Silt Layers Research Articles

New and interesting records of marine fishes (Actinopterygii) from the Maltese Islands (central Mediterranean)

The occurrence of three bony ray-finned fishes, Thorogobius ephippiatus (Lowe, 1839), Chlopsis bicolor Rafinesque, 1810, and Grammonus ater (Risso, 1810) is reported for the first time in the scientific literature from Maltese coastal waters. The leopard-spotted goby, T. ephippiatus, was mostly recorded within the 8–32 m depth range on soft sediment and rocky bottoms within caves, but one individual was recorded on a rocky bottom with a thin layer of silt at a depth of 117 m where no cave was present. The bicolour eel, C. bicolor, was recorded within the 318–518 m depth range on rocky bottoms covered with a thin layer of muddy-detritic sediment; and the cusk-eel G. ater was recorded at a depth of 10 m within a cave. Notes on these three species as well as on another bony fish, the Azores rockling, Gaidropsarus granti (Regan, 1903), including new information on their bathymetric range and habitat association, are presented.

Shear Characteristics of Soil—Concrete Structure Interaction Interfaces

The shear characteristics of the interfaces between soil and concrete structures are essential for the safety of the structures. In this study, a large-scale direct shear test apparatus was developed to measure the mechanical parameters of soil–concrete interfaces under conditions with different soil types, soil moisture contents, and interfacial filling materials. The results showed that the shear stress of the soil–concrete interface increased initially and then became stable with the increase in the shear displacement. The shear displacement of the sandy soil when the shear stress became stable was smaller than that of the clayey soil. The silty sand–concrete interface had a smaller friction angle than the interface with the medium-coarse sand. Moreover, with the increase in the soil moisture content, the friction angle of the clayey soil–concrete interface decreased rapidly, whereas the cohesion first increased and then decreased, and the peak cohesion was near the plastic limit of the soil. Under the same moisture content, the friction angle and cohesion of the clay–concrete interface was reduced by filling the interface with a thin layer of sandy soil, while filling the silty sand–concrete interface with a thin layer of silt reduced the friction angle and increased the interfacial cohesion. Nonetheless, the filling had little impact on the overall shear strength of the interface.

CHARACTERISATION OF RADIOACTIVE CAESIUM IN SEDIMENTS AT THE NOGAWA RIVER, JAPAN.

The TEPCO Fukushima Daiichi Nuclear Power Plant accident that occurred in March 2011 resulted in the release of radioactive caesium into the environment. The radioactive caesium has been detected in the Tama River watershed. Previous investigations have shown that the concentration of radioactive caesium in sediment was relatively high in the Nogawa River. In this study, the relationship between the concentration of radioactive caesium in the sediment and the sediment characteristics was investigated. We found that 137Cs concentration in the tributary sediment has difficulty migrating downstream, while exhibiting a strong correlation with the amount of organic matter and a correlation with the clay, silt layer. Based on the results, we inferred that 137Cs is deposited together with the organic matter and clay, silt layer in the sediment and migrates at a slower pace than that in the mainstem.

Analysing Effects on Ground Water Levels Due to Conversion of Rural to Urban Landscapes

