Infiltration Water Research Articles

Improved Calculation of Hydraulic Conductivity for Small Disk Tension Infiltrometers

AbstractBecause tension infiltrometers apply water through a disk of finite size, the infiltrated water moves laterally as well as downward. Only the vertical component of this flow is indicative of the hydraulic conductivity K, so the algorithm for computing K must include a way of isolating that component from the total flow. Some commonly used formulas correct for the multidimensional effects by subtracting an estimate of the laterally spreading flow. For disks smaller than about 200 mm in diameter, however, lateral spreading constitutes so much of the total flow that these subtractive formulas lose considerable accuracy, and sometimes overcorrect so severely as to produce a negative number for K. Other methods rely on empiricisms that are not completely consistent with unsaturated‐flow theory and that require prior knowledge of certain soil properties. We developed a new formula that uses a multiplicative factor instead of a subtracted term to achieve the needed correction. For testing we conducted numerical experiments with synthetic data produced by solving the Richardson‐Richards equation using the code VS2DRTI, for diverse media and a range of disk sizes, including the widely used 45‐mm diameter. We compared K values calculated from our formula to the actual K used to generate the simulated data, as well as to results from other published formulas. This comparison shows that our method provides an algorithm based in unsaturated‐flow theory that produces more reliable values for small disks without requiring prior knowledge of soil properties.

Estimating Soil Hydraulic Parameters during Ponding Infiltration Using a Hybrid Algorithm

Accurate inversion of soil hydraulic parameters based on the van Genuchten–Mualem model has received much attention in soil science research. Herein, a hybrid algorithm method using particle swarm optimization and vector-evaluated genetic algorithm was used to invert the parameters θs, α, n, and Ks, with the objective functions of infiltration rate, cumulative infiltration, and soil water content. Then, numerical experiments were conducted on four typical soils at three initial water content levels (20, 40, and 60% effective saturation) to verify the accuracy of the inverse method. The results showed that the inversed soil water retention and conductivity curves were approximately the same as the real curves, with the root mean square errors of 0.00101–0.00192 cm3·cm−3, 0.00800–0.02519 cm3·cm−3, respectively, and both the Nash-Sutcliffe coefficients were approximately 1.0. Additionally, laboratory experiments were also performed to compare with the inversed parameters for verification, within small root mean squared errors and approximately 1.0 Nash–Sutcliffe coefficients. Furthermore, the method can also achieve acceptably accurate parameter inversion even with substantial measurement errors included in the cumulative infiltration, initial water content, and final water content. Thus, the method is effective and robust and found to be practical in field experiments.

Chemical and Isotopic Features of a High pCO2 Natural Mineral Water from Essentuki Field (Caucasian Mineral Water Region, Russia)

This article presents the new data on the chemical and gas composition, the content of stable isotopes of oxygen, hydrogen, carbon, and sulfur in natural mineral waters of the Essentuki field. A detailed study of the geological and hydrogeological features of the water circulation area, its major chemical composition, the content of organic matter in water, temperature conditions and δ18OSMOW, δDSMOW, δ13CDIC, δ18ODIC, δ34SVCDT, δ13CCO2, δ13CCH4, δ15N values made it possible to specify the genesis of water, gas, and solute components of the Essentuki CO2-rich mineral water field. The stable isotopes values (δ18OSMOW and δDSMOW) in the water phase ranges from −13.75 to −9.69‰ and from −101.08 to −74.34‰, respectively. They correspond to GMWL, which indicates their predominantly infiltration genesis. The values of δ13CDIC in mineral waters of the Essentuki field vary widely from −14.43 to +8.59‰ and indicate their mixed genesis. δ15N gas values in mineral waters of the Essentuki field vary quite widely from −2.31 to 2.50‰ indicating a different source of this gas. Obtained data prove that all mineral waters in the Essentuki field are infiltration waters, and the heterogeneous component composition of waters circulating in different aquifers reflects the lithological composition of water-bearing strata, the rate of openness/closure of faults and the intensity of reactions in the «water-rock-gas-organic matter» system.

