Saline Groundwater Flow Research Articles

Research on influences of groundwater salinity and flow velocity on artificial frozen wall

Groundwater flow has a negative impact on the artificial freezing project, especially when the salt content of the groundwater is high, it will change the thermophysical properties, which isn’t conducive to the formation of the frozen wall. In this paper, the changes in temperature and seepage fields during the formation of frozen wall under the flow of saline groundwater were studied. By established the seepage-freezing hydrothermal coupling calculation model, and combined with a small seepage-freezing model test, which based on the theory of heat transfer and seepage in porous media. Results show that the frozen wall is in an uneven state under the action of horizontal seepage. The frozen wall perpendicular to the direction of groundwater flow is formed slowly, while the frozen wall parallel to the direction of water flow is formed quickly. The salt content affects the development of the frozen wall. As the salt content increases, the thickness of the frozen wall decreases. The maximum percentage of reduction of the upstream and downstream frozen wall thickness can reach 80.4% and 59.5%, respectively. With the gradual expansion of the frozen wall around two freezing pipes, the flow around and the change of the flow velocity occur. The maximum value of the flow rate is about 3–4 times of the initial flow rate, and then the flow rate decreases rapidly until the frozen wall encloses. When the seepage velocity increases to 5.5 m/d and the salt content reaches 15‰ and above, the time for the closure of the frozen wall is significantly delayed or even impossible. The conclusions obtained in this study can provide a theoretical reference for the design and construction of the similar engineering.

Selection of Colloidal Silica Grouts with Respect to Gelling and Erosion Behaviour

Cembinder, Eka EXP36, and MEYCO MP320 are three colloidal silica materials that have been proposed for post-excavation grouting of deep tunnels in a radioactive waste repository. In this study, samples of these colloidal silicas were tested for their particle size distribution, gel induction time (tG), gel time (TG), and physical erosion, under mildly saline groundwater flow conditions. In order to achieve a desired gel time range, from 15 to 50 min, it is recommended that the colloidal silica is mixed with a NaCl accelerator at a 5:1 volume ratio. At 20 °C, the concentration range for the NaCl solution should be 1.5 to 1.7 M for MEYCO, 1.23 to 1.38 M for Eka EXP36, and 1.3 to 1.47 M for Cembinder. The physical erosion of the set silicas remained steady during a 10 h flow cell experiment, when grouts were subjected to 0.05 M NaCl at a superficial velocity of 2.2 × 10−5 m/s. For these test conditions, the results show that MEYCO has the highest average erosion rate (0.85 mg/h) of the three grout materials, as well as the greatest variability in this rate. Cembinder performed best with the lowest silica removal rate. Extrapolation of the measured erosion rates suggests that grout fracture dilation would not be significant under natural quiescent groundwater flow conditions, but would be high if there was hydraulic communication between the geosphere and the repository.

Mineralogical evolution of salt over nine years, after removal of efflorescence and saline crusts from Elche’s Old Bridge (Spain)

The Old Bridge Elche’s showed abundant efflorescence and salt crusts that were eliminated in an intervention in 2005. We have followed the development of efflorescence after the intervention. And nine years later the efflorescence mineralogy was quite similar to the mineralogy of the pre-restoration efflorescence.The efflorescence on Elche’s Old Bridge (Puente Viejo) shows a wide mineralogical variation in the vertical profile, which is the result of a balance between two diffusive processes: the evaporation–condensation of atmospheric water vapor on/inside the wall, and the capillary flow of saline groundwater. Diurnal variations in atmospheric relative humidity (RH) and the low deliquescence relative humidity (DRH) values of some saline minerals (nitrate & chloride) play an important role in the vertical distribution of minerals.The mineral composition of efflorescence and saline crusts prior to cleaning the monument was similar to that identified nine years later.The chemical composition of groundwater, with a high sodium chloride component and much lower concentrations of sulfate and bicarbonate, explained the presence of halite, while the presence of demolition waste of a gypsiferous nature near the bridge explained the presence of sulfate salts, thenardite, konyaite, aphthitalite, and arcanite. The dissolution of airborne particles in condensation water probably contributed to the genesis of nitrate-rich minerals such as nitratine, darapskite, and especially humberstonite.

