements under clear sky is the tilt of the surface when the sensors are placed parallel to the horizon the error depends on the surface slope and aspect a hemispherical radiation sensor receives its signal from within a surface area of several square meters which generally is not a plane here we examined the influence of slope and aspect combinations related to surface irregularities on albedo measurements at two locations on the zongo glacier bolivia the slope and aspect distributions determined through topographic measurements were used to correct the albedo measurements the corrections were different between the two sites but resulted in similar albedo changes the substantial albedo reductions observed from morning until evening were measurement artifacts even for slight slopes an error of a few degrees on the slope estimation or an error of roughly 20 on the aspect estimation had an appreciable influence on the corrections if the topography around the measurement site is not precisely known the most reliable method for determining the daily albedo is to observe the measurements around solar noon corrected albedo diurnal variations were low and symmetrical centered on a minimum at noon during the dry season the southern hemisphere winter the diurnal fluctuations of the snow albedo on the zongo glacier seem to be controlled by the incidence angle cycle of solar radiation

a method for monitoring glacier mass balance using satellite albedo measurements application to vatnajskull iceland we compare satellite albedo images of vatnajokull iceland with mass balance measurements for the years 1991 99 we find that the equilibrium line is mostly not visible when it is located above its position of the previous year s equilibrium line detection is further hindered by clouds and a gradual transition between ice and firn or snow consequently firn line elevation at the end of the melting season is not particularly useful for estimating the annual mass balance instead we propose to study the mean albedo of the entire ice cap throughout the melting season so that all available information about the surface albedo is taken into account the mean net potential global radiation which can be estimated from the mean surface albedo alone both depends on and influences summer melt it also depends on winter precipitation and integrated over the melting season is found to relate linearly to the specific mass balance b r 0 87 and 0 94 for different outlets of vatnajokull b can be estimated quantitatively when this relation is known and qualitatively when it is not the uncertainty in the satellite derived value of b is 0 5 0 8 m w e which for vatnajokull corresponds to about 27 of the interannual variability of b

glaciological studies at siple station antarctica potential ice core paleoclimatic record the quality and utility of the records of oxygen isotopic abundances dust concentrations and anionic concentrations preserved in the ice at siple station 75 55 s 84 15 w are assessed from four shallow 20 m cores the combination of high accumulation 0 56 m a 1 w e and low mean annual temperature 24 c preserves the prominent seasonal variations in 18 which are very spatially coherent sulfate concentrations vary seasonally and in conjunction with 18 will allow accurate dating of deeper cores from siple station the concentrations of insoluble dust are the lowest measured in antarctica making siple station an excellent location to examine large increases in atmospheric tubidity the seasonal variations and annual fluxes of the anions are examined for the last two decades ad 1966 85 with regard to probable sources an unusually high sulfate flux in 1976 may reflect the february 1975 eruption of mount ngauruhoe new zealand no annual signal in nitrate concentration is confirmed and no unusually high nitrate fluxes support the suggestion of nitrate production by large solar flares however nitrate flux is higher for the latter half of the 1970s and early 1980s possibly reflecting the recent loss of stratospheric ozone finally comparison of the 18 o record with available surface temperature data ad 1957 85 reveals that multi year trends along the western coast of the antarctic peninsula are recorded at siple more importantly comparison with areally weighted temperature reconstructions suggests that the 18 record may reflect larger scale persistent trends in the high southern latitudes the strong spatial coherence of the preserved records the potential for accurate dating and possible relevance to larger scale processes make siple station an excellent site for paleoenvironmental reconstruction from ice cores

development and validation of a snow albedo algorithm for the modis instrument a prototype snow albedo algorithm has been developed for the moderate resolution imaging spectroradiometer modis it complements existing modis products by providing albedo measurements for areas mapped as snow on a global daily basis by modis cloud detection and atmospheric correction are accomplished using existing modis products models of the bidirectional reflectance of snow created using a discrete ordinate radiative transfer disort model are used to correct for anisotropic scattering effects over non forested surfaces initial algorithm validation is undertaken through comparisons with broadband albedo measurements made at the u s national oceanic and atmospheric administration noaa surface radiation budget network surfrad site in fort peck mt in situ surfrad albedo measurements are compared to daily modis snow albedo retrievals for the period 21 26 november 2000 created from five narrow to broadband albedo conversion schemes the prototype modis algorithm produces reasonable broadband albedo estimates maximum daily differences between the five modis broadband albedo retrievals and in situ albedo are 15 daily differences between the best modis broadband estimate and the measured surfrad albedo are 1 8 however no single conversion scheme consistently provides the closest albedo estimate further validation and algorithm development using data from north america and greenland is ongoing

altimetric observations of surface characteristics of the antarctic ice sheet the aim of this paper is to investigate the geophysical characteristics of the antarctic ice sheet using radar altimetric observations to do this we use an altimetric waveform simulator in situ observations ers 1 european remote sensing satellite data and spot satellite pour l observation de la terre images the small scale study takes place at dome c terre adelie which is a relatively flat region with gentle undulations and low wind speed despite this the altimetric waveform parameters height energy leading edge and trailing edge are highly noisy the effect of undulations on the waveform parameters is found to be dominant the combination of a subsurface signal and a rough surface produces a linear effect on the altimetric backscattering or on the trailing edge of the waveform but a strongly non linear effect on the leading edge of the waveform or height estimation as a consequence the height measurement is very sensitive to the altimeter technical or orbital characteristics and is not reproducible from one mission to another observations show sastrugi fields that enhance the leading edge and affect the whole waveform observed local backscattering changes probably due to local variations in surface microroughness enhance the backscattered energy and may artificially create a topographic signal the continental scale study shows coherent patterns even if both surface and subsurface components affect the altimetric observation the large scale signal is mostly controlled by surface backscattering variations the surface or near subsurface characteristics of the snowpack may then be reached by altimetric observations

