Concerning the media’s properties, there is always a possibility of changing groundwater flow conditions surrounding hydroelectric power plants. Causes for such events could be natural or ...anthropogenic, which is, in many cases, not so obvious to determine. In addition, determining a period when changes in the groundwater flow occur is a complex task. All of the above mentioned are of crucial importance due to the operational work of hydropower plants, i.e., the optimization of the inflow and outflow of the water in the turbine, regardless of the hydropower plant type. All types listed require a particular approach for solving such issues. Rescaled Adjusted Partial Sums (RAPS) is an appropriate time-series analysis method. In this specific case, observed fluctuations in the time series of the groundwater levels could lead to conclusions about possible irregularities in the shallow as well as the deep zones of the underground water. The concept was shown in this paper in the example of the hydroelectric power plant Mostar dam in Bosnia and Herzegovina. It should be noted that the defined methodology was a novel procedure for analyzing and determining the pathways of the flow of groundwater in the surrounding hydropower plant dams. In other words, such analysis could be conducted without the need for complex and expensive drilling and geophysical surveys, tracing, and all other methods.
At the Department of TOT, an experimental setup was created to measure the density of a binary gas system from 100 to 300 K and pressures up to 16 MPa and with any mixture compositions. Experimental ...density for the helium-nitrogen system were determined by the piezometer of constant volume method. The amount of substance in the piezometer was measured by volumetric method. In this setup, the mixture of He - N2 was prepared in a special mixer for a series of p-v-T experiments, the concentration was determined by calculation using the equations of state of pure components. In the experiment, mixtures were prepared with molar concentrations, lying close to the range: 0.2, 0.4, 0.6 and 0.8.
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•Research showed the origin of DIC in the groundwater around a reclaimed landfill.•Carbon isotope was used to evaluate the contributions of carbon from different sources.•The ...leachate-contaminated water was isotopically distinct from the natural groundwater.•DIC in the natural groundwater comes from organic matter and dissolution of carbonates.•In the contaminated water, DIC comes from organic matter in the aquifer and landfill.
Chemical and isotopic analyses of groundwater from piezometers located around a reclaimed landfill in Otwock (Poland) were performed in order to trace the origin of dissolved inorganic carbon (DIC) in the groundwater. Due to differences in the isotopic composition of carbon from different sources, an analysis of stable carbon isotopes in the groundwater, together with the Keeling plot approach and a two-component mixing model allow us to evaluate the relative contributions of carbon from these sources in the groundwater. In the natural (background) groundwater, DIC concentrations and the isotopic composition of DIC (δ13CDIC) comes from two sources: decomposition of organic matter and carbonate dissolution within the aquifer sediments, whereas in the leachate-contaminated groundwater, DIC concentrations and δ13CDIC values depend on the degradation of organic matter within the aquifer sediments and biodegradation of organic matter stored in the landfill. From the mixing model, about 4–54% of the DIC pool is derived from organic matter degradation and 96–46% from carbonate dissolution in natural conditions. In the leachate-contaminated groundwater, about 20–53% of the DIC is derived from organic matter degradation of natural origin and 80–47% from biodegradation of organic matter stored in the landfill. Partial pressure of CO2 (P CO2) was generally above the atmospheric, hence atmospheric CO2 as a source of carbon in DIC pool was negligible in the aquifer.
P CO2 values in the aquifer in Otwock were always one to two orders of magnitude above the atmospheric P CO2, and thus CO2 escaped directly into the vadose zone.
Piezometers are commonly used for monitoring the dissipation of pore water pressure and therefore the determination of degree of consolidation of soft soils after ground improvement in land ...reclamation projects. This paper compares the degree of consolidation obtained using pore pressure monitoring data from vibrating wire piezometers and pneumatic piezometers installed in a test site in the Changi East Reclamation project in Singapore. The test site consisted of a vertical drain sub-area at which prefabricated vertical drains were installed at 2.0m×2.0m square spacing as well as an adjacent control sub-area where no prefabricated vertical drains were installed. Pneumatic piezometers were installed at the same elevations as the vibrating-wire piezometers in both sub-areas for comparison purposes. During the surcharge period of 32months, the piezometer monitoring data were analysed at various periods to determine the degree of consolidation of the underlying soft marine clay. The degree of consolidation values interpreted from both types of piezometers were compared with predictions from neighbouring settlement plates to evaluate their performance. The findings of the comparison between pneumatic and electric vibrating-wire piezometers indicate that both types of piezometer are suitable for monitoring the consolidation behaviour of soft soil under land reclamation fills.