Abstract Greater NOIDA evolved from 1991 with 101 villages to 2020 with 293 villages. This is an ideal case of rural to urban transformation in the immediate past. This transformation led to a decrease in recharging natural surfaces and an increase in impermeable surfaces. Along with the reduction in recharge areas, an increase in population has necessitated more and more extraction of groundwater resulting in an imbalance of water extraction and recharge. The result is depletion of groundwater levels in this area. The area is part of the wide Indo-Gangetic alluvium with sand, silt and clay layers resting on quartzite’s of Delhi Super Group. Geomorphological map prepared using digital elevation models of the area shows older and younger alluvial plains and active flood plains of the river Hindan. Time series analysis of key land use land cover classes shows that recharge areas were reduced from 77 % to 30 % from 2005 to 2019 and impervious surfaces have increased from 19 % to 65 % for the same period. Aquifers of the area are both phreatic and semi-confined. The aquifer parameters estimated through step drawdown test and long duration aquifer performance test indicates that the average coefficient of transmissivity of the area is 1752 m2/day and the average coefficient of storage is 4.84 x 10-4. Discharge of the wells shows a yield of 8 to 16 lps for a drawdown of 3 to 6 m. An attempt has been made to know the behaviour of groundwater levels during the same period as that of land use land cover. The results indicate a 74 % depletion in groundwater levels with an average annual depletion of 21 %. An interrelationship between urban growth and groundwater levels has been established in this study. This analysis indicates that as agriculture declined water levels also depleted and have a positive correlation of 0.852. On the contrary, as the built-up increased water level has depleted hence have a negative relationship with a correlation coefficient of -0.851. To make it a sustainable resource, these overexploited aquifers need careful participatory management by communities, Scientists, and policymakers.

Site-specific seismic hazard and risk potential of Bengal Basin with emphasis on holistic seismic hazard microzonation and its structural impact assessment in the cities of Dhanbad and Mymensingh

The Bengal Basin located in the eastern part of the Indian subcontinent at the conjunction of the Eurasian, Indian, and Indo-Burma plates with two progressing deformation fronts viz. the Himalayas and the Indo-Burmese orogenic belts is one of the largest fluvio-deltaic to shallow marine sedimentary basin covered by alluvial plains of Holocene deposits extending from the Himalayas to the Bay of Bengal over thick younger alluvium comprising shallow layers of silt, clay, and sand that can have disastrous consequences due to site-specific ground motion amplification and liquefaction effects. The basin surrounded by Shillong and Assam plateaus in the Northeast is in the active tectonofabric of major active faults and lineaments triggering many devastating earthquakes in the past implicating the MM Intensity of VIII–XI in the near-source region causing widespread damage and destruction in the basin, thus bringing in the essence of assessing surface level seismic hazard and the risk imposed on the basin. Consideration of seismicity patterns, fault networks, and similarity in focal mechanisms yielded 49 areal seismogenic sources and additional active tectonic features in the 0–25 km, 25–70 km, and 70–180 km hypocentral depth ranges, which along with 14 ground motion prediction equations that include site-specific next generation spectral attenuation models pertaining to Northeast India, East-Central Himalaya, and Bengal Basin tectonic provinces yielded probabilistic peak ground acceleration (PGA) at engineering bedrock in the range of 0.08–0.58 g. Both the geophysical and geotechnical investigations at 6,000 sites provided effective shear wave velocity distribution in the range of 113–948 m/s on the geographical information system, thus classifying the basin into 11 site classes with “None” to “Severe” liquefaction hazard potential. A systematic non-linear/equivalent linear site response analysis and its spectral convolution with firm rock peak ground acceleration yielded surface-consistent hazard in the range of 0.09–1.17 g, thus opening up the issue of risk assessment and holistic seismic hazard microzonation of all the cities in the basin and their structural impact assessment using the SELENA-based capacity spectrum method on FEMA and BMTPC-regulated 11 model building types in the damage states of “none,” “slight,” “moderate,” “extensive,” and “complete” for all of those, however, in-depth studies carried out for Mymensingh and Dhanbad have been presented.

Field Research on the Treatment of Coastal Phase Liquefaction Foundation with Clay Interlayer Using Resonance Probe Compaction Method

