character of the englacial and subglacial drainage system in the upper part of the ablation area of storglaciaren sweden on 4 july 1986 dye was injected at a point slightly above the equil ibrium line on storglac iliren a small valley glacier in northern sweden just below the equilibrium line the glacier bed is over deep ened the dye re appeared in a stream at the glacier terminus over the next 35 d this stream normally carries relatively little sediment in constrast to the situ ation in another nearby stream that also emerges from the glacier this sugge sts that the dye traveled in englacial rather than subglacial conduits tracer tests utilizing salt in bore holes in the overde epening support this interp retation as the bore holes were draining well above the bed the dye appeared during three distinct events suggesting that it became divided into at least three separate parcels shortly after iojection this probably occurred in the crevassed area in the vicinity of the inje ction point the englacial location of the drainage may be explained by the fact that in order to remain at the pressure melting p oint water in subg lacial conduits coming out of the overde epening may have had to warm up faster than would be possible by visc ous heating alone such

geochemistry origin and recharge mechanisms of groundwaters from the garoua sandstone aquifer northen cameroon this paper presents results of the geochemical and isotopic studies on groundwater samples from the garoua sandstone basin in northern cameroon chemical and environmental isotope data are presented and discussed in terms of the origin of dissolved species and of groundwater all of the investigated groundwaters are categorized into two chemical types low mineralized and acidic waters of ca na hco3 type and relatively high mineralized waters of na hco3 type with relatively high ph between 7 40 and 8 22 interpretation of chemical data based upon both thermodynamic calculations and stability diagrams suggests that the chemical evolution of groundwater is primarily controlled by water rock interactions involving 1 acidic weathering of aluminosilicates 2 dissolution of secondary carbonate minerals and 3 cation exchange of na for ca2 however the original composition of groundwater may have been modified by further secondary processes such as mixing of chemically different water masses and anthropogenic no 3 pollution tritium contents in the considered groundwaters are very heterogeneous suggesting differences in the water turnover time or in the recharge conditions or both on the basis of the geographical distribution of 3h contents a hydrogeological relation between river and the groundwater systems has been proposed for the study site interpretation of both 18o and 2h as well as 3h suggests that the recharge of the investigated groundwaters may result from three major mechanisms 1 direct infiltration of local precipitation 2 lateral inflow of river waters 3 probably upward leakage of old groundwaters

surface water and groundwater contaminations and the resultant hydrochemical evolution in the yongxiu area west of poyang lake china major ion and stable hydrogen and oxygen isotopic compositions were employed in this study of surface water and groundwater contaminations and their impacts on intrinsic hydrochemical evolution in the yongxiu area west of poyang lake south china a total of 36 samples were collected from surface water and groundwater in the study area where water pollution risk is high due to the fertilizer use for farmland and the waste drainage from a nearby silicon industry site the results show that the surface water bodies have been badly polluted and are characterized by low ph values minimum 2 85 and high concentrations of chemical compounds such as cl na nh4 n no3 n and tds groundwater has also been polluted with the similar specific contaminates as both surface water and groundwater may have similar contamination sources and groundwater is recharged from the precipitation infiltration and surface water leakage as indicated by oxygen 18 and deuterium compositions due to the thin unsaturated zone in the area the acidification and the intrusion of contamination further lead to hydrogeochemical reactions and changed hydrochemical type of groundwater from ca mg hco3 to ca mg na cl the data evaluation methods and results of this study could be useful to the water sustainable usage management in this area and other environmental vulnerable areas

model experiments on the evolution and stability of ice streams this is the publisher s version also available electronically from http www igsoc org annals 23

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

modeling the diurnal variation of tracer transit velocity through a subglacial channel 1 tracer injections into a moulin connecting to a subglacial channel at unteraargletscher were repeated at intervals of about two hours over two diurnal discharge cycles in august and september 2000 the pronounced hysteresis in the relationships between tracer transit velocity and proglacial discharge may be explained by adjustments of the channel cross section in response to discharge variations or alternatively by modulation of inflow from the tributary moulin into a main subglacial channel to test these hypotheses we employ a physically based time dependent model of channelized subglacial drainage in a series of numerical experiments we explore the general characteristics of each mechanism before the model is applied to diurnal discharge variations measured during the tracer tests at unteraargletscher we found that the ability of a rothlisberger channel to adjust its size to the prevailing hydraulic conditions can contribute to the hysteresis in the velocity discharge relationships however using plausible parameter values r channel hydraulics alone is not satisfactory in reproducing the magnitude of observed transit velocities the model further confirms that retardation of the tracer in the tributary moulin due to inflow modulation has major effects on transit velocities both in magnitude and timing with appropriate assumptions on channel sinuosity and moulin size a combination of both mechanisms can be found that is capable of reproducing the observed transit velocities

