fracture propagation to the base of the greenland ice sheet during supraglacial lake drainage surface meltwater that reaches the base of an ice sheet creates a mechanism for the rapid response of ice flow to climate change the process whereby such a pathway is created through thick cold ice has not however been previously observed we describe the rapid 2 hours drainage of a large supraglacial lake down 980 meters through to the bed of the greenland ice sheet initiated by water driven fracture propagation evolving into moulin flow drainage coincided with increased seismicity transient acceleration ice sheet uplift and horizontal displacement subsidence and deceleration occurred over the subsequent 24 hours the short lived dynamic response suggests that an efficient drainage system dispersed the meltwater subglacially the integrated effect of multiple lake drainages could explain the observed net regional summer ice speedup

interferometric daylight seismic imaging summary claerbout s daylight imaging concept is generalized to a theory of interferometric seismic imaging ii interferometric seismic imaging is defined to be any algorithm that inverts correlated seismic data for the reflectivity or source distribution as examples we show that ii can image reflectivity distributions by migrating ghost reflections in passive seismic data and generalizes the receiver function imaging method used by seismologists interferometric seismic imaging can also migrate free surface multiples in common depth point cdp data and image source distributions from passive seismic data both synthetic and field data examples are used to illustrate the different possibilities of ii the key advantage of ii is that it can image source locations or reflectivity distributions from passive seismic data where the source position or wavelet is unknown in some cases it can mitigate defocusing errors as a result of statics or an incorrect migration velocity the main drawback with ii is that severe migration artefacts can be created by partial focusing of virtual multiples

jokulhlaups a reassessment of floodwater flow through glaciers 1 in glaciated catchments glacier generated floods jokulhlaups put human activity at risk with large sporadic jokulhlaups accounting for most flood related fatalities and damage to infrastructure in studies of jokulhlaup hydrodynamics the view predominates that floodwater travels within a distinct conduit eroded into the underside of a glacier however some jokulhlaups produce subglacial responses wholly inconsistent with the conventional theory of drainage by focusing on icelandic jokulhlaups this article reassesses how floodwater flows through glaciers it is argued that two physically separable classes of jokulhlaup exist and that not all jokulhlaups are an upward extrapolation of processes inherent in events of lesser magnitude and smaller scale the hydraulic coupling of multiple nonlinear components to the flood circuit of a glacier can induce extreme responses including pressure impulses in subglacial drainage representing such complexity in mathematical form should be the basis for upcoming research as future modeling results may help to determine the glaciological processes behind heinrich events moreover such an approach would lead to more accurate predictive models of jokulhlaup timing and intensity

spurious velocity changes caused by temporal variations in ambient noise frequency content ambient seismic noise cross correlations are now being used to detect temporal variations of seismic velocity which are typically on the order of 0 1 per cent at this small level temporal variations in the properties of noise sources can cause apparent velocity changes for example the spatial distribution and frequency content of ambient noise have seasonal variations due to the seasonal hemispherical shift of storms here we show that if the stretching method is used to measure time shifts then the temporal variability of noise frequency content causes apparent velocity changes due to the changes in both amplitude and phase spectra caused by waveform stretching with realistic seasonal variations of frequency content in the los angeles basin our numerical tests produce about 0 05 per cent apparent velocity change comparable to what meier et al observed in the los angeles basin we find that the apparent velocity change from waveform stretching depends on time windows and station pair distances and hence it is important to test a range of these parameters to diagnose the stretching bias better understanding of spatiotemporal noise source properties is critical for more accurate and reliable passive monitoring

an integrative geospatial and hydrogeochemical analysis for the assessment of groundwater quality in mahakalapara block odisha india a comprehensive hydrogeochemical and geospatial analysis has been carried out for the assessment of geochemical evolution and groundwater potability of the coastal aquifer system underlying the mahakalapara block odisha india the major ion chemistry of groundwater is primarily made up of alkali cations and strong acidic anions having a strong influence of the aquifer lithology geochemical analysis of the sample points towards the occurrence of dissolution and ion exchange processes across the study area spatially the former is the principal influencing process along the western part of the block whereas the latter is active across the entire study area increased alkali and chloride concentration during post monsoon period indicates potential saline and formational water influences potability analysis of the samples is suggestive of widespread unsuitability for domestic agricultural and industrial uses all the evaluating parameters except ph and residual sodium carbonate indicate a general unsafe characteristic of the subsurface water for domestic and agricultural utility from an industrial perspective the subsurface waters are corrosive but not incrusting

using a binary logistic regression method and gis for evaluating and mapping the groundwater spring potential in the sultan mountains aksehir turkey summary the purpose of this study is to produce a groundwater spring potential map of the sultan mountains in central turkey based on a logistic regression method within a geographic information system gis environment using field surveys the locations of the springs 440 springs were determined in the study area in this study 17 spring related factors were used in the analysis geology relative permeability land use land cover precipitation elevation slope aspect total curvature plan curvature profile curvature wetness index stream power index sediment transport capacity index distance to drainage distance to fault drainage density and fault density map the coefficients of the predictor variables were estimated using binary logistic regression analysis and were used to calculate the groundwater spring potential for the entire study area the accuracy of the final spring potential map was evaluated based on the observed springs the accuracy of the model was evaluated by calculating the relative operating characteristics the area value of the relative operating characteristic curve model was found to be 0 82 these results indicate that the model is a good estimator of the spring potential in the study area the spring potential map shows that the areas of very low low moderate and high groundwater spring potential classes are 105 586 km 2 28 99 74 271 km 2 19 906 101 203 km 2 27 14 and 90 05 km 2 24 671 respectively the interpretations of the potential map showed that stream power index relative permeability of lithologies geology elevation aspect wetness index plan curvature and drainage density play major roles in spring occurrence and distribution in the sultan mountains the logistic regression approach has not yet been used to delineate groundwater potential zones in this study the logistic regression method was used to locate potential zones for groundwater springs in the sultan mountains the evolved model was found to be in strong agreement with the available groundwater spring test data hence this method can be used routinely in groundwater exploration under favourable conditions

groundwater salinization in semi arid zones an example from nador plain tipaza algeria the groundwater of nador plain has been overexploited during the last two decades the goal was to meet the demands of intensive agricultural activities and at the same time the supply of drinking water as a result the dynamic balance between freshwater and seawater has been disturbed and the quality of the groundwater has deteriorated the degradation of the groundwater quality is characterized by salinization phenomena in this project the analysis of the piezometric map indicates a piezometric water level of 0 m inside the plain the chemical analysis of major ions in the groundwater was carried out on the water samples of 24 wells it indicates an electrical conductivity of water exceeding 1 500 s cm and chloride concentrations exceeding 500 mg l in the downstream of the plain presently the groundwater in this coastal sector is used neither for drinking water nor for irrigation in this study 35 vertical electrical soundings ves were carried out in the area with geoelectrical sections and maps of iso resistivity created to delineate the zones that are affected by saltwater intrusion the findings suggest that saltwater intrusion has reached a distance of approximately 1 600 m inside the aquifer

finite difference modeling experiments for seismic interferometry in passive seismic interferometry new reflection data can be retrieved by crosscorrelating recorded noise data the quality of the retrieved reflection data is among others dependent on the duration and number of passive sources present during the recording time the source distribution and the source strength to investigate these relations we set up several numerical modeling studies to carry out the modeling in a feasible time we design a finite difference algorithm for the simulation of long duration passive seismic measurements of band limited noise signatures in the subsurface novel features of the algorithm include the modeling of thousands of randomly placed sources during one modeling run the modeling experiments explore the dependency relation between the retrieved reflections and source signature length source positions number of sources and source amplitude variations from these experiments we observed that the positions of the passive sources and the length of the source signals are of direct influence on the quality of the retrieved reflections random amplitude variations among source signals do not seem to have a big impact on the retrieved reflections

gis based groundwater spring potential mapping in the sultan mountains konya turkey using frequency ratio weights of evidence and logistic regression methods and their comparison summary in this study groundwater spring potential maps produced by three different methods frequency ratio weights of evidence and logistic regression were evaluated using validation data sets and compared to each other groundwater spring occurrence potential maps in the sultan mountains konya turkey were constructed using the relationship between groundwater spring locations and their causative factors groundwater spring locations were identified in the study area from a topographic map different thematic maps of the study area such as geology topography geomorphology hydrology and land use cover have been used to identify groundwater potential zones seventeen spring related parameter layers of the entire study area were used to generate groundwater spring potential maps these are geology lithology fault density distance to fault relative permeability of lithologies elevation slope aspect slope steepness curvature plan curvature profile curvature topographic wetness index stream power index sediment transport capacity index drainage density distance to drainage land use cover and precipitation the predictive capability of each model was determined by the area under the relative operating characteristic curve the areas under the curve for frequency ratio weights of evidence and logistic regression methods were calculated as 0 903 0 880 and 0 840 respectively these results indicate that frequency ratio and weights of evidence models are relatively good estimators whereas logistic regression is a relatively poor estimator of groundwater spring potential mapping in the study area the frequency ratio model is simple the process of input calculation and output can be readily understood the produced groundwater spring potential maps can serve planners and engineers in groundwater development plans and land use planning