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•Land reclamation site on soft soils treated with prefabricated vertical drains•Pore pressure monitoring data from piezometers were analysed for the test site.•Vibrating wire and pneumatic piezometer performance were compared.•Comparisons were made with predictions from neighbouring settlement plates.•Piezometers found to be suitable for monitoring ground improvement of soft soils.
•Density of (water+1-propanol) mixtures.•Excess molar volumes of (water+1-propanol) mixtures.•Apparent molar volumes of (water+1-propanol) mixtures.
Densities of (water+1-propanol) mixtures have been ...measured over the temperature range from 298K to 582K and at pressures up to 40MPa using the constant-volume piezometer immersed in a precision liquid thermostat. The measurements were made for six compositions of (0.869, 2.465, 2.531, 7.407, 14.377, and 56.348)mol·kg−1 of 1-propanol. The expanded uncertainty of the density, pressure, temperature, and concentration measurements at the 95% confidence level with a coverage factor of k=2 is estimated to be 0.06%, 0.05%, 15mK, and 0.015%, respectively. The derived volumetric properties such as excess (VmE), apparent (VΦ), and partial (V¯2∞) molar volumes were calculated using the measured values of density for the mixture and for pure components (water and 1-propanol). The concentration dependences of the apparent molar volumes were extrapolated to zero concentration to yield the partial molar volumes of 1-propanol at infinite dilution (V¯2∞). The temperature, pressure, and concentration dependence of density and derived properties of the mixture were studied. All experimental and derived properties (excess, apparent, and partial molar volumes) were compared with the reported data by other authors. The small and negative values of excess molar volume for the mixtures were found at all experimental temperatures, pressures, and over the entire concentration range. The excess molar volume minimum is found at concentration about 0.4mole fraction of 1-propanol. The concentration minimum of the derived apparent molar volumes VΦ near the 2.5mol·kg−1 (dilute mixture) was observed.
Signatures of the Earth's crustal tides are recorded in the groundwater regime, particularly in confined aquifers in the form of rise and fall of its piezometric surface. Though this phenomenon is ...universal, and exists in the entire groundwater regime, the recording at a few places and in some rare situations is doubtful. An attempt is made here to study the conditions required for recording this phenomenon along with its basic principles. The Central Ground Water Board has constructed 115 piezometer wells and monitored piezometric heads with high frequency digital water level recorder. The impact of Earth tide on groundwater regime is clearly recorded at two sites namely, Kothagudem (Khammam district) and Mangapet (Warangal district). The wells at these sites are constructed in the confined aquifer of Kamthi sandstone in Godavari valley which is nearly 200 km inland from the east coast. Analysis of the data reveals that the piezometric level heads fluctuate in a cyclic manner and the variations for each lunar cycle of 13–14 days with high peaks on new Moon and full Moon days. The peaks observed in the piezometric heads gradually decline coinciding with the lunar phase. Distinct changes in piezometric heads are observed for each phase of the Moon in both of the above-mentioned places. An account of impact of lunar and solar attraction forces on piezometric level heads of groundwater, the ideal conditions required for recording this phenomenon along with a comparison of these hydrographs with examples from the literature are provided in the present study.
Densities of ternary water + 1-propanol + KNO
3
mixtures have been measured over the temperature range from 303 to 448 K and at pressures up to 35 MPa using a constant-volume piezometer immersed in a ...precision liquid thermostat. The effect of salt and alcohol concentrations on the ternary mixture densities and partial molar volumes were studied. The derived volumetric property such as partial molar volumes of the salt (KNO
3
,
V
¯
2
) and the alcohol (1-propanol,
V
¯
1
) were calculated using the measured values of the densities. The volumetric behavior of the ternary mixtures was interpreted in terms of changes in the water structure caused by the added alcohol and salt. It was shown that changes in the volumetric behavior of the complex solutions are the results of the structural changes in water structure caused by solutes (alcohol and salt).