diurnal variability of subglacial drainage conditions as revealed by tracer experiments 1 the morphology of the drainage system of unteraargletscher switzerland and the diurnal variability of drainage conditions were investigated by conducting a series of tracer tests over a number of discharge cycles during the ablation season 2000 dye injections into a moulin were repeated at intervals of a few hours and were accompanied by simultaneous measurements of discharge of supraglacial meltwater draining into the moulin and bulk runoff in the proglacial stream fast transit velocities in conjunction with low dispersion values suggest that the tracer was routed through a hydraulically efficient channelized drainage system however detailed analyses reveal a large diurnal variability in terms of transit velocity and dispersion coefficient this finding underlines the difficulty of detecting a possible drainage system evolution based on single tracer tests conducted at coarse temporal intervals furthermore the obtained velocity discharge relationships display pronounced hysteresis we suggest that the evolution of the cross sectional area of an ice walled conduit and the modulation of inflow at the junction of a tributary moulin to a main subglacial channel are responsible for the observed behavior

hydrochemical processes governing groundwater quality of sedimentary aquifers in central saudi arabia and its environmental implications the present study deals with the interpretation of the major processes governing the groundwater chemistry in parts of qassim and riyadh province of saudi arabia the study area that is dominated by agricultural activities is represented by a multi layered aquifer system with sedimentary formations ranging from cambrian to the quaternary present as outcrops groundwater samples from 97 agricultural bore wells in the area were collected and analyzed for 16 physio chemical parameters the evaluation of the main hydrochemical processes affecting the groundwater quality was carried out by interpreting the ionic relationships and hydrochemical facies analysis the interpretation pointed toward evaporation gypsum dissolution and ion exchange as main factors controlling the major ion groundwater chemistry the piper plot showed so4 cl type of groundwater with majority of the samples falling in the zone of permanent hardness due to the formation of non carbonate salts principal component analysis that helps to understand the underlying natural and anthropogenic factors controlling the groundwater chemistry in an area was used in the present study based on which four principal components pcs were extracted the first pc as expected was dominated by the major ions and was attributed to natural processes whereas the extracted components mainly heavy metals in pc 2 3 and 4 pointed toward anthropogenic activities playing an active role in affecting the trace element hydrochemistry

bed properties and hydrological conditions underneath mccall glacier alaska usa during three summer field seasons 2003 2005 and 2006 we carried out radio echo sound ing measurements with a 5 mhz central frequency ice penetrating radar on mccall glacier arctic alaska usa along the central flowline and 17 cross profiles two way travel time was after migration converted to ice thickness which in combination with a recent digital elevation model of the surface of the glaciated area resulted in a detailed map of the bed topography this reveals a complex basal topography in the confluence area of the different glacial cirques the pattern of subglacial water flow following the hydraulic potential gradient was calculated for the whole glacier area and shows a confluence of subglacial water downstream from the confluence of the glacier cirques from the ice thickness map the total ice volume was estimated as slightly less than 0 5 km 3 bed reflection power brp was determined for the glacier after correction for ice thickness dependence results reveal a clear relationship between the brp pattern and basal sliding anomalies along the central flowline

elucidating changes in the degree of tracer dispersion in a subglacial channel tracer injections into a subglacial channel at unteraargletscher switzer land were repeated at intervals of about 2 hours over two diurnal discharge cycles in august and september 2000 records of dye concentration reveal a pronounced hysteresis in the velocity dispersion relationship thereby indicating alterations in the drainage system theoretical considerations for ro thlisberger channels suggest an evolution of the conduit cross section in response to a diurnally varying discharge we studied the relation between conduit cross section and tracer dispersion with numerical tracerexperiments thevelocity fieldforsteady flow throughagivenconduitgeometry is calculated using a commercial flow solver tracer transport is represented by a scalar volume which is advected by the velocity field experiments were conducted for several scenarios by varying flow velocity conduit geometry and conduit roughness results show only a weak dependence of dispersion on conduit size in contrast changes in roughness of the conduit walls reveal a strong effect on tracer dispersion therefore to explain the observed hysteresis in the velocity dispersion relationship we suggest that the evolution of a subglacial flow path might involve changes in roughness

alpine subglacial hydrology abstract the size and shape of subglacial flow pathways exert a strong influence over the pressure and speed at which meltwaters are routed through glaciers these characteristics in turn influence glacier sliding velocity and the quantity and quality of bulk meltwaters discharging from glaciers in this paper we summarise four empirical research approaches that have been developed to improve our understanding of the subglacial hydrology of predominantly temperate based alpine glaciers investigations of bulk meltwater discharge and chemistry tracer studies proglacial bedrock investigations and borehole investigations as a result of linking these studies to conceptual or numerical models three arborescent and four non arborescent or distributed subglacial drainage configurations are described these drainage networks may be neither spatially nor temporally persistent but may compete with and replace each other on a seasonal basis a qualitative model of the temporal and spatial evolution of a typical alpine subglacial drainage system is advanced on the basis of research conducted at haut glacier d arolla switzerland

