ammonium in granites and its petrogenetic significance abstract ammonium is present as a trace constituent in all granites with an average concentration of 45 ppm nh4 equivalent to 35 ppm of elemental n it shows wide variations related to petrography and region but the only significant correlation between ammonium and other geochemical parameters is that it is most abundant in peraluminous granites and least abundant in peralkaline granites these variations can be related to a the amount of sedimentary material in the magmatic source region and b redox conditions in the source region the ammonium content of granitic magmas can also be modified by fractionation or contamination hydrothermal alteration has a major effect on the ammonium content of granitic rocks and variation due to this cause may exceed the magmatic variation most hydrothermally altered granites are enriched in ammonium as a result of the transfer of ammonium from sedimentary country rocks by the hydrothermal fluids

a quantitative method for the characterisation of karst aquifers based on spring hydrograph analysis this paper presents a method for characterizing flow systems in karst aquifers by acquiring quantitative information about the geometric and hydraulic aquifer parameters from spring hydrograph analysis numerical sensitivity analyses identified two fundamentally different flow domains depending on the overall configuration of aquifer parameters these two domains have been quantitatively characterized by deducing analytical solutions for the global hydraulic response of simple two dimensional model geometries during the baseflow recession of mature karst systems the hydraulic parameters of karst conduits do not influence the drainage of the low permeability matrix in this case the drainage process is influenced by the size and hydraulic parameters of the low permeability blocks alone this flow condition has been defined as matrix restrained flow regime mrfr during the baseflow recession of early karst systems and fissured systems as well as the flood recession of mature systems the recession process depends on the hydraulic parameters and the size of the low permeability blocks conduit conductivity and the total extent of the aquifer this flow condition has been defined as conduit influenced flow regime cifr analytical formulae demonstrated the limitations of equivalent models while equivalent discrete continuum models of early karst systems may reflect their real hydraulic response there is only one adequate parameter configuration for mature systems that yields appropriate recession coefficient consequently equivalent discrete continuum models are inadequate for simulating global response of mature karst systems the recession coefficient of equivalent porous medium models corresponds to the transition between matrix restrained and conduit influenced flow consequently equivalent porous medium models yield corrupted hydrographs both in mature and early systems and this approach is basically inadequate for modelling global response of karst aquifers

karst and karst groundwater resources in the mediterranean karst landforms were first described and studied in mediterranean regions where these common landforms display their main hydrological characteristics for this reason mediterranean karst is often considered to be the common reference however when we examine the general settings of mediterranean karst and their groundwater resources more carefully it becomes obvious that carbonate formations around the mediterranean have been subject to various and complex conditions of development and functioning this paper is an attempt to characterize the various types of carbonate karst aquifers present in the mediterranean region according to the geological events that led to the development of different karst conditions in terms of geological conditions three major events caused the development of specific karst drainage structures that produced the various characteristics of mediterranean carbonate aquifers the main consequence of these complex geological conditions is the existence of large aquifers with successive karst structures developed at different depths and large storage capacities when karstification occurred along the coasts it may have caused carbonate aquifers to become connected to the sea sometimes at great depths although it may be possible to provide an overall estimate of resources relatively easily from climatic and geological data a groundwater storage assessment requires detailed knowledge of aquifer functioning and local geological evolution because of the complexity of karst development in mediterranean regions it is unrealistic to expect to manage them in a sustainable way without a thorough assessment of these karst aquifers

