Sample records for aquicludes

  1. Partitions, Compartments and Portals: Cave Development in internally impounded karst masses.

    Osborne R. Armstrong L.


    Dykes and other vertical bodies can act as aquicludes within bodies of karst rock. These partitions separate isolated bodies of solublerock called compartments. Speleogenetically each compartment will behave as a small impounded-karst until the partition becomesbreached. Breaches through partitions, portals, allow water, air and biota including humans to pass between sections of caves thatwere originally isolated.

  2. Partitions, Compartments and Portals: Cave Development in internally impounded karst masses.

    Osborne R. Armstrong L.


    Full Text Available Dykes and other vertical bodies can act as aquicludes within bodies of karst rock. These partitions separate isolated bodies of solublerock called compartments. Speleogenetically each compartment will behave as a small impounded-karst until the partition becomesbreached. Breaches through partitions, portals, allow water, air and biota including humans to pass between sections of caves thatwere originally isolated.

  3. Measurement of fluid velocity using temperature profiles: Experimental verification

    Cartwright, K.


    Temperature profiling has been used to predict the rate and direction of groundwater movement. A controlled field experiment was conducted to ascertain the validity of the rate calculations made using this method. The vertical velocity, or leakage, of groundwater between two aquifers was calculated utilizing both hydrologic and temperature measurements in a well drilled into the Paw Paw buried bedrock valley in northern Illinois. The experiment showed that accurate estimates of leakage can be made in stable boreholes where there are no geologic complications. Estimates utilizing temperature and hydrologic methods produced similar results for one of two aquicludes. However, the methods produced dissimilar results for the second aquiclude. It is speculated that the presence of a thin organic silt caused most of the problem; other complicating factors were lithologic variation and a very low hydraulic gradient. Nevertheless, the method appears to have great promise in many geologic environments. ?? 1979.

  4. The hydrogeochemistry of methane : evidence from English groundwaters

    Darling, W. G.; Gooddy, D.C.


    The presence of methane (CH4) in groundwater is usually only noticed when it rises to high concentrations; to date rather little is known about its production or natural ‘baseline’ conditions. Evidence from a range of non-polluted groundwater environments in England, including water supply aquifers, aquicludes and thermal waters, reveals that CH4 is almost always detectable, even in aerobic conditions. Measurements of potable waters from Cretaceous, Jurassic and Triassic carbonate and sandsto...

  5. Investigation of a shallow aquifer near the Fenton Hill hot dry rock site using DC resistivity

    Pearson, C.F.


    A shallow aquifer in the base of the Tertiary volcanic sequence was investigated using a series of 9 DC Schlumberger soundings taken within 10 km of the Fenton Hill hot dry rock geothermal site. The aquifer dips to the southwest following the top of the Abo formation, which acts as an aquiclude. Depth increases from 130 m in the eastern part of the study area to 260 m at 1.5 km west of the Fenton Hill site. Aquifer resistivities varied from 13..cap omega..-m to 126..cap omega..-m, which could be caused by variable permeability in the aquifer. Using results from empirical studies permeabilities ranging from 40 darcies to less than 0.3 darcies were estimated with the highest values occurring nearest to the Fenton Hill site.

  6. Site qualification studies of the UCG-SDB at North Knobs, Wyoming

    Davis, B.E.; Krajewski, S.A.; Ahner, P.F.; Avasthi, J.M.; Dolde, M.E.; Greenman, C.A.; Miranda, J.E.


    The site qualification program for the North Knobs UCG site near Rawlins, Wyoming has been completed. This site will be the location for the field tests of Underground Coal Gasification of Steeply Dipping Beds undertaken by Gulf Research and Development Company for DOE in a cost shared contract. Site characterization included a comprehensive geotechnical analysis along with vegetation, historical, and archeological studies. The G coal seam chosen for these tests is a subbituminous B coal with a true seam thickness of 22 feet and has thin coal benches above and below the main seam. The water table is at 90 feet below the surface. Hydrologic studies have defined the seam as an aquiclude (non-aquifer). The site is deemed restorable to regulatory requirements. Evaluation of this site indicates total acceptability for the three-test program planned by GR and DC.

  7. Well, hydrology, and geochemistry problems encountered in ATES systems and their solutions

    In aquifer thermal energy storage (ATES) systems, wells provide the interface between the energy storage and use. Efficient operational wells are, therefore, essential for the system to run at maximum (design) efficiency. Adequate test drilling to accurately predict aquifer properties is essential in the design phase; proper construction and development are crucial; and proper monitoring of performance is necessary to identify the early stages of clogging and to evaluate the adequacy of well rehabilitation. Problems related to hydrology, well, and aquifer properties include: loss of permeability resulting from gas exsolution, chemical precipitation, and dispersion and movement of fine-grained particles; loss of recoverable heat caused by excessive regional ground-water gradient, hydrodynamic mixing of injected and native ground water, buoyancy flow and heat conduction through the cap and base of the storage zone; leakage up along the well casing; and ''fracturing'' of a shallow upper aquiclude as a result of an injection pressure greater than the hydrostatic pressure on the aquiclude. The predominant geochemical problems encountered are precipitation of carbonates in some areas and iron plus manganese oxides in others. These precipitation problems can be anticipated, and thus avoided, via geochemical calculations. The likelihood of iron carbonate precipitation is less certain because of the lack of adequate research. Corrosion is a frequent problem. Most of the hydrochemically related clogging and corrosion problems that have been encountered in ATES systems can be predicted and avoided by appropriate design, construction, and operation of new ATF-S systems, assuming that appropriate hydrologic and geochemical modeling is carried out in advance. It is prudent to carefully consider the need for water treatment and to anticipate that there will be some increase in injection pressure and decrease of specific capacity over time