groundwater prospecting and management in an agro based rural environment of crystalline terrain of india an integrated hydrogeological investigation was made to delineate the socioeconomic problems in the agro based rural environment of the crystalline terrain of guntur district andhra pradesh india the integrated investigation comprised geoelectrical ge surveys remotely recorded data and pumping tests the subsurface layer parameters obtained from the sounding interpretation are presented in the form of ge sections and a fence diagram characteristic resistivities of various layers were obtained by correlating the known lithology with the ge sounding data total transverse resistance ttr and total longitudinal conductance tlc were computed from the interpretation of the sounding data the ttr map was compared with the depth of bedrock map and the values of tlc were correlated with the thickness of geoelectrical layers and water quality lineaments were mapped from the satellite imageries hydraulic properties were determined using the standard pumping test analysis potentiality of aquifer zones was assessed after comparing the known thickness of aquifer formations with the corresponding discharge q values the integrated study helps to evolve a criterion to classify the groundwater potential zones gpz into low medium and high based on the thickness of the aquifer zone and its corresponding resistivity ttr tlc and q a management plan has been proposed for sustainable development of groundwater in the region to eliminate water scarcity and its related problems

hydrogeochemical controls and usability of groundwater in the semi arid mayo tsanaga river basin far north province cameroon deuterium 18o major ions and dissolved silica in groundwater from semi arid mayo tsanaga river basin in the far north province cameroon were used to trace hydrogeochemical processes that control their concentrations and to explore for usability of the water electrical conductivity ranges from 57 2 581 s cm with alternating low and high values along the hydraulic gradient waters from piedmont alluvium show low concentrations in major cations which peak in mg within basalt na within plain alluvium and ca within basalt and the sandy limani yagoua ridge the initial dominant groundwater composition is cahco3 which did not evolve within the basalt and piedmont alluvium but evolved to nahco3 in the granite and plain alluvium the main processes controlling the major ions composition include the following 1 dissolution of silicates and fluorite 2 precipitation of fluorite and carbonate 3 cation exchange of ca in water for na in clay 4 and anthropogenic activities the d and 18o ratios vary from 35 to 0 7 and 5 3 to 1 1 respectively the lowest and highest isotope ratios are observed in groundwater within the downstream sandy limani yagoua ridge and the upstream graintes respectively variation in isotope ratios depends on altitude effect of 0 48 per 100 m between 600 and 850 m asl and on evaporation which had insignificant effect on the water salinity seventy percent of the groundwater shows poor drinking quality and 90 is suitable for irrigation

geochemical and statistical evaluation of groundwater in imphal and thoubal district of manipur india abstract in order to identify the hydrogeochemical process controlling the quality of groundwater an extensive study was carried out in imphal and thoubal district of manipur india the objectives of the studies were to delineate the spatial and temporal variability in groundwater quality and understand its suitability for human uses in the study area groundwater samples from 45 location have been collected during the pre monsoon monsoon and post monsoon seasons and analyzed for the major ions such as ca2 mg2 na k hco 3 cl so 4 2 no 3 po 4 3 f fe and silica the water quality of both districts was good for domestic and agricultural uses except for few samples these saline samples were localized and were due to the inherent lithology of the study area three major hydrochemical facies ca hco3 type mixed ca na hco3 and ca mg cl types in imphal district and ca hco3 mixed ca mg cl and ca cl type in thoubal district were identified the mineral stability diagrams indicated that the groundwater is in equilibrium with kaolinite and ca montmorillonite whereas gibbs plot showed that the chemical composition of ground water in both districts is controlled by the natural weathering processes irrespective of seasons among the chemical weathering processes silicate weathering was dominant the results were supported by wilcox plot and ussl diagrams the study reflected the overall suitability of groundwater for anthropogenic use

monitoring velocity variations in the crust using earthquake doublets an application to the calaveras fault california we present a technique that greatly improves the precision in measuring temporal variations of crustal velocities using an earthquake doublet or pair of microearthquakes that have nearly identical waveforms and the same hypocenter and magnitude but occur on different dates we compute differences in arrival times between seismograms recorded at the same station in the freqency domain by cross correlation of short windows of signal a moving window analysis of the entire seismograms including the coda gives t the difference in arrival times versus running time along the seismogram the time resolution of the method is an order of magnitude better than the digitization interval the t technique is illustrated with a pair of microearthquakes m 1 7 and 2 0 that occurred before and after the coyote lake california earthquake m 5 9 of august 6 1979 and on the same segment of the calaveras fault that ruptured during the earthquake the coda wave arrivals for some stations are progressively delayed for the second earthquake in the doublet so that its seismogram appears as a stretched version of the earlier event we interpret this systematic variation in t along the coda as a change in the average s velocity in the upper crust in the time interval between the two doublets s wave velocities appear to have decreased by 0 2 in an oblong region 5 10 km in radius at the south end of the aftershock zone

multi year monitoring of rift propagation on the amery ice shelf east antarctica we use satellite imagery from four sensors multi angle imaging spectroradiometer misr enhanced thematic mapper etm and radarsat and ers synthetic aperture radar sar to monitor the lengths of two rifts on the amery ice shelf from 1996 to 2004 we find that the rifts have each been propagating at a steady annual rate for the past 5 years superimposed on this steady rate is a seasonal signal where propagation rates are significantly higher in the summer period i e september april than in the winter period i e april september possible causes of this summer winter effect are changing properties of the ice melange which fills the rifts and seasonal changes in ocean circulation beneath the ice shelf

groundwater potential index in a crystalline terrain using remote sensing data demand for groundwater for drinking agricultural and industrial purposes has increased due to uncertainty in the surface water supply agriculture is the main occupation of the rural people in guntur district andhra pradesh india development of groundwater in the district is very less indicating a lot of scope for further development of groundwater resources however assessment of groundwater conditions particularly in a crystalline terrain is a complex task because of variations in weathering and fracturing zones from place to place systematic studies for evaluation of groundwater potential zones have been carried out in a crystalline terrain of the district information on soils geological formations and groundwater conditions is collected during the hydrogeological survey topographical and drainage conditions are derived from the survey of india topographical maps geomorphological units and associated landform features inferred and delineated from the indian remote sensing satellite imagery irs id liss iii fcc are moderately buried pediplain bpm shallow buried pediplain bps valley fills vf structural hill sh residual hills rh lineaments and land use land cover a groundwater potential index gpi is computed for relative evaluation of groundwater potential zones in the study area by integrating all the related factors of occurrence and movement of groundwater resources accordingly the landforms bpm bps vf sh and rh of the area are categorized as very good groundwater potential zone good to moderate groundwater potential zone moderate to poor groundwater potential zone poor to very poor groundwater potential zone and very poor groundwater potential zone respectively for development and utilization of both groundwater and surface water resources for eliminating water scarcity this study could help to improve the agrarian economy for better living conditions of the rural people taking the total weight score of the gpi into account a generalized classification of groundwater potential zones is evaluated for a quick assessment of the occurrence of groundwater resources on regional scale

estimating the rayleigh wave impulse response between seismic stations with the cross terms of the green tensor 1 the development of ambient noise tomography has provided a powerful tool to investigate the earth s subsurface with increased resolution most commonly surface wave tomography is performed on inter station estimates of the vertical component of rayleigh waves stemming from crosscorrelations of ocean generated noise here we estimate the cross terms of the rayleigh wave green tensor and show this is less sensitive to signal not in line with the seismic stations we illustrate this result with the batholiths temporary seismic deployment showing estimates of the rayleigh wave with a higher signal to noise ratio and a consequently better phase velocity dispersion curve this approach provides an opportunity for reliable ambient noise crosscorrelations over shorter time windows and more closely spaced stations in the future