evaluation of aquifer thickness by analysing recession hydrographs application to the oman ophiolite hard rock aquifer for more than a century hydrologists and hydrogeologists have been investigating the processes of stream and spring baseflow recession for obtaining data on aquifer characteristics the maillet formula librairie sci a hermann paris 1905 218 an exponential equation widely used for recession curve analysis is an approximate analytical solution for the diffusion equation in porous media whereas the equation proposed by boussinesq c r acad sci 137 1903 5 j math pure appl 10 1904 5 that depicts baseflow recession as a quadratic form is an exact analytical solution other formulas currently used involve mathematical functions with no basis on groundwater theory only the exact analytical solutions can provide quantitative data on aquifer characteristics the efficiency of the two methods was compared on the basis of recession curves obtained with a 2d cross sectional finite differences model that simulates natural aquifers simulations of shallow aquifers with an impermeable floor at the level of the outlet show that their recession curves have a quadratic form thus the approximate maillet solution largely overestimates the duration of the influenced stage and underestimates the dynamic volume of the aquifer moreover only the boussinesq equations enable correct estimates of the aquifer parameters numerical simulations of more realistic aquifers with an impermeable floor much deeper than the outlet proves the robustness of the boussinesq formula even under conditions far from the simplifying assumptions that were used to integrate the diffusion equation the quadratic form of recession is valid regardless of the thickness of the aquifer under the outlet and provides good estimates of the aquifer s hydrodynamic parameters nevertheless the same numerical simulations show that aquifers with a very deep floor provide an exponential recession thus in that configuration the maillet formula also provides a good fit of recession curves even if parameter estimation remains poor in fact the recession curve appears to be closer to exponential when flow has a very important vertical component and closer to quadratic when horizontal flow is dominant as a consequence aquifer permeability anisotropy also changes the recession form the combined use of the two fitting methods allows one to quantify the thickness of the aquifer under the outlet

recharge rate estimation in the mountain karst aquifer system of figeh spring syria figeh watershed spring is one of the important groundwater aquifer which is considered a major source for drinking waters of damascus city and countryside the origin identification and recharge estimates of groundwater are significant components of sustainable groundwater development in this mountain karst aquifer of figeh spring during the period 2001 2009 monthly groundwater and precipitation samples were taken and the isotopic compositions of 18o 2h and chloride contents were analyzed to identify groundwater origins and to estimate recharge rates the 18o 2h of the groundwater show that the groundwater recharge is of meteoric origin the chloride mass balance cmb method was used to quantify recharge rates of groundwater in the mountain karst aquifer of figeh spring the recharge rate varies from 192 to 826 mm year which corresponds to 43 and 67 of the total annual rainfall recharge rates estimated by cmb were compared with values obtained from other methods and were found to be in good agreement this study can be used to develop effective programs for groundwater management and development

monthly karstic spring flow forecasting using a sequential gaussian simulation technique analyzing groundwater hydrologic equations related to karstic aquifers and spring hydrograph simulation have become the focus of many researches having double or triple porosity structure mixed flow nature and varying conduit permeability have made these formations become complex heterogenic systems with great temporal and spatial hydrodynamic variability in this paper a conditional sequential gaussian simulation sgs is used to simulate monthly flow data of five karstic springs with different hydrogeological properties located in zagros mountain chain in western iran to evaluate the performance of the sgs algorithm the results are compared with those of an autoregressive integrated moving average arima model the results demonstrate the efficiency of the sgs model in simulation of monthly flows compared to the arima model they also show the suitability of this model for handling uncertainty associated with karstic spring flows through generation of several equally probable stochastic realizations

focused groundwater flow in a carbonate aquifer in a semi arid environment summary an efficient conveyance system for groundwater is shown to have formed in a carbonate aquifer even though it is situated in a semi arid environment this conveyance system comprises preferential flow pathways that developed coincident with river channels a strong correlation between high capacity wells and proximity to higher order river channels i e within 2 5 km is used as evidence of preferential flow pathways factors that contributed to development of the preferential flow paths i karst development in carbonate rocks ii structural exhumation of a carbonate plateau and iii the requirement that the groundwater regime of the watershed has adequate capacity to convey sufficient quantities of water at the required rates across the full extent of the watershed recognition of these preferential pathways in proximity to river channels provides a basis to locate where high capacity wells are likely and unlikely and indicates that groundwater flow within the watershed is relatively rapid consistent with flow rates representative of karstic aquifers this understanding provides a basis for better informed decisions regarding water resource management of a carbonate aquifer in a semi arid environment