  8. Hydrogeological investigation of Melendiz basin (Aksaray)

    Within the scope of this M.Sc, study entitled Hydrogeologic Investigation of Melendiz basin, the geological, hydrological, hydrogeological and hydrochemical features of a 600 km2 area have been studied and, 1/100.000 scale geological and hydrogeological maps have been prepared. Tetriary-Guaternary aged young volkanic rocks occupy nearly 80% (480 km2 ) of the area. The major aquifers are alluvium and andesite and basalt which are extensively fractured and jointed. Aquitard units comprise of ignimbirite, some of the andesites-basalts and formations that composes of limestone-sandstone-marl intercalations. The youngest geologic unit of the area, Hasandag volcanic ash formation, and also the tuffs have been indentified as aquiclude units. Mean areal precipitation, potential and real evapotranspiration rates and mean annual streamflow have been calculated on the basis of available data and, a hydrologic budget of the basin has been established. Hydrogeologic units have been classified as aquifer, aquitard and aquiclude with respect to their geohydrologic properties, field observations and the results of the pumping tests. On the other hand, hydrodynamic mechanism of the groundwater flow reaching major cold and thermal water discharges have also been explained. A hydrogeologic budget for the area covering Ciftlik township and its vicinity where extensively joint and fractured andesite-basalt and alluvial aquifers outcrop has been established. Major water points as thermal and cold springs, wells and streams have been sampled for major ion analysis. Beyond this, some water points have also been sampled for organic, trace,metal ald environmental isotropic analyses. Environmental isotope data of thermal springs point out a long-deep groundwater flow path

  9. 小庄矿井采煤对地下水的影响及保水采煤措施%The influence of underground coal mining on groundwater and measures for water conservation while mining in Xiaozhuang mine

    徐海红; 乔皎; 王铮


    针对煤炭开采易造成地表塌陷及含水层破坏等问题,采用类比法计算了彬长矿区规划新建的矿井——小庄矿井开采导水裂缝带高度,在此基础上分析了采煤对地下水的影响,并提出保水采煤的措施。经计算,采用分层开采时产生的导水裂隙带最大高度为147.84 m,在三盘区将导通安定组隔水层,造成宜君组、洛河组承压含水层破坏,导通区域面积为0.7736 km2。因此,在可能导通的区域应进行保水采煤以保证安定组隔水层的稳定,从而达到保护具有供水意义的含水层和保障矿井生产安全的双重目的。%Aiming at the problems such as collapse of ground surface and damage of aquifer induced by coal mining this paper calculates height of water flowing fractured zone in XiaoZhuang mine by using the analogy method. In addition, based on this, we analyzed the influence of mining and put forward water conservation while mining.Calculated from experimental data, height of water flowing fractured zones has an absolute maximum of 147.84 m by slice mining. Breakover of aquiclude of Anding Formation results in the destruction of confined aquifer of Luohe Formation in the third panel, the breakover area reached 0.7736 km2. Mining with water conservation should be applied in the area where the breakover may occur to ensure the stability of the aquiclude of Anding formation so as to achieve the double goals of protecting the water supplying aquifer and ensuring the safety of mine production.

  10. High=porosity Cenozoic carbonate rocks of South Florida: progressive loss of porosity with depth

    Halley, Robert B.; Schmoker, James W.


    Porosity measurements by borehole gravity meter in subsurface Cenozoic carbonates of South Florida reveal an extremely porous mass of limestone and dolomite which is transitional in total pore volume between typical porosity values for modern carbonate sediments and ancient carbonate rocks. A persistent decrease of porosity with depth, similar to that of chalks of the Gulf Coast, occurs in these rocks. Carbonate strata with less than 20% porosity are absent from the rocks studied here. Aquifers and aquicludes cannot be distinguished on the basis of porosity. Aquifers are not exceptionally porous when compared to other Tertiary carbonate rocks in South Florida. Permeability in these strata is governed more by the spacial distribution of pore space and matrix than by total volume of porosity present. Dolomite is as porous as, or slightly less porous than, limestones in these rocks. This observation places limits on any model proposed for dolomitization and suggests that dolomitization does not take place by a simple ion-for-ion replacement of magnesium for calcium. Dolomitization may be selective for less porous limestone, or it may involve the incorporation of significant amounts of carbonate as well as magnesium into the rock. The great volume of pore space in these rocks serves to highlight the inefficiency of early diagenesis in reducing carbonate porosity and to emphasize the importance of later porosity reduction which occurs during the burial or late near-surface history of limestones and dolomites.