an appraisal of groundwater quality in seymour and blaine aquifers in a major agro ecological region in texas usa aquifer based groundwater quality assessment offers critical insight into the major hydrochemical processes and aids in making groundwater resources management decisions the texas rolling plains trp spanning over 22 counties is a major agro ecological region in texas from where highest groundwater nitrate no3 levels in the state have been reported in this study we present a comparative assessment of major hydrochemical facies pertaining to no3 contamination and a host of species such as sulfate so42 chloride cl and total dissolved solids tds in different water use classes in the seymour and blaine aquifers underlying the trp aquifer stratified groundwater quality information from 1990 to 2010 was obtained from the texas water development board and aggregated over decadal scale high groundwater salinization was found in the municipal water use class in the blaine aquifer with about 100 87 and 50 of observations exceeding the secondary maximum contaminant level for tds so42 and cl respectively in the 2000s 2000 2010 the no3 contamination was more alarming in the seymour aquifer with 82 and 61 of observations respectively exceeding the maximum contaminant level mcl in the irrigation and municipal water use classes in the 2000s salinization was more influenced by so42 and cl in the blaine aquifer and by no3 in the seymour aquifer high no3 mcl observations in the seymour aquifer occurred in the ca hco3 and ca mg hco3 facies the domains of fresh water recharge and anthropogenic influences e g agricultural activities waste disposal high so42 cl and tds observations in the blaine aquifer dominated the ca cl na cl and mixed ca mg so4 cl facies indicating evaporite dissolution mixing and solute exchange and lack of fresh recharge

hydrogeology and geochemistry of the ogallala aquifer southern high plains the ogallala aquifer which underlies the southern high plains consists of saturated sediments of the ogallala formation neogene that are deposited mainly as a set of humid type alluvial fans derived from the rocky mountains the ogallala aquifer the main source of water for the high plains of texas and new mexico has been severely depleted by extensive pumpage the hydrology and geochemistry of the aquifer are controlled by the surface topography of the underlying formations and by the thickness and permeability of the alluvial fan deposits axes of three major alluvial fans trend from northwest to southeast the fans have increased thickness and permeability compared with interfan areas flow lines follow the orientation of the alluvial fans along these major axes the saturated section is thick and the chemical composition is relatively constant ca hco3 to mixed cation hco3 water depleted in 18o d and tritium external effects on the chemical composition are less pronounced the aquifer is thinner and less permeable in areas between major fan axes and along the caprock escarpment in these areas groundwater can discharge from aquifers in the cretaceous triassic and permian formations into the ogallala formation cross formational movement of water and low permeabilities in the ogallala formation result in varying hydrochemical facies and in isotopic compositions that differ from those of the major depositional areas areas where upward cross formational flow occurs are evident by the presence of permeable contacts between the ogallala and the underlying formations water level head differences and chemical and isotopic similarities secondary factors that locally affect the chemical composition of ogallala formation groundwater include contamination from evaporating saline lakes agricultural chemicals and fertilizers and oil field brines impact of chemicals and brines may increase in the future because much of these contaminants may still be moving through the unsaturated zone toward the water table

geometry and flow conditions of subglacial water at south cascade glacier washington state u s a an analysis of tracer injections tracers were injected into south cascade glacier to determine the flow condition and geometry of the subglacial water system results indicate that two distincts drainage basins on the glacier feed the two main streams flowing from the glacier in the largest basin two parallel drainage networks exist one englacial and the other subglacial

prediction of some weathering trends of plutonic and volcanic rocks based on thermodynamic and kinetic considerations abstract the exposed crust consists mainly of plagioclase 35 quartz 20 k feldspar 11 volcanic glass 12 biotite 8 and muscovite 5 quartz is a resistate thus feldspars and glass represent approximately 75 percent of the labile minerals the weathering characteristics of these constituents are summarized in the context of thermodynamic mass balance and kinetic considerations experimentally determined release rate constants were used to predict the proportions of ca na and k released by feldspars of plutonic rocks granites to gabbros to weathering solutions the chemical weathering trends of the weathered residues calculated from the kinetic data conform closely to the initial trends observed in some recent weathering profiles demonstrating the accuracy of the predictions since the weathering of feldspars is controlled by processes that should not change through geological time the relative release rates of ca na and k from the feldspars of granitic rocks can be calculated for future and past episodes of continental weathering experimentally determined release rate constants are not available for a wide range of volcanic glass compositions but the limited data indicate that compositional trends are predictable in weathering profiles developed on volcanic rocks the kinetic data available for rhyolitic glasses accurately predict the initial weathering trends observed in a recent rhyolite weathering profile