structural aspects of suspect terranes and accretionary tectonics in western north america abstract the regional structural relationships between the cordilleran suspect terranes and cratonic north america and within the suspect terranes themselves are reviewed for eastern alaska western canada and united states and northern mexico a distinctive characteristic of the relationships between the suspect terranes and the north american craton is that although much modified by post accretionary strike slip faulting thrust faulting and extensional detachment faults the generally more distal and or oceanic terranes are frequently found as rootless nappes or thin thrust sheets sitting upon more inboard terranes or upon the craton itself the amount of tectonic transport implied is large strike slip faulting has been a very significant aspect of the structural evolution of the north american cordillera with total distributed displacements of over 2000 km documented on geologic relationships alone and much more implied by paleomagnetic evidence at least since later mesozoic time to the present movements were such that the terranes moved northward post accretionary intraplate telescoping along thrust faults transpressional strike slip faulting and delamination at mid to upper crustal levels were important processes in cordilleran tectonic evolution

metamorphic origin of ore forming fluids for orogenic gold bearingquartz vein systems in the north american cordillera constraints froma reconnaissance study of δ15n δd and δ18o the western north american cordillera hosts a large number of gold bearing quartz vein systems from the mother lode of southern california through counterparts in british columbia and southeastern alaska to the klondike district in central yukon these vein systems are structurally controlled by major fault zones which are often reactivated terrane bounding sutures that formed in orogens built during accretion and subduction of terranes along the continental margin of north america mineralization ages span mid jurassic to early tertiary and encompass much of the evolution of the cordilleran orogen nitrogen contents and 15n values of hydrothermal micas from veins are between 130 and 3 500 ppm and 1 7 to 5 5 per mil respectively these values are consistent with fluids derived from metamorphic dehydration reactions within the phanerozoic accretion subduction complexes which have 15n values of 1 to 6 per mil the 18o values of gold bearing vein quartz from different locations in the cordillera are between 14 6 and 22 2 per mil but are uniform for individual vein systems the d values of hydrothermal micas are between 110 and 60 per mil ore fluids have calculated 18o values of 8 to 16 per mil and d values of 65 to 10 per mil at an estimated temperature of 300 c d values of ore fluids do not show any latitudinal control these results indicate a deep crustal source for the ore forming fluids most likely of metamorphic origin low dh2o values of 120 to 130 per mil for a hydrous muscovite from the sheba vein in the klondike district reflect secondary exchange between recrystallizing mica and meteoric waters collectively the n h and o isotope compositions of ore related hydrothermal minerals indicate that the formation of these gold bearing veins involved dilute aqueous carbonic and nitrogen bearing fluids that were generated from metamorphic dehydration reactions at deep crustal levels these data are not consistent with either mantle derived fluids or granitoid related magmatic fluids nor do they support a model involving deeply circulated meteoric water

a fluid inclusion and stable isotope study of au quartz veins in the klondike district yukon territory canada a section through a mesothermal vein system gold bearing quartz veins in the klondike district of yukon territory are of earliest cretaceous age and are hosted by permian middle to upper greenschist facies metasedimentary and meta igneous lithologies belonging to the yukon tanana terrane the veins occur in brittle extensional structures which may have developed during extensional deformation during uplift of the klondike region in the late jurassic to early to middle cretaceous following thrust imbrication in the early jurassic the quartz veins are massive and unbanded with localized carbonate flooding and or pyritization of the wall rocks fluid inclusion studies have delineated significant regional p t x trends in primary inclusion fluids from the au quartz veins the fluids have low salinities 6 wt nacl equiv but variable co 2 concentrations decreasing from approximately 0 13 to 0 18 mole fraction co 2 in the southeastern klondike through variable concentrations in the central klondike x sub co 2 0 01 to asymp 1 00 to dominantly aqueous fluids x sub co 2 0 01 in veins from the northwest portion of the region estimated trapping pressures decrease from 2 300 or 700 bars to between 300 to 900 bars from southeast to northwest estimated fluid temperatures range from 300 degrees to 350 degrees c in central and southern lodes to 200 degrees to 250 degrees c in the northwest klondike the p x trends are interpreted as evidence for 1 effervescence of co 2 from the mineralizing fluid most likely in response to regional uplift during the life of the hydrothermal system and 2 that the au quartz vein system represents a section through a mesothermal vein system with deeper structural levels exposed in the southeastern klondike convection of the hydrothermal fluid may have been driven by an elevated geothermal gradient resulting from the rapid uplift the calculated isotopic composition of the au quartz vein fluids delta 18 o fluid 8 3 or 1 2ppmsmow delta d fluid asymp 150 or 18ppmsmow indicates that the mineralizing fluid was meteoric in origin but underwent considerable isotopic evolution prior to mineralization additionally the delta d fluid values of extracted inclusion fluids 166 or 11ppm and from hydrothermal muscovites 174 or 3ppm from the sheba vein system are in good agreement and indicate that the deuterium signature reflects that of the primary mesothermal fluid