  11. Hydrogeological Model of an Urban City in a Coastal Area, Case study: Semarang, Indonesia

    Thomas Putranto


    Full Text Available In Semarang City, groundwater has been exploited as a natural resource since 1841. The groundwater exploited in deep wells is concentrated in confined aquifers. The previous hydrogeological model was developed in one unit of aquifer and refined then by using several hydrostratigraphical units following a regional hydrogeological map without any further analysis. At present, there is a lack of precise hydrogeological model which integrates geological and hydrogeological data, in particular for multiple aquifers in Semarang. Thus, the aim of this paper is to develop a hydrogeological model for the multiple aquifers in Semarang using an integrated data approach. Groundwater samples in the confined aquifers have been analyzed to define the water type and its lateral distribution. Two hydrogeological cross sections were then created based on several borelog data to define a hydrostratigraphical unit (HSU. The HSU result indicates the hydrogeological model of Semarang consists of two aquifers, three aquitards, and one aquiclude. Aquifer 1 is unconfined, while Aquifer 2 is confined. Aquifer 2 is classified into three groups (2a, 2b, and 2c based on analyses of major ion content and hydrostratigraphical cross sections.

  12. Proceedings of GeoEdmonton 2008 : the 61. Canadian geotechnical conference and 9. joint CGS/IAH-CNC groundwater conference : a heritage of innovation

    Martin, D. [Alberta Univ., Edmonton, AB (Canada); Skirrow, R. [Alberta Transportation, Edmonton, AB (Canada); Froese, C. [Alberta Geological Survey, Edmonton, AB (Canada)] (comps.) (and others)


    This conference provided a forum for more than 500 delegates from industry, government universities and research centres to share their professional knowledge on research and development that affects all sectors of geotechnical engineering, applied geology and hydrogeology. Accomplishments in the geoenvironmental field were also highlighted. The geotechnical sessions were entitled: pile foundations and load testing; excavations and special foundation issues; reinforced soil and soil-structure interactions; advances in modelling, constitutive issues; advances in modelling, consolidation and other applications; advances in modelling, discrete elements and slope stability; embankments and dams; landfills and barriers; fundamental soil mechanics; soil mechanics and ground movement; GIS and remote sensing; landslides and slopes; cone penetration tests and liquefaction assessment; rock mechanics; engineering geology; geoenvironmental sustainability; oilsand and petroleum geomechanics; and, oilsand tailings. The hydrogeology sessions were entitled: paste tailings and cemented paste backfill; acid mine drainage and containment issues; contaminated sites; cold regions; instrumentation, insitu testing and field applications; transportation geotechniques; urban geohazards; staff retention and motivation; geotechnical education for modern practice; regional issues and studies; policy, regulation and conservation; groundwater and development; groundwater and surface water interactions; groundwater and terrain interactions; aquicludes and aquitards; general hydrogeology; and, geochemistry and contaminant hydrogeology. The conference featured more than 250 presentations, of which 42 have been catalogued separately for inclusion in this database. refs., tabs., figs.

  13. Lithologic environments: the controlling factor for Green Mountain-type uranium deposits

    Much has been written about Wyoming's roll-front uranium deposits, but little has been published about what is hereafter referred to as the Green Mountain-type uranium deposits. They occur in the Eocene Battle Spring Formation, a sequence of continental fluvial deposits over 5000 ft thick. This sequence consists of arkosic sandstones, conglomeratic sandstones, and siltstones. The Granite Mountains, an ancient crystalline high now partially buried in part by material eroded from it, supplied both the detritus and the uranium for the Battle Spring and the Wind River Formations, the latter being the host for uranium of the Gas Hills district. Both the similarities and dissimilarities of the Green Mountain-type vs. the roll-front-type uranium occurrences are discussed. Most of the Battle Spring Formation is a leaky aquifer devoid of consistent aquicludes, which explains the lack of high-grade uranium concentrations at the frontal or closure redox boundary. Instead, the high-grade mineralization occurs at the interface between carbonaceous debris-rich siltstone lenses and the permeable arkosic sandstone and conglomeratic sandstone. Economically significant deposits occur where mineralizing fluids penetrate a high frequency of these interfaces. Published minable reserves of Atlantic Richfield's Round Park deposit are 42 million lb U3O8 with an average grade of 0.23%. These and other deposits are examples of Green Mountain-type uranium deposits

  14. Flow in horizontally anisotropic multilayered aquifer systems with leaky wells and aquitards

    Cihan, Abdullah; Zhou, Quanlin; Birkholzer, Jens T.; Kraemer, Stephen R.


    Flow problems in an anisotropic domain can be transformed into ones in an equivalent isotropic domain by coordinate transformations. Once analytical solutions are obtained for the equivalent isotropic domain, they can be back transformed to the original anisotropic domain. The existing solutions presented by Cihan et al. (2011) for isotropic multilayered aquifer systems with alternating aquitards and multiple injection/pumping wells and leaky wells were modified to account for horizontal anisotropy in aquifers. The modified solutions for pressure buildup distribution and leakage rates through leaky wells can be used when the anisotropy direction and ratio (Kx/Ky) are assumed to be identical for all aquifers alternating with aquitards. However, for multilayered aquifers alternating with aquicludes, both the principal direction of the anisotropic horizontal conductivity and the anisotropy ratio can be different in each aquifer. With coordinate transformation, a circular well with finite radius becomes an ellipse, and thus in the transformed domain the head contours in the immediate vicinity of the well have elliptical shapes. Through a radial flow approximation around the finite radius wells, the elliptical well boundaries in the transformed domain are approximated by an effective well radius expression. The analytical solutions with the effective radius approximations were compared with exact solutions as well as a numerical solution for elliptic flow. The effective well radius approximation is sufficiently accurate to predict the head buildup at the well bore of the injection/pumping wells for moderately anisotropic systems (Kx/Ky≤25). The effective radius approximation gives satisfactory results for predicting head buildup at observation points and leakage through leaky wells away from the injection/pumping wells even for highly anisotropic aquifer systems >(Kx/Ky≤1000>).