calving processes and the dynamics of calving glaciers abstract calving of icebergs is an important component of mass loss from the polar ice sheets and glaciers in many parts of the world calving rates can increase dramatically in response to increases in velocity and or retreat of the glacier margin with important implications for sea level change despite their importance calving and related dynamic processes are poorly represented in the current generation of ice sheet models this is largely because understanding the calving problem involves several other long standing problems in glaciology combined with the difficulties and dangers of field data collection in this paper we systematically review different aspects of the calving problem and outline a new framework for representing calving processes in ice sheet models we define a hierarchy of calving processes to distinguish those that exert a fundamental control on the position of the ice margin from more localised processes responsible for individual calving events the first order control on calving is the strain rate arising from spatial variations in velocity particularly sliding speed which determines the location and depth of surface crevasses superimposed on this first order process are second order processes that can further erode the ice margin these include fracture propagation in response to local stress imbalances in the immediate vicinity of the glacier front undercutting of the glacier terminus by melting at or below the waterline and bending at the junction between grounded and buoyant parts of an ice tongue calving of projecting submerged ice feet can be regarded as a third order process because it is paced by first or second order calving above the waterline first order calving can be represented in glacier models using a calving criterion based on crevasse depth which is a function of longitudinal strain rate modelling changes in terminus position and calving rates thus reduces to the problem of determining the ice geometry and velocity distribution realistic solutions to the problem of modelling ice flow therefore depend critically on an appropriate choice of sliding law models that assume that basal velocities are controlled by basal drag can replicate much of the observed behaviour of calving glaciers with grounded termini but an important limitation is that they cannot be used to model floating glacier termini or ice shelves alternative sliding laws that parameterise drag from the glacier margins provide more flexible and robust ways of representing calving in ice sheet models such models can explain a remarkable range of observed phenomena within a simple unifying framework including downglacier increases in velocity and strain rates where basal and or lateral drag diminishes flow acceleration in response to thinning through time the tendency for glaciers to stabilise at pinning points in relatively shallow water or fjord narrowings the constraints on ice shelf stability and the contrasts in calving rates between tidewater and freshwater calving glaciers many unresolved issues remain however including the role played by the removal of backstress in the acceleration of retreating calving glaciers and the controls on melting at and below the waterline

glacier crevasses observations models and mass balance implications we review the findings of approximately 60 years of in situ and remote sensing studies of glacier crevasses as well as the three broad classes of numerical models now employed to simulate crevasse fracture the relatively new insight that mixed mode fracture in local stress equilibrium rather than downstream advection alone can introduce nontrivial curvature to crevasse geometry may merit the reinterpretation of some key historical observation studies in the past three decades there have been tremendous advances in the spatial resolution of satellite imagery as well as fully automated algorithms capable of tracking crevasse displacements between repeat images despite considerable advances in developing fully transient three dimensional ice flow models over the past two decades both the zero stress and linear elastic fracture mechanics crevasse models have remained fundamentally unchanged over this time in the past decade however multidimensional and transient formulations of the continuum damage mechanics approach to simulating ice fracture have emerged the combination of employing damage mechanics to represent slow upstream deterioration of ice strength and fracture mechanics to represent rapid failure at downstream termini holds promise for implementation in large scale ice sheet models finally given the broad interest in the sea level rise implications of recent and future cryospheric change we provide a synthesis of 10 mechanisms by which crevasses can influence glacier mass balance

dna labeled clay a sensitive new method for tracing particle transport the behavior of mobile colloids and sediment in most natural environments remains poorly understood in part because characteristics of existing sediment tracers limit their widespread use here we describe the development of a new approach that uses a dna labeled montmorillonite clay as a highly sensitive and selective sediment tracer that can potentially characterize sediment and colloid transport in a wide variety of environments including marine wetland ground water and atmospheric systems characteristics of dna in natural systems render it unsuitable as an aqueous tracer but admirably suited as a label for tracing particulates the dna labeled clay approach using techniques developed from molecular biology has extremely low detection limits very specific detection and a virtually infinite number of tracer signatures furthermore dna labeled clay has the same physical characteristics as the particles it is designed to trace it is environmentally benign and it can be relatively inexpensively produced and detected our initial results show that short 500 base pair strands of synthetically produced dna reversibly adsorb to both na montmorillonite and powdered silica surfaces via a magnesium bridge the dna montmorillonite surface complexes are stable in calciumbicarbonate spring waters for periods of up to 18 days and only slowly desorb to the aqueous phase whereas the silica surface complex is stable only in distilled water both materials readily release the adsorbed dna in dilute edta solutions for amplification by the polymerase chain reaction pcr and quantification the stability of the dna labeled clay complex suggests that this material would be appropriate for use as an extremely sensitive sediment tracer for flow periods of as long as 2 weeks and possibly longer

aquifer vulnerability and seawater intrusion risk using galdit gqiswi and gis case of a coastal aquifer in tunisia due to increase in population and agricultural activities the sfax coastal aquifer is under tremendous stress and seawater intrusion becomes a serious concern this situation needs an assessment of aquifer vulnerability and seawater intrusion risk a new approach for vulnerability mapping using galdit groundwater quality index for seawater intrusion gqiswi geostatistics the ghyben herzberg model and gis was developed the model is used to determine the trend of groundwater contamination by seawater intrusion in the coastal aquifer in sfax basin tunisia vulnerability assessment method is recognized through assessing weight and ratings of the galdit relevant parameter a second vulnerability map was realized based upon the groundwater quality index for seawater intrusion integrating the water quality parameters for delineating seawater intrusion in the aquifer the validation of gqiswi and galdit vulnerability maps was undertaken through comparison of areas of high jones ratio chloride and tds concentration and their relative vulnerability index the ghyben herzberg model has been used to predict the actual seawater intrusion extend and evaluate the freshwater saltwater dynamics the results reveal that the coastal area is currently undergoing seawater intrusion and its northern part is the most affected one by this contamination

monitoring a temporal change of seismic velocity in a volcano application to the 1992 eruption of mt merapi indonesia multiplets i e events with similar waveforms are selected from shallow earthquakes recorded on merapi volcano indonesia before the eruption of february 2nd 1992 two multiplet families are found with their sources close to the summit their seismograms are analyzed using the moving window cross spectrum technique which measures the precise time delay between seismic phases in the entire seismogram for both families of multiplets a gradual decrease in the arrival times of coda waves is observed as a function of the date prior to the eruption coda waves are becoming progressively faster up to 1 2 per cent as the time interval to the eruption shortens this observation is interpreted as the consequence of an increase in the seismic velocity inside the volcano the increase in velocity started in may 1991 and was observed until september 1991 4 months before the eruption this velocity increase may be related to an increase in pressure in the magma chamber or in the conduits and to the resulting closure of the surrounding cracks

geochemistry of groundwater in parts of guntur district andhra pradesh india hydrogeochemical investigations which are significant for the assessment of water quality have been carried out to study the sources of dissolved ions in groundwaters of some rural areas of guntur district andhra pradesh india groundwaters in the area are mostly brackish high contents of sio2 and na and cl ions in groundwater in comparison with those of seawater suggests a meteoric origin of groundwater the high concentration of sio2 and various geochemical signatures reflect the weathering of minerals however the na k vs cl ratio suggests weathering has occurred only to some extent the chemistry of groundwater favours the formation of clay minerals montmorillonite illite and chlorite because of evapotranspiration the positive saturation index of caco3 and the high signatures of ma2 ca2 and na ca2 reveals the occurrence of evaporation the evaporation enhances the concentration of ions which occurred originally in the water in the soils during summer the very high so 4 2 and cl contents in some groundwaters and the occurrence of kankar caco3 in the area suggest a long history of evaporation greater ionic concentration in the groundwaters of post monsoon compared with pre monsoon indicates the increasing addition of leachates into the groundwater from the soils in the monsoon and anthropogenic activities which leads to a deteriorating quality of groundwater according to the gibbs diagrams rock weathering to some extent and evaporation are the dominant phenomena responsible for the higher ionic concentrations found in groundwater measures that benefit sustainable management of groundwater quality are suggested in this study

integration of hydrological factors and demarcation of groundwater prospect zones insights from remote sensing and gis techniques the study demonstrates the potential of geographical information system and statistical based approaches to identify the hydrological processes and demarcate the groundwater prospect zones of the gangolli basin karnataka state india the basin is situated in humid tropical climate and influenced by three major rivers viz kollur 6th order stream chakra 6th order stream and haladi 7th order stream which cover an area of 1 512 km2 and cumulative length of 84 km various thematic maps drainage geomorphology geology slope soil lineament and lineament density were prepared using survey of india topographic maps indian remote sensing irs p6 images and other published maps hydrogeomorphologic characteristics were correlated with different morphometric parameters to identify the hydrological processes and demarcate the groundwater potential zones of the basin all the hydrological units and morphometric parameters were assigned suitable weightages according to their relative importance to groundwater potentiality to identify the most deficit surplus zones of groundwater based on hydrological characteristics integrated thematic maps reveal that 14 217 km2 of basin area falls under very good 32 486 km2 under good 23 353 km2 under moderate and 30 443 km2 under poor zones for groundwater potential from the sub basin wise prioritisation it has been inferred that sb iii scored highest groundwater potential followed by sb x result of morphometric analyses with the hydrologic parameters indicates that 99 area of sb iii and sb x are under very good to moderate groundwater potential zone this study clearly demonstrates that hydrological parameters in relation with morphometric analyses are useful to demarcate the prospect zones of groundwater