red staining of the wall rock and its influence on the reducing capacity around water conducting fractures abstract red staining and alteration of wall rock is common around water conducting fractures in the laxemar simpevarp area se sweden which is currently being investigated by the swedish nuclear fuel and waste management co skb in common with many other places red staining is often interpreted as a clear sign of oxidation but relevant analyses are seldom performed the area is dominated by palaeoproterozoic crystalline rocks ranging in composition from quartz monzodiorite to granite in this study wall rock samples have been compared with reference samples from within 0 1 to 1 m of the red stained rock in order to describe mineralogical and geochemical changes but also changes in redox conditions a methodology for tracing changes in mineralogy mineral and whole rock chemistry and fe3 fetot ratio in silicates and oxides in the red stained wall rock and the reference rock is reported the results show that the red stained rock adjacent to the fractures displays major changes in mineralogy biotite plagioclase and magnetite have been altered and chlorite k feldspar albite sericite prehnite epidote and hematite have been formed the changes in chemistry are however moderate k enrichment ca depletion and constant fetot are documented the fe3 fetot ratio in the oxide phase is higher in the red stained samples whereas the fe3 fetot ratio in the silicate phase is largely similar in the wall rock and the reference samples because most of the fe is hosted in the silicate phase the decrease in reducing capacity fe2 if any in the red stained wall rock is very small and not as high as macroscopic observations might suggest instead the mineralogical changes in combination with the modest oxidation and formation of minute hematite grains in porous secondary minerals in pseudomorphs after plagioclase have produced the red staining increased porosity is also characteristic for the red stained rock moderate alteration in the macroscopically fresh reference rock shows that the hydrothermal alteration reaches further from the fracture than the red staining the extent of the red staining can therefore not be used in the same way as the extent of the alteration adjacent to a fracture the increase in porosity in the red stained rock may result in enhanced retention of radio nuclides due to an increased sorptivity and diffusion close to the fracture the hydrothermal alteration causing the red staining is thought to have occurred at temperatures of about 250 400 c based on the secondary mineralogy the major part of this alteration in the area is assumed to be related to fluid circulation associated with the intrusion of the mesoproterozoic gotemar and uthammar granites nearby

fracture pattern and electrical resistivity studies for groundwater exploration the occurrence movement and control of groundwater particularly in hard rock areas are governed by different factors such as topography lithology structures like fractures faults and nature of weathering an attempt is made in the present study to investigate the extent of the influence of structures such as fractures and thereby delineate the nature of subsurface lithology with the help of an electrical resistivity method for this study the upper gunjanaeru river basin cuddapah district andhra pradesh was chosen to determine groundwater potentials in order to understand the significance of the fracture pattern geological hydrogeomorphological and lineament maps were prepared based on the field data and also from the landsat tm imagery further electrical resistivity surveys were conducted to determine the subsurface lithology and also to confirm the studies of landsat imagery the isoresistivity contour map has been prepared based on the 45 ves conducted to determine the resistivity variations in the study area the isoresistivity contours obtained were found to conform to the structural trends obtained by geological studies and also confirm the relationship between the structure and secondary porosity present in the rocks the lineaments in the area have two preferred directions one set is a ne sw direction n 30 70 e s 30 70 w and another is a nw se direction n 0 30 w s 0 30 e and n 60 80 w s 60 80 e the water table contour map shows that the direction of groundwater flow is south to north

effect of sastrugi on snow bidirectional reflectance and its application to modis data 1 snow surface roughness such as sastrugi on the antarctic ice sheet can be a cause of error for remote sensing of snow parameters the effect of sastrugi on snow bidirectional reflectance was assessed by a field experiment model simulations and satellite measurements the hemispherical directional reflectance factor hdrf of artificial sastrugi like linear ridges measured at nakasatsunai hokkaido japan exhibited different patterns from that of a flat surface with the difference of more than 50 for some geometries a 3 d monte carlo radiative transfer model mc model reproduced both the hdrf measurements for the artificial ideal sastrugi and previous measurements for natural sastrugi at the south pole furthermore the sastrugi effect was applied to remote sensing failure to include the surface roughness in models for developing snow grain size lookup tables can lead to order of magnitude retrieval errors using the mc model and multiangle data derived from the moderate resolution imaging spectrometer over the south pole during the 2003 2004 summer the sastrugi and snow parameters were retrieved the height to width ratio of sastrugi reduced from 0 1 to 0 02 whereas the azimuth angle was nearly constant within the range of 0 30 during the summer the snow grain size showed a seasonal variation which depended on the spectral channel these retrieved parameters were consistent with existing ground measurements the results suggest that a combination of multiangle data and a 3 d radiative transfer model can be used to quantitatively estimate surface roughness along with snow grain size on ice sheets

ice flow physical processes derived from the ers 1 high resolution map of the antarctica and greenland ice sheets accepted 1999 july 7 received 1999 june 7 in original form 1998 june 24 summary the ers 1 satellite launched in 1991 has provided altimetric observations of the greenland ice sheet and 80 per cent of the antarctica ice sheet north of 82 s it was placed in a geodetic 168 day repeat orbit between april 1994 and march 1995 yielding a 1 5 km across track spacing at latitude 70 with a higher along track sampling of 350 m we have analysed the waveform altimetric data from this period to compute maps with a 1 30 grid size data processing consists of correcting for environmental factors and editing and retracking the waveforms a further step consists of reducing the radial orbit error through crossover analysis and correcting the slope error to second order the high resolution topography of both ice sheets reveals numerous details a kilometre scale surface roughness running at 45 from the flow direction is the dominant topographic characteristic of both continents antarctica also exhibits many scars due to local flow anomalies several physical processes can be identified abrupt transitions from deformation to sliding and vice versa and impressive strike slip phenomena inducing en echelon folds