  15. Development of isotopically heterogeneous infiltration waters in an artificial catchment in Chuzhou, China

    The existence of spatial and temporal isotopic variability of infiltration waters during storm events can pose substantial difficulties in the use of stable isotopes for tracing sources and flow paths of water contributing to storm flow. The 490 m2 Hydrohill experimental catchment near Nanjing, China, was used to investigate the development of isotopic heterogeneity in subsurface waters. This catchment contains a network of lysimeters, troughs and wells installed within a 1 m thick layer of silty loam emplaced above a concrete aquiclude. During a storm on 1989-07-05, a complete suite of samples (precipitation, surface runoff, unsaturated zone flow from four lysimeters, saturated zone flow and groundwater from 16 sites) was collected and analysed for δ18O. The contributions of rain water to subsurface flow ranged from 5 to 95%, depending on the time, location and depth of sampling. During peak flows, many subsurface waters are apparently composed of mixtures of rapidly moving rain water travelling through macropores, with smaller amounts of pre-storm water flowing downwards by matrix flow; as the soils drain between rain pulses, the subsurface samples approach their pre-storm isotopic compositions. Surface and shallow subsurface processes appear to have a significant effect on the development of isotopic variability in soil waters and shallow groundwaters. Thus, if such shallow hill slope waters are a significant source of water to streams during storm events, then an understanding of the processes and flow paths on the hill slope is critical to the development of accurate models of storm flow generation. (author). 7 refs, 5 figs

  16. 3D coexisting modes of thermal convection in the faulted Lower Yarmouk Gorge

    Magri, Fabien; Inbar, Nimrod; Möller, Peter; Raggad, Marwan; Rödiger, Tino; Rosenthal, Eliyahu; Siebert, Christian


    Numerical investigations of 3D modes of large-scale convection in faulted aquifers are presented with the aim to infer possible transport mechanisms supporting the formation of thermal springs in the Lower Yarmouk Gorge (LYG), at the border between Israel and Jordan. The transient finite elements models are based on a geological model of the LYG that introduces more realistic structural features of the basin, compared to previous existing models of the area (Magri et al., submitted). The sensitivity analysis of the fault permeability showed that faults cross-cutting the main regional flow direction allow groundwater to be driven laterally by convective forces within the fault planes. Therein thermal waters can either discharge along the fault traces or exit the fault through adjacent permeable aquifers. The location of springs can migrate with time, is not strictly constrained to the damage zones and reflects the interplay between the wavelength of the multicellular regime in the fault zone and the regional flow toward discharge areas in the lowlands. The results presented here suggest that in the LYG case, crossing flow paths result from the coexistence of fault convection, that can develop for example along NE-SW oriented faults within the Gorge, and additional flow fields that can be induced either by topography N-S gradients, e.g. perpendicular to the major axe of the Gorge, or by local thermal convection in permeable aquifers below Eocene aquiclude. The sensitivity analysis is consistent with the analytical solutions based on viscous-dependent Rayleigh theory. It indicates that in the LYG coexisting transport processes likely occur at fault hydraulic conductivity ranging between 2.3e-7 m/s and 9.3e- 7 m/s (i.e. 7 m/yr and 30 m/yr). The LYG numerical example and the associated Rayleigh analysis can be applied to study the onset of thermal convection and resulting flow patterns of any fractured hydrothermal basin. References Magri F, Möller S, Inbar N, M

  17. Ground-water resources for emergency cases in the lower reaches of the Labe (Elbe) River (Czech Republic)

    Full text: Floods in the Czech Republic and elsewhere in the world during past years contaminated a large number of wells. The conventional water supply from individual wells and public water supply systems collapsed and had to be interrupted to prevent epidemic diseases. The substitution of water supply by import of drinking water in bottles and tanks became one of most topical tasks of the emergency activities right after rescuing of human lives endangered by floods. Similar cases repeated during transportation of liquid fuels and toxic chemicals and during accidents in chemical plants and elsewhere. The valley of the Labe (Elbe) River in Northern Bohemia in the Czech Republic is an industrial region with a frequent risk of endangering drinking water resources. The potential accidents in water supply have to be considered and measures of prevention have to be at hand to attenuate the consequences and to make sure supplementary water resources for the period until the consequences of accidents are removed. The water supply systems of numerous towns along the Labe (Elbe) River use groundwater resources of the fluviatile sediments and are exposed to a similar danger as the water supply in Moravia in 1997 and 1998. This has been proved again during the floods in the Labe and Vltava (a tributary of Labe) watershed in summer 2002. Because of this, the aquifers in the Cretaceous formation beyond the alluvial plain, which were considered safe and protected from the surface pollution, were investigated in the first step. They include a confined aquifer in the Cenomanian sandstone at the base and an unconfined aquifer in the Coniacian sandstone at the top of the Cretaceous strata. Between the aquifers, there is an about 350 m thick aquiclude of the Turonian strata consisting mainly of marlstones. Radiocarbon ground-water dating, together with analyses of tritium and stable isotopes, was used. The aim was to determine the time of ground-water origin in the geological past