abrupt changes in indian summer monsoon strength during the last deglaciation and early holocene based on stable isotope evidence from lake chenghai southwest china identifying variability and the mechanisms driving variability in the indian summer monsoon ism since the last deglaciation is critical for understanding past hydroclimatic change in this study we present an accelerator mass spectrometry radiocarbon dated record of delta o 18 variations in authigenic carbonates derived from lake chenghai in southwest china a region that receives moisture mainly from the indian ocean the delta o 18 values vary from 11 9 to 0 1 parts per thousand providing a detailed record of variations in ism precipitation delta o 18 values and lake hydrological balance the record shows that the ism generally strengthened in the post glacial between 15 6 and 8 8 cal ka bp but that three centennial to millennial scale drought events were superimposed on the long term trend drought events as indicated by substantial positive shifts in 8 18 0 value occurred from 15 6 0 2 to 14 4 0 2 12 5 0 2 to 11 7 0 2 and 10 1 0 1 to 10 0 0 1 cal ka bp corresponding to the heinrich 1 younger dryas and bond 7 cold events in the north atlantic region respectively the timings of these droughts are suggested to be related to meltwater discharge into the north atlantic the weakened atlantic meridional overturning circulation which leads in turn to the southward migration of the intertropical convergence zone and cooling in the tropical indian ocean

surface wave array tomography in se tibet from ambient seismic noise and two station analysis i phase velocity maps summary empirical green s functions egfs between pairs of seismographs can be estimated from the time derivative of the long time cross correlation of ambient seismic noise these egfs reveal velocity dispersion at relatively short periods which can be used to resolve structures in the crust and uppermost mantle better than with traditional surface wave tomography we combine rayleigh wave dispersion estimates from egfs and from traditional two station ts analysis into a new approach to surface wave array tomography with data from dense receiver arrays we illustrate the methodology with continuous broad band recordings from a temporary seismographic network on the southeastern part of the tibetan plateau in sichuan and yunnan provinces sw china the egfs are robust under temporal changes in regional seismicity and the use of either ambient noise approximated by records without signal from events with magnitude mb 5 or 4 or surface wave coda produces similar results the egfs do not strongly depend on the presence of large earthquakes but they are not reciprocal for stations aligned in the n s direction this directionality reflects the paucity of seismicity to the north of the array using a far field representation of the surface wave green s function and an image transformation technique we infer from the egfs the rayleigh wave phase velocity dispersion in the period band from 10 30 s a classical ts approach is used to determine rayleigh wave phase velocity dispersion between 20 120 s together they constrain phase velocity variations for t 10 120 s which can be used to study the structure from the crust to the upper mantle beneath se tibet short and intermediate period 10 80 s phase velocities are prominently low suggesting that the crust and upper mantle beneath se tibet is characterized by slow shear wave propagation

seismic interferometry using multidimensional deconvolution and crosscorrelation for crosswell seismic reflection data without borehole sources crosswell reflection method is a high resolution seismic imaging method that uses recordings between boreholes the need for downhole sources is a restrictive factor in its application for example to time lapse surveys an alternative is to use surface sources in combination with seismic interferometry seismic interferometry si could retrieve the reflection response at one of the boreholes as if from a source inside the other borehole we investigate the applicability of si for the retrieval of the reflection response between two boreholes using numerically modeled field data we compare two si approaches crosscorrelation cc and multidimensional deconvolution mdd si by mdd is less sensitive to underillumination from the source distribution but requires inversion of the recordings at one of the receiver arrays from all the available sources we find that the inversion problem is ill posed and propose to stabilize it using singular value decomposition the results show that the reflections from deep boundaries are retrieved very well using both the cc and mdd methods furthermore the mdd results exhibit more realistic amplitudes than those from the cc method for downgoing reflections from shallow boundaries we find that the results retrieved from the application of both methods to field data agree well with crosswell seismic reflection data using borehole sources and with the logged p wave velocity

time lapse monitoring of rock properties with coda wave interferometry 1 the coda of seismic waves consists of that part of the signal after the directly arriving phases in a finite medium or in one that is strongly heterogeneous the coda is dominated by waves which have repeatedly sampled the medium small changes in a medium which may have no detectable influence on the first arrivals are amplified by this repeated sampling and may thus be detectable in the coda we refer to this use of multiple sampling coda waveforms as coda wave interferometry we have exploited ultrasonic coda waves to monitor time varying rock properties in a laboratory environment we have studied the dependence of velocity on uniaxial stress in berea sandstone the temperature dependence of velocity in granite and in aluminum and the change in velocity due to an increase of water saturation in sandstone there are many other possible applications of coda wave interferometry in geophysics including dam and volcano monitoring time lapse reservoir characterization earthquake relocation and stress monitoring in mining and rock physics

seismic attenuation from recordings of ambient noise abstractwe applied seismic interferometry to data from an ocean bottom survey offshore norway and found that ambient seismic noise can be used to constrain subsurface attenuation on a reservoir scale by crosscorrelating only a few days of recordings by broadband ocean bottom seismometers we were able to retrieve empirical green s functions associated with surface waves in the frequency range between 0 2 and 0 6 hz and acoustic waves traveling through the sea water between 1 0 and 2 5 hz we discovered that the decay of these surface waves cannot be explained by geometrical spreading alone and required an additional loss of energy with distance we quantified this observed attenuation in the frequency domain using a modified bessel function to describe the cross spectrum in a stationary field we averaged cross spectra of equally spaced station couples and sorted these azimuthally averaged cross spectra with distance we then obtained frequency dependent estimates of attenuation by minimizing the misfit

direct and indirect effects of holocene climate variations on catchment and lake processes of a treeline lake sw china sedimentary records of inorganic elements and pigments over the last 12 000 years are used to assess major changes in limnological conditions of tiancai lake a small treeline lake sw china in response to holocene climate variations algal communities shifted from the dominance of cyanobacteria and cryptophytes in the early holocene towards siliceous algae in the mid holocene and chlorophytes in the late holocene algae responded to a combination of climate mediated vegetation and soil development associated with allochthonous inputs of dissolved nutrients and organic matter and sediment infilling decreases in al pb cu and zn from the early holocene probably resulted from soil podsolization and the sequestration of these elements within soils changes in mn and fe were likely linked to redox condition in catchment soils and water column synchronous peaks in ti ba ca sr na k and mg median grain size and magnetic susceptibility coincided with the troughs in the chemical index of alteration indicating that episodic cold events enhanced upland bedrock erosion and transported unleached and coarse detritus into the lake these cold events broadly correlate with holocene ice rafting events in the north atlantic although the cold events altered the influx of minerogenic elements by regulating upland bedrock erosion climate mediated vegetation and soil development led to a muted impact on primary producers holocene algal community shifts were subtle reflecting the relative abundance of p derived from weathering and n derived from soils throughout the record with the most pronounced effects on the lake biota being benthic expansion which occurred in response to sediment infilling

hydrogeochemical characterization and quality assessment of groundwater around umrer coal mine area nagpur district maharashtra india quality assessment as well as hydrogeochemical characterization of 45 representative groundwater samples around umrer coal mine area was undertaken the ph of the water lies in the normal range i e from 7 5 to 8 5 the electrical conductivity varies from 826 to 1 741 the total hardness varies from 289 to 1 302 and the tds values range from 528 6 to 1 114 2 mg l which reflects variation in lithology and thus the distinction in hydrogeological regime the cation chemistry is dominated by ca2 and mg2 while anion chemistry is dominated by cl and hco3 out of total ten hydrochemical facies the two dominant facies are mg ca hco3 37 7 and ca mg so4 hco3 17 7 the groundwater in the study area in general is useful for drinking and domestic use however it has marginal utility for irrigation purpose standard us salinity laboratory classification shows that water of the study area belongs to c2 s1 and c3 s1 classes the concentration of 9 trace elements analysed from 18 samples did not exceed the desirable limit

coda wave interferometry for estimating nonlinear behavior in seismic velocity in coda wave interferometry one records multiply scattered waves at a limited number of receivers to infer changes in the medium over time with this technique we have determined the nonlinear dependence of the seismic velocity in granite on temperature and the associated acoustic emissions this technique can be used in warning mode to detect the presence of temporal changes in the medium or in diagnostic mode where the temporal change in the medium is quantified

calving of large tabular icebergs from ice shelf rift systems 1 we used interferometric synthetic aperture radar to study the detachment process that allowed two large icebergs to calve from the ross ice shelf antarctica time series of rift geometries indicate that rift widths increased steadily whereas rift lengths increased episodically through several discrete rift tip propagation events we also conducted modeling experiments constrained by the observed rift geometry both the observations and model suggest that rift opening and thus tabular iceberg calving are largely driven by glaciological stresses stress introduced by the effect of gravity on the ice shelf rather than by stress introduced by the ocean and atmosphere e g tides and storms this style of rift propagation is expected to determine the steady background calving rate of ice shelves and thus differs significantly from styles that led to the recent disintegration of ice shelves in response to climate warming e g the larsen b ice shelf on the antarctic peninsula