dye tracing a jokulhlaup i subglacial water transit speed and water storage mechanism we present results of an investigation of two j okulhlaups glacial lake outburst floods at gornergletscher switzerland using dye tracer experiments and complementary hydrological measurements repeated dye injections into moulins showed that tracer transit speeds were larger after the lake had emptied but when proglacial discharge was still high than during the main phase of the j okulhlaup this counter intuitive finding was modelled by tracer retardation inside the injection moulin this model together with an estimate of the maximum time the tracer takes to transit the injection moulin allows us to calculate bounds on the transit speed in the main drainage channel where the lake water flows these results indicate that the main drainage channel transit speeds are indeed highest during the peak of the flood moreover it is known from a previous study that water amounting to half of the lake volume is temporarily stored within the glacier during a gornergletscher j okulhlaup our observations suggest that this process occurred via lateral spreading of water at the glacier bed

identification of groundwater contamination zones and its sources by using multivariate statistical approach in thirumanimuthar sub basin tamil nadu india hydrogeochemical studies have been made in the study area by using multivariate statistical analysis which is mainly helpful for interpretation of complex data matrices to better understand the geochemical evolution of the area and it allows identifying the possible factors sources that influence water systems the spatial distribu tion of electrical conductivity reveals that an untreated industrial effluents landfill and anthropogenic activities affecting their groundwater quality in its vicinity and the surrounding area the dominance of ions was in the order of na ca 2 mg 2 k cl hco3 so4 2 no3 and ca 2 mg 2 na k hco3 cl no3 so4 2 during pre monsoon prm and post monsoon pom respectively the statistical results reveals that the groundwater chemistry gets altered by silicate weathering ion exchange leaching anthropogenic input from agricultural return flow and longer distance of migrating groundwater the hydrogeochemical regimes are distributed along the upstream side northwestern western and eastern parts of the study area the study highlights the descriptive capabilities of conventional and multivariate techniques as effective tools in groundwater evaluation

solute and isotopic geochemistry and ground water flow in the central wasatch range utah ground water flow systems in the rugged central wasatch range utah were investigated by solute and isotopic methods six types of ground water systems were identified on the basis of rock type and structure the systems are broadly grouped into four categories 1 granitic systems 2 non granitic systems a unconsolidated alluvial systems b consolidated sedimentary rock systems and c fault controlled systems 3 thermal systems 4 mine drainage systems these ground water systems have distinctive solute and isotopic chemistries based on an analysis of 3h and 14c data all of the ground waters have a component of post 1952 recharge water and most of the ground waters are composed almost entirely of post 1952 recharge water a few of the ground water systems contain some water which is hundreds to perhaps thousands of years old the 18o and 2h data plot on a local meteoric water line and none of the data exhibit a positive 18o shift the absence of a positive 18o shift suggests maximum aquifer temperatures are approximately 100 c granitic terrains are dominated by fracture controlled local ground water flow systems which respond rapidly to recharge events the granitic ground water systems have estimated maximum circulation depths of about 160 m below land surface all the alluvial most of the consolidated sedimentary bedrock and some of the fault controlled ground water systems are shallow circulating local flow systems with short travel times ground water circulation of most of the local flow systems is within 200 m of land surface and is bedding plane controlled some of the consolidated bedrock and many of the fault controlled ground water systems are of the intermediate type and have circulation depths to 500 m four thermal ground water systems have been identified the thermal systems are heated by the geothermal gradient and have not circulated deeper than 2 2 5 km the thermal systems are of the intermediate and regional type the solute chemistry of most of the non granitic ground waters may be attributed to the dissolution of carbonate minerals and minor amounts of gypsum contributions of external co2 g to some of the thermal systems from either metamorphic or silicate hydrolysis processes is suspected

on the role of mechanical energy in maintaining subglacial water conduits at atmospheric pressure recent theo retical studies of glacier hydrology have assumed that subglacial conduits are completely filled with water under steady state conditions this however is not necessarily the case where discharges are larger than a few tens of liters per second and the down glacier slope of the bed is more than a few degrees the potential energy released by water descending this slope may be capable of melting the walls of a subglacial conduit many times faster than the conduit can close by plastic flow of the ice as a result the pressure in such tunnels may normally be atmospheric or possibly even at the triple point pressure if there is no open connection to the glacier surface simple calcu lations suggest that such pressures in subglacial conduits may be more common than herclofore anticipated the positions of such open conduits may be unstable to small per turbations in discharge or ice veloci ty this is because the mechanical energy available in excess of that needed to balance closure can instead offset the gene ral flow of the ice cond ui ts can thus trend diago nally across the direction of ice aow if an increase in the angle which such a conduit makes with the ice flow direction also results in an increase in slope of he conduit more mechanical energy will become available resulting in a positive feedback process subglacial channels at atmospheric pressure may inauence the origin and morphology of certain glacial landforms such as eskers and plastically molded features resume sur le role de l inergie newtonnienne dam le maintien du riseau aquiflrl sous glaciaire cl la pression almosph irique de recentes etudes theoriques d hydrologie glaciaire ont suppose que le reseau sous glaci aire clait corn pletement rempli d eau en condition d cquil ibre stable ceci neanmoins n est pas necess airement le cas lorsque les debits sonl superieurs a quelques dizaines de litres par seconde et que la pente du lit du glacier est superieure a quelques degres i energie potentielle mise en oeuvre par i eau descendant celle pente peut ire capable de fondre les parois d un chenal sous glaciaire beaucoup plus vite que le chenal ne peut se refermer par le auage plastique de la glace il en resuhe que la pression dans de tels chenaux peut nor rnalement etre atrnospherique