Impacts of elevational variability of climate and frozen ground on streamflow in a glacierized catchment in Tibetan Plateau

In cold and high-elevation mountainous catchments, climate and landscape vary with elevation, which leads to elevational variability in runoff. The short-term variation and long-term change of climate would temporally and permanently alter the conditions of frozen ground and runoff characteristics at different elevation zones. In this study, a conceptually hydrological model is developed to investigate the responses of soil freeze–thaw and runoff processes to climate change from 1979 to 2013 in a glacierized catchment in the Tibetan Plateau (TP). Results show that our model can accurately reproduce the observed daily streamflow. In addition to rainfall (63.8%), meltwater from glacier (22.2%) and snowpack (14.0%) are also key contributors to streamflow, especially at high elevations. As temperature declines with rising of elevation, the elevation-runoff relationship depicts a convex formation with a runoff peak at the elevation of ∼5800 m. Below 5800 m, surface flow increases towards high elevations accompanied by the increase of glacier coverage, while groundwater flow reduces because the enlarged frozen ground areas inhibit the percolation of the infiltrated water. Above 5800 m, the runoff declines sharply as the ground changes to a perennially freezing condition. The long-term climate warming during 1979 ∼ 2013 significantly increases annual runoff with a rate of 12.2 mm/10a. The increment in streamflow is primarily attributed to an increase in surface flow in the summer season when glacier meltwater increases at high elevations. Whereas the permafrost degradation enhances infiltrated water percolation and hence, groundwater flow in the low elevations and the low flow periods. Although climate warming benefits the local water resources availability during the historical periods, streamflow could be substantially decreased if the glacier vanished, which threatens the sustainability of the “water tower” over TP.

Hydrogeochemical characteristics and the genesis of the No. Lu 32 well in the Jiaodong Peninsula, China

The No. Lu 32 well is a seismic observation well situated on the easternmost tip of the Penglai–Weihai fault zone in the Jiaodong Peninsula. It is necessary to reveal the genetic mechanism of the water in this well for earthquake forecasting along the Penglai–Weihai fault zone. Water samples were collected from the No. Lu 32 well, neighboring wells, and seawater to measure the hydrochemical composition and main hydrogen and oxygen isotopic compositions. The water type of the No. Lu 32 well is Cl–Na, which may be due to the influence of seawater intrusion. Hydrogen and oxygen isotopes indicate that the No. Lu 32 well and adjacent wells are mainly influenced by meteoric water, that the high salinity in the water is mainly from the mixing of modern seawater, and that the proportion of seawater there is approximately 5%. Observation of water temperature data in the No. Lu 32 well over several years shows regular annual variations. This comprehensive study shows that the well is greatly affected by seawater backflow infiltration and shallow water. The results of this paper provide an important reference for exploring the hydrogeochemical characteristics and genesis of wells in other coastal zones.

S-wave velocity characteristics and mineralization of the southern tibet detachment system-yalaxiangbo dome

A series of extensional structures, including the southern Tibet detachment system (STDS), the north-south trending rifts (NSTR), and the northern Himalayan gneiss dome (NHGD), developed from the collision and compression between the Indian and Eurasian plates. These tectonic movements were accompanied by magmatism and polymetallic mineralization. Cuona Rift (CR) is located on the STDS next to the Yalaxiangbo Dome (YD) and passes through the Zhegucuo-longzi fault (ZLF), the Lhozhag fault (LZF), the Rongbu-Gudui fault (RGF), the Cuonadong dome (CD), and the YD. The study area contains numerous metal deposits, such as rare metal ore, lead zinc ore, gold deposits, and two geothermal fields, i.e., the Cuona geothermal field (CGF) and the Gudui geothermal field (GGF). Current research on the geological structures from the STDS to the YD is mainly based on magnetotelluric and natural seismic imaging. These surveys have a low resolution, making it impossible to image the shallow crust in detail. This study obtained about a 112 km S-wave velocity profile from the STDS to the YD using the multichannel surface wave imaging method. The profile results indicated that the average thickness of the sedimentary layer from the STDS to the YD is 400–500 m, while it is more than 800 m at certain fault zones. The CD is connected to the high-velocity body below the Zhaxikang ore concentration area (ZOCA) and may have the same provenance. The thermal conductivity reveals that the CGF, the GGF, and the ZOCA have high values and a more intense thermal radiation capacity. This drives the migration and circulation of the thermal fluids in the CGF and the GGF, causing them to continuously transmit heat to the shallow surface along the fault system. The migration of the thermal fluids extracts useful elements from the geological bodies through which it flows. When these elements mix with the atmospheric infiltration water, it precipitates to form the Zhaxikang hydrothermal superimposed transformation type lead-zinc polymetallic deposit.

