Field investigation of a suction break designed to control slope-induced desaturation in an oxygen barrier

Covers with capillary barrier effects (CCBEs) can be used as oxygen barriers to limit gas flux into waste disposal sites. Laboratory and field measurements show that the hydraulic behaviour of such a layered cover system is influenced by its slope geometry and gravity drainage, which can result in local desaturation that may be detrimental to cover performance. Such desaturation can be minimized by placing a suction break in the moisture-retaining layer of the inclined cover. This novel approach was applied in the field to an existing inclined CCBE. The three-layer cover was then subjected to different boundary conditions to evaluate the influence of the suction break on hydraulic behaviour. Volumetric water content and suction measurements demonstrated that a zone of water saturation and low suction was created upslope of the suction break under natural climatic conditions. The hydrological behaviour close to the suction break was not significantly affected by a forced drought of 78 days (without water infiltration). The results also reveal that the suction break had a relatively limited upslope zone of influence (typically less than 10 m). The monitoring results are confirmed by geophysical measurements used to characterize water distribution in the inclined CCBE.

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Analyses of water diversion along inclined covers with capillary barrier effects

Canadian Geotechnical Journal ◽

10.1139/t09-050 ◽

2009 ◽

Vol 46 (10) ◽

pp. 1146-1164 ◽

Cited By ~ 51

Author(s):

M. Aubertin ◽

E. Cifuentes ◽

S. A. Apithy ◽

B. Bussière ◽

J. Molson ◽

...

Keyword(s):

Climatic Conditions ◽

Water Infiltration ◽

Water Diversion ◽

Key Factors ◽

Capillary Barrier ◽

Fine Grained ◽

Barrier Effects ◽

Fine Grained Soil ◽

Cover Systems ◽

Recharge Rates

Various types of cover systems can be used to control water infiltration into waste disposal sites. One promising option is to combine different types of soil to create a layered cover with capillary barrier effects (CCBE). A CCBE basically involves the placement of a relatively fine-grained soil, which acts as a water-retention layer, over a coarser capillary break material. On slopes, a CCBE promotes lateral water diversion. Inclined CCBEs, however, are relatively complex, as their behaviour is influenced by numerous factors. In this paper, the authors present the key results obtained from a numerical investigation into the response of steeply inclined CCBEs. The study evaluates the behaviour of covers under dry and humid climatic conditions. After a review of the physical processes and background studies, the paper presents simulation results that demonstrate the effect of key factors on the diversion length of covers, including layer thicknesses, material properties, and recharge rates. The results shown here indicate that increasing the thickness of the cover may improve its efficiency, but only up to a certain maximum beyond which the gain becomes minimal. These results should be of help to those involved in the design of inclined CCBEs.

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Sediment Transport and Water Flow Resistance in Alluvial River Channels: Modified Model of Transport of Non-Uniform Grain-Size Sediments

Water ◽

10.3390/w13152038 ◽

2021 ◽

Vol 13 (15) ◽

pp. 2038

Author(s):

Gennady Gladkov ◽

Michał Habel ◽

Zygmunt Babiński ◽

Pakhom Belyakov

Keyword(s):

Sediment Transport ◽

Water Flow ◽

Transport Model ◽

Flow Characteristics ◽

Field Measurements ◽

Field Investigation ◽

Empirical Modeling ◽

River Channels ◽

Channel Deformations ◽

East European

The paper presents recommendations for using the results obtained in sediment transport simulation and modeling of channel deformations in rivers. This work relates to the issues of empirical modeling of the water flow characteristics in natural riverbeds with a movable bottom (alluvial channels) which are extremely complex. The study shows that in the simulation of sediment transport and calculation of channel deformations in