groundwater quality assessment and its suitability in celtikci plain burdur turkey the celtikci burdur plain is located in the southwest of turkey and is a semi closed basin groundwater is densely used as drinking irrigation and domestic water in the plain hydrogeochemical processes controlling groundwater chemistry and geochemical assessment of groundwater were investigated in the celtikci burdur turkey plain in this study groundwater samples for two seasons were analyzed and major ion chemistry of groundwater was researched to understand the groundwater geochemistry two major hydrochemical facies ca hco3 and ca mg hco3 were determined in the area various graphical plots and multivariate statistical analysis were used for identifying the occurrence of different geochemical processes in the study area weathering is one of the key geochemical processes which controlled the solute concentration in groundwater chemical indexes such as sodium adsorption ratio na residual sodium carbonate magnesium hazard and permeability index were calculated and results show that groundwater is suitable for irrigation purpose except for permeability index values concentrations of mn no3 and total hardness exceed the prescribed limits of who and are the major limiting parameters of groundwater use for potable and domestic purposes

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

identification and evolution of hydrogeochemical processes in the groundwater environment in an area of the palar and cheyyar river basins southern india the palar and cheyyar river basins in tamil nadu state of southern india are characterised by different geological formations and groundwater is the major source for domestic agricultural and other water related activities hydrogeochemical studies were carried out in this area with the objective of identifying the geochemical processes and their relation to groundwater quality groundwater samples were collected once a month from 43 groundwater wells in this area from january 1998 to july 1999 sampling procedures and chemical analysis were carried out as per the standard methods chemical data are used for mathematical calculations and graphical plots to understand the chemical process and its relation to the groundwater quality the chemical composition of groundwater in the central part of the study area mainly depends on the recharge from lakes and the river which is explained by a mixing mechanism in addition weathering of silicate minerals controls the concentration of major ions such as sodium calcium magnesium and potassium in the groundwater of this area further the activity ratios indicate that the groundwater is in equilibrium with kaolinite smectite and montmorrillonite the reverse ion exchange process controls the concentration of calcium magnesium and sodium in hard rock formations and dissolution of carbonate minerals and accessory minerals is the source of ca and mg in addition to cation exchange in the sedimentary formations in general the chemical composition of the groundwater in this area is influenced by rock water interaction dissolution and deposition of carbonate and silicate minerals ion exchange and surface water interactions

character of the englacial and subglacial drainage system in the lower part of the ablation area of storglaciaren sweden as revealed by dye trace studies

rothlisberger channel theory its origins and consequences the theory of channelized water flow through glaciers most commonly associated with the names of hans rothlisberger and ron shreve and their 1972 papers in the journal of glaciology was developed at a time when interest in glacier bed processes was expanding and the possible relationship between glacier sliding and water at the bed was becoming of keen interest the r channel theory provided for the first time a physically based conceptual model of water flow through glaciers the theory also marks the emergence of glacier hydrology as a glaciological discipline with goals and methods distinct from those of surface water hydrology

recharge mechanisms and geochemical processes in a semi arid sedimentary basin eastern cape south africa abstract stable isotope 18 o and 2 h and geochemical signatures are used to gain some insight into recharge processes and groundwater salinization mechanisms in a semi arid rangeland catchment the 665 km 2 catchment is underlain by fractured lower beaufort sandstones and mudstones and is intruded by several dolerite dykes chloride and isotopic relationships suggest that chloride ions in ground water are of meteoric origin the hypothesized recharge and salinization mechanism is that large storm events periodically dissolve accumulated surficial meteoric salts and after a period of evaporative enrichment at or near the soil surface leach them into the ground water geochemical variations imply that spatial differences exist in recharge volumes in evaporative enrichment or in the extent of leaching of surficial salts meteoric sodium chloride contributes greater than 90 of the dissolved sodium except at low salinities where cation exchange processes yield additional sodium inputs in exchange for dissolved calcium and magnesium at high salinities this process reverses and sodium is adsorbed releasing calcium and magnesium this process accounts for up to 40 of the dissolved calcium and magnesium contributions from geochemical weathering are relatively uniform in spite of highly variable salinities which implies that residence times are also relatively uniform