an assessment of groundwater salinization in haryana state in india using hydrochemical tools in association with gis unplanned abstraction of groundwater due to various land use land cover activities and variations in monsoonal rainfall have greatly affected the availability and quality of groundwater resources in semi arid regions of india in the present study a study of the hydrogeochemical characteristics of groundwater was undertaken in the sonipat district of haryana in india together with the use of stable isotope 18o and d measurements and gis analysis a total of 53 groundwater samples were collected from seven blocks of the district and 14 water quality parameters and stable isotopes 18o and d were analysed to infer hydrogeochemical processes taking place in the area the integration of hydrochemistry with gis is very helpful to understand the factors governing in the area the majority of the samples showed na cl type of hydrochemical facies the trilinear plot for major cations and anions in groundwater indicates dominance of sodium calcium chloride and bicarbonate ions nitrate plumes in the groundwater appear to be migrating in groundwater from the central and south western parts of the area towards the urbanized areas a total of 64 of the samples exceed the maximum permissible limit of 1 5 mg l given by who for fluoride besides natural sources such as silicate and carbonate weathering ion exchange and reverse ion exchange the leaching of surficial salts and untreated industrial wastes along with unregulated abstraction are contributing to poor groundwater quality in the study area an assessment of saturation indices has shown that groundwater in the area is unsaturated with respect to anhydrite halite and gypsum suggesting significant contribution of ca2 mg2 and other ions in the groundwater a scatter plot of 18o versus cl also suggests mixing of saline water with fresh groundwater

rapid collapse of northern larsen ice shelf antarctica in january 1995 4200 square kilometers of the northern larsen ice shelf antarctic peninsula broke away radar images from the ers 1 satellite complemented by field observations showed that the two northernmost sections of the ice shelf fractured and disintegrated almost completely within a few days this breakup followed a period of steady retreat that coincided with a regional trend of atmospheric warming the observations imply that after an ice shelf retreats beyond a critical limit it may collapse rapidly as a result of perturbated mass balance

retrieving surface waves from ambient seismic noise using seismic interferometry by multidimensional deconvolution retrieving virtual source surface waves from ambient seismic noise by cross correlation assumes among others that the noise field is equipartitioned and the medium is lossless violation of these assumptions reduces the accuracy of the retrieved waves a point spread function computed from the same ambient noise quantifies the associated virtual source s spatial and temporal smearing multidimensional deconvolution mdd of the retrieved surface waves by this function has been shown to improve the virtual source s focusing and the accuracy of the retrieved waves using synthetic data we tested mdd on data recorded during the batholiths experiment a passive deployment of broadband seismic sensors in british columbia canada the array consisted of two approximately linear station lines using 4 months of recordings we retrieved fundamental mode rayleigh waves 0 05 0 27 hz we only used noise time windows dominated by waves that traverse the northern line before reaching the southern 2 5 of all data compared to the conventional cross correlation result based on this subset the mdd waveforms are better localized and have significantly higher signal to noise ratio furthermore mdd corrects the phase and the spatial deconvolution fills in a spectral f k domain gap between the single frequency and double frequency microseism bands frequency whitening of the noise also fills the gap in the cross correlation result but the signal to noise ratio of the mdd result remains higher comparison of the extracted phase velocities shows some differences between the methods also when all data are included in the conventional cross correlation

paleoclimate of southwestern china for the past 50 000 yr inferred from lake sediment records abstract long sediment cores 12 5 and 13 5 m from two lakes in yunnan province were used to infer the paleoclimate of southwest china over the past 50 000 yr during the holocene and marine isotope stage mis 3 bio induced carbonate precipitation and organic matter om production was high suggesting warm temperatures and high primary productivity in contrast sediment inorganic carbon ic and organic carbon oc concentrations were low in last glacial deposits from 38 000 to 12 000 cal yr b p indicating cool temperatures and low productivity the 50 000 yr record has alternating peaks of carbonate and coarse grain 38 m quartz that reflect warm moist interglacial or interstadial conditions alternating with cold dry glacial or stadial conditions respectively spectral analysis of the carbonate and quartz signals reveals power concentrated at periods of 7200 and 8900 cal yr respectively that may reflect a nonlinear climate response to precessional forcing at a time of reduced eccentricity modulation mcintyre and molfino 1996 oxygen isotope values of calcite from yunnan lake cores indicate the summer monsoon was weak during the last glaciation from 50 000 to 12 000 cal yr b p the summer monsoon intensified between 12 000 and 8000 cal yr b p but weakened gradually in response to insolation forcing during the mid to late holocene our results support the overpeck et al 1996 model that posits a weak summer monsoon during the last glaciation that responded nonlinearly to insolation forcing when its intensity was affected by eurasian snow cover and ice sheet extent the summer monsoon intensified and responded linearly to seasonal insolation forcing in the holocene when ice volume diminished

dynamic damage model of crevasse opening and application to glacier calving 1 theory and applications of continuum damage mechanics for ice are discussed and on this basis an ice damage model valid at low stresses is proposed the model describes the damage itself the rheology of the damaged ice and the damage evolution a local damaging and healing law is considered and its parameterization is motivated the model parameters are inferred from published data of laboratory experiments the model is subsequently implemented in a finite element code and applied to the prediction of a calving process and to the destabilization of an ice chunk from a hanging glacier numerical results show good agreement with field measurements

seismic noise correlations to image structural and mechanical changes associated with the mw 7 9 2008 wenchuan earthquake we locate temporal changes of seismic wave speed and scattering properties of the crust associated with the 2008 mw7 9 wenchuan earthquake to that end we analyze ambient seismic noise records from 2007 until the end of 2008 in the 1 3 s period band and in the 12 20 s period band measured in a region that covers the southern two thirds of the fault activated during the earthquake to locate the changes we use a refined imaging procedure based on the sensitivity of scattered waves to weak perturbations this inverse method uses the radiative transfer approximation to describe the intensity of the noise correlation coda our results show that the largest structural changes are observed northeast of the wenchuan epicenter around the fault zone where aftershocks are distributed the spatial and temporal characteristics of the behavior of the crust at depth around the wenchuan earthquake suggest a postseismic and geology dependent signature of the middle crust we also observe a clear seasonal signature within the sichuan basin at depth that we relate to the heavy rainfalls during the monsoon season this seasonality can also be observed at the surface in form of a waveform decoherence our study highlights that seismic velocity changes and waveform decoherence are independent measurements that are sensitive to different parameters and can thus give complementary information in our study we also point out the value of studying the evolution of the changes at different times in the coda

hydrochemical assessment of pond and stream water near abandoned barite mine sites in parts of oban massif and mamfe embayment southeastern nigeria hydrochemical studies were carried out in parts of oban massif and mamfe embayment southeastern nigeria to examine the contributions of barite mining activities on water quality pond and stream water samples were collected from six abandoned barite mines and adjoining streams areas during dry and wet seasons these samples were analysed for physicochemical parameters using standard techniques the results showed that the quality of water samples in the vicinity of barite mine sites was characterized by low ph low mineralization high suspended solids and deep colour sodium na and calcium ca2 are the dominant cations and bicarbonate hco3 and sulphate so4 2 the dominant anions the low concentration of dissolved silica relatively high concentrations of na hco3 and so4 2 suggest a combined influence of silicate carbonate and weathering of mine spoils the total dissolved solids total suspended solids electrical conductivity and major ions except na and k are higher for water draining barite mines from cretaceous sediments while na k ba2 are higher in basement rock areas correlation and factor analyses suggest that the main components of the water samples are related to anthropogenic geogenic mineralization and environmental controls while gibbs diagram plots indicate weathering as the main process controlling the chemistry of water computed values of hardness and some irrigational parameters showed that the pond and stream water samples are generally soft and can be used for irrigation generally the water quality satisfied the who 2008 and nis 2007 standards for domestic agriculture and industrial however there is the need to assess the impact of the pollution on the ecosystem and human health while remediation measures are being considered

holocene monsoon climate documented by oxygen and carbon isotopes from lake sediments and peat bogs in china a review and synthesis there has been much recent debate about holocene climate variation in the monsoon region of china especially the temporal pattern of variations in precipitation the time transgressive nature of the holocene precipitation maximum and the extent to which variations in regions influenced by the indian summer monsoon ism and the east asian summer monsoon easm have been synchronous we summarize and compare carbonate oxygen isotope records delta o 18 carb from ten lakes within the present day ism region we discuss their paleoclimate significance considering the present day moisture source isotopic composition of precipitation and the hydrological setting the delta o 18 carb records are controlled mainly by the isotopic composition of lake water which in turn is a function of regional precipitation evaporation p e balance and the proportion of precipitation that is monsoon derived we normalized the delta o 18 carb data and used these records to generate an integrated moisture index this index along with oxygen isotope records from speleothems and carbon isotope records delta c 13 org from peats within the monsoon region suggests that holocene climate was broadly synchronous across the monsoon region and within the limits of accuracy of the existing age models provides no strong evidence for previously proposed anti phasing of the ism and the easm stable isotope records from lake sediments and peat bogs have excellent potential for providing high quality paleoclimate data for monsoon asia and complement high resolution speleothem sequences which are only found in certain localities c 2011 elsevier ltd all rights reserved