comparison of microwave backscatter anisotropy parameterizations of the antarctic ice sheet using ascat the c band eumetsat advanced scatterometer ascat was launched in 2007 and provides backscatter measurements with excellent azimuth and incidence angle diversity in polar regions c band backscatter measurements can be used to retrieve near surface snow firn properties such as grain size and accumulation rate however the antarctic ice sheet ais exhibits strong microwave backscatter anisotropy as a function of both incidence and azimuth angles and this anisotropy must be well understood before such physical parameter retrieval can be accurately performed this paper presents a detailed comparison of several different parameterizations of both the azimuth and the incidence anisotropy parameterizations used here result in residuals similar to the radiometric performance of ascat indicating accurate characterization of the anisotropy the analysis of these parameterizations provides an insight into the physical mechanisms taking place near the surface of the ais 30 day composite maps of several parameters are presented and discussed in the context of near surface glaciology this anisotropy characterization will form the basis of a technique for extraction of physical parameters of the ais

an integrated geophysical investigation of the hydrogeology of an anisotropic unconfined aquifer abstract the predictive capability of groundwater flow models is frequently restricted by insufficient characterisation of a typically heterogeneous and anisotropic subsurface trace levels of volatile organic compounds have been detected at municipal water supply wells in gray maine groundwater flow modelling based on available hydrogeologic data defines a dominant w e transport vector that is inconsistent with the apparent n40e transport of a plume emanating from a road salt storage facility as mapped with a terrain conductivity instrument a local scale geophysical study at an undisturbed site in the glacial marine delta deposit aquifer was conducted to investigate the possible influence of anisotropy on flow through these unconsolidated sediments ground penetrating radar and terrain conductivity measurements reveal evidence for structural features that are likely to promote preferential transport paths orientated in a general ne sw direction two conductive tracers one deep and one surficial were injected and monitored for direct evaluation of the groundwater flow vector using resistivity and self potential methods although interpretation was limited by an incomplete resistivity dataset the results and modelling of both methods supports a general n30e n40e flow vector furthermore consistent flow velocity estimates 0 15 m day are obtained from the two methods analysis of this integrated dataset suggests that anisotropy exerts a significant control on flow in this unconsolidated aquifer predictions of sources of groundwater contamination at municipal wells based on flow models not accounting for this anisotropy will likely be in error this study illustrates the potential value of an integrated geophysical study which will aid the development of accurate flow models for unconsolidated aquifers

high cesium concentrations in groundwater in the upper 1 2 km of fractured crystalline rock influence of groundwater origin and secondary minerals abstract dissolved and solid phase cesium cs was studied in the upper 1 2 km of a coastal granitoid fracture network on the baltic shield aspo hard rock laboratory and laxemar area se sweden there unusually high cs concentrations up to 5 6 g l 1 occur in the low temperature 1 median laxemar 3 7 g l 1 and groundwater with marine origin aspo hrl 4 2 g l 1 overall lower but variable cs concentrations were found in other types of groundwater the similar concentrations of cs in the saline groundwater which had a residence time in the order of millions of years and in the marine groundwater which had residence times in the order of years shows that duration of water rock interactions is not the single and primary control of dissolved cs in these systems the high cs concentrations in the saline groundwater is ascribed to long term weathering of minerals primarily cs enriched fracture coatings dominated by illite and mixed layer clays and possibly wall rock micaceous minerals the high cs concentrations in the groundwater of marine origin are in contrast explained by relatively fast cation exchange reactions as indicated by the field data and predicted by 1d solute transport modeling alkali cations with low energy hydration carried by intruding marine water are capable of nh 4 in particular and k to some extent replacing cs on frayed edge fes sites on illite in the fracture coatings the result is a rapid and persistent at least in the order of decades buildup of dissolved cs concentrations in fractures where marine water flows downward the identification of high cs concentrations in young groundwater of marine origin and the predicted capacity of nh 4 to displace cs from fracture solids are of particular relevance in the disposal of radioactive nuclear waste deep underground in crystalline rock

modeling the effect of sastrugi on snow reflectance a snow reflectance model was developed to assess the bidirectional reflectance distribution function brdf of snow over anisotropic rough surfaces such as fields of sastrugi commonly encountered in some areas of the ice sheets of antarctica and greenland the sastrugi are modeled as regularly spaced identical rectangular protrusions with the same orientation interfacet multiple scattering is ignored each model sastruga has vertical walls and a small width compared to its length and to its height the input data for the model are the sun and the viewing directions the number of sastrugi per pixel their dimensions and the bidirectional reflectance for a flat snow surface the latter is computed by a multiple scattering model and snow particles are assumed to be spherical mie theory in order to compare the model results with ground measurements acquired at the south pole by grenfell et al 1994 and brandt et al 1991 atmospheric effects were taken into account the model reproduces the global influence of sastrugi on the shape of the brdf the influence of sastrugi is clearly visible for zenith viewing angles larger than 50

variations in snowpack melt on the greenland ice sheet based on passive microwave measurements a simple microwave emission model is used to simulate 37 ghz brightness temperatures associated with snowpack melt conditions for locations across the greenland ice sheet the simulated values are utilized as threshold values and compared to daily gridded smmr and ssm i passive microwave data in order to reveal regions experiencing melt the spatial extent of the area classified as melting is examined on a daily monthly and seasonal may august basis for 1979 91 the typical seasonal cycle of melt coverage shows melt beginning in late april a rapid increase in the melting area from mid may to mid july a rapid decrease in melt extent from late july through mid august and cessation of melt in late september seasonal averages of the daily melt extents demonstrate an apparent increase in melt coverage over the 13 year period of approximately 3 8 annually significant at the 95 confidence interval this increase is dominated by statistically significant positive trends in melt coverage during july and august in the west and southwest of the ice sheet we find that a linear correlation between microwave derived melt extent and a surface measure of ablation rate is significant in june and july but not august so caution must be exercised in using the microwave derived melt extents in august nevertheless knowledge of the variability of snowpack melt on the greenland ice sheet as derived from microwave data should prove useful in detecting climate change in the arctic and examining the impact of climate change on the ice sheet