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

hydrochemical characteristics of groundwater and surface water for domestic and irrigation purposes in vea catchment northern ghana the vea catchment mainly underlain by crystalline basement rocks is located in northern ghana hydrogeochemical studies were carried out in this area with the objective of identifying the geochemical processes influencing water quality and suitability of surface and groundwater for agricultural and domestic uses sixty one groundwater and four surface water samples were collected from boreholes dams and rivers and analysed for ca2 mg2 na k hco3 cl and so4 2 fetot po4 3 mntot nh4 no3 no2 in addition ph total dissolved solids electrical conductivity total hardness turbidity colour salinity and dissolved oxygen were analysed chloro alkaline indices 1 and 2 and characterization of weathering processes suggest that the chemistry of groundwater is dominated by the interaction between water and rocks cation exchange and silicate weathering are the dominant processes controlling the chemical composition of the groundwater in the area studied mineral saturation indices indicate the presence of at least three groups of groundwater in the vea catchment with respect to residence time the meteoric genesis index suggests that 86 of the water samples belong to the shallow meteoric water percolation type the findings further suggest that the groundwater and surface water in the basin studied are mainly ca mg hco3 water type regardless of the geology compared to the water quality guidelines of who the study results on sodium absorption ratio sodium percentage magnesium hazard permeability index and residual sodium carbonate indicate that groundwater and surface water in the vea catchment are generally suitable for drinking and irrigation purposes

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

linear kernels for karst aquifers karst aquifers contain significant water reserves in many parts of the world but development and management of these reserves is difficult because of the complexity of the aquifers this paper presents a method of characterizing karst aquifers based on the use of single linear kernel functions the kernels are identified with a deconvolution technique proposed by neuman and de marsily 1976 by using estimated groundwater recharge during isolated storms as the system input and the rapid storm response of spring flow as the system output derived kernels for large springs from data for different storms are similar in shape and time to peak average kernels derived from spring flow responses for multiple storms differ in shape for different springs but suggest a regularity in the response of individual springs to precipitation the derived kernel functions presently cannot be validated because of the use of a scaling factor in the moisture balance for the springs they can be used however to predict the storm response of a spring if the total volume of the rapid spring flow response is known

using concurrent dna tracer injections to infer glacial flow pathways author s dahlke he williamson ag georgakakos c leung s sharma an lyon sw walter mt abstract 2015 john wiley a sons ltd catchment hydrology has become replete with flow pathway characterizations obtained via combinations of physical hydrologic measurements e g streamflow hydrographs and natural tracer signals e g stable water isotopes and geochemistry in this study we explored how our understanding of hydrologic flow pathways can be improved and expanded in both space and time by the simultaneous application of engineered synthetic dna tracers in this study we compared the advective dispersive transport properties and mass recovery rates of two types of synthetic dna tracers one consisting of synthetic dna strands encapsulated into biodegradable microspheres and another consisting of free dna i e not encapsulated the dna tracers were also compared with a conservative fluorescent dye all tracers were injected into a small 3 2 km2 valley glacier storglaciaren in northern sweden seven of the nine dna tracers showed clear recovery during the sampling period and similar peak arrival times and dispersion coefficients as the conservative fluorescent dye however recovered dna tracer mass ranged only from 1 to 66 while recovered fluorescent dye mass was 99 resulting from the cold and opaque subglacial environment provided by the glacier mass loss associated with microbial activity and photochemical degradation of the dna is likely negligible leaving sorption of dna tracers onto suspended particles and loss of microtracer particles to sediment storage as probable explanations despite the difference in mass recovery the advection and dispersion information derived from the dna tracer breakthrough curves provided spatially explicit information that allowed inferring a theoretical model of the flow pathways that water takes through the glacier

determining the extent of pressurized flow beneath storglaciaren sweden using results of tracer experiments and measurements of input and output discharge two experiments were conducted on the drainage system beneath the lower part of the ablation zone of storglaciaren a small valley glacier in northern sweden in the first experiment over 70 tracer tests were performed in a cluster of moulins during a 1 month period at sub daily intervals in the second experiment input and output discharge signals were measured on the supraglacial melt stream emptying into a moulin and on the proglacial stream to which the moulin drains the data from these two experiments are used in an idealized model of the subglacial drainage system to calculate the percentage of the system flowing as an open channel results from the tracer experiment suggest that the system is pressurized to within 60 340 m of the snout while analysis of the discharge data indicates pressurized conduits to within 0 415 m of the snout