  18. Fluid transport processes in the passive margins of the Eastern Mediterranean

    Bertoni, Claudia; Foschi, Martino; Cartwright, Joe; Levell, Bruce


    We analyse and produce a synoptic model of the different styles of fluid transport occurring in the various passive margin settings in the Eastern Mediterranean. The common tectonic-stratigraphic setting is dominated, from the Mesozoic, by the interaction of the Tethyan platforms with Cenozoic to recent, mainly clastic, deposits interacting with the ubiquitous thick late Miocene (Messinian) evaporitic sediments. This created different specific modes of fluid-lithology coupling behaviours, and generated an extraordinary suite of seismically resolvable fluid flow phenomena, including mud volcanoes, pockmarks, dissolution/collapse structures, chimneys and pipes. We integrate this evidence with the analysis of the regional pressure/temperature gradient, and with published hydrocarbon generation models, to propose a regional synthesis of all fluid transport processes in a specific basinal context. We place the fluid flow evidence observed in the Eastern Mediterranean in the framework of the three main fluid flow settings, which are typically defined in sedimentary basins, in terms of depth: 1) A thermobaric fluid regime, where fluid transport is limited and convection can be the dominant transport mechanism, 2) A thermogenic regime, where fluids supplied by hydrocarbon generation can migrate by hydraulic fracturing and advection (along open faults/conduits), by matrix flow and in the longer term, by diffusion processes, 3) A shallow compactional regime, where the fluids are generated by sediment dewatering and shallow diagenesis, and the main transport mechanism is characterised by vertical fluid flow, either through advection and hydrofracturing along faults, or matrix flow. In the Eastern Mediterranean passive margins, this depth-related subdivision needs to be modified in order to accommodate the influence of the laterally and vertically extensive evaporitic series, which acts as a regional aquitard/aquiclude to water or a seal to hydrocarbon flow. The presence of

  19. Spatiotemporal relationships among Late Pennsylvanian plant assemblages: Palynological evidence from the Markley Formation, West Texas, U.S.A

    Looy, Cindy V.; Hotton, Carol L.


    organic beds appear to have formed as a single genetic unit, with the kaolinite forming an impermeable aquiclude upon which a poorly drained wetland subsequently formed. Within a single inferred glacial/interglacial cycle, lithological data indicate significant fluctuations in water availability tracked by changes in palynofloral and megafloral taxa. Palynology reveals that elements of the dryland floras appear at low abundance even within wetland deposits. The combined data indicate a complex pattern of succession and suggest a mosaic of dryland and wetland plant communities in the Late Pennsylvanian. Our data alone cannot show whether dryland and wetland assemblages succeed one another temporally, or coexisted on the landscape. However, the combined evidence suggests relatively close spatial proximity within a fragmenting and increasingly arid environment. PMID:26028779

  20. Ice marginal dynamics during surge activity, Kuannersuit Glacier, Disko Island, West Greenland

    Roberts, David H.; Yde, Jacob C.; Knudsen, N. Tvis; Long, Antony J.; Lloyd, Jerry M.


    The Kuannersuit Glacier surged 11 km between 1995 and 1998. The surge resulted in the formation of an ice cored thrust moraine complex constructed by subglacial and proglacial glaciotectonic processes. Four main thrust zones are evident in the glacier snout area with phases of compressional folding and thrusting followed by hydrofracture in response to the build-up of compressional stresses and the aquicludal nature of submarginal permafrost and naled. Various types of stratified debris-rich ice facies occur within the marginal zone: The first (Facies I) comprises laterally continuous strata of ice with sorted sediment accumulations, and is reworked and thrust naled ice. The second is laterally discontinuous stratified debris-rich ice with distinct tectonic structures, and is derived through subglacial extensional deformation and localised regelation (Facies II), whilst the third type is characterised by reworked and brecciated ice associated with the reworking and entrainment of meteoric ice (Facies III). Hydrofracture dykes and sills (Facies IV) cross-cut the marginal ice cored thrust moraines, with their sub-vertically frozen internal contact boundaries and sedimentary structures, suggesting supercooling operated as high-pressure evacuation of water occurred during thrusting, but this is not related to the formation of basal stratified debris-rich ice. Linear distributions of sorted fines transverse to ice flow, and small stratified sediment ridges that vertically cross-cut the ice surface up-ice of the thrust zone relate to sediment migration along crevasse traces and fluvial infilling of crevasses. From a palaeoglaciological viewpoint, marginal glacier tectonics, ice sediment content and sediment delivery mechanisms combine to control the development of this polythermal surge valley landsystem. The bulldozing of proglacial sediments and the folding and thrusting of naled leads to the initial development of the outer zone of the moraine complex. This becomes

  1. Hydrogeological characteristics of the Paraíba do Sul river flood plains: a case study of a mining area in the Tremembé municipality, SP, Brazil