bidirectional anisotropic reflectance of snow and sea ice in avhrr channel 1 and channel 2 spectral regions ii correction applied to imagery of snow on sea ice for pt i see ibid vol 37 no 1 p 543 54 1999 advanced very high resolution radiometer avhrr images acquired over the arctic ocean often show strong bidirectional reflectance of snow on sea ice the observed anisotropic reflectance characteristics of these images are consistent with the theoretical analysis presented in part i of this study the anisotropic reflectance at the top of atmosphere toa is simulated by radiative transfer modeling and the results show a good model observation agreement based on these modeling results a method was developed to correct the effect of anisotropic reflectance on avhrr images in channels 1 and 2 results show the method is effective and efficient comparisons of toa snow reflectance before and after anisotropic correction show that the systematic and large variation of snow reflectance across the scan lines of an image due to satellite viewing illumination geometry can either be eliminated or greatly reduced by applying the correction algorithm

diffusion controlled tracer retention in crystalline rock on the field scale 1 tracer retention is a key process for the barrier function of crystalline rock to any contaminant here we investigate the nature of retention mechanisms and their field scale parametrization using results of a comprehensive tracer transport experiment in crystalline rock on the field scale aspo hard rock laboratory sweden a method for identifying dominant retention mechanisms and inferring key parameters on the site scale is presented taking advantage of multiple tracer tests with a wide range of sorption affinities retention is shown to be diffusion controlled for the considered site robust features of tracer migration can be reasonably well predicted within a rock volume on at least 200 m scale by combining independent information with a simple model

modeling transport of cesium in grimsel granodiorite with micrometer scale heterogeneities and dynamic update of kd transport and retardation of cesium in grimsel granodiorite taking into account heterogeneity of mineral and pore structure was studied using rock samples overcored from an in situ diffusion test at the grimsel test site the field test was part of the long term diffusion project ltd designed to characterize retardation properties diffusion and distribution coefficients under in situ conditions results of the ltd experiment for cesium showed that in diffusion profiles and spatial concentration distributions were strongly influenced by the heterogeneous pore structure and mineral distribution in order to study the effect of heterogeneity on the in diffusion profile and spatial concentration distribution a time domain random walk tdrw method was applied along with a feature for modeling chemical sorption in geological materials a heterogeneous mineral structure of grimsel granodiorite was constructed using x ray micro computed tomography x ct and the map was linked to previous results for mineral specific porosities and distribution coefficients kd that were determined using c 14 pmma autoradiography and batch sorption experiments respectively after this the heterogeneous structure contains information on local porosity and kd in 3d it was found that the heterogeneity of the mineral structure on the micrometer scale affects significantly the diffusion and sorption of cesium in grimsel granodiorite at the centimeter scale furthermore the modeled in diffusion profiles and spatial concentration distributions show similar shape and pattern to those from the ltd experiment it was concluded that the use of detailed structure characterization and quantitative data on heterogeneity can significantly improve the interpretation and evaluation of transport experiments

classification of glacier zones in western greenland using albedo and surface roughness from the multi angle imaging spectroradiometer misr the greenland ice sheet has been the subject of mass balance and melt measurements over the past two decades and its margins have shown significant thinning in recent years surface characteristics of the ice sheet margins are strongly modified by the annual process of snow accumulation and melt in this work we explore spatial and temporal relationships between near infrared albedo and surface roughness from the multi angle imaging spectroradiometer misr aboard nasa s terra satellite our study area is a region in western greenland in the vicinity of jakobshavn glacier and its upland drainage basin we compute near infrared albedo from misr data using imagery over the april to september period for 2000 through 2005 near infrared albedo is inversely related to both snow age and melt intensity we map surface roughness using the normalized difference angular index ndai applied to misr atmospherically corrected surface hemispherical directional reflectance in previous work the ndai has been correlated with surface roughness on the scale of about 70 m we have further substantiated that relationship here the ndai and albedo images for each of the six years are used in an isodata unsupervised classification classification results for the individual years show year to year differences which appear to depend on the number and temporal distribution of images with minimal cloud cover as well as interannual differences in ice sheet surface properties the year 2003 which had the greatest number of images with minimal cloud cover shows good correspondence with previously mapped glacier zones however we do not have an isodata class that corresponds to the dry snow zone and we see greater differentiation between zones at lower elevations within each isodata class distinct relationships between near infrared albedo and surface roughness emerge and in all cases but one there is an inverse temporal relationship between albedo and roughness the one class that shows a direct relationship between albedo and surface roughness is hypothesized to be the superimposed ice zone while still somewhat preliminary these results suggest that concurrent measurements of near infrared albedo and surface roughness have significant potential for ice sheet surface characterization as well as for ongoing monitoring

transport and retention from single to multiple fractures in crystalline rock at aspo sweden 2 fracture network simulations and generic retention model hydrogeologic characterization of crystalline rock formations on the field scale is important for many applications but still presents a multitude of challenges neuman 2005 in this work we use

geoelectric resistivity sounding of riverside alluvial aquifer in an agricultural area at buyeo geum river watershed korea an application to groundwater contamination study twenty profiles of vertical electric soundings ves were obtained in a riverside alluvium at the buyeo area south korea to examine the variations of subsurface geology and associated groundwater chemistry the combination of the ves data with the borehole data provided useful information on subsurface hydrogeologic conditions the vestige of an ancient river channel e g oxbow lake was identified on the resistivity profiles by the lateral continuation of a near surface perched aquifer parallel to the river such a perched aquifer is typically developed in the area with a clay rich silty surface alluvium which prohibits the infiltration of oxygen therefore groundwater below the oxbow lake shows a very low nitrate concentration and eh values under the strong anoxic condition the distribution of water resistivity is correlated with that of measured total dissolved solids concentration in groundwater while the earth resistivity of the aquifer shows a significant spatial variation it is interpreted that the earth resistivity of the aquifer is mainly controlled by the soil type rather than by the water chemistry in the study area