evolution of the internal drainage system in the lower part of the ablation area of storglaci aren sweden during the 1989 melt season ten tracer experiments were conducted to investigate seasonal diurnal and spatial variations in the internal drainage system in the ablation area of storglaciaren sweden dye was injected into moulins and dye concentration and discharge were monitored in two streams at the glacier terminus sydjakk and nordjakk dye emerged only in sydjakk transit velocities ranged from 0 07 to 0 29 m s implying that drainage was through a well defined conduit system velocity and discharge relations suggest that these conduits are part of a multi branched arborescent network of individually braided wide low passages a progressive decline in dispersivity during the early part of the melt season reflects structural changes in these conduits presumably including a decrease in the degree of braiding and an increase in size the system reached its late season configuration in early august by which time the energy dissipated by the flowing water would have sufficed to melt between 0 7 and 21 m 3 of ice per meter of conduit length depending on conduit size potential closure rates exceed melt rates on conduit walls throughout most of the drainage system and so conduits are probably full of water during periods of higher daily discharge with water pressures exceeding atmospheric pressure variations in tracer return curves and dispersivity on a diurnal time scale also appear to reflect changes in the degree of braiding in this case resulting from drowning of low divides between channels as discharge increases

pliocene calcium carbonate sedimentation patterns of the ontong java plateau odp sites 804 and 806 abstract two deep sea cores from the northeastern slope of the ontong java plateau ocean drilling program site 806 2520 mbsl and site 804 3861 mbsl has been studied with the purpose of investigating pliocene site 806 2 4 3 8 ma site 804 1 8 4 4 ma sub and supralysoclinal changes in calcium carbonate accumulation based on caco3 coarse fraction and faunal data at the shallower site site 806 there is a slight decrease in carbonate content and a distinct long term trend in decreasing accumulation rate throughout the studied interval small scale changes in density hence accumulation rate are related to grain size changes due to winnowing at this site but the overall pattern of decreasing carbonate accumulation seems to be the result of both winnowing and a decrease in productivity the deeper site site 804 exhibits a general increase in carbonate content after about 3 15 ma as well as a long term increase in mass accumulation rate throughout the pliocene interval studied detailed comparison of the records of density and carbonate content emphasizes the strong relationship between carbonate content and accumulation rate at this site the observed pattern of decreasing accumulation rate at shallow depth parallel to enhanced preservation at greater depths may be explained by a decrease in the production of north atlantic deep water nadw a reduction of the volume of nadw pumped into the pacific would reduce the supply of nutrients and deep water co2 this could account for both the decrease in accumulation rate at the shallower site due to decreased productivity and the enhanced preservation at the deeper site due to a decrease in the corrosiveness of deep waters

identifying source and evaluation of hydrogeochemical processes in the hard rock aquifer system geostatistical analysis and geochemical modeling techniques in order to quantify spatio temporal changes in the hydrogeochemistry of swarnamukhi river basin andhra pradesh india a total of 239 groundwater samples have been collected for pre and post monsoon seasons of 2014 and 2015 the geology of the study area is comprised of granite granitic gneisses shales quartzites laterites and recent alluvium along the river course based on the study of geochemical processes of different seasons it is found that the occurrence of na and hco3 in 2014 shifted toward ca and hco3 in 2015 due to cation exchange process fe shows the higher concentration value than safe limit due to dissolution of ferruginous minerals and domestic sewage discharges bivariate plots of various ions and ratios depict the predominance of silicate weathering over carbonate and evaporite dissolution apart from anthropogenic activities in the enrichment of groundwater constituents high nitrate concentration was observed in the urbanized regions of the basin followed by intense agricultural areas geochemical modeling was carried out using mineral saturation index and thermodynamic stability plots to deduce major weathered products most of the groundwater samples in the study area are saturated with carbonate minerals but are undersaturated with silicate minerals thermodynamic stability plots suggest the formation of kaolinite secondary mineral and presence of aluminosilicate minerals fuzzy calculation is applied to determine the water quality index which categorizes a majority of the samples as excellent to good category for human use factor analysis points toward the mixed source identification of ionic constituents saline water mixing index model calculation suggests the effect of salinization in coastal areas due to heavy withdrawal of the fresh groundwater resources for various uses whereas in the mainland it is due to agricultural runoff and domestic waste water

short term velocity and water pressure variations down glacier from a riegel storglaciaren sweden during the 1991 94 summer field seasons time correlated measurements of water pressure and surface speed were made over and down glacier from a major riegel on storglaciaren sweden measurements were made at sub hourly time scales in order to discern details in the diurnal cycle large water input events typically associated with rain storms produced coherent lagged surface velocity responses that could be understood in terms of till deformation or decoupling and these have been discussed elsewhere the consequences of smaller diurnal water pressure events were more enigmatic in that acceleration of ice flow generally preceded the onset of the local water pressure rise from consideration of these data and other work done on the hydrology of storglaciaren we infer that the ice in this area is generally pushed from behind via a relaxation in extensional strain across the riegel hence accelerations occur in response to increases in water pressure that occur up glacier and that precede local water pressure rises in addition following a period of large storm events surface speeds became more spatially coherent and were in phase with the diurnal ater pressure cycle this suggests that the large water pressure events lead to a spatially more homogeneous subglacial drainage system sliding laws need to take into accoun such temporal changes in spatial coherence of the subglacial drainage system