Geologically controlled bi-directional exchange of groundwater with a hypersaline lake in the Canadian prairies

Hypersaline lakes occur in hydrologically closed basins due to evaporitic enrichment of dissolved salts transported to the lakes by surface water and groundwater. At the hypersaline Lydden Lake in Saskatchewan, Canada, groundwater/lake-water interaction is strongly influenced by the geological heterogeneity of glacial deposits, whereby a highly permeable glaciofluvial sand/gravel deposit is underlain by glaciolacustrine deposits consisting of dense clay interspersed with silt/sand lenses. Pressure head distribution in a near shore area indicates a bi-directional flow system. It consists of topographically driven flow of fresh groundwater towards the lake in the sand/gravel aquifer and density-driven, landward flow of saline groundwater in the underlying glaciolacustrine deposits. Electrical resistivity tomography, and chemical and isotopic composition of groundwater clearly show the landward intrusion of saline water in the heterogeneous unit. The feasibility of bi-directional flow and transport is supported by numerical simulations of density-coupled groundwater flow and transport. The results suggest that the geologically controlled groundwater exchange processes have substantial influences on both inputs and outputs of dissolved minerals in hypersaline lakes in closed basins.

Erratum to: 3D Modeling of Saline Groundwater Flow and Transport in a Flooded Salt Mine in Stassfurt, Germany

Erratum to: 3D Modeling of Saline Groundwater Flow and Transport in a Flooded Salt Mine in Stassfurt, Germany

3D Modeling of Saline Groundwater Flow and Transport in a Flooded Salt Mine in Stassfurt, Germany

The abandoned, flooded deep salt mine in Stassfurt, Germany has been extensively studied. The mine causes serious uncontrolled salt leaching and mass displacement effects underground that have led to significant regional-scale subsidence. Collapsing mined areas and further large-scale subsidence pose a potential danger to the city of Stassfurt. Comprehensive modeling of the three dimensional (3-D) variable density flow dynamics is required at both large and local scale to assess the stability of the cap rocks and the potential of subsidence due to salt leaching processes, and to better control (minimize) salt leaching. The impact of different engineering solutions and appropriate remedial strategies (e.g. pumping schemes) on the subsurface spatio-temporal distribution of salinity is of specific concern. Coupled variable density flow and transport simulations were performed using FEFLOW, a finite-element simulator, which is capable of both porous media (Darcy-type) flow computations and lower-dimensional discrete elements for laminar or turbulent flow. The geometry of the mine workings is incorporated in suitable detail and resolution in the developed 3-D model. Computational results were successfully compared with field observations and geophysical measurements. Different model scenarios provide better insight into flow and mass transport processes in the study area, which could provide significant information to quantify subsidence potential of the mine site.

The Karun River waters in the Ambal ridge region (Zagros mountain Range, southwestern Iran): mixing calculation and hydrogeological implications

The Karun River is one of the most important waterways in Iran and the quality level of its waters is very important for all the communities living around it. The salinity of river waters increases and the water quality decreases while it passes through the four km long valley consist of Gachsaran geological formation (mainly gypsum and halit), in the Ambal ridge area. This ridge is located some 5 km upstream of the Gotvand dam (under construction), which in the future will be inundated. In this section of the river, water chemistry suddenly evolves from Ca-HCO3 type with TDS of ~0.4 g/l to Na(Ca)-Cl(SO4) type with TDS of ~1.5 g/l, possibly due to mixing, carbonates precipitation and dolomitization. These variations suggest that saline water mixed with the river water extensively in the Ambal ridge area. Two hypotheses are suggested for the origin of the saline waters: first, in situ dissolution of halite and gypsum units of exposed Gachsaran Formation of the nearby area could produce saline ground-water flow into the river, and second, the intrusion of Karun River water itself through fractures of evaporite layers at location, where it first comes in contact with the Ambal area and in consequence, dissolution of halite and gypsum by the water, which discharge into the river via a number of exposed and underwater springs in the ridge. Calculations indicate that the average annual saline water seepage required for the change of the chemical composition is ~0.24% of the total river flow rate. Water balance calculations suggest that the required catchment area for the saline ground-water flow should be >300 km2, much larger than the Ambal area itself. However, this excess area almost is exist in a closed by plain, the impermeable marl layers in the Gachsaran Formation restraint the flow of groundwater and suggest that the first hypothesis is less likely.