The resonance probe compaction (RPC) method is an effective technique for particular soils, which mainly includes sandy and loess. However, the application of RPC on contaioning clay interlayer area has never been seen. In this study, a successful case of using the RPB method to treat the clay interlayer foundation is presented in detail. The test results of Huaiyan high-speed railway construction project are introduced. The test is divided into the laboratory test and the field test, mainly including standard penetration test (SPT), cone penetration test (CPT) and seismic wave cone penetration test (SCPT). The test results indicated that the cone resistance of silt and silty sand layers increased to an average of 2.13 times compared with an average of 4.39 MPa before treatment, and the sleeve friction whose initial average is 54.17 kPa increased to an average of 1.74 times. The existence of the clay interlayer does not affect the consolidation and drainage of the silt layer and the silt sand layer, and after the construction, the excess pore water pressure around the vibration point can be dissipated by more than 90% within 15 minutes. After reinforcement, the standard penetration number of subsoil, increased by about 15%–95% compared with an average of 19 blows before treatment and the clay particle content of some clay interlayers are reduced to less than 10%. The shear wave velocity of the subsoil in the treatment depth increased by about 15%–48% compared with 140 m/s before treatment. The RPC method was successful for the coastal phase liquefaction foundations.

Subsurface Weathering Zone Determination Using Down-Hole Seismic Surveys, Majnoon Oil Field, Southern Iraq

Detecting the weathering zone is one of the required data correction steps to process reflection seismic data collected at the Majnoon oil field, south of Iraq. Two subsurface layers represent the weathering zone in this field. Those two layers were inferred by primary seismic waves utilizing the down-hole seismic method. Five wells in the studied area were drilled and named DH-1, DH-2, DH-3, DH-4 and DH-5. The collected seismic data was analyzed to determine the depths, thicknesses and lithology of the subsurface layers. The primary seismic wave velocities were calculated and applied to eliminate two sub-surface layers. The average primary wave velocities and thicknesses of the first layer were 374, 240, 211, 277, 370 m/s, and 2.8, 2, 2, 2, 4.9 m, respectively. In the second layer, the primary waves velocities were 1125, 1284, 1201, 1395 and 1008 m/s, and the thicknesses were 13.2, 11, 13, 11.5, 21.4 m. The first weathered layer represented on the five wells is clay. The second layer has different geometry on different wells, which is represented by a sandy clay layer on DH-1, and muddy clay on DH-2. Then, it is changed to be a silt layer in DH-3, sandy clay in DH-4 and DH-5.

Cyclic behaviour of stratified soil under liquefied states

A substantial amount of work on the cyclic behaviour of cohesionless soil has been performed after neglecting the reality of stratification existing nearby marine structures or alluvial plains. This complicated mechanism of stratified soil failure on earthquake-induced soil liquefaction is affected significantly by the presence of a less permeable soil layer. Several past studies investigated that under the action of dynamic loads, the presence of a silt layer in homogeneous sandy soil crucially modifies the pore pressure dissipation characteristics, axial strain rate and stress–strain behaviour of the whole stratified specimen. In the present study, cyclic behaviour of sand specimen interlayered with silt layer has been presented in respect of its pre-and post-liquefaction behaviour. Undrained stress-controlled cyclic triaxial tests have been performed on homogeneous sand specimens and on specimens interlayered with a silt layer, placed at H/4, H/2 and 3H/4 (where H is the height of the specimen from the top) to signify the role of placement depth. The instability and failure of such specimens have been compared using the failure line and phase transformation line. Few key observations suggested that the number of liquefaction failure cycles enhanced two times and secant modulus (under post liquefied state) improved by 4.8 times when the placement depth of the silt layer increased from H/4 to 3H/4 under similar loading conditions. Additionally, the role of initial static shear stress has been investigated at three different confining pressures in a few stratified specimens. It has been observed that failure of the stratified specimen is due to the obstruction of pore water movement caused by the presence of the silt layer. A comparison of the present work has been made with significant studies using liquefaction resistant curves to ensure the efficacy of this study.