assessment of hydrogeochemistry and the quality of groundwater in 24 parganas districts west bengal hydrogeochemistry of an area helps in understanding the geological processes which control the chemistry of water and play an important role in determining the suitability of groundwater for various purposes in the present study an attempt has been made to understand the geological processes controlling the quality of water in a part of north and south 24 parganas districts of west bengal 39 representative groundwater samples were collected from the study area and physico chemical parameters were analyzed for all the samples schoeller and durov diagram were used to understand the hydrochemical nature of water results obtained from water chemistry were used in the interpretation of controlling processes using different conventional graphs and determining the quality of groundwater silicate weathering and ion exchange are the dominant processes controlling the chemistry of groundwater in the study area where calcium and magnesium in the water are replaced by the sodium and potassium in the minerals from the host rock as chloro alkaline indices are negative at most of the places saturation index was calculated to understand the mineralogy of the subsurface the groundwater is oversaturated with iron containing minerals like fe oh 3 goethite and hematite while undersaturated with anhydrite and gypsum the groundwater suitability was determined by calculating water quality index for drinking purpose while sar and residual sodium carbonate indices for the agricultural purpose the groundwater in the study area is not suitable for drinking but can be used for other household use and in irrigation for agriculture

seismic surface waves in a suburban environment active and passive interferometric methods seismic interferometry refers to a new range of methods where inter receiver wavefields those that would have been recorded if one of each pair of receivers had been a source can be estimated by cross correlation of wavefields recorded at each of the receivers these methods have found many applications in different fields of seismology including creating virtual sources in wells under complex overburdens computational full wavefield modelling and passive construction of surface wave waveforms from background noise in the earth curtis et al 2006 provide an overview of various applications of seismic interferometry referred to herein and more in depth works can be found in the special supplement on seismic interferometry in the july august issue of geophysics

the use of magnetic and geo electrical data to delineate the subsurface structures and groundwater potentiality in southeastern sinai egypt the study area is located in the southern part of sinai peninsula this study was done to delineate the subsurface structure of the basement rocks affecting the groundwater potentiality in the study area and to perform the lateral and vertical variations in the subsurface lithologic properties to achieve these a high resolution total intensity magnetic map and geo electrical survey were acquired two dimensional power spectrum analytical signal and euler deconvolution techniques are applied on magnetic data the geo electric data interpretations concluded that the study area can be classified into five units of sediments arranged as 1 the top surficial layer of dry sand and gravels 2 the second layer of silty sand layer with thickness ranging from 5 to 35 m 3 the third layer of dry sand with thickness ranging from 5 to 130 m 4 the fourth layer composed of saturated sand which was considered as the water bearing zone of the investigated interval its thickness ranges between 50m and more than 200 m 5 the fifth layer is interpreted as basement rocks the depth to the basement surface has an average value of 156 m at the eastern side and 758 m at the western side of the study area this area is characterized by a graben structure bounded by major faults striking in the nw se direction and is considered one of the most promising regions for water resources in sinai

multiscale matched field processing for noise source localization in exploration geophysics abstractin the study we investigate the use of ambient noise data to locate microseismic sources at the exploration scale we develop a multiscale matched field processing mfp approach to localize seismic sources at frequencies below 10 hz an application to an actual data set acquired over a hydrocarbon field is presented to determine the reliability of the mfp procedure the data used were continuously recorded over five days at a total of 397 stations on a 1 km per side square seismic network the mfp results show 1 a dominant and stable surface source associated with human activities road and exploration platforms around the reservoir and 2 weaker sources at depth below the seismic network that are related to the injection extraction process

high frequency rayleigh wave tomography using traffic noise from long beach california abstractusing a dense seismic array in long beach california we have investigated the effectiveness of using traffic noise for passive subsurface imaging spectral analysis revealed that traffic induced vibrations dominate the ambient seismic noise field at frequencies between 3 and 15 hz using the ambient noise crosscorrelation technique at these frequencies we have extracted fundamental and first order mode rayleigh waves generated by interstate 405 and local roads we picked group traveltimes associated with the fundamental mode and used them in a straight ray tomography procedure to produce group velocity maps at 3 0 and 3 5 hz the velocity trends in our results corresponded to shallow depths and coincided well with lithologies outlined in a geologic map of the survey area the most prominent features resolved in our velocity maps were the low velocities to the north corresponding to less consolidated materials high velocities to the south corresponding to more consolidated materials a low vel

the isotopic response of lake chenghai sw china to hydrologic modification from human activity the human modification of lake hydrology is widespread in the industrial era however anthropogenic impacts have occurred for thousands of years in regions of the world with long histories of human occupation here we use geochemical analyses of lake sediment to document the isotopic and geochemical response of cheng lake chenghai in southwestern china to catchment modification including the construction of a downstream dam the chenghai record indicates that land use changes affected the lake catchment by at least ad 1150 as evidenced by an increased flux of terrestrial organic matter sediment with high concentrations of sorbed metals and variations in stable isotopes of oxygen in precipitated aragonite decreases in magnetic susceptibility and metal concentrations after ad 1360 indicate a change in sediment basin dynamics the construction of a downstream dam between ad 1573 and 1620 caused positive shifts in the isotopic composition of aragonite indicative of increased evaporative loss and a lo

characterization and evaluation of processes governing the groundwater quality in parts of the sabarmati basin gujarat using hydrochemistry integrated with gis intense agricultural and industrial activities in any area are likely to make groundwater vulnerable with respect to its quality in one such area which is a part of sabarmati river basin of gujarat factors influencing the groundwater hydrochemistry in pre and post monsoon season were evaluated groundwater samples were collected from 5 km 5 km grids on the basis of spectral signature of vegetation and soil observed on satellite image integration of conventional graphical plots piper plot saturation index values estimated using phreeqc and gis was helpful not only to create the database for analysis of spatial variation in respective water quality parameters but also to decipher the hydrogeochemical process occurring in such a large area ussl diagram and sodium were used to characterise the suitability of groundwater for irrigation it was observed that leaching of wastes disposed from anthropogenic activities and agrichemicals is the major factor influencing the groundwater quality in addition to the natural processes such as weathering dissolution and ion exchange sea water relics are also impacting the groundwater quality control of indiscriminate and unplanned exploitation of groundwater application of fertilizers and disposal of industrial wastes in the affected areas can possibly ensure groundwater protection from further pollution and depletion copyright 2011 john wiley sons ltd

quality assessment of potable water in the town of kolasib mizoram india the potable water for the residents of the town of kolasib in mizoram state india is supplied by the public health engineering department phed of the government of mizoram without any notable treatment the source of water is the tuichhuahen river flowing from north to south in the area water samples were analyzed for their physicochemical and bacteriological characteristics in order to obtain the current quality level of the potable water in the twon the samples were collected from two different sources i e the supply from the government agency phed and from the naturally occurring springs tuikhurs the results suggest that the water supplied by the phed is better than that from the tuikhurs however the quality of water from both sources which are used for drinking and domestic purposes were found to be more or less within the tolerance limits

observation of surface seismic activity changes of an alpine glacier during a glacier dammed lake outburst during the 2004 outburst flood of gornersee switzerland we observed surface microseismic activity so called icequakes near the glacier dammed lake on gornergletscher using surface waves we located near surface tensile fracturing events by inverting time delays using a quasi newton scheme we located 8520 near surface events with uncertainties of less than 10 m seismic activity increased during the lake drainage and the icequake epicenters migrated downglacier furthermore we identified events whose fault plane orientations are nearly perpendicular to the local pattern of surface crevassing these observations can be explained by the rotation of principal strains at the glacier surface deduced from local ice flow measurement which occurred during the flotation of the ice dam at the onset of the lake drainage in general we suggest that our technique is a useful tool to locate large data sets of microseismic events and can be used to monitor the temporal evolution of fracture processes and their dependence on glacier flow and glacier hydrology