Changeability of rill erosion properties due to microorganism inoculation

This study aimed to assess the impacts of using soil microorganisms onrill erosion prosses. Consequently, the efficacy of individual bacteria (Ba) and combined inoculation of bacteria and cyanobacteria (Ba + Cy) extracted from a Marl region's soil microorganism bank in changing rill erosion processes was investigated. The experiment was carried out on mid-sized plots (1 × 6 m) with a 30 % slope and three replicates. Plots were subjected to a design simulated rain with an intensity of 50 mm.h−1 and a duration of 30 min. A supplementary runoff with a discharge of 2 L.min−1 was also used to mimic more extended slope conditions to motivate the rilling phenomenon. The results of the study disclosed that the control (i.e., not inoculated) and treated plots (i.e., Ba and Ba + Cy) behaved differently in the viewpoint of runoff, soil loss, flow hydraulics, and rill morphometry. Statistical analyses revealed that Ba and Ba + Cy treatments controlled all runoff and soil loss components, flow hydraulic characteristics, and rill morphologic factors significantly (p < 0.05) except the infiltrated water (p = 0.56) and the Froude number (p = 0.11) compared to the control plots. The findings implied that Ba and Ba + Cy inoculations, compared to control plots, increased infiltrated water by 1.73 and 1.55 folds and reduced soil loss by 100.31 and 273.94 folds, respectively. The Froude and Reynolds numbers declined by 2.34 and 5.77 folds when Ba was applied. At the same time, Ba + Cy decreased the Froude and Reynolds numbers by 1.24 and 20.08 folds, respectively. Furthermore, rill frequencies in the treated plots by Ba and Ba + Cy were tobogganed by 3.67 and 2.20 folds with a high effect on increasing initiation times by 17.80 and 28.29 folds compared to the control treatment. Our findings suggest endemic microorganism inoculation as an effective bioengineering technique for managing rill erosion-prone regions.

A Simple Method to Assess Key Soil Hydraulic Properties

We devised a simple infiltrometer to easily assess soil infiltration capacity and key soil hydraulic properties considering the impact of soil structure on soil infiltration. We conducted two series of five in situ infiltration experiments each on undisturbed forest and grassland soil of contrasting bulk densities and saturated hydraulic conductivity (Ks), and one on six soil columns with mineral soil and various textures without structure. Finally, we measured Ks, saturated water content and the van Genuchten parameters of these soils. Based on the obtained results, we found the best correlations to be exponential correlations between clay content and infiltrated water volume on the one hand and between clay content and the hydraulic properties on the other hand in all cases. Considering the infiltrated volume obtained by the infiltrometer and the measured soil parameters in mineral soil columns as references, we hypothesized that any change in hydraulic parameters of the natural soil is proportional to the change in infiltration volume. Thus, a second term accounting for water volume changes was therefore included in the correlation equations. The first validations of Ks values in forest soil showed good agreement with the laboratory measurements. Further investigations are needed to extend our validation to other soils with various textures.