nivlisen an antarctic ice shelf in dronning maud land geodetic glaciological results from a combined analysis of ice thickness ice surface height and ice flow observations extensive observations on nivlisen an ice shelf at antarctica s atlantic coast are analysed and combined to achieve a new quality description of its complex glaciological regime we generate models of ice thickness primarily from ground penetratingradar ellipsoidal ice surface height primarily from ers 1 satellite altimetry freeboard height by utilising precise sea surface information and ice flow velocity from ers 1 2 sar interferometry and gps measurements accuracy assessmentsare included exploiting the hydrostatic equilibrium relation we infer the apparent air layer thickness as a useful measure for a glacier s density deviation from a pure ice body this parameter exhibits a distinct spatial variation ranging from 2 m to 16 m which we attribute to the transition from an ablation areato an accumulation area we compute mass flux and mass balance parameters on a local and areally integrated scale the combined effect of bottom mass balance and temporal change averaged over an essential part of nivlisen is 654 170 kgm2a 1 which suggests bottom melting processes to dominate we discuss our results in view of temporal ice mass changes including remarks on historical observations basal processes near surface processes and ice flow dynamical features the questionfor temporal changes remains open from the data at hand and we recommendfurther observations and analyses for its solution

bedrock features and ice flow near the epica ice core site dome c antarctica the precise bedrock topography near the epica ice core site at dome c in antarctica exhibits impressive bedrock mountains bowls and a clear network of elongated valleys some of these features are probably tectonic and are likely to be buried pre ice sheet landforms the elongated bedrock valleys are clearly detectable in the surface topography suggesting a large scale network the analysis of the relationship between basal and surface elongated structures indicates a damping factor decreasing from 120 near the dome to 80 at few tens of kilometer there is evidence of presence of subglacial water and of erosed bed that can play a role of the ice flow a complete flow modeling taking into account longitudinal stresses should be performed around epica site in order to improve dating of the ice

a comparison between active and passive microwave measurements of the antarctic ice sheet and their association with the surface katabatic winds the intensity of the seasat altimeter return power over antarctica varies in strong correlation with the intensity of model katabatic winds it is also strongly correlated with the polarization of the passive microwave signal at 37 ghz of the nimbus 7 smmr data it is shown that this is most likely the result of the wind induced micro roughness of the ice surface

sorbing tracer experiments in a crystalline rock fracture at aspo sweden 1 experimental setup and microscale characterization of retention properties 1 mineralogical and retardation properties of rock materials responsible for water rock interaction in in situ migration experiments with sorbing radioactive tracers were studied in laboratory experiments the porosity was studied by water saturation measurements and the pmma method was used for detailed porosity characterization of heterogeneity distributions and porosity profiles toward the fracture surface mylonite and altered diorite sampled in the rim zone of the fracture and representative bulk rock types were investigated by batch sorption measurements with crushed materials and through diffusion and in diffusion experiments in intact rock pieces autoradiography was used for visualization of in diffusion profiles of sorbing tracers the use of detailed porosity information and quantitative data on heterogeneity in porosity is shown to significantly improve the interpretation and evaluation of laboratory scale diffusion experiments we show through the combined approach of detailed porosity characterization and laboratory sorption and diffusion investigations that we can distinguish retention properties of bulk rock and altered rock and provide qualitative and quantitative data of heterogeneous rock properties that expand the possibility for including relevant processes in the interpretation of the results of in situ tracer tests

comparison of avhrr derived and in situ surface albedo over the greenland ice sheet abstract this paper discusses a methodology for computing the clear sky surface albedo over the greenland ice sheet by using advanced very high resolution radiometer avhrr global area coverage visible and near infrared reflectances this approach is then used to map the monthly changes in albedo over the entire greenland ice sheet during the spring and summer months the methodology includes corrections for the intervening atmosphere by using the 6s radiative transfer model additional corrections for the anisotropic nature o f snow reflectance and the conversion from a marrow into a broadband albedo are made based on in site measurements from the swiss federal institute of technology university of colorado camp at 69 34 n 49 18 w comparison with surface albedo field ineasureinents indicates that before the onset of snoic melt agreement is good between the satellite derived and measured surface albedo after melt begins it is difficult to compare the satellite values with the field data owing to melt water ponding on the ice sheet surface with appropriate modifications the 6s radiative transfer model is suitable for atmospherically correcting avhrr visible and near infrared radiances atmospherically polar regions

antarctica ice sheet curvature and its relation with ice flow and boundary conditions the map of the antarctica ice sheet surface curvature in the across slope direction shows a very coherent pattern related to ice flow anomalies of each flowline with respect to adjacent ones near the coast these anomalies are correlated to bedrock features which suggests that they result from outlet flow conditions that are transmitted from coast to domes as a consequence they should represent the drainage pattern glacier positions and 3 dimensional flowline directions thus a large part of the ice sheet flow pattern seems controlled by outflow boundary conditions which can be empirically estimated

modelling the diffusion available pore space of an unaltered granitic rock matrix using a micro dfn approach abstract in sparsely fractured rock the ubiquitous heterogeneity of the matrix which has been observed in different laboratory and in situ experiments has been shown to have a significant influence on retardation mechanisms that are of importance for the safety of deep geological repositories for nuclear waste here we propose a conceptualisation of a typical heterogeneous granitic rock matrix based on micro discrete fracture networks micro dfn different sets of fractures are used to represent grain boundary pores as well as micro fractures that transect different mineral grains the micro dfn model offers a great flexibility in the way inter and intra granular space is represented as the different parameters that characterise each fracture set can be fine tuned to represent samples of different characteristics here the parameters of the model have been calibrated against experimental observations from granitic rock samples taken at forsmark sweden and different variant cases have been used to illustrate how the model can be tied to rock samples with different attributes numerical through diffusion simulations have been carried out to infer the bulk properties of the model as well as to compare the computed mass flux with the experimental data from an analogous laboratory experiment the general good agreement between the model results and the experimental observations shows that the model presented here is a reliable tool for the understanding of retardation mechanisms occurring at the mm scale in the matrix

using the temporal variability of satellite radar altimetric observations to map surface properties of the antarctic ice sheet the problem of measuring surface height and snowpack characteristics from satellite radar altimeter echoes is investigated in this paper we perform an analysis of the ers1 altimeter dataset acquired during a 3 day repeat orbit the analysis reveals that there are temporal variations in shapes of the radar altimeter echo and that these variations are linked to meteorological phenomena the time and space scales over which these variations apply are a few to tens of days and a few hundred kilometres respectively this phenomenon if not accounted for can create error in the height measurement a numerical echo model is used to recover snowpack characteristics by taking advantage of the temporal variations of the radar echoes a map of penetration depth of the radar waves in the ku band over the antarctic continent is obtained and suggests that grain size produces the dominant effect on radar extinction in the snowpack at this frequency finally a procedure is proposed to correct the height measurement within the context of ice sheet mass balance survey