suitability assessment of deep groundwater for drinking and irrigation use in the djeffara aquifers northern gabes south eastern tunisia the multilayered djeffara aquifer system south eastern tunisia has been intensively used as a primary source to meet the growing needs of the various sectors drinking agricultural and industrial purposes the analysis of groundwater chemical characteristics provides much important information useful in water resources management detailed knowledge of the geochemical evolution of groundwater and assessing the water quality status for special use are the main objective of any water monitoring study an attempt has been made for the first time in this region to characterize aquifer behavior and appreciate the quality and or the suitability of groundwater for drinking and irrigation purposes in order to attend this objective a total of 54 groundwater samples were collected and analyzed during january 2008 for the major cations sodium calcium magnesium and potassium anions chloride sulfate bicarbonate trace elements boron strontium and fluoride and physicochemical parameters temperature ph total dissolved salts and electrical conductivity the evolution of chemical composition of groundwater from recharge areas to discharge areas is characterized by increasing sodium chloride and sulfate contents as a result of leaching of evaporite rock in this study three distinct chemical trends in groundwater were identified the major reactions responsible for the chemical evolution of groundwater in the investigated area fall into three categories 1 calcite precipitation 2 gypsum and halite dissolution and 3 ion exchange based on the physicochemical analyses irrigation quality parameters such as sodium absorption ratio sar percentage of sodium residual sodium carbonate residual sodium bicarbonate and permeability index pi were calculated in addition groundwater quality maps were elabortaed using the geographic information system to delineate spatial variation in physico chemical characteristics of the groundwater samples the integration of various dataset indicates that the groundwater of the djeffara aquifers of the northern gabes is generally very hard brackish and high to very high saline and alkaline in nature the water suitability for drinking and irrigation purposes was evaluated by comparing the values of different water quality parameters with world health organization who guideline values for drinking water piper trilinear diagram was constructed to identify groundwater groups where the relative major anionic and cationic concentrations are expressed in percentage of the milliequivalent per liter meq l and it was demonstrated that the majority of the samples belongs to so4 cl ca na cl so4 na ca and na cl hydrochemical facies as a whole all the analyzed waters from this groundwater have revealed that this water is unsuitable for drinking purposes when comparing to the drinking water standards salinity high electric conductivity sodium adsorption ratio and sodium percentages indicate that most of the groundwater samples are inappropriate for irrigation the sar vary from medium s2 to very high s4 sodicity therefore the water of the djeffara aquifers of the northern gabes is dominantly of the c4 s2 class representing 61 23 of the total wells followed by c4 s3 and c4 s4 classes at 27 27 and 11 5 of the wells respectively based on the us salinity classification most of the groundwater is unsuitable for irrigation due to its high salt content unless certain measures for salinity control are undertaken

geochemistry of groundwater burdwan district west bengal india hydrogeochemical investigations are carried out in the different blocks of burdwan district west bengal india in order to assess its suitability for drinking as well as irrigation water purpose altogether 49 representative groundwater samples are collected from bore wells and the water chemistry of various ions viz ca2 mg2 na k co32 hco3 cl so42 and no3 are carried out the chemical relationships in piper and gibbs diagram suggest that the groundwater mainly belongs to alkali type and cl group and are controlled by rock dominance a comparison of groundwater quality in relation to drinking water quality standards proves that most of the water samples are suitable for drinking water purpose whereas groundwater in some areas of the district has high salinity and high sodium adsorption ratio sar indicating unsuitability for irrigation water and needs adequate drainage

seasonal variation of groundwater quality in a part of guntur district andhra pradesh india the area in guntur district andhra pradesh india is selected to discuss the impact of seasonal variation of groundwater quality on irrigation and human health where the agriculture is the main livelihood of rural people and the groundwater is the main source for irrigation and drinking granite gneisses associated with schists and charnockites of the precambrian eastern ghats underlie the area groundwater samples collected seasonally pre and post monsoons during three years from forty wells in the area were analyzed for ph ec tds ta th ca2 mg2 na k co 3 2 hco 3 cl so 4 2 no 3 and f the chemical relationships in piper s diagram chebotarev s genetic classification and gibbs s diagram suggest that the groundwaters mainly belong to non carbonate alkali type and cl group and are controlled by evaporation dominance respectively due to the influence of semi arid climate gentle slope sluggish drainage conditions greater water rock interaction and anthropogenic activities a comparison of the groundwater quality in relation to drinking water quality standards proves that most of the water samples are not suitable for drinking especially in post monsoon period us salinity laboratory s and wilcox s diagrams and na used for evaluating the water quality for irrigation suggest that the majority of the groundwater samples are not good for irrigation in post monsoon compared to that in pre monsoon these conditions are caused due to leaching of salts from the overlying materials by infiltrating recharge waters a management plan is suggested for sustainable development of the area

assessment of resolution and accuracy of the moving window cross spectral technique for monitoring crustal temporal variations using ambient seismic noise summary temporal variations in the elastic behaviour of the earth s crust can be monitored through the analysis of the earth s seismic response and its evolution with time this kind of analysis is particularly interesting when combined with the reconstruction of seismic green s functions from the cross correlation of ambient seismic noise which circumvents the limitations imposed by a dependence on the occurrence of seismic events in fact because seismic noise is recorded continuously and does not depend on earthquake sources these cross correlation functions can be considered analogously to records from continuously repeating doublet sources placed at each station and can be used to extract observations of variations in seismic velocities these variations however are typically very small of the order of 0 1 per cent such accuracy can be only achieved through the analysis of the full reconstructed waveforms including later scattered arrivals we focus on the method known as moving window cross spectral analysis that has the advantage of operating in the frequency domain where the bandwidth of coherent signal in the correlation function can be clearly defined we investigate the sensitivity of this method by applying it to microseismic noise cross correlations which have been perturbed by small synthetic velocity variations and which have been randomly contaminated we propose threshold signal to noise ratios above which these perturbations can be reliably observed such values are a proxy for cross correlation convergence and so can be used as a guideline when determining the length of microseismic noise records that are required before they can be used for monitoring with the moving window cross spectral technique

seismic characterization of a rapidly rising jokulhlaup cycle at the a p olsen ice cap ne greenland rapidly rising jokulhlaups or glacial outburst floods are a phenomenon with a high potential for damage the initiation and propagation processes of a rapidly rising jokulhlaup are still not fully understood seismic monitoring can contribute to an improved process understanding but comprehensive long term seismic monitoring campaigns capturing the dynamics of a rapidly rising jokulhlaup have not been reported so far to fill this gap we installed a seismic network at the marginal ice dammed lake of the a p olsen ice cap apo in ne greenland episodic outbursts from the lake cause flood waves in the zackenberg river characterized by a rapid discharge increase within a few hours our 6 months long seismic dataset comprises the whole fill and drain cycle of the ice dammed lake in 2012 and includes one of the most destructive floods recorded so far for the zackenberg river seismic event detection and localization reveals abundant surface crevassing and correlates with changes of the river discharge seismic interferometry suggests the existence of a thin basal sedimentary layer we show that the ballistic part of the first surface waves can potentially be used to infer medium changes in both the ice body and the basal layer interpretation of time lapse interferograms is challenged by a varying ambient noise source distribution

assessment of the hydrogeochemical characteristics of groundwater in two aquifer systems in cumra plain central anatolia located in a semi arid climate cumra konya plain is one of the most important agricultural regions in turkey groundwater is the major source for agricultural domestic and other water related activities due to the insufficiency of surface water as groundwater is the only major source of water in this area it is important to know the effects of geological formations and anthropogenic activities on groundwater chemistry this study was carried out with the objective of identifying the hydrogeochemical characteristics and processes controlling the groundwater chemistry in cumra plain central anatolia turkey the study area is comprised of two main aquifers which are the semi confined aquifer of the neogene age and the unconfined aquifer of the quaternary age to identify the hydrogeochemical characteristics of groundwater in two aquifer systems and to understand the major factors and mechanisms controlling the groundwater chemistry graphical plots mineral saturations and multivariate statistical analysis of chemical constituents in the groundwater were used study results show that groundwater is generally neutral to slightly alkaline in nature with a ph ranging from 6 67 to 8 10 and the dominance of ions is in the order of ca2 mg2 na k for the neogene aquifer and hco3 so4 2 cl no3 mg2 ca2 na k and so4 2 hco3 cl no3 for the quaternary aquifer while the chemical composition of groundwater in the neogene aquifer is mainly controlled by water rock interaction including dissolution of carbonates and gypsum calcite precipitation and de dolomitization the main geochemical processes in the quaternary aquifer are reverse ion exchange evaporation dissolution of carbonates gypsum and soil salts calcite precipitation and silicate weathering the mechanism controlling groundwater chemistry in the neogene aquifer is actually regulated by the geogenic processes water rock interaction rather than by anthropogenic activities however the mechanism controlling groundwater chemistry in the quaternary aquifer is regulated by both geogenic processes and anthropogenic activities in addition anthropogenic nitrogen pollution in the study area is currently not serious but evaporation and leaching of soil salts due to anthropogenic activities increase the concentrations of ions in the quaternary aquifer

towards monitoring the englacial fracture state using virtual reflector seismology in seismology coda wave interferometry cwi is an effective tool to monitor time lapse changes using later arriving multiply scattered coda waves typically cwi relies on an estimate of the medium s impulse response the latter is retrieved through simple time averaging of receiver receiver cross correlations of the ambient field that is seismic interferometry si in general the coda is induced by heterogeneities in the earth being comparatively homogeneous however ice bodies such as glaciers and ice sheets exhibit little scattering in addition the temporal stability of the time averaged cross correlations suffers from temporal variations in the distribution and amplitude of the passive seismic sources consequently application of cwi to ice bodies is currently limited nevertheless fracturing and changes in the englacial macroscopic water content alter the bulk elastic properties of ice bodies which can be monitored with cryoseismological measurements to overcome the current limited applicability of cwi to ice bodies we therefore introduce virtual reflector seismology vrs vrs relies on a so called multidimensional deconvolution mdd process of the time averaged crosscorrelations the technique results in the retrieval of a medium response that includes virtual reflections from a contour of receivers enclosing the region of interest i e the region to be monitored the virtual reflections can be interpreted as artificial coda replacing the lacking natural scattered coda hence this artificial coda might be exploited for the purpose of cwi from an implementation point of view vrs is similar to si by mdd which as its name suggests also relies on a multidimensional deconvolution process si by mdd however does not generate additional virtual reflections advantageously both techniques mitigate spurious coda changes associated with temporal variations in the distribution and amplitude of the passive seismic sources in this work we apply si by mdd and vrs to synthetic and active seismic surface wave data the active seismic data were acquired on glacier de la plaine morte switzerland we successfully retrieve virtual reflections through the application of vrs to this active seismic data in application to both synthetic and active seismic data we show the potential of vrs to monitor time lapse changes in addition we find that si by mdd allows for a more accurate determination of phase velocity