    Marcelo dos Santos Targa


    Full Text Available The sand mining activity in the São Paulo part of the Paraíba do Sul River Valley started in the 1950s, in the area of Jacareí municipality, located in the Southwestern part of the basin. From there, it advanced by the neighboring municipalities, fostered by urbanization and industrialization processes, especially of São Paulo Metropolitan Region. The lack of detailed hydrogeological studies in this area motivated this study that had the objective of verifying the hypothesis that sand mining pits interfere on the quality and storage of the water in the quaternary sedimentary aquifer. This study focused specifically in the eastern part of the Tremembé Municipality, São Paulo State, in a mining place called “Mineração Paraíso”. The investigation involved infiltration and flow tests, laboratory analyses of soil physical parameters and estimation, water quality indices and infrastructure construction for equipment installation including piezometers, dynamic penetration tests – (SPT - Standard Penetration Test, wells opening and office analyses. The soil physical parameters analyses revealed high porosity (66% in the friable soils. This in addition to the high levels of transmissivity (15.5 m2/h measured in Well 1 and 33 m2/h in Well 3, obtained from the flow test, increases the speed of the transportation of solutes including bacteria, to the underground water. Results of the granulometric analyses showed that the sand mining technique is not only predatory, but also inefficient, since the sand at the bottom of the pit is left unexploited, as well as the bentonite clay found in the deeper layers. According to the penetration tests (SPT, the aquifer has an average thickness of 5.5 m and an upper layer of impermeable organic clays that confine the sand deposits. Furthermore, an aquiclude composed of green bentonitic clays was identified just below the confined layer. However, it is necessary to point out that the confinement condition

  2. Land subsidence, structures and processes at the Dead Sea shoreline as revealed by a near-field photogrammetry survey at Ghor Haditha, Jordan

    Al-Halbouni, Djamil; Holohan, Eoghan P.; Walter, Thomas; Alrshdan, Hussam; Sawarieh, Ali; Dahm, Torsten


    Rapid recession of the Dead Sea in the last few decades has led to an increasing rate of sinkhole formation around the lake shore. The development of these sinkholes and other land subsidence phenomena poses a major geological hazard to the local population, agriculture and industry. For a better understanding of the underlying physical processes and for determining current and future areas of sinkhole hazard, we conducted field investigations and a first low altitude ("near-field") aerial photogrammetric survey with a Helikite Balloon at Ghor Haditha, Jordan, in October 2014. From the near-field photogrammetry, we generated a high resolution Digital Elevation Model of the surveyed area. This enables a detailed quantification of sinkhole sizes and distribution as well of morphological parameters such as the sinkhole depth/diameter ratio (D). Values of the latter are generally greater in the mechanically stronger alluvial fan sediments (D = 3.0 - 0.4) than in the weaker muds of the former Dead Sea lakebed (D = 0.3 - 0.1). Importantly, the point of emanation of a very recent and sediment-laden stream at c. 10m below the former floor of the Dead Sea can be structurally and morphologically connected to the main sinkhole area. This provides evidence for channelised subterranean groundwater flows beneath this area. From our observations, two processes were identified as key factors for the development of large land subsidence structures and local sinkhole clusters: (1) Subrosion of weak material due to groundwater following preferred flow paths of ancient and current wadi riverbeds and (2) rapid dissolution of soluble material (salt) in this aragonite-rich mud. The heterogeneous geology and alternation of aquifers (alluvial fan sediments) and aquicludes (mud-flats) lead to the formation of complex subsurface flow channels that represent the secondary porosity of the internal structure of karst aquifers. As a consequence of these subterranean channels, local bending and

  3. A Study on Saltwater Intrusion Around Kolleru Lake, Andhra Pradesh, India



    Full Text Available Kolleru Lake, the largest natural fresh water lake in Andhra Pradesh in India, located between Krishna and Godavari deltas is acting as a natural flood balancing reservoir and is fed directly by water from the seasonal rivers Budameru, Ramileru and Tammileru, and is also connected to the Krishna and Godavari drainage system consists of over 68 inflowing drains and channels. Over-exploitation of groundwater and land use conversions to aqua-culture are becoming the sources for salt-water intrusion to this lake and coastal aquifers, in specific, are highly vulnerable to seawater intrusion. Hydrogeomorphological study indicates that the potential aquifers around the Kolleru lake are paleo beach ridges and buried river courses. All other geomorphic features either aquiclude or aquitards are may not be considered as prospective zones for groundwater. Though there are number of open wells present in the villages used for potable water earlier, people switched over to imported water as their drinking water source may be due to significant contaminationof groundwater resources. Present land use activities like aqua-culture, agriculture, large-scale industries and allied industries in and around the Kolleru lake region has large contribution for the change of water quality. The paleo beach ridge areas, where the permeability of the sandy soil is very high, are also converted into aqua ponds. Integrated study using remote sensing, hydrogeology, hydrochemistry and geophysical investigations revealed the extent of salt-water intrusion up to the northern part of the lake which is about 40 km from the coast line. The electrical resistivity of aquifers is less than 1.0 (ohm-m having salinity of more than 1.2 ppt and the resistivity is around 20 (ohm-m where the salinity is less than 0.5 ppt, has also served as an excellent criteria for delineating the fresh-water and salt-water interface. Lenses of fresh water/ brackish water are noticed only in the beach