Evolution process and hardening mechanism of consolidated silt in silty seabed subject to waves

In this study, the entire evolution process of consolidated silt in a silty seabed under the action of waves is reproduced via a flume experiment. The response of pore water pressure in the seabed, variation of soil strength, and change in characteristic parameters of the soil particles are studied. From the experiment, the silty seabed is inferred to undergo two stages, i.e., failure and reconsolidation, finally forming a high-strength consolidated silt layer. The rapid accumulation of pore water pressure in the seabed under the action of waves provides the initial conditions for the formation of consolidated silt. The shear of the wave and seepage of pore water pressure provide power for the reconsolidation of the seabed. Macroscopically, reconsolidation of an unstable seabed results in consolidated silt. Microscopically, consolidated silt is the product of coarsening, homogenization, and embedment of particles. The hardening mechanism of consolidated silt is driven by increases in the internal friction angles of the particles and existence of hardening forces between the particles. The empirical formula for the internal hardening force of consolidated silt is obtained experimentally.

Geoelectrical Investigation of Groundwater at Northern Gaza Strip, Palestine

A vertical electrical sounding survey was carried out in northern Gaza Strip (Gaza City, Jibalya, Bayt Lahya and Bayt Hanun), Palestine to study the groundwater conditions and evaluate its quality and distribution. The survey included twenty-six (26) traverses with variable lengths in the range 200-500 m. The geoelectrical survey revealed that the resistivity of the study area varies in a wide range mostly 9 to 850 Ωm, subdivided into three subsurface zones. The first zone represents the dry sandstone and alluvial that attains the highest resistivities (100-850 Ωm) with variable thicknesses in the range 26-80 m beneath the whole study area. This zone is characterized by the presence of thin layers of clay and silt in some localities that reduced the resistivity to 15-25 Ωm. The second zone represents the fresh water saturated calcareous sandstone (locally named Kurkur) with resistivities in the range 22 -39 Ωm). The thicknesses of this zone is about 55-70 m in the western part of the study area and increased to 110 m in the east. The surface of this zone shows a gentle westward gradient, which indicates a general flow of water towards the Mediterranean Sea. The third zone represents saline water saturation with low resistivities, mostly 9 Ωm -10 Ωm close to the Mediterranean shore, located at 60 m below sea level and 100 m beneath the eastern side of the study area. Beneath the eastern part of the study area, an anomalous low resistivity of 2-3 Ωm is observed within the fresh water zone, which indicates groundwater pollution near the buffer zone caused by agriculture activities and untreated pumped wastewater.

An improved non-stationary geostatistical method for three-dimensional interpolation of Benzo(a)pyrene at a contaminated site

Intense industrial activities and complex hydrogeological conditions at contaminated sites make accurate three-dimensional (3D) mapping challenging. The cause is the non-stationarity in the variance of soil pollutants in geographical space (G-space), making the stationary hypothesis required by the Kriging method unsatisfactory. To handle the variance non-stationarity, a Variance-Octree-Kriging (VOK) method was proposed. VOK is a spatial deformation method that constructs a stationary deformation space (D-space) by stretching and shrinking the G-spaces with low and high spatial correlation, respectively. VOK method consists of 3D stratification in G-space, space scaling and transformation, and ordinary Kriging (OK) in D-space. 3D stratification uses variance octree (VOT) to generate a set of anchor points in the G-space. The spatial scaling and transformation use the virtual force algorithm (VFA) and thin-plate spline to evenly distribute the anchor points and obtain the D-space, where the OK is implemented. The method was applied to predict the distribution of soil Benzo(a)pyrene (BaP) at a contaminated site in North China Plain. The results show that the interpolation accuracy of VOK was 9% higher than that of OK. The VOK method also changed the spatial structure from anisotropic to isotropic. The root mean squared error (RMSE) of fill, silt and clay layers decreased by 4.67%, 11.39%, and 20.46%, respectively. This method is applicable to the 3D interpolation of pollutants at contaminated sites, with the advantages of high interpolation accuracy and the ability to handle the non-stationarity in variance.