internal geometry and evolution of moulins storglaciaren sweden depart ment of physical geog raphy university of stoc kholm s 106 91 stockholm sweden abstract the initial conditions needed for formation of moulins are crevasses and a supply of melt water water pouring into a crevasse may fill it until it ove rflows at the lowest point which is normally near the margin however as the crev asse deepens it intersects englacial chann els through which the water can drain these chann els may be finger tip tributaries in a dendritic system such as that described by shreve 1972 and observ ed by raymond and harrison 1975 when the cre vasse closes heat in the melt water keeps the conne ction open and a moulin is formed the englacial channel enlarges rapidly by melt ing utilizing mechanical energy released by the descending water descents into moulins and mapping of stru ctures exposed at the surface after many years of melting demonstrate that the drainage channels leading down from the bottoms of the moulins have incli nations of 0 450 from the vertical these channels trend in the dire ction of the original crevasse but appear to be deeper than the expected depth of the crevasse they have not

sodium calcium ion exchange in the weathering of shales implications for global weathering budgets unpolluted rivers and streams that drain marine shales show an excess of sodium compared to chloride and a deficiency of calcium and magnesium compared to sulfate and alkalinity this is due in part to cation exchange of sodium for divalent cations on clay minerals consideration of the global weathering budget suggests that up to 34 of the sodium in the total dissolved stream load may be due to cation exchange rather than sodium production via silicate dissolution weathering reactions these results suggest that the weathering budgets for sodium and calcium are in need of revision because of the inclusion of cation exchange processes in the weathering cycle this implies that silicate dissolution is less important in determining the composition of global river water than was previously thought

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

subseasonal changes observed in subglacial channel pressure size and sediment transport water that pressurizes the base of glaciers and ice sheets enhances glacier velocities and modulates glacial erosion predicting ice flow and erosion therefore requires knowledge of subglacial channel evolution which remains observationally limited here we demonstrate that detailed analysis of seismic ground motion caused by subglacial water flow at mendenhall glacier alaska allows for continuous measurement of daily to subseasonal changes in basal water pressure gradient channel size and sediment transport we observe intermittent subglacial water pressure gradient changes during the melt season at odds with common assumptions of slowly varying low pressure channels these observations indicate that changes in channel size do not keep pace with changes in discharge this behavior strongly affects glacier dynamics and subglacial channel erosion at mendenhall glacier where episodic periods of high water pressure gradients enhance glacier surface velocity and channel sediment transport by up to 30 and 50 respectively we expect the application of this framework to future seismic observations acquired at glaciers worldwide to improve our understanding of subglacial processes

investigations of glacier hydrological systems using dye tracer techniques observations at pasterzengletscher austria a l aide de traceurs colores on a mis en evidence une division laterale du drainage dans le bas de la langue qui n est pas determinee par la direction des crevasses obliques la reapparition de l eau dans les differents moulins est complexe bien qu elle reste constante dans le temps

delays of supraglacial runoff from differently defined microbasin areas on the peyto glacier microbasin runoff experiments were conducted on ice surfaces of the peyto glacier during the 1971 and 2008 ablation seasons when half hourly measurements of net radiation wind speed temperature vapour pressure and supraglacial runoff were obtained on warm sunny days with daily mean temperatures 6 1 10 1 c and daily total ablation amounts of 43 95 mm net radiation contributed almost 70 of the melt energy in 1971 and nearly 60 in 2008 with the remainder supplied by turbulent transfers of sensible and latent heat thus the two experiments are similar in finding that radiation dominates surface melt energy inputs to microbasin runoff outputs they differ with respect to area definitions and microbasin shapes 1 a purposely delineated rhomboidal area 30 m long 15 m wide covering 386 m2 in 1971 2 a naturally delineated elongated area approximately 600 m long 2 m wide covering an estimated 1200 m2 in 2008 three 24 hour periods beginning at 0700 h were obtained for experimental work in 1971 and 8 such periods in 2008 supraglacial runoff was modelled by passing melt energy water equivalents through a simple storage reservoir and forcing closure with measured runoff by optimising for delay time optimal times of 1 2 h were found for 1971 and 7 5 11 5 h for 2008 thus indicating a major difference between the runoff responses of the two microbasins it is possible that different basin shapes may explain the contrasting delay times perhaps because different shapes signify different flow connections to meltwater storage in the weathering crust if the elongated microbasin response is typical of the elemental hydrological response unit of the melting ice surface distributed glacier runoff models should incorporate it as part of the model structure copyright 2011 john wiley sons ltd