  4. Eight years of groundwater monitoring at the building site of the MOSE system for the safeguard of Venice

    Casasso, Alessandro; Sethi, Rajandrea; Di Molfetta, Antonio


    The survival of Venice is threatened by the continuous increase of frequency and intensity of tidal floods. To prevent these events, a safeguarding system known as MOSE is under construction at the inlets of the Lagoon of Venice. Four arrays of mobile barriers will be lifted in the case of exceptionally high tides (>1.10 m) to insulate the Lagoon. The prefabrication of the mobile barriers required a large construction area close to the final installation sites. Given the lack of space in the inlets of Lido and Chioggia, two basins of the future navigation locks were used for this purpose, and a system of water pumps and wells was therefore installed in each site to ensure the accessibility and safety of the construction areas. The impact of dewatering on the aquifers on the mainland in Punta Sabbioni (inlet of Lido) was monitored by means of continuous hydraulic head measurements in a network 25 piezometers, 11 screened in the phreatic aquifer and 14 in the shallowest confined aquifer. These aquifers are separated by a 5 m thick clayey aquiclude, and a 30 m thick impervious layer isolates them from the underlying confined aquifers, which were therefore not monitored. Each monitoring well was equipped with an automatic water pressure transducer and the hourly recorded hydraulic heads were compensated with the barometric pressure. The time series were compared with the natural driving forces (tides, rainfall, evapotranspiration) and the anthropogenic impact sources (dewatering pumping, slurry walls, land reclamation channels). The dynamics of seawater intrusion were also studied through monthly measurements of the vertical profiles of the electrical conductivity (EC) of groundwater. The monitoring activity was successful in assessing the impacts of the construction works. A drawdown was observed in the confined aquifer due to the dewatering pumping, with a maximum displacement of some 5 m on the mainland and an extension of some 1000 m from the dewatered basin. By

  5. Antarctic Dry Valley Streams and Lakes: Analogs for Noachian Mars?

    Head, James; Marchant, David


    Recent climate models suggest that Noachian Mars may have been characterized by a "cold and icy", rather than a "warm and wet" climate. Noachian valley networks and open basin lakes have been cited as key evidence for a "warm and wet" early Mars. We investigate fluvial and lacustrine processes in the Mars-like Antarctic McMurdo Dry Valleys (MDV) to assess whether such processes, which take place in the absence of pluvial activity and with mean annual temperatues (MAT) well below zero, can serve as informative proxies for Noachian Mars. In contrast to temperate climates, fluvial processes in the MDV (and thus a host of weathering, erosion and transport processes there) are severely limited by the lack of rainfall. The limited sources of meltwater provide very local streams and hyporheic zones, serving to concentrate chemical weathering processes and biological ecosystems. The horizontally stratified hydrologic system means that localized meltwater is constrained to flow in a very shallow and narrow aquifer perched on top of the ice table aquiclude. Lakes and ponds in temperate areas are largely of pluvial origin and characterized by abundant vegetation, large drainage basins and higher order streams delivering rainwater. In contrast, the hyperarid, hypothermal conditions in the MDV mean that there is no rainfall, water sources are limited primarily to meltwater from the surface of cold-based glaciers, and drainage into lakes is seasonal and highly variable, being related to changing and sluggish response to surface ice hypsometry, itself a function of changing climate. Lake surface fluctuations are caused by imbalances between meltwater input and sublimation from the lake surface ice and this sensitive balance tends to magnify even minor climate signals. Where does the lakewater come from and under what conditions is excess meltwater produced to cause modifications in their levels? The dominant means of supply (meltwater) and loss (ablation) are clearly seasonally

  6. Impacts of convection on high-temperature aquifer thermal energy storage

    Beyer, Christof; Hintze, Meike; Bauer, Sebastian


    Seasonal subsurface heat storage is increasingly used in order to overcome the temporal disparities between heat production from renewable sources like solar thermal installations or from industrial surplus heat and the heat demand for building climatisation or hot water supply. In this context, high-temperature aquifer thermal energy storage (ATES) is a technology to efficiently store and retrieve large amounts of heat using groundwater wells in an aquifer to inject or withdraw hot or cold water. Depending on the local hydrogeology and temperature amplitudes during high-temperature ATES, density differences between the injected hot water and the ambient groundwater may induce significant convective flow components in the groundwater flow field. As a consequence, stored heat may accumulate at the top of the storage aquifer which reduces the heat recovery efficiency of the ATES system. Also, an accumulation of heat at the aquifer top will induce increased emissions of heat to overlying formations with potential impacts on groundwater quality outside of the storage. This work investigates the impacts of convective heat transport on the storage efficiency of a hypothetical high-temperature ATES system for seasonal heat storage as well as heat emissions to neighboring formations by numerical scenario simulations. The coupled groundwater flow and heat transport code OpenGeoSys is used to simulate a medium scale ATES system operating in a sandy aquifer of 20 m thickness with an average groundwater temperature of 10°C and confining aquicludes at top and bottom. Seasonal heat storage by a well doublet (i.e. one fully screened "hot" and "cold" well, respectively) is simulated over a period of 10 years with biannual injection / withdrawal cycles at pumping rates of 15 m³/h and for different scenarios of the temperature of the injected water (20, 35, 60 and 90 °C). Simulation results show, that for the simulated system significant convective heat transport sets in when

  7. A refined genetic model for the Laisvall and Vassbo Mississippi Valley-type sandstone-hosted deposits, Sweden: constraints from paragenetic studies, organic geochemistry, and S, C, N, and Sr isotope data

    Saintilan, Nicolas J.; Spangenberg, Jorge E.; Samankassou, Elias; Kouzmanov, Kalin; Chiaradia, Massimo; Stephens, Michael B.; Fontboté, Lluís


    hydrocarbons in sandstone. Other minor H2S sources are identified. Upward migration and fluctuation of the hydrocarbon-water interface in sandstone below shale aquicludes and the formation of H2S along this interface explain the shape of the orebodies that splay out like smoke from a chimney and the conspicuous alternating layers of galena and sphalerite. Intimate intergrowth of bitumen with sphalerite suggests that subordinate amounts of H2S might have been produced by TSR during Pb-Zn mineralization. Gas chromatograms of the saturated hydrocarbon fraction from organic-rich shale and from both mineralized and barren sandstone samples indicate that hydrocarbons migrated from source rocks in the overlying Alum Shale Formation buried in the foredeep into sandstone, where they accumulated in favorable traps in the forebulge setting.