Groundwater connections under a barrier beach: A case study in the Venice Lagoon

The flow of groundwater beneath barrier islands has been cited as a possible pathway for salt water and chemical exchange between a protected embayment and the open sea. Evidence is presented that identifies an exchange of groundwater through a highly permeable paleoinlet along the barrier beach of Cavallino, which separates the northern Venice Lagoon from the Adriatic Sea. We utilized both point measurements of submarine groundwater discharge (SGD) and a geophysical investigation of the subsurface resistivity to analyze the movement of saline groundwater. Discharge of groundwater and associated nutrients, was higher at the site of a former inlet than at a similar site along the barrier and modulated by the difference in tidal water level between the lagoon and Adriatic Sea. If the measured conditions are typical, storm surge barriers could potentially result in a saline groundwater flow of up to 1.5×10 6 m 3 d −1 into the lagoon.

The Effect of Air Entry Values on Hysteresis of Water Retention Curve in Saline Soil

Problem statement: The saline soil in Northeast Thailand is caused by saline groundwater rise in unsaturated zone to accumulate as salt at soil surface. Approach: This problem had been exacerbated in the last few decades by human activities e.g., deforestation and salt mining. This salinity problem can be solved by capillary rise control of saline groundwater flow. Results: The soil water retention curve formulation was essential for the control procedure design. In this study, the soil water retention curves of saline soil samples were derived by the hanging column and pressure plate apparatus techniques. The hysteresis of the curves together with air and water entry values were scrutinized from the primary wetting and drying retention curves. Conclusion: The experimental results showed that the degree of hysteresis varies with the air entry value of the soil. The new finding can be very useful in modeling for salinity control.

Quantifying saline groundwater flow into a freshwater lake using the Ra isotope quartet: A case study from the Sea of Galilee (Lake Kinneret), Israel

We investigated the Ra isotope quartet in order to quantify the discharge of saline groundwater into a freshwater lake. The activities of 226Ra, 228Ra, 223Ra, and 224Ra were measured in the Sea of Galilee, Israel, surrounding saline springs, and the Jordan River, coupled with U, Th, and 226Ra measurements in sediment cores and laboratory Ra adsorption experiments under different salinity conditions. The 226Ra activity (0.007–0.008 Bq L−1) and 226Ra : Cl ratio in the lake were significantly lower than those of the inflowing saline springs, indicating that 75-86% of the incoming 226Ra is removed from the lake water. This "missing" Ra is likely adsorbed onto suspended particles. Given the observed differential depletion of Ra isotopes, we present a model consisting of adsorption-desorption, recoil, and decay of the short-lived 224Ra and 223Ra isotopes. We predict a removal time of ~2 weeks for Ra, inferring the apparent residence time of suspended matter in the lake. A mass-balance calculation of the different 226Ra inventories reveals a saline groundwater flux of 44–61 × 109 L yr–1 for "Fuliyatype" water. The residence time of dissolved 226Ra in the lake is estimated as 3–4 yr. The 228Ra : 226Ra ratio of the lake water and a mass-balance calculation show that 228Ra arrives from regeneration though bottom sediments, in addition to groundwater flux. Mass-balance calculations of the expected saline fluxes before the diversion of saline inflows to the lake (early 1960s) provide 226Ra activity estimates in the lake (0.018-0.020 Bq L−1) that are similar to the value (0.018 ± 0.0001 Bq L−1) measured in the lake in 1962.

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Deep reaching fluid flow in the North East German Basin: origin and processes of groundwater salinisation

Major element chemistry, rare-earth element distribution, and H and O isotopes are conjointly used to study the sources of salinisation and interaquifer flow of saline groundwater in the North East German Basin. Chemical analyses from hydrocarbon exploration campaigns showed evidence of the existence of two different groups of brines: halite and halite Ca–Cl brines. Residual brines and leachates are identified by Br−/Cl− ratios. Most of the brines are dissolution brines of Permian evaporites. New analyses show that the pattern of rare-earth elements and yttrium (REY) are closely linked to H and O isotope distribution. Thermal brines from deep wells and artesian wells indicate isotopically evaporated brines, which chemically interacted with their aquifer environment. Isotopes and rare-earth element patterns prove that cross flow exists, especially in the post-Rupelian aquifer. However, even at depths exceeding 2,000 m, interaquifer flow takes place. The rare-earth element pattern and H and O isotopes identify locally ascending brines. A large-scale lateral groundwater flow has to be assumed because all pre-Rupelian aquifer systems to a depth of at least 500 m are isotopically characterised by Recent or Pleistocene recharge conditions.