structure and water storage capacity of a small karst aquifer based on stream discharge in southwest china summary karst spring stream discharge reflects the global configuration of the aquifer however quantitative description of the aquifer structure such as effective porosity neff and water storage capacity by the discharge analysis is difficult because of the complex conduit fracture system this study attempted to quantify the characteristics of karst aquifer based on discharge recession and time series analysis methods three recession models including modified maillet mangin and boussinesq models were evaluated to choose the most suitable one for analyzing the aquifer structure and auto correlation and cross correlation functions were applied to study the aquifer response in both year and rainfall event time scales the results showed that the modified maillet model was more suitable in the study catchment with mangin model overestimating and boussinesq model underestimating the discharge the neff was 3 73 for the total aquifer and it was 0 07 0 33 and 3 33 for the conduit fracture and matrix respectively based on a case study of a rainfall event with precipitation of 68 mm the water volumes drained by the three media were 25 43 33 40 and 41 17 respectively this indicates that although conduit network is not very developed with lower neff it is still an important water transmissive element draining more than a quarter of water after the rainfall event the memory time of the aquifer was 4 days for the year scale and 8 h for the rainfall event 68 mm scale this demonstrates that the aquifer has a well developed drainage system with a quick response to the rainfall the above results provide further insights for hydrological processes modeling and water resources management for the small catchment in karst regions

quantifying and numerically representing recharge and flow components in a karstified carbonate aquifer karstified carbonate aquifers are highly heterogeneous systems characterized by multiple recharge flow and discharge components the quantification of the relative contribution of these components as well as their numerical representation remains a challenge this paper identifies three recharge components in the time and frequency domain while the analysis in the time domain follows traditional approaches the analysis of the power spectrum allows frequencies associated with specific spectral coefficients and noise types to be distinguished more objectively the analysis follows the presented hypothesis that the different frequency noise components are the result of aquifer heterogeneity transforming the random rainfall input into a sequence of non gaussian signals the distinct signals are then numerically represented in the context of a semidistributed pipe network model in order to simulate recharge flow and discharge of an irish karst catchment more realistically by linking the power spectra of the modeled recharge components with the spectra of the spring discharge the information usually gained by classical performance indicators is significantly widened the modeled spring discharge is well matched in the time and frequency domain yet the different recharge dynamics explain the signal of the aquifer outlet in different noise domains across the spectrum this study demonstrates the conjunctive use of frequency analysis in conceptualization of a hydrological system together with modeling and evaluation

ground water behaviour in karst example of the ombla spring croatia abstract the hydro electric power plant hepp which will exclusively use water from a karst underground storage basin will be built in the vicinity of the abundant karst spring ombla in croatia this paper presents the results obtained by hydrogeologic hydrologic and hydraulic investigations related to the principles of ground water circulation in the karst the analyses included the determination of the effective porosity ne of the karst aquifer and the definition of the volume of large conduits and small fractures in the karst which form the aquifer volume the position and dimensions of large karst conduits have also been defined it was established that in three small springs zaton zavrelje and slavljan water overflows from the ombla spring in periods of high ground water levels it was also discovered that at certain periods the dupuit expression for steady state flow in an unconfined aquifer can be used in accordance with this it was possible to determine the values of hydraulic conductivity k in m s 1 for the ombla aquifer they range from 2 10 3 to 5 10 3 m s 1 and are inversely proportional to the ombla spring discharge continuous measurements of the ground water level by several piezometers located in the karst hinterland of the ombla spring and simultaneous measurement of the discharge made it possible to define discharge curves of the ombla spring dependent upon the ground water levels at various locations characteristic features of the discharge curves made the identification of the position and dimensions of the main karst conduits possible