Disentangling runoff generation mechanisms: Combining isotope tracing with integrated surface/subsurface simulation

The majority of runoff studies to date have reported a similar pattern of rapid rain-to-runoff conversion via overland flow and shallow subsurface water flow, as well as the ubiquity of thresholds and hysteresis in rainfall-runoff response. But each of those approaches has limitations in terms of inference and process description. Processes of water transport and mixing and how they influence runoff generation are still not well understood or quantified. In this study, HydroGeoSphere, a fully-integrated surface/subsurface flow model, was used together with stable isotopes for disentangling runoff generation mechanisms in a headwater catchment. The study area (0.21 km2) is the first-level tributary of the Xin’an Jiang River located in a humid climate region of eastern China. Water flow simulation elucidated the spatial water transport process, and isotope tracing quantified the complex water mixing process between the shallow soil and hillslope surface. This study provides insights into the rapid transformation of rainfall infiltration and mixing in soil and exfiltration to a hillslope. Results show that the stream runoff was separated into rainfall-induced overland flow (9 %), exfiltration-induced overland flow (including the 53 % of mixed water from rainfall infiltration and 6 % of the stored soil water), and subsurface flow (32 %). Exfiltration-induced overland flow was the dominant water source in the headwater catchment during a rainfall-runoff event. The mutual influence of rainfall infiltration and soil water exfiltration caused the shallow soil to rapidly become saturated, thus forming saturation excess overland flow. The consistence of estimated soil water velocity based on the integrated isotope and numerical modeling approach, at about 0.4 m/d nearby the stream channel, improved the reliability of model visualizations. Further analysis indicates that water flow paths and velocities responding to the rainfall event were attributed to the soil moisture conditions and topography. This study demonstrates that identifying the rapid mixing processes between the rain and the soil water was crucial for understanding hillslope overland flow and runoff generation in headwater catchments.

Study on groundwater recharge based on chloride mass balance and hydrochemistry in the irrigated agricultural area, North China Plain

In the North China Plain, water shortage seriously restricts economic development, and agricultural irrigation depends heavily on groundwater extraction. Irrigation water and precipitation may directly recharge groundwater in the irrigated agricultural region. Therefore, calculating the recharge of precipitation and irrigation to groundwater is essential for the sustainable utilization of water resources. Furthermore, determining the transformation relationship of precipitation-soil water-groundwater is helpful to understand the hydrological cycle process better. The average groundwater recharge calculated by the chloride mass balance method is between 66 and 144 mm/year, accounting for only 7–17% of the total precipitation and irrigation water. The hydrogen (2H) and oxygen (18O) isotopes reveal that precipitation only affects soil water in topsoil, and soil water in deep soil is recharged upward by groundwater. The hydrochemical composition of soil water shows high concentrations of salt in unsaturated zones. Infiltration water dissolves salt through the unsaturated zone and carries them into the shallow groundwater, causing the deterioration of shallow groundwater quality. These results contribute to the effective management of groundwater resources and the control of agricultural pollution in groundwater.

The Application of Porous Material in the Capillary Barrier System for Residual Soil Slope Stabilization

A drainage system that is used to flow excess rainfall infiltration is an excellent alternative to enhance lateral diversion capacity at the interface of Grade VI and Grade V soil slope layers thus delaying breakthrough occurrences. This study aims to explore the performance of porous transport layer on slope behavior via numerical simulation by GeoStudio SEEP/W. In this study, a 2-dimensional non-homogenous residual soil configuration model, which is composed of Grade VI and Grade V residual soil was constructed. Laboratory tests were conducted on the soil samples collected from the Faculty of Engineering, UTM JB to determine the soil properties as input parameters in numerical modeling. The soil slope model is designed as an infinite residual soil slope according to Jabatan Kerja Raya (JKR) design specification on the cut slope and fill slope with 27 ° inclination respectively. High rainfall intensities were chosen to represent rainfall infiltration in Johor. The slope model was modeled with a porous transport layer at the Grade VI and Grade V layer interfaces. The porous transport layer is introduced as the transport layer and its effectiveness is expected to be similar to the optimum compacted soil mix in the previous study. In addition, porous concrete as a transport layer is introduced and it must meet the adequate porosity and hydraulic conductivity requirements. The suction distribution pattern with depth and time was subsequently observed to identify the volume of infiltrated water and retention time in the transport layer. The porous transport layer is also expected to be efficient in diverting infiltrating water and decreasing the interface's suction distribution between Grade VI and Grade V soil layers. HIGHLIGHTS The water built up within the residual soil slope is one of the common factors of rainfall-induced residual soil slope failure thus porous transport layer introduced The detailed laboratory testing and numerical modelling conducted in order to identify the performance of porous transport layer within residual soil slope The application of porous transport layer sandwiched between residual soil is effective to decrease the water built up and matric suction thus decrease the risk of slope failure GRAPHICAL ABSTRACT