The Water Crisis in the Gaza Strip: Prospects for Resolution

Israel and the Palestinian Authority share the southern Mediterranean coastal aquifer. Long-term overexploitation in the Gaza Strip has resulted in a decreasing water table, accompanied by the degradation of its water quality. Due to high levels of salinity and nitrate and boron pollution, most of the ground water is inadequate for both domestic and agricultural consumption. The rapid rate of population growth in the Gaza Strip and dependence upon ground water as a single water source present a serious challenge for future political stability and economic development. Here, we integrate the results of geochemical studies and numerical modeling to postulate different management scenarios for joint management between Israel and the Palestinian Authority. The chemical and isotopic data show that most of the salinity phenomena in the Gaza Strip are derived from the natural flow of saline ground water from Israel toward the Gaza Strip. As a result, the southern coastal aquifer does not resemble a classic "upstream-downstream" dispute because Israel's pumping of the saline ground water reduces the salinization rates of ground water in the Gaza Strip. Simulation of different pumping scenarios using a monolayer, hydrodynamic, two-dimensional model (MARTHE) confirms the hypothesis that increasing pumping along the Gaza Strip border combined with a moderate reduction of pumping within the Gaza Strip would improve ground water quality within the Gaza Strip. We find that pumping the saline ground water for a source of reverse-osmosis desalination and then supplying the desalinated water to the Gaza Strip should be an essential component of a future joint management strategy between Israel and the Palestinian Authority.

Geophysical Monitoring Through a Tidal Cycle at Crescent Beach State Park, Maine

This paper presents results of an experiment in which data from a combination of geophysical methods (resistivity, induced polarization, electromagnetic profiling, and magnetic profiling) were used to identify shallow geologic and hydrogeologic structure, and to enhance understanding of groundwater flow in a dynamic beach environment. Based on this study, well sorted beach sand is underlain by laterally variable glacial till, which overlies bedrock. An extensive patch of glacial till was mapped toward the ocean side of the beach. Bedrock has lithologic variability, as evidenced by a non-uniform magnetic response. In particular, a northeast-southwest trending magnetic body, believed to be a basalt dyke, was detected by its magnetic signature. During the transgressive phase of the tidal cycle, saline groundwater flow appeared to be quite rapid, extending ahead of the surfical water by at least [Formula: see text], as evidenced by the electromagnetic response. During the regressive phase, a slug of saline water remained up beach from the high tide mark for several hours prior to draining. Also during this regression, electromagnetic evidence for preferential groundwater flow pathways, probably bedrock fracture zones, was observed. These fracture zones appear to contain a relatively constant concentration of saltwater, while surficial sediments above and to the side are flushed with fresh groundwater during tidal regression.

Flow systems, tree plantations, and salinisation in a Western Australian catchment

A lower hillslope in the Western Australian wheatbelt had become waterlogged and saline by 1981, when close-spaced rows of eucalypts were planted in blocks both in and adjacent to the discharge area and piezometers were established on the site. We analysed the trends in the piezometric heads and salinity concentrations over the period of record. We also modelled the hillslope profile using finite element analysis to determine the water flow mechanisms and to see how a change in vegetation in the upland area would affect the waterlogging and salinity. Piezometric levels under the trees decreased for the first 5 years after planting and then stabilised until 1991 when they started gradually decreasing again. The non-treed area between the plantation blocks remained unaffected until about 1991, when the levels there also started to decrease quite significantly, probably because of the trees. The trees therefore appear to have been effective and beneficial in the short to medium term. However, the salinity of the groundwater under the trees has increased significantly in the last 5 years, particularly where the tree density is highest. The continued flow of saline groundwater to the trees is believed to be increasing the salinity. It could not be expected that plantations of this type will maintain health and be able to control the excess water in such an hydrologic setting in the long term. Tree plantations on discharge areas are a short to medium term management strategy, not a solution, and the only way to control salinity in the long term is to plant vegetation species in the recharge areas that use all of the water that falls there. Modelling showed that only a small surplus of water over winter, in the order of 50 mm/year, caused the increased recharge and consequent salinisation. The modelling results also show that the surplus could be managed with an effective vegetation species (e.g. lucerne) with a rooting depth of about 1·5 m that would be able to transpire at least until early to mid summer.