analytical 1d dual porosity equivalent solutions to 3d discrete single continuum models application to karstic spring hydrograph modelling abstract one dimensional analytical porosity weighted solutions of the dual porosity model are derived providing insights on how to relate exchange and storage coefficients to the volumetric density of the high permeability medium it is shown that porosity weighted storage and exchange coefficients are needed when handling highly heterogeneous systems such as karstic aquifers using equivalent dual porosity models the sensitivity of these coefficients is illustrated by means of numerical experiments with theoretical karst systems the presented 1d dual porosity analytical model is used to reproduce the hydraulic responses of reference 3d karst aquifers modelled by a discrete single continuum approach under various stress conditions simulation results show the relations between the dual porosity model coefficients and the structural features of the discrete single continuum model the calibration of the equivalent 1d analytical dual porosity model on reference hydraulic responses confirms the dependence of the exchange coefficient with the karstic network density the use of the analytical model could also point out some fundamental structural properties of the karstic network that rule the shape of the hydraulic responses such as density and connectivity

environmental isotope study of the major karst springs in damascus limestone aquifer systems case of the figeh and barada springs abstract the groundwaters of major karst springs and several piezometers and wells in the damascus limestone aquifer systems syria have been investigated using chemical and environmental isotope techniques the groundwater bodies of major karst springs mainly originate from direct infiltration of atmospheric water the groundwaters emerging from the figeh main spring have lower stable isotope concentrations than those emerging from the barada spring stable isotopes show that the elevation of the recharge zones of the figeh main spring 1750 m above sea level is higher than those for the figeh side spring 1500 m and the harouch spring 1300 m the groundwater in the barada spring seems to be recharged in a catchment area with a mean elevation of about 1250 m the temporal evolution of stable isotope concentrations tritium content and hydrochemistry show the existence of an interconnection between the aquifers of the figeh main spring and the figeh side spring especially during flood periods the distinct independent isotopic composition of harouch spring from those of figeh main and side springs suggests no interconnection with the figeh aquifers adopting a model with exponential time distribution the mean turnover time residence time of groundwater in figeh main spring was evaluated to be 50 years on the basis of this evaluation a value of about 3 9 billion m 3 was obtained for the maximum groundwater reservoir size 1997 elsevier science b v

hydrogeological investigation of karst system properties by common use of diverse methods a case study of licka jesenica springs in dinaric karst of croatia licka jesenica is a sinking river situated in the dinaric karst environment of the lika region of croatia the two main karst springs veliko vrelo and malo vrelo provide the majority of licka jesenica s water because of the quality and abundance of the water they contain these springs are strategically important to the public water supply previous knowledge regarding the springs karst system has been negligible therefore a bulk hydrogeological research program was conducted with the purposes of establishing protection zones and assessing the springs water supply potential the research work comprised the following methods hydrogeological mapping setting up of monitoring stations for evaluating discharge and water quality time series analyses hydrograph chemograph hydrochemical analyses and geophysical surveys the main results and conclusions of the research include 1 confirmation that both springs drain a common aquifer 2 determination of the highly vulnerable nature of the karst systems 3 identification of the veliko vrelo spring s more direct connection to the aquifer drainage system in comparison to the malo vrelo 4 estimation of the positions and depths of the springs main feeding conduits 5 confirmation of the extent of the geologically presumed catchment area and 6 finally establishment of sanitary protection zones

a deterministic approach to the coupled analysis of karst springs hydrographs and chemographs abstract during the chemically based recession flow phase of karstic springs the carbonate dissolved limestone concentration can be expressed as negative power of the flow rate the empirically determined conc q relationship allows two parameters and a to be defined of which one depends on the geometric dimensions of the saturated submerged karstic network in this paper we present a deterministic model which simulates the concentration of carbonate at the outlet of a network of circular rectilinear conduits as a function of flow rate this model based on hydraulic principles and the calcite dissolution kinetics allows the sensitivity of the and a parameters to be studied under different chemical physical and geometric scenarios simulation results show that a is a function of the calcite saturation concentration whereas depends on the spatial dimensions of the karstic network void length and aperture the deterministic model results were applied to real karstic systems to evaluate the geometric dimensions of submerged karstic networks