water flow through temperate glaciers understanding water movement through a glacier is fundamental to several critical issues in glaci ology including glacier dynamics glacier induced floods and the prediction of runoff from glacierized drainage basins to this end we have synthesized a conceptual model of water movement through a temper ate glacier from the surface to the outlet stream pro cesses that regulate the rate and distribution of water input at the glacier surface and that regulate water movement from the surface to the bed play important but commonly neglected roles in glacier hydrology where a glacier is covered by a layer of porous perme able firn the accumulation zone the flux of water to the glacier interior varies slowly because the firn tempo rarily stores water and thereby smooths out variations in the supply rate in the firn free ablation zone in con trast the flux of water into the glacier depends directly on the rate of surface melt or rainfall and therefore varies greatly in time water moves from the surface to the bed through an upward branching arborescent net work consisting of both steeply inclined conduits formed by the enlargement of intergranular veins and gently inclined conduits spawned by water flow along the bottoms of near surface fractures crevasses engla cial drainage conduits deliver water to the glacier bed at a limited number of points probably a long distance downglacier of where water enters the glacier englacial conduits supplied from the accumulation zone are quasi steady state features that convey the slowly varying water flux delivered via the firn their size adjusts so that they are usually full of water and flow is pressurized in contrast water flow in englacial conduits supplied from the ablation area is pressurized only near times of peak daily flow or during rainstorms flow is otherwise in an open channel configuration the subglacial drainage system typically consists of several elements that are distinct both morphologically and hydrologically an up glacier branching arborescent network of channels in cised into the basal ice conveys water rapidly much of the water flux to the bed probably enters directly into the arborescent channel network which covers only a small fraction of the glacier bed more extensive spatially is a nonarborescent network which commonly includes cav ities gaps between the glacier sole and bed channels incised into the bed and a layer of permeable sediment the nonarborescent network conveys water slowly and is usually poorly connected to the arborescent system the arborescent channel network largely collapses during winter but reforms in the spring as the first flush of meltwater to the bed destabilizes the cavities within the nonarborescent network the volume of water stored by a glacier varies diurnally and seasonally small temper ate alpine glaciers seem to attain a maximum seasonal water storage of 200 mm of water averaged over the area of the glacier bed with daily fluctuations of as much as 20 30 mm the likely storage capacity of subglacial cavities is insufficient to account for estimated stored water volumes so most water storage may actually occur englacially stored water may also be released abruptly and catastrophically in the form of outburst floods

an investigation into the forces that drive ice shelf rift propagation on the amery ice shelf east antarctica for three field seasons 2002 03 2004 05 2005 06 we have deployed a network of gps receivers and seismometers around the tip of a propagating rift on the amery ice shelf east antarctica during these campaigns we detected seven bursts of episodic rift propagation to determine whether these rift propagation events were triggered by short term environmental forcings we analyzed simultaneous ancillary data such as wind speeds tidal amplitudes and sea ice fraction a proxy variable for ocean swell we find that none of these environmental forcings separately or together correlated with rift propagation this apparent insensitivity of ice shelf rift propagation to short term environ mental forcings leads us to suggest that the rifting process is primarily driven by the internal glaciological stress our hypothesis is supported by order of magnitude calculations that the glaciological stress is the dominant term in the force balance however our calculations also indicate that as the ice shelf thins or the rift system matures and iceberg detachment becomes imminent short term stresses due to winds and ocean swell may become more important

water quality and sediment geochemistry in lakes of yunnan province southern china yungui plateau lakes in southwestern china are economically important although few have been studied previously water and sediments of 24 lakes throughout yunnan province were sampled in october 1994 we describe the chemical and physical characteristics of yunnan lakes and address effects of regional geology and human influences on water quality and sediment type water quality differs between deep yunnan lakes of tectonic origin and shallow solution basins shallow lakes generally have higher nutrient concentrations and appear to be more susceptible to riparian disturbance than deeper lakes shallow lakes with high macrophyte standing crops nevertheless exhibit nutrient poor waters principal ions ca2 mg2 and hco3 reflect regional carbonate geology except in cheng hai which is a sodium bicarbonate lake specific conductance and 18o are positively correlated indicating that evaporation concentrates both solutes and 18o large shallow lakes in southeastern yunnan exhibit 18o enriched waters because of substantial evaporation whereas small deep lakes are 18o depleted lake waters are 18o depleted in small shallow basins that receive substantial rainwater input relative to their small volumes 18o enrichment in cheng hai suggests that a recent 5 m water level decline in this lake was caused by increased evaporation or diversion of freshwater inflow yunnan watersheds have undergone substantial deforestation agricultural cultivation soil erosion and industrialization limnetic nutrient concentrations indicate that human activities have affected water quality organic matter content is low in sediments because of increased non carbonate clastic sediment yield from watersheds environmental policies are needed to balance ecological contraints with economic activities that impact water quality

glacier fjord and seismic response to recent large calving events jakobshavn isbrae greenland 1 the recent loss of jakobshavn isbrae s extensive floating ice tongue has been accompanied by a change in near terminus behavior calving currently occurs primarily in summer from a grounded terminus involves the detachment and overturning of several icebergs within 30 60 min and produces long lasting and far reaching ocean waves and seismic signals including glacial earthquakes calving also increases near terminus glacier velocities by 3 but does not cause episodic rapid glacier slip thereby contradicting the originally proposed glacial earthquake mechanism we propose that the earthquakes are instead caused by icebergs scraping the fjord bottom during calving

application of seismic interferometry by multidimensional deconvolution to ambient seismic noise recorded in malargue argentina obtaining new seismic responses from existing recordings is generally referred to as seismic interferometry si conventionally the si responses are retrieved by simple crosscorrelation of recordings made by separate receivers one of the receivers acts as a virtual source whose response is retrieved at the other receivers when si is applied to recordings of ambient seismic noise mostly surface waves are retrieved the newly retrieved surface wave responses can be used to extract receiver receiver phase velocities these phase velocities often serve as input parameters for tomographic inverse problems another application of si exploits the tempo ral stability of the multiply scattered arrivals of the newly retrieved surface wave responses temporal variations in the stability and or arrival time of these multiply scattered arrivals can often be linked to temporally varying parameters such as hydrocarbon production and precip itation for all applications however the accuracy of the retrieved responses is paramount correct response retrieval relies on a uniform illumination of the receivers irregularities in the illumination pattern degrade the accuracy of the newly retrieved responses in practice the illumination pattern is often far from uniform in that case simple crosscorrelation of separate receiver recordings only yields an estimate of the actual correct virtual source response re formulating the theory underlying si by crosscorrelation as a multidimensional deconvolution mdd process allows this estimate to be improved si by mdd corrects for the non uniform illumination pattern by means of a so called point spread function psf which captures the irregularities in the illumination pattern deconvolution by this psf removes the imprint of the irregularities on the responses obtained through simple crosscorrelation we apply si by mdd to surface wave data recorded by themalargue seismic array in western argentina the aperture of the array is approximately 60 km and it is located on a plateau just east of the andean mountain range the array has a t shape the receivers along one of the two lines act as virtual sources whose responses are recorded by the receivers along the other perpendicular line we select time windows dominated by surface wave noise travelling in a favourable direction that is traversing the line of virtual sources before arriving at the receivers at which we aim to retrieve the virtual source responses these time windows are selected through a frequency dependent slowness analysis along the two receiver lines from the selected time windows estimates of virtual source responses are retrieved by means of crosscorrelations similarly crosscorrelations between the positions of the virtual sources are computed to build the psf we use the psf to deconvolve the effect of illumination irregularities and the source function from the virtual source responses retrieved by crosscorrelation the combined effect of time window selection and mdd results in more accurate and temporally stable surface wave responses

combined measurements of subglacial water pressure and surface velocity of findelengletscher switzerland conclusions about drainage system and sliding mechanism interpretation des mesures de pression dans les forages et des vitesses superficielles la comparaison avec les modeles suggere que l on a neglige le frottement du aux debris dans les modeles et qu il n existe jamais de chenaux cylindriques rectilignes