Methane migration mechanisms for the Green Canyon Block 955 gas hydrate reservoir, northern Gulf of Mexico

In marine continental margins, high saturations of natural gas hydrate are observed within the gas hydrate stability zone, but the gas migration pathways to the hydrate reservoir are not often clear. We focus on a site in Green Canyon Block 955 (GC 955) in the Gulf of Mexico, where gas hydrate occurs in a 35 m-thick reservoir with saturations of 79-93% in numerous centimeter- to decimeter-thick sandy silt layers and little to no gas hydrate in the interbedded cm to decimeter-thick clayey silt layers. Different datasets (well logging, coring, and seismic data) suggest different types of potential methane migration mechanisms. For example, relatively high particulate organic carbon content in the reservoir and the microbial methane source indicated by gas chromatography and methane isotopes suggest gas might be made locally and migration could occur through dissolved methane sources or water advection. In contrast, the visible deeply rooted faults intersecting the gas hydrate reservoir and the gas pockets adjacent to the faults on seismic data suggest that free gas may migrate directly into the reservoir. We tested three different mechanisms to form gas hydrate at GC 955: short-range methane diffusion, short-range methane diffusion coupled with upward water advection, and free gas flow. The 1-D and 2-D numerical models show that both the short-range migration and the upward water advection are not enough to form high saturations gas hydrate at GC 955, and that free gas flow is required to form the high saturations of gas hydrate observed at GC 955.

Diversity and Metabolism of Microbial Communities in a Hypersaline Lake along a Geochemical Gradient.

Simple SummaryIn the south of western Siberia (Russia), there are many unique and unexplored lakes. This work focused on Lake Solenoe, a component of a poorly studied lake system in the south of western Siberia. The diversity of microorganisms of Lake Solenoe was evaluated in the floating community and in the bottom sediments. The aim was to assess the metabolic potential of this lake ecosystem and to describe the identified relations between the mineral and living components. This is the first detailed study on the microbial diversity, its metabolic potential, and their relations with a series of geochemical parameters in the lake ecosystem of Novosibirsk Oblast. In the south of western Siberia (Russia), there are many unique and unexplored soda, saline, and freshwater lakes. In this study, the results are presented on microbial diversity, its metabolic potential, and their relation with a set of geochemical parameters for a hypersaline lake ecosystem in the Novosibirsk region (Oblast). The metagenomic approach used in this work allowed us to determine the composition and structure of a floating microbial community, the upper layer of silt, and the strata of bottom sediments in a natural saline lake via two bioinformatic approaches, whose results are in good agreement with each other. In the floating microbial community and in the upper layers of the bottom sediment, bacteria of the Proteobacteria (Gammaproteobacteria), Cyanobacteria, and Bacteroidetes phyla were found to predominate. The lower layers were dominated by Proteobacteria (mainly Deltaproteobacteria), Gemmatimonadetes, Firmicutes, and Archaea. Metabolic pathways were reconstructed to investigate the metabolic potential of the microbial communities and other hypothetical roles of the microbial communities in the biogeochemical cycle. Relations between different taxa of microorganisms were identified, as was their potential role in biogeochemical transformations of C, N, and S in a comparative structural analysis that included various ecological niches.

Centrifuge Tests of Cone-Penetration Test of Layered Soil

Two centrifuge model tests were used to examine the effect of soil interlayering on the measured cone-penetration resistance in a layered soil model. The first centrifuge model included four soil profiles: two uniform loose and dense soil profiles and two two-layer sand profiles of loose over dense and dense over loose sands. The other centrifuge model involved a layer of loose or dense sand with varying thickness between overlying and underlying layers of low-plasticity clayey silt. Multiple cone-penetration soundings were performed using cone penetrometers with diameters of 6 and 10 mm. The results showed that the measured tip resistance in layered soils as well as the sensing and development distances depend on sand layer thickness and stiffness contrast between the subsequent soil layers. The results of these experiments were compared with the results obtained from analytical and numerical solutions. The results provide insights on the effect of thin-layer presence on cone tip measurements and an archived data set for evaluating design procedures and numerical analysis methods.