on the upscaling of chemical transport in fractured rock the impact of flow heterogeneity on chemical transport from single to multiple fractures is investigated the emphasis is on the dynamic nature of the specific surface area ssa due to heterogenei

theory of metamorphism of dry snow the growth of ice particles in dry seasonal snow is caused by vapor diffusion among particles due to temperature gradients imposed on the snow cover the diffusion is calculated by using the potential field solutions for electrostatically charged particles the stereography of snow is represented by using a log normal distribution function for a geometrical enhancement factor defined here reasonable crystal growth rates and supersaturations are found the transition between the growth of highly faceted crystals and the growth of highly rounded crystals is determined by the critical supersaturation for the onset of dislocation aided growth thermal convection and the continuous movement of vapor around the particles due to the imposed temperature gradient are accommodated in the theory although both have little effect relative to the interparticle diffusion the growth of a layer of faceted crystals just below semi permeable crusts is explained by showing that crusts can cause the local supersaturation to exceed the critical value faceted crystals are shown to grow most rapidly in the lower warmer portions of the snow cover because of temperature effects on growth rate

solute transport through fractured rock radial diffusion into the rock matrix with several geological layers for an arbitrary length decay chain the paper presents a model development to derive a semi analytical solution to describe reactive solute transport through a single channel in a fracture with cylindrical geometry the model account

tracer attenuation in groundwater the self purifying capacity of aquifers strongly depends on the attenuation of waterborne contaminants i e irreversible loss of contaminant mass on a given scale as a result of coupled transport and transformation processes a general formulation of tracer attenuation in groundwater is presented basic sensitivities of attenuation to macrodispersion and retention are illustrated for a few typical retention mechanisms tracer recovery is suggested as an experimental proxy for attenuation unique experimental data of tracer recovery in crystalline rock compare favorably with the theoretical model that is based on diffusion controlled retention non fickian hydrodynamic transport has potentially a large impact on field scale attenuation of dissolved contaminants

geoelectrical method in the investigation of groundwater resource and related issues in ophiolite and flysch formations of port blair andaman island india geoelectrical resistivity investigation using vertical electrical sounding ves technique was conducted at port blair south andaman island to locate the fractures in different formations and to decipher its groundwater potential a total of 40 ves were carried out covering the entire study area using schlumberger electrode configuration out of which 34 ves fall in andaman flysch formations and the remaining ves in ophiolite formations the interpreted resistivity results were integrated with nine borehole lithologs for the subsurface analysis the combination of ves with borehole litholog data has provided a close correspondence on subsurface hydrogeological conditions the interpreted ves data of various formations showed drastic variations in the resistivity ranging from higher in ophiolite moderate in andaman flysch and very low in valleys of andaman flysch formations the study further revealed that the weathered and fractured volcanics of ophiolite groups of rocks and sandstone that occur in the andaman flysch formations constitute the productive water bearing zones categorized as good groundwater potential zone based on the geoelectrical parameters viz thickness of layers and the layer resistivity values a groundwater potential map was prepared in which good moderate and poor groundwater zones were demarcated further numerical spatial and litho geoelectric models of resistivity were analyzed in terms of groundwater potential and these models have thus enabled to prepare a comprehensive groundwater development and management plans proving its efficacy in this art of exploratory investigations

impact of fracture coatings on fracture matrix flow interactions in unsaturated porous media groundwater flow in unsaturated fractured rock is often assumed to be dominated by the porous matrix component this is frequently the result of reasoning that water flowing in the fractures is rapidly imbibed into the rock matrix by capillary suction forces with negligible resistance to uptake at the fracture matrix interface however the existence of a low permeability mineralized layer or coating at this interface may substantially reduce matrix imbibition and could consequently result in fracture dominated flow to test this idea four tuff samples containing natural fractures were obtained from tuff formations in southern nevada by performing imbibition experiments into the matrix rock across a mineralized fracture face and then across a fresh uncoated fracture face water uptake as a function of time and coating was measured a model combining darcy s law and the washburn equation has been used to describe the imbibition behavior before testing the tuff samples the experimental technique and imbibition model were first tested using ordered sphere packings with known pore size and structure from the tuff imbibition data the ratio of the permeability through the mineralized face to the permeability through the uncoated face was found to be 0 3 relatively little effect of the mineralized layer for two samples 0 01 for one sample and 10 7 uptake strongly restricted by the mineralized layer for one sample using a simple fracture flow model and the imbibition model mentioned above to simulate matrix uptake from the fracture numerical simulations indicate that the existence of fracture coatings could significantly decrease the travel time and increase the travel depth of water flowing through fractures

hydropedological investigations with ground penetrating radar gpr estimating water table depths and local ground water flow pattern in areas of coarse textured soils in coarse textured soils ground penetrating radar gpr can provide continuous high resolution records that chart the depth to water tables the use of this information can increase confidence in hydropedological site assessments and reduce the number of wells needed for water table depth and ground water flow determinations ground penetrating radar was used to map spatial and temporal variations in water table depths and ground water flow patterns within an unconfined aquifer located beneath an eolian landscape in northwestern indiana compared with the data collected at a limited number of wells the greater number of observations with gpr provided more comprehensive site coverage and mapped more intricate local ground water flow patterns over a 2 year period gpr revealed systematic temporal and spatial variations in water table depths and local ground water flow patterns