Relationships between the recrystallized grain size and stress are investigated for experimentally deformed water‐added quartz aggregates. For stresses ≥100 MPa there is a variation in the measured ...recrystallized grain size for a given stress. This variation correlates with a change in the c‐axis fabric in general shear experiments, where samples with larger recrystallized grain sizes for a given stress have dominantly prism c‐axis fabrics and samples with smaller recrystallized grain sizes for a given stress have dominantly basal c‐axis fabrics. The dislocation creep flow law also changes at conditions where these two c‐axis fabrics form (Tokle et al., 2019, https://doi.org/10.1016/j.epsl.2018.10.017). Using the wattmeter model (Austin & Evans, 2007, https://doi.org/10.1130/G23244A.1), different piezometric relationships are quantified for samples that develop prism and basal c‐axis fabrics, respectively. The wattmeter model is sensitive to grain growth kinetics; a new grain growth law for quartz is formulated based on reanalysis of microstructures in samples from previous work. The activation enthalpies and water fugacity exponents for our grain growth law and dislocation creep flow laws are the same within error, suggesting the recrystallized grain size versus stress relationships are nearly independent of temperature and water fugacity, consistent with laboratory observations. The wattmeters successfully predict the recrystallized grain size versus stress relationships of all quartzite samples from experiments with added water. These results support the use and extrapolation of the wattmeter model for both experimental and geologic conditions to investigate the stress state and grain size evolution of quartz rich rocks.
Plain Language Summary
Stress is a fundamental rheological parameter in understanding how rocks deform; however, stress is hard to quantify in rocks that flow rather than fracture at geologic conditions. The relationship between the recrystallized grain size and stress is established through rock deformation experiments where both the stress and grain size can be measured. Therefore, the stress can be estimated in naturally deformed rocks by measuring the recrystallized grain size and applying the experimentally calibrated relationship. Here we show new evidence for different recrystallized grain size versus stress relationships in quartz, and that these different relationships correlate with the crystallographic orientations of grains in samples deformed in the shear geometry. To quantify these new observations, we use the wattmeter model, which models the recrystallized grain size of a deforming aggregate based on the balance between the rates of grain growth and grain size reduction, to predict the quartz recrystallized grain size. This model is sensitive to grain growth kinetics; therefore, we formulated a new grain growth law for quartz. The calibrated wattmeters predict the recrystallized grain size versus stress relationships in experimentally deformed wet quartzite samples. The wattmeter model can therefore be used to estimate stress magnitudes in naturally deformed quartz‐rich rocks.
Key Points
Different recrystallized grain size versus stress relationships in samples with prism and basal c‐axis fabrics
New grain growth law for wet quartzite
No temperature or water fugacity dependence on the recrystallized grain size within error, consistent with experimental observations
Iron‐rich olivine is mechanically weaker than olivine of mantle composition, ca. Fo90, and thus is more amenable to study under a wide range of laboratory conditions. To investigate the effects of ...iron content on deformation‐produced crystallographic preferred orientation (CPO) and grain size, we analyzed the microstructures of olivine samples with compositions of Fo70, Fo50, and Fo0 that were deformed in torsion under either anhydrous or hydrous conditions at 300 MPa. Electron backscatter diffraction (EBSD) observations reveal a transition in CPO from D‐type fabric, induced by dislocation glide on both the (010)100 and the (001)100 slip systems, at low strains, to A‐type fabric, caused by dislocation glide on the (010)100 slip system, at high strains for all of our samples, independent of iron content and hydrous/anhydrous conditions. A similar evolution of fabric with increasing strain is also reported to occur for Fo90. Radial seismic anisotropy increases with increasing strain, reaching a maximum value of ∼1.15 at a shear strain of ∼3.5 for each sample, demonstrating that the seismic anisotropy of naturally deformed olivine‐rich rocks can be well approximated by that of iron‐rich olivine. Based on EBSD observations, we derived a piezometer for which recrystallized grain size decreases inversely with stress to the ∼1.2 power. Also, recrystallized grain size increases with increasing iron content. Our experimental results contribute to understanding the microstructural evolution in the mantle of not only Earth but also Mars, where the iron content in olivine is higher.
Key Points
The weakest slip system does not change with Fe content, such that CPO development is similar for Fe‐rich and Fe‐poor olivine
Seismic anisotropy due to the formation of CPOs in natural olivine aggregates can be modeled using CPOs obtained from iron‐rich olivine
Recrystallized grain size at a given normalized stress increases with increasing Fe content
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