Coupled thermo-hydro-mechanical modeling of frost heave and water migration during artificial freezing of soils for mineshaft sinking

Artificial freezing of water-bearing soil layers composing a sedimentary deposit can induce frost heave and water migration that affect the natural stress–strain state of the soil layers and freezing process. In the present paper, a thermo-hydro-mechanical (THM) model for freezing of water-saturated soil is proposed to study the effects of frost heave and water migration in frozen soils on the formation of a frozen wall and subsequent excavation activity for sinking a vertical shaft. The governing equations of the model are formulated relative to porosity, temperature, and displacement which are considered as primary variables. The relationship between temperature, pore water, and ice pressure in frozen soil is established by the Clausius–Clapeyron equation, whereas the interaction between the stress–strain behavior and changes in porosity and pore pressure is described with the poromechanics theory. Moreover, constitutive relations for additional mechanical deformation are incorporated to describe volumetric expansion of soil during freezing as well as creep strain of soil in the frozen state. The ability of the proposed model to capture the frost heave of frozen soil is demonstrated by a comparison between numerical results and experimental data given by a one-sided freezing test. Also to validate the model in other freezing conditions, a radial freezing experiment is performed. After the validation procedure, the model is applied to numerical simulation of artificial freezing of silt and sand layers for shaft sinking at Petrikov potash mine in Belarus. Comparison of calculated temperature with thermal monitoring data during active freezing stage is presented. Numerical analysis of deformation of unsupported sidewall of a shaft inside the frozen wall is conducted to account for the change in natural stress–strain state of soil layers induced by artificial freezing.

Study on the Floating Law of Metro Segments in Water-Rich Sandy Silt and Silty Clay Strata

During the construction of subway shields, the problem of floating segments is particularly prominent in silty clay strata. The resulting segment problems, such as cross-platform, cracks, damage and leakage, cause great harm to the tunnel. Through field test, combined with mathematical theory and numerical simulation analysis, this paper studies the floating law of segments in water rich sandy silt and muddy clay layer, which provides a basis for analysing the control measures of segment floating, which can improve the safety of the project and save the project cost. The typical section of shield tunnel of Hangzhou Metro Line 7 is selected as the test section, and the segment floating law is deeply analysed through field test. By combining numerical simulation and theoretical research, the mechanism underlying the effects of the grouting slurry properties, the main physical parameters of the soil and the distance of the segment from the shield tail on segment floating is discussed. The results show that shield segments floating in muddy clay strata can be divided into three typical stages: rapid change, buffering and stability. In the first stage, segment up-floating develops rapidly, accounting for 70–90% of the total up-floating within 15 hours after leaving the shield tail. In the second stage, buffer up-floating develops slowly, and the average up-floating amount accounts for 7.59% of the total amount of up-floating. In the third stage, segment up-floating gradually stops with the condensation and hardening of the slurry. The results show that there is a negative correlation between the slurry condensation rate and the number of floating segments, a negative correlation between the segment distance from the shield tail and the number of floating segments, and a positive correlation between the elastic modulus of the soil and the number of floating segments. The multifactor calculation model is proven to have good adaptability in silty soft soil layers.

Modern and early Holocene ice shelf sediment facies from Petermann Fjord and northern Nares Strait, northwest Greenland