significance of fracture rim zone heterogeneity for tracer transport in crystalline rock 1 conducting fractures of crystalline rock are typically altered over long periods of time the fracture rim zone a result of these alterations will as a rule have different physical and chemical properties from the unaltered fresh rock depending on various microscopic and macroscopic factors of the alterations in this paper we study the impact of rim zone heterogeneity exemplified by a decreasing porosity trend as inferred from the aspo hard rock laboratory site sweden on short and long term tracer transport our main finding is that this particular rim zone structure will have a dominant effect on transport of moderately to strongly sorbing tracers on experimental time scales and a notable effect on application time scales the findings of this work lend further support to the interpretation of the relatively strong retention reported by cvetkovic et al the fracture rim zone porosity structure may provide an additional safety margin for sorbing radionuclides in crystalline rock at sites where fracture alteration is prevalent

surface characterisation of the dome concordia area antarctica as a potential satellite calibration site using spot 4 vegetation instrument a good calibration of satellite sensors is necessary to derive reliable quantitative measurements of the surface parameters or to compare data obtained from different sensors in this study the snow surface of the high plateau of the east antarctic ice sheet particularly the dome c area 75js 123je is used first to test the quality of this site as a ground calibration target and then to determine the inter annual drift in the sensitivity of the vegetation sensor onboard the spot4 satellite dome c area has many good calibration site characteristics the site is very flat and extremely homogeneous only snow there is little wind and a very small snow accumulation rate and therefore a small temporal variability the elevation is 3200 m and the atmosphere is very clear most of the time finally due to its location it is frequently within view of many satellites vegetation visible blue channel data 0 43 0 47 am of a 716716 km 2 area centred on the french italian dome concordia station during the 1998 1999 1999 2000 2001 2001 and 2001 2002 austral summers were cloud masked and atmospherically corrected the snow surface bidirectional reflectance distribution function is very high with little spatial and seasonal variability which is a major advantage for sensor calibration the inter annual variation is found to be very small proving that the stability of the site is very good

ground penetrating radar for high resolution mapping of soil and rock stratigraphy ground penetrating radar is a technique which offers a new way of viewing shallow soil and rock conditions the need to better understanding overburden conditions for activities such as geochemical sampling geotechnical investigations and placer exploration as well as the factors controlling groundwater flow has generated an increasing demand for techniques which can image the subsurface with higher resolution than previously possible the areas of application for ground penetrating radar are diverse the method has been used successfully to map ice thickness water depth in lakes bedrock depth soil stratigraphy and water table depth it is also used to delineate rock fabric detect voids and identify karst features the effective application of the radar for the high resolution definition of soil stratigraphy and fractures in bedrock is highlighted the basic principles and practices involved in acquiring high quality radar data in the field are illustrated by selected case histories one example demonstrates how radar has been used to map the bedrock and delineate soil horizons to a depth of more than 20 m two case histories show how radar has been used to map fractures and changes of rock type to 40 m range from inside a mine another case history demonstrates how radar has also been used to detect and map the extent of groundwater contamination the corroboration of the radar results by borehole investigations demonstrates the power and utility of the high resolution radar method as an aid for interpolation and extrapolation of the information obtained with conventional coring programmes with the advent of new instrumentation and field procedures the routine application of the radar method is becoming economically viable and the method will see expanded use in the future

double porosity models for a fissured groundwater reservoir with fracture skin theories of flow to a well in a double porosity groundwater reservoir are modified to incorporate effects of a thin layer of low permeability material or fracture skin that may be present at fracture block interfaces as a result of mineral deposition or alteration the commonly used theory for flow in double porosity formations that is based upon the assumption of pseudo steady state block to fissure flow is shown to be a special case of the theory presented in this paper the latter is based on the assumption of transient block to fissure flow with fracture skin under conditions where fracture skin has a hydraulic conductivity that is less than that of the matrix rock it may be assumed to impede the interchange of fluid between the fissures and blocks resistance to flow at fracture block interfaces tends to reduce spatial variation of hydraulic head gradients within the blocks this provides theoretical justification for neglecting the divergence of flow in the blocks as required by the pseudo steady state flow model coupled boundary value problems for flow to a well discharging at a constant rate were solved in the laplace domain both slab shaped and sphere shaped blocks were considered as were effects of well bore storage and well bore skin resultsmore obtained by numerical inversion were used to construct dimensionless type curves that were applied to well test data for a pumped well and for an observation well from the fractured volcanic rock terrane of the nevada test site less

katabatic wind intensity and direction over antarctica derived from scatterometer data although satellite radar scatterometers are initially designed to measure ocean surface wind speed and direction they also provide important observations over continental ice sheets data from the seasat scatterometer analysed over a sector of antarctica show that the signal is strongly dependent on the incidence angle of observation but that it also depends on azimuth ledroit et al 1992 the minimum values of the backscatter coefficient the ratio of backscattered versus incident power are always observed in the direction of katabatic winds a theoretical analysis shows that the backscatter coefficient must be very sensitive to the sastrugi slopes and orientations which are streamlined features formed on the snow surface in the wind direction parish and bromwich 1987 satellite scatterometers can thus map the characteristics of sastrugis of importance for the interpretation of microwave measurements above ice sheets this indirectly provides the intensity and direction of these very persistent and strong winds which play a important role in the behaviour of the atmosphere and ocean in high southern latitudes

aquifer architecture analysis using ground penetrating radar triassic and quaternary examples s germany applying the concept of analogue studies long used in reservoir characterization outcrop analogues in two aquifer units of southern germany have been investigated upper triassic keuper alluvial sandstones stubensandstein and quaternary glaciofluvial gravels architectural element analysis of the outcrops is combined with ground penetrating radar profiles derived a few meters behind the outcrop walls such calibration is used to better understand the three dimensional sedimentary architecture many sedimentary units at the same time represent hydraulic flow units and are characterized by specific radar signatures this approach leads to promising results not only in unconsolidated aquifers but also in fully consolidated sedimentary rocks our studies will lead to a database with which more realistic predictions of the hydraulic behaviour of sedimentary aquifers systems needed for numerical hydrogeological simulations will be possible