significance and origin of very large regulating power of some karst aquifers in the middle east implication on karst aquifer classification summary karst aquifers are the main groundwater resource in lebanon as well as in most mediterranean countries most of them are not exploited in a sustainable way partly because their characteristics remain unknown karst aquifers are so complex that the assessment of their resource and their exploitable storage requires an analysis of their whole functioning particularly by analysing the spring hydrograph among all various methods the method proposed by mangin aims to characterize at the same time the recharge conditions and the storage and recession of the saturated zone by analyzing the spring hydrograph this method defines two parameters the infiltration delay i and the regulating power k which are the roots of a classification of karst systems this classification makes the distinction between karst and porous aquifers considering the value of the regulating power k is assumed to be lower than 0 5 in karst and between 0 5 and 1 for all other aquifers 1 being the upper limit the study of karst aquifers in lebanon shows values of k 0 5 and even 1 former data from the literature show that other karst springs in middle east have comparable characteristics in fact what is not considered by mangin and others k is equivalent to a mean residence time in years of water in the saturated zone so long residence times are normally observed in poorly karstified aquifers or containing abandoned not functioning karstification the geological framework in which the studied springs are located in fact shows that these aquifers have been subject to a long complex evolution as a consequence of the base level rising this rising produced the flooding of the successive karst drainage network which does not really function anymore and provides a large storage capacity to the aquifer the very interesting properties of these aquifers make them prime targets for fulfilling the increasing needs of water

a preliminary study of 15n14n in octahedral growth form diamonds abstract the 13 c 15 n and nitrogen concentrations have been determined in 43 octahedral diamonds from southern africa australia and north america the sample set included locations such as finsch south africa a mine which produces diamonds having 13c values close to 5 and argyle australia a mine which produces 13c depleted diamonds the nitrogen within high 13c diamonds 13 c 6 4 to 2 9 was generally depleted in 15n relative to atmospheric nitrogen 15n 12 3 to 5 9 mode 4 similar to the results which have been obtained previously from fibrous diamond it is believed that the volatiles from which these diamonds grew are primitive being derived from a source located beneath the continental lithosphere which may have changed little in terms of 13c and 15n since the mid archean the low 13c diamonds 13c 19 4 to 9 5 contained nitrogen generally enriched in 15n relative to air 15n 3 0 to 16 4 mode 5 it is suggested that the major carbon isotope heterogeneity within the mantle as represented by diamonds such as these is located in deep mechanically unstable regions of the continental lithosphere the isotopic compositions of both c and n are consistent with this heterogeneity resulting from the subduction of crustal material however isotope fractionation related directly to diamond growth cannot be ruled out

groundwater flow characterization in a multilayered karst aquifer on the edge of a sedimentary basin in western france abstract on the edge of sedimentary basins burial of geological layers can involve the formation of confined karst aquifers in some cases relationships between confined and unconfined karst aquifers can exist and imply an increased difficulty in delineating contributive areas of karst system outlets with accuracy this work aims to develop a multi disciplinary approach to highlight groundwater exchanges between multilayered karst aquifers feeding a single spring toulon springs located in western france provides the opportunity to study relationships between two multilayered karst aquifers hydrograph and chemograph analysis coupled with principal component analysis pca are used to evaluate groundwater flow origins on the northern edge of a sedimentary basin natural hydrodynamic responses baseflow recession analysis auto cross correlation function show an important volume of water located in a saturated zone of the toulon karst system significant contrasts in water quality as a function of the hydrological regime flood recession and baseflow regime and comparison with shallow and deep water show the participation of a deep aquifer supporting the flow of toulon springs

on the inclusion of ground based gravity measurements to the calibration process of a global rainfall discharge reservoir model case of the durzon karst system larzac southern france thiswork examines the relevance of the inclusion of ground based gravity data in the calibration process of a global rainfall discharge reservoir model the analysis is performed for the durzon karst system larzac france the first part of the study focuses on the hydrological interpretation of the ground based gravity measurements the second part of the study investigates further the information content of the gravity data with respect to water storage dynamics modelling the gravity derived information is found unable to either reduce equifinality of the single objective dischargebased model calibration process or enhance model performance through assimilation