Anthropogenic Impacts on the Water Cycle over Drylands in the Northern Hemisphere

Abstract The effects of anthropogenic factors on the water cycle in drylands of the Northern Hemisphere (NH) are unclear. Here, we used the Community Earth System Model (CESM2.1.0) to quantify the influences of greenhouse gases (GHGs) and anthropogenic aerosols (AAs) on the water cycle and precipitation recycling rate (PRR) over drylands from 1980 to 2014. The corresponding mechanisms are also revealed in this study. The results show that GHGs can intensify the water cycle over drylands by increasing precipitation (P; 0.023 mm day−1) and evapotranspiration (ET; 0.037 mm day−1). Consequently, the negative P − ET (−0.014 mm day−1) is induced because infiltration (I; −0.014 mm day−1) and total water storage (S; −0.011 mm day−1) are decreased, implying a loss of soil water. The PRR is reduced by approximately −0.18% because of the GHG-induced extra water vapor export, which originated from ET. In contrast, AAs can weaken the water cycle over drylands by decreasing P (−0.03 mm day−1) and ET (−0.039 mm day−1). Correspondingly, positive P − ET (0.009 mm day−1) is induced, reflecting an input of soil water. Because of the AA-induced persistent ET from a wetter land and the reduced export water vapor from ET, the PRR increases by approximately 0.15%. Mechanistically, GHGs and AAs can affect the water cycle over drylands by perturbing the descending branches of Hadley circulation in midlatitude regions. Quantifying the climate effects of GHGs and AAs on the regional water cycle improves our understanding of the regional water cycle; the results of this study could also be conducive to the climate predictions for drylands.

Submarine discharge of underground waters: research experience, еxploration practices, methods and technologies for possible use

In view of the need to solve problems related to the population's access to sufficient drinking water, the search for submarine discharge zones is currently the most important economic task. Infiltration waters generated within the land, being filtered through bottom sediments, are directed to the seas and oceans and are irretrievably lost for practical use. According to numerous data on the dynamics of underground water supply systems, the movement of underground flows in coastal areas under undisturbed conditions is always directed towards the sea, where discharge is carried out. Infiltration waters flowing from the land to the seabed are predominantly distributed in the shelf zone, but under favorable conditions (tectonic disturbances, paleo-river beds, etc.) their flows can reach the continental slope, so significant areas of the ocean shelf deserve to be explored for fresh and slightly salty, brackish water. In some countries, they are already used to provide water supply. The article assesses the feasibility of practical use of subaquatic waters using specific examples. It analyzes hydrogeological potential, economic factors, and presents technical concepts for water intake, transportation, and treatment. Based on these factors, we are analyzing the possibility of replacing the seawater desalination process with its extraction from submarine underground horizons on the shelf. The article provides a comparative assessment of energy consumption obtained from fossil fuels in the process of seawater desalination and its extraction from underwater horizons. The material presented in the article shows that there are no insurmountable obstacles to the use of submarine discharge waters as an additional source of drinking water.

Scientific and methodological substantiation of measures for environmental management of upstream area Tupolangsky waterworks

For the 8.2 hectares of the Tupolang hydroscheme near the dam, the measures for its landscaping with the help of a drip irrigation system have been developed. The source of irrigation is infiltration water from the old riverbed. After natural filtration, the water is clear, without mechanical impurities, with a salinity of 0.2 g/l and a flow rate of about 50 l/s. At the end of this pipe, the head is 4 MPa, which eliminates the traditional device of the pumping station to create the required head in a closed irrigation network. This allows the application of these irrigation systems without a pumping station and water treatment. The article presents the initial data for the calculation of drip irrigation: 1. Soils are typical gray soils, non-saline, medium loam by mechanical composition; 2. Groundwaters are at a depth of &gt; 3 m; 3. Mass volume of soils is 1.4 t/m3; 4. Marginal field moisture capacity (MWC) - 28 %; 5. Ultimate moisture capacity is accepted at 85 % of FWP and makes 23.8 %. And most importantly, such irrigation saves water resources.