geodynamic evolution of the outer arc forearc belt in the andaman islands the central part of the burma java subduction complex the andaman islands the central part of burma java subduction complex expose tectonostratigraphic units of an accretionary prism in an outer arc setting and turbidites of a forearc setting a number of n s trending dismembered ophiolite slices of cretaceous age occurring at different structural levels with eocene trench slope sediments were uplifted and emplaced by a series of e dipping thrusts subsequently n s normal and e w strike slip faults resulted in the development of a forearc basin with deposition of oligocene and mio pliocene sediments metapelites and metabasics of greenschist to amphibolite grade occur in a melange zone of ophiolites the eocene mithakhari group represents pelagic trench sediments and coarser clastics derived from ophiolites evidence of frequent facies changes predominance of mass flow deposits syn sedimentary basinal disturbance and wide palaeogeographic variation indicate deposition of eocene sediments in isolated basins of an immature trench slope setting deposition of the oligocene andaman flysch group in a forearc setting is indicated by the large scale persistence of beds lack of small scale lithological variation bimodal provenance less deformation a well defined submarine fan sequence and development predominantly on the eastern part of the outer arc the mio pliocene archipelago group includes alternations of siliciclastic turbidites and subaqueous pyroclastic flow deposits in the lower part and carbonate turbidites in the upper part suggesting its deposition in the shallower forearc compared to the siliciclastic oligocene sediments

spectral bi directional reflectance of snow and glacier ice measured in dronning maud land antarctica visible and near infrared spectral reflectances of snow and superimposed ice were measured in dronning maud land antarctica during the 1992 93 austral summer spectral reflectance curves of both snow and superimposed ice remain high 80 in the visible region a pronounced decrease in reflectance appears in the near infrared especially for superimposed ice superimposed ice with a 1 cm thick surface layer of ice bound snow crystals had a considerably higher reflectance than superimposed ice containing only a few snow crystals furthermore these data prove that snow and superimposed ice reflect solar radiation specularly and suggest that the anisotropy strengthens with increasing wavelengths integrated in situ reflectances corresponding to landsat tm bands 1 4 show that tm band 1 is least affected whereas tm band 4 is most affected by anisotropy furthermore the anisotropy increases with increasing off nadir viewing angles up to an angle corresponding to 90 s s solar elevation for a 15 off nadir sensor observation angle the average snow reflectance for tm bands 1 4 is about 10 higher than at nadir similarly the apparent reflectance can be more than 50 higher than the nadir reflectance for larger observation angles consequently if satellite derived reflectances are going to be considered as absolute values a topographic correction model is needed to correct for the effects of anisotropy

solute transport in fractured rocks with stagnant water zone and rock matrix composed of different geological layers model development and simulations a model is developed to describe solute transport and retention in fractured rocks it accounts for the fact that solutes can not only diffuse directly from the flowing channel into the adjacent ro

three dimensional high resolution fluvio glacial aquifer analog part 1 field study summary describing the complex structures that exist in many sedimentary aquifers is crucial for reliable groundwater flow and transport simulation however hardly any aquifer can be inspected in such detail that all decimeter to meter heterogeneity is resolved aquifer analogs serve as surrogates to construct models of equivalent heterogeneity and thus imitate those features relevant for flow or transport processes gravel pits found in excavation show excellent sections of the sedimentary sequence and thus offer direct insight into the structural and textural composition of the subsoil this paper describes an approach to also inspect the third dimension by mapping during the ongoing excavation it is possible to obtain a three dimensional representation of the subsurface within a short period of time a detailed description of a case study is presented and the findings from sedimentological hydrogeological and geophysical analyses are compared the gravel pit is located near the town of herten in southwest germany where relatively young unconsolidated fluvio glacial and fluvial sediments in the rhine basin are mined the excavated gravel body is built up by architectural elements typical for braided river deposits the study generated a high resolution data set of lithofacies hydrofacies and ground penetrating radar gpr profiles it represents the basis for a full three dimensional geostatistical reconstruction presented in the second part comunian et al 2011

the surface windfield over the antarctic ice sheets the intense radiative cooling of air over the ice slopes of antarctica generates a surface wind regime that is strongly controlled by topography and plays a key role in determining the behaviour of the atmosphere and ocean in high southern latitudes1 7 resultant surface winds are intimately linked to the orientation of the ice terrain fig 1 and display the highest degree of persistence found on earth the close coupling between wind and topography allows estimation of the former if the latter is known with some precision here we report on time averaged near surface airflow over the antarctic continent during winter diagnosed from a recent accurate synthesis of terrain slopes and from estimates of the lower atmospheric temperature structure the simulated drainage pat tern exhibits strong spatial variability with the airflow concentrated into several zones near the coastal margin these confluence regions are responsible for strong persistent katabatic winds over downstream coastal stretches and are indicative of zones of greatest katabatic potential

light reflection and transmission by a temperate snow cover an understanding of the reflection and transmission of light by snow is important for snow thermodynamics hydrology ecology and remote sensing snow has an intricate microstructure replete with ice air interfaces that scatter light spectral observations of light reflection and transmission from 400 to 1000 nm were made in temperate snowpacks under cold and under melting conditions the optical observations were made using a dual detector spectroradiometer one detector was placed above the snow surface to monitor the incident and reflected solar irradiance and the second detector was placed at the base of snow cover to measure downwelling irradiance the optical measurements were supplemented by a physical characterization of the snow including depth density and an estimate of grain size in general transmitted light levels were low and showed a strong spectral dependence with maximum values between 450 and 550 nm for example a 10 cm thick snow layer reduced visible transmission 500 nm to about 5 of the incident irradiance and infrared transmission 800 nm to less than 1 extinction coefficients were in the range 3 30 m 1 and tended to decrease slightly as the snow aged and increase as snow density increased

an overview of seasonal snow metamorphism the grains in seasonal snow undergo rapid and radical transformations in size shape and cohesion these grain characteristics affect all of the basic properties of snow snow is characterized as either wet or dry depending on the presence of liquid water wet snow is markedly different at low and high liquid contents dry snow is characterized as either an equilibrium form or a kinetic growth form that is it is either well rounded or faceted of course many snow grains display either transitional features between two of these categories or features which arise from other processes snow is classified depending on the dominant processes of its metamorphism