seismic sources in open and cased boreholes theoretical modeling based on the equations of linear elasticity is used to analyze the performance of downhole seismic sources specifically symmetrical radial sources which exert outward pressure on a length of the borehole wall and vertically driven sources clamped to the borehole wall torsional sources radiate pure s waves whose form is independent of the existence of the borehole and therefore requires no special discussion the radial sources discussed are airguns waterguns and implosive sources such sources are in widespread use and development at present from the calculations we find that radial sources emit almost all 99 percent their energy as tube waves which travel along the borehole and not out into the formation vertical sources radiate almost all their energy into the formation as p and s waves however if the casing bond slips the vertical sources lose efficiency and radiate energy as extensional waves along the casing the radial sources are little affected by the quality

karst and artificial recharge theoretical and practical problems a preliminary approach to artificial recharge assessment summary managed aquifer recharge mar is an emerging sustainable technique that has already generated successful results and is expected to solve many water resource problems especially in semi arid and arid zones it is of great interest for karst aquifers that currently supply 20 25 of the world s potable water particularly in mediterranean countries however the high heterogeneity in karst aquifers is too complex to be able to locate and describe them simply via field observations hence as compared to projects in porous media mar is still marginal in karst aquifers accordingly the present work presents a conceptual methodology for aquifer rechargeability assessment in karst referred to as arak the methodology was developed noting that artificial recharge in karst aquifers is considered an improbable challenge to solve since karst conduits may drain off recharge water without any significant storage or recharge water may not be able to infiltrate the aim of the arak method is to determine the ability of a given karst aquifer to be artificially recharged and managed and the best sites for implementing artificial recharge from the surface arak is based on multi criteria indexation analysis modeled on karst vulnerability assessment methods arak depends on four independent criteria i e epikarst rock infiltration and karst after dividing the karst domain into grids these criteria are indexed using geological and topographic maps refined by field observations arak applies a linear formula that computes the intrinsic rechargeability index based on the indexed map for every criterion coupled with its attributed weighting rate this index indicates the aptitude for recharging a given karst aquifer as determined by studying its probability first on a regional scale for the whole karst aquifer and then by characterizing the most favorable sites subsequently for the selected sites a technical and economic feasibility factor is applied weighted by the difficulties that could occur when trying to undertake a recharge operation at a selected site from the surface each site is finally rated by its rechargeability index the product of two factors the intrinsic rechargeability and the feasibility index arak was applied to the region of damour lebanon on the mediterranean coast where uncontrolled exploitation of public and private wells led to its partial salinization by seawater a mar system in damour region represents an interesting solution to cope with salinization and the insufficiency of the resource

contribution a l etude des courbes de recession des sources karstiques exemples du pays hellenique abstract a study of the recession curves of the major springs of some systems of karstic aquifers in greece shows that each of these aquifers is unique in respect of its boundary conditions its internal organization and its hydrodynamics differences which result in different forms of recession curves these case studies can therefore form the basis for the prediction of the recession curves of karstic springs and hence for the classification of the systems of aquifers

an integrated hydrogeological approach to evaluate the leakage potential from a complex and fractured karst aquifer example of abolabbas dam iran the design and construction of dams are risky in karst regions with active tectonic settings and strong heterogeneity due to their leakage potential hydrogeological characterization by karst specific methods can be used to reduce the risk of improper dam construction numerous karstic dams have been constructed in the world in simple tectonic settings in this study a combination of geological and hydrogeological investigations is used with extensive data collection to evaluate the leakage potential of the abolabbas dam construction project at the malagha karst aquifer a tectonized highland karst region in the southwest of iran two thrust faults which bounded the malagha karst aquifer overthrusting caused extensive crushed zones continuous lengths with high permeabilities in most of the boreholes extensive open joints and small size solution cavities the results of artificial tracer tests imply that the flow regime is diffuse the flat water table diffuse flow regime extensive crushed zones and continuous high permeabilities most probably imply that the groundwater flows through an extensive network of joints without main conduits to drain the system despite a diffuse flow regime an extensive grout curtain both in length and depth is required to prevent leakage because the loose materials of the crushed zones will be washed out without it under high hydraulic gradients after dam impoundment the impermeable formation is too deep due to overthrusting therefore a huge leakage may occur under the hanging grout curtain the results allow a clearer understanding of the location and properties of fracture zones erodible materials high permeability zones groundwater flow regime and zones of preferential flow which are essential for reducing the failure of dam construction in such environments overall it is demonstrated that integrating different complementary methods can help to minimize the uncertainties inherent in engineering problems in similar karst scarce data regions