Impact of Forestry Interventions on Groundwater Recharge and Sediment Control in the Ganga River Basin

Water related services of natural infrastructure will help to combat the risk of water crisis, and nature-based solutions involve the management of ecosystems to mimic or optimize the natural processes for the provision and regulation of water. Forested areas provide environmental stability and supply a high proportion of the world’s accessible freshwater for domestic, agricultural, industrial and ecological needs. The present work on “Forestry Interventions for Ganga” to rejuvenate the river is one of the steps toward the Ganga River rejuvenation programme in the country. The consequences of forestry interventions for Ganga will be determined on the basis of water quantity and water quality in the Ganga River. The study conservatively estimated the water savings and sedimentation reduction of the riverscape management in the Ganga basin using the Soil Conservation Service Curve Number (SCS-CN) & GEC, 2015 and Trimble, 1999 & CWC, 2019 methodologies, respectively. Forestry plantations and soil and moisture conservation measures devised in the programme to rejuvenate the Ganga River are expected to increase water recharge and decrease sedimentation load by 231.011 MCM·yr-1 and 1119.6 cubic m·yr-1 or 395.20 tons·yr-1, respectively, in delineated riverscape area of 83,946 km2 in Ganga basin due to these interventions. The role of trees and forests in improving hydrologic cycles, soil infiltration and ground water recharge in Ganga basin seems to be the reason for this change. Forest plantations and other bioengineering techniques can help to keep rivers perennial, increase precipitation, prevent soil erosion and mitigate floods, drought & climate change. The bioengineering techniques could be a feasible tool to enhance rivers’ self-purification as well as to make river perennial. The results will give momentum to the National Mission of Clean Ganga (NMCG) and its Namami Gange programme including other important rivers in the country and provide inputs in understanding the linkages among forest structure, function, and streamflow.

Grazing management under integrated crop-livestock system on physical soil attributes and grain yield soybean

Integrated crop-livestock system (ICLS) can help improve the soil physical attributes, increasing the nutrients cycling and yield potential. We evaluated the effect of forage height management under ICLS on physical soil attributes and water infiltration. Field experiment was carried out for two consecutive years in a randomized complete block design, with three repetitions. Forage was managed under continuous grazing, grazing up to 30 cm (G30), 20 cm (G20) and 10 cm (G10) of height, and control without grazing. Soil bulk density (SBD), microporosity (MIP), macroporosity (MAP), and total porosity (TP) were measured before and after the grazing at 0-5; 5-10 and 10-20 cm layer depth. Water infiltration rate was evaluated using the concentric rings in eight periods (5, 10, 15, 20, 30, 60, 90 e 120 min after beginning of the process). SBD at 0-5 cm layer was not affected by the grazing management, whereas the MIP, MAP, and TP reduced after sheep grazing compared to ungrazed. Water infiltration rate was higher for the G10 management, with greater amount of accumulated infiltrated water. Path analysis showed positive effects of the soil physical attributes under ICLS to the grain yield soybean, allowing the farmers to enhance their profitability.