  8. Lessons Learned from a Complex FUSRAP Site - Sylvania Corning FUSRAP Site - 12269

    Since its addition to the Formerly Utilized Sites Remedial Action Program (FUSRAP) in 2005, the Sylvania Corning FUSRAP Site (the Site) in Hicksville, New York, has provided challenges and opportunities from which to gain lessons learned for conducting investigation work at a complex multi-contaminant FUSRAP Site. The United States Army Corps of Engineers (USACE) and its contractors conducted a Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) Remedial Investigation (RI) and are currently in the Feasibility Study (FS) phase at the Site. This paper presents the planning, execution, and reporting lessons learned by USACE during the RI/FS. The Site, operated from 1952 to 1967 for the research, development, and fabrication of nuclear elements under the Atomic Energy Commission, and other government and commercial contracts. Previous investigations performed by the New York State Department of Environmental Conservation (NYSDEC) and the current property owner have identified uranium, thorium, nickel, and chlorinated solvents, as Site contaminants [1]. The property owner is currently under two separate voluntary agreements with NYSDEC to investigate and remediate the Site. USACE's work at the site has been independent of this voluntary agreement and has moved on a parallel path with any work the property owner has completed. The project at the Site is complex because of the radiological and chemical concerns in both soils and groundwater, high hydraulically conductive soils, lack of a shallow aquiclude/aquitard, and a principal water table aquifer underlying the site. Contaminants are migrating from the Site and may potentially impact local drinking water supplies (municipal wells). During the RI/FS process the project team has encountered many issues and has thus developed many resolutions. The issues are organized into three categories: Planning and Contracting, Execution, and Reporting. Planning and Contracting lessons learned include: how

  9. Kinematics of the 1991 Randa rockslides (Valais, Switzerland

    M. Sartori


    mineralogical alteration of the fault gouge accumulated along the sliding surface, reducing its angle of internal friction, and sealing the surface against water circulation. Once this basal fracture began to act as an aquiclude, the seasonal increase of the hydraulic head in the fissures promoted hydraulic fracturing on the highly stressed edges of the key block. Acceleration of this mechanical degradation occurred during the 20-year period before the 1991 rockslides, giving rise to an increasing rockfall activity, that constituted a forewarning sign. The final triggering event corresponded to a snow-melt period with high water table, leading to fracturation around the key block. On 18 April 1991, the key block finally failed, allowing subsidiary orthogneiss blocks to slide. They fell in turn over a period of several hours. The 9 May 1991, rockslide was the first of a series of expected future retrogressive reequilibrium stages of the very fractured and decompressed paragneisses, which lie on the orthogneiss base cut by the 18 April event.

  10. 浅埋煤层高强度开采覆岩(土)破坏演化及溃沙控制技术%Failure characteristics of overburden rock (soil) and sand control technology in high strength mining of shallow coal seam

    张玉军; 李凤明


    随着我国煤炭资源的大规模和高效开采,薄基岩浅埋深的矿区常发生切冒、抽冒、台阶下沉,造成水资源和环境破坏严重.但是,赋存于萨拉乌苏组含水层下伏的连续黏土层的存在,使得基岩及其黏土隔水层组合结构下采动破坏规律不同于传统的基岩岩层,这将为防治矿井突水和实现保水采煤提供了条件.论文采用数值模拟和理论分析的方法,模拟了“黏土隔水层-基岩风化带-基岩”结构特征下不同黏土层与基岩厚度条件下覆岩(土)裂隙发育、顶板破断运动的基本特征,获得了浅埋深条件下采动覆岩(土)的破坏变异规律与发育高度,分析了渍沙的致灾因素和预测判据,并据此提出防治突水溃砂的技术手段.研究结果表明:浅埋煤层“沙土基型”覆岩(土)结构条件下,由于不同基岩与土层厚度的控制作用,使得覆岩(土)破坏发育高度和特征产生变异;水砂源、通道、动力源和空间是近松散含水层溃砂的主要致灾因素,并提出了预测溃沙发生的判据;可通过防止顶板切冒、含水砂层水头压力疏降、局部注浆固沙和合理留设防砂(塌)煤岩柱等技术控制浅埋煤层渍砂灾害发生.%With the large-scale and efficient mining of coal resources in China,local caving and bench convergence accidents frequently occur in the mining area with thin bedrock and shallow depth,which cause serious water resources and environmental damage.However,the mining failure rules of bedrock and clay aquiclude combination structure are different to traditional rock strata because of continuous clay layer,which will provide conditions for the prevention and treatment of mine water inrush and water preserved mining.In this paper,the methods of numerical simulation and theoretical analysis were conducted to simulate the basic characteristics of overlying rock (soil) fracturing and roof breaking movement under the "clay aquifuge