Based on sediment cores and geophysical data collected from Petermann Fjord and northern Nares Strait, NW Greenland, an Arctic ice shelf sediment facies is presented that distinguishes sub and pro ice shelf environments. Sediment cores were collected from sites beneath the present day Petermann Ice Tongue (PIT) and in deglacial sediments of northern Nares Strait with a focus on understanding the glacial and oceanographic history over the last 11,000 cal yr BP. The modern sub ice shelf sediment facies in Petermann Fjord is laminated and devoid of coarse clasts (IRD) due to strong basal melting that releases debris (debris filtering) from the basal ice at the grounding zone driven by buoyant subglacial meltwater and entrained Atlantic Water. Laminated sediments in the deep basin proximal to the gounding zone comprise layers of fine mud formed by suspension settling from turbid meltwater plumes (plumites) interrupted by normally graded very fine sand to medium silt layers with sharp basal contacts and rip-up clasts of mud, interpreted as turbidites. An inner fjord sill limits distribution of sediment gravity flows from the grounding zone to the deep inner fjord basin, such that sites on the inner sill and beyond the ice tongue largely only comprise plumites. Bioturbation and foraminiferal abundances increase with distance from the grounding zone. The benthic foraminiferal species, Elphidium clavatum is absent beneath the ice tongue, but dominant in the turbid meltwater influenced environment beyond the ice tongue. The very sparse IRD in sediments beneath the PIT and in the fjord beyond the PIT derives mainly from englacial debris in the ice tongue, side valley glaciers, rock falls from the steep fjord walls and sea ice.We use the modern ice shelf sediment facies characteristics to infer the past presence of ice shelves in northern Nares Strait using analyses of sediment cores from several cruises (OD1507, HLY03, 2001LSSL, RYDER19). On bathymetric highs, bioturbated mud with dispersed IRD overlies a 10–15 m thick, distinctly laminated silt and clay unit with rare coarse clasts and sparse foraminifera which forms a sediment drape of nearly uniform thickness. We interpret these laminated sediments to represent glaciomarine deposition by meltwater plumes emanating from ice streams that terminated in floating ice shelves. IRD layers, shifts in sediment composition (qXRD, MS and XRF) and faunal assemblage changes in the laminated unit document periods of ice-shelf instability sometimes, but not always, coupled with grounding zone retreat. Our deglacial reconstruction, including ice shelves, begins ∼10.7 cal ka BP, with confluent ice streams grounded in Hall Basin fronted by the Robeson Channel ice shelf. Ice shelf breakup and grounding zone retreat to relatively stable grounding zones at Kennedy Channel and the mouth of Petermann Fjord was accomplished by 9.4 cal ka BP when the Hall Basin ice shelf was established. This ice shelf broke up and reformed once prior to the final break up at 8.5 to 8.4 cal ka BP marking ice stream collapse, separation of Greenland and Innuitian ice sheets, and the opening of Nares Strait for Arctic-Atlantic throughflow. The Petermann ice shelf remained in Hall Basin until the Petermann Glacier retreated from the fjord mouth ∼7.1 cal ka BP. The resilience of these northern ice streams to strong early Holocene insolation and subsurface Atlantic Water advection is attributed to their northern aspect, buttressing by narrow passages, and high ice flux from the Greenland Ice Sheet (GIS).

Estimation of Hydrogeological Parameters by Using Pumping, Laboratory Data, Surface Resistivity and Thiessen Technique in Lower Bari Doab (Indus Basin), Pakistan

Determination of hydrological properties of the aquifer is of fundamental importance in hydrogeological and geotechnical studies. An attempt has been made to refine the hydraulic conductivity values computed from the pumping test by utilizing the hydraulic values computed in the laboratory. This study uses hydraulic conductivity computed in the laboratory of rock samples, pumping test data in conjunction with the empirical equations, and vertical electric sounding (VES) to determine the hydraulic properties of Lower Bari Doab (LBD) in the Indus Basin of Pakistan. The utilized dataset comprises pumping test results (Kpump) from 17 water wells, hydraulic conductivity values (Klab) of different grain size subsurface lithologies, and 50 VES stations. To this end, the investigated area is divided into 17 polygons by using the Thiessen technique, and equal distribution/weight of conductivities values is assigned to 17 polygons (one polygon around each water well where pumping test is conducted). The true resistivity ranging from 20–90 ohm-m along with an average thickness of the aquifer is computed using the VES data for each polygon. A novel approach has been developed to estimate the hydraulic conductivity of the aquifer by combining laboratory data and pumping test which is used to compute the other hydraulic properties. The calculated hydraulic conductivity, transmissivity, and tortuosity values of the aquifer range from 4.4 to 85.6 m/day, 674 to 8986 m2/day, and 13 to 20, respectively. The porosity ranges from 32 to 45% and the formation factor values fall in the range 4 to 12. Higher hydraulic conductivities were encountered in the southern portion of the area near the junction of the rivers, and it increases with an increase in porosity. The aquifer having T > 5700 m2/day and K > 40 m/day, yields a large quantity of water whereas the portion of an aquifer with T < 1100 m2/day and K < 13 m/day are combatively low yield aquifer. The results of the resistivity method show that the subsurface geological material, as depicted from true resistivity, is composed of layers of sand, clay, and silt mixed with gravel/sand. This study improves the understanding of the aquifer and will help in the development and management of groundwater resources in the area including the prediction of future behavior of the aquifer.