Response of Permeable Pavement under Wheel Truck to Rainfall Runoff and its Effects (Laboratory Model)

Good water drainage from different sources is one of the most important factors that must be considered when designing subways and highways. The research aims to study and analyze the effect of heavy, medium, and low rainfall, select suitable materials to drain rainwater from the surface and vertical drains, and evaluate the rutting that appeared on the compacted surface asphalt layer. The methodology of this research includes the laboratory model (prototype model). A laboratory model consisting of typical structure layers of flexible pavement was used in this research with a 2% slope for degradations and changes in the volumetric properties and permeability of the surface and binder layers of the highway section. A wheel truck was manufactured and used for a continuous go-and-forth with the influence of three different rain intensities to identify and simulate the actual situation of highways and roads. The rainfall duration of 30 mm/min rainfall intensity was 90 minutes, and the rain intensity of 60 mm/min had a rainfall duration of 60 minutes. For the rainfall intensity of 90 mm/min, the time of rainfall was equal to 30 minutes. The results obtained from the laboratory simulation model (box model) indicated that the average quantity of infiltrated water produced by the 30mm/min rainfall intensity in the pavement structure is 36.4 % greater than the average infiltration of this water from the 60mm/min intensity and 52% higher than the 90mm/min intensity of rain. The time of surface drainage ending and the ending time of vertical drainage increases when the rain duration is long, even if the rain intensity is low. The rut depth appeared after 2816 wheel load repetitions to increase this depth by 96% after 127 days of load passage under three different rainfall intensities of a different time. The tensile strength was significantly reduced by 17.25%. The TSR values indicate that the mixtures of the surface and binder layers have good resistance to moisture damage.

Modeling the content of chloroform in drinking water infiltration intake by periods of the annual cycle: low-water and permanent watercourse

The results of a study to find a relationship between the chloroform content in drinking water and the parameters characterizing water quality over an eighteen-year period of the infiltration water intake operation are presented. To increase the reliability of the model, the annual cycle is divided into two periods: an extended flood, including four months (April - June) and a period of low water and permanent watercourse, including eight months (August - March). Three time series were formed from the initial data: from the monthly average values of the parameters for the entire observation period; as a result of averaging the parameter values corresponding to each year; average values characterizing the low-water period and permanent watercourse for the entire observation period. It was found that the period of low water and permanent watercourse can be described by regression equations characterized by a smaller value of the average approximation error and a large value of the correlation coefficient. It was revealed that April introduces a significant stochasticity in the annual period. It is shown that the results obtained can be used to assess the value of the chloroform content in drinking water.

Моделирование процесса инфильтрации грунтовых вод в самотечные трубопроводы с использованием программного комплекса ANSYS CFX

The article is devoted to the development of models of groundwater infiltration processes into sewer pipelines using the ANSYS CFX program. Using the finite element method, the program allows implementing a simulation of the filtration process through a slit hole in the pipeline wall. Various cases of the location of the hole and the inflow of groundwater to it are regarded, as well as possible options for setting the porous domain. The models obtained make it possible to visualize the process of groundwater inflow, evaluate quantitative indicators of the inflow of infiltration waters into drainage systems, and assess the speeds and flow rates of the infiltered liquid.

Numerical Evaluation of Slope Stability based on Temporal Variation of Hydraulic Conductivity

Slope failure is a common phenomenon all over the world on both man-made and natural slopes. Prolonged rainfall is one of the climatic factors which is largely responsible for slope failure. During heavy and prolonged rainfall, a part of the rainwater infiltrates through the soil and seeps into the slope. The infiltrated water lowers the matric suction and increases the porewater pressure. Eventually, the generated porewater pressure decreases the strength of the soil which results in slope failures. To evaluate the effect of rainwater seepage on slope stability, it is necessary to investigate the hydraulic conductivity of the slope soil. The objective of this study is to evaluate the effect of hydraulic conductivity on slope failure mechanisms. A finite element analysis of slope stability was conducted using Geo-Studio software. A numerical model was developed and calibrated with field monitoring data. The field monitoring data included the observation of hydraulic conductivity using a Guelph Permeameter. Afterward, the temporal variation of rainfall and hydraulic conductivity was incorporated into the SEEP/W program and the consequent changes in slope stability were evaluated in SLOPE/W. From the numerical analysis, with the identical strength parameters of the soil, different factors of safety were observed when the slope sections retain different hydraulic properties. Based on the numerical analysis, it was observed that hydraulic conductivity greater than 4×10-6 cm/s leads to slope failure. Periodic monitoring of hydraulic conductivity in the field may provide deep insight into rainfall-induced slope failures.