karst groundwater resources in the countries of eastern mediterranean the example of lebanon the hydrogeological study of some karst systems in lebanon shows important storage capacity up to 27 billions m3 for zarka system the spring of orontes river their geological and morphological settings as well as their hydrodynamic function show structures developed below the level of present springs probably up to several hundreds meters at depth since miocene those carbonate formations were subject to a remarkable instability of their base levels variations of sea level of which the messinian salinity crisis is the major phase and effects of the alpine orogenesis combined with climate variations to develop complex multiphased karst systems karstification occurs frequently in the whole formation often deeply below sea level or underneath sediment filling of continental basins the surface karst landscape is often intensely eroded those multiple superimposed karst phases give the carbonate aquifers their large extension and storage capacity these karst aquifers show the typical easy restoration of storage they have the ability to bear large interannual recharge variations and support exploitation under high pumping rates however these aquifers have some disadvantages for sustainable management in some regions successful boreholes which allow high pumping rates also induce uncontrolled exploitation another consequence is natural seawater intrusion as well as the submarine discharge of fresh groundwater in coastal aquifers those carbonate aquifers are subject to important economical stress which jeopardizes their durability the systematic study and understanding of carbonate aquifers in eastern mediterranean is a preliminary condition to any integrated and sustainable management of water resources studies in progress in lebanon may serve as examples to the whole region

rb sr k ar and stable isotope evidence for the ages and sources of fluid components of gold bearing quartz veins in the northern sierra nevada foothills metamorphic belt california gold bearing quartz veins occur in and near major fault zones in deformed oceanic and island arc rocks west of the main outcrop of the sierra nevada composite batholith veins typically occupy minor reverse faults that crosscut blueschist to amphibolite grade metamorphic rocks whose metamorphic ages range from early paleozoic to jurassic vein micas and carbonate quartz mica assemblages that formed by hydrothermal metasomatism of ultramafic wall rocks in the alleghany grass valley washington and mother lode districts yield concordant k ar and rb sr ages the dated veins are significantly younger than prograde metamorphism penetrative deformation and accretion of their host rocks to the continental margin new and previously published mineralization ages from 13 localities in the sierra foothills range from about 140 to 110 m y ago with mean and median between 120 and 115 m y the age relations suggest that mineralizing fluids were set in motion by deep magmatic activity related to the resumption of east dipping subduction along the western margin of north america following the late jurassic nevadan collision event co 2 bearing fluids responsible for metasomatism and much of the vein mica carbonate albite and quartz deposition in several northern mines were isotopically heavy delta 18 o asymp 8 14ppm delta d between about 10 and 50ppm and do not resemble seawater magmatic or meteoric waters metasomatic and vein filling mica dolomite magnesite and quartz in altered ultramafic rocks generally formed from fluids with similar sr and o isotope ratios at a given locality consistent quartz mica delta 18 o fractionations delta 18 o sub q m 4 5 4 9ppm from various localities imply uniform equilibration temperatures probably between 300 degrees and 350 degrees c on a local mine scale fluids responsible for both carbonate alteration of mafic and ultramafic wall rocks and albitic alteration of felsic and pelitic rocks had similar sr isotope ratios samples from three veins in the central alleghany district fit a 115 7 or 3 m y rb sr isochron with a 87 sr 86 sr i value of approximately 0 7119 inferred 87 sr 86 sr ratios of metasomatic fluids from mines in different parts of the foothills region vary considerably 0 704 0 718 suggesting that sr was derived from sources ranging from western assemblage mesozoic ophiolitic or arc volcanic rocks to early paleozoic continent derived clastic rocks of the shoo fly complex systematic geographic variations in both sr and o isotopes can be rationalized by assuming extensive fluid interaction with rocks similar to the ones that are exposed within a few kilometers of the veins but the ultimate sources of the fluids and of au and other constituents may be independent of these isotopically lighter meteoric fluids deposited some late quartz overgrowths and occupied secondary fluid inclusions in earlier vein quartz