Application of geotextile containers for removal of silt layers of the Krasnodar reservoir

The article deals with the issues of improving the methods of removing silt layers of the Krasnodar reservoir using geotextile containers. The new technology exceeds all the characteristics of the dewatering facilities available in Russia. The necessary stage of preparation of wastes for disposal is dewatering to a humidity of 50-60%, which allows you to reduce their volume tenfold and improve the structure of raw materials. For these purposes, Russia has quite a lot of different structures and a large number of sludge dewatering methods. For the construction of sludge dewatering facilities and various types of precipitation of sewage, much less time and economic costs are required than for the construction of mechanical cleaning facilities. Also, new technologies occupy quite a little free land area compared to silt sites and they do not depend on climatic factors because atmospheric precipitation falling on the container drains from its surface. The impact of negative temperatures provides the deep moisture drainage after thawing of organogenic silts and hydroxide slimes. Also, new technologies occupy. Geotextile container technology is ideal for silt maps cleaning, sludge storage facilities and reservoirs, for temporary storage of dewatered sludge on a site, and, most importantly, for disposal of wastes directly at the dewatering site in the form of a highly loaded landfill that is resistant to wind and water erosion. When reducing the area of silt maps, the containers can be used as an emergency reserve, since their guaranteed storage period is 25 years. The main principle of the technology is to provide the sludge into the container through a pulp pipeline and then wait for the free water to drain. When dewatering granular suspensions (from sand to dense slimes), the container is filled with natural pulp. When fine silts and hydroxide slimes are dewatered, a flocculant is added to the pulp. After the initial filling of the container with pulp, its subsequent pumping is carried out from 1 to 5 times, after which the process of consolidation of the dehydrated material to the limit of free water release occurs, the duration of which depends on the properties of the solid phase. The main thing is that waiting does not consume any resources, except for the area provided for containers. After consolidation, a loose or refractory material is formed, the size of which depends on the size of the geotextile container used.

Improvement of design parameters of geotextile containers made of polypropylene for removal of silt layers and industrial waste

The article deals with the issues of improving the design parameters of geotextile containers made of polypropylene for the removal of silt layers and industrial waste as exemplified by the Krasnodar reservoir. The article presents statistics of waste accumulation in the Russian Federation in recent years. A new technology for transportation and disposal of liquid waste is proposed. The calculation of the parameters of geotextile containers made of high-strength fabric materials based on polypropylene has been developed. The development of chemical industry has allowed us to offer a new cost-effective innovative technology of dewatering and waste disposal based on the use of geotextile containers made of high-strength fabric material. In the Russian Federation, more than 3.5 billion tons of waste are accumulated annually, the amount of which increases with the growth of economic activity. Of the waste produced in 2020, 47% was placed at the enterprises’ own facilities, and 19% was buried. In order to improve the state of the environment, it is necessary to improve waste storage and disposal technologies. The use of geotextile containers made of high-strength fabric materials for dewatering and waste disposal is the most environmentally and cost-effective technology that has no restrictions and contraindications for technical equipment and has all the necessary indicators of strength, rigidity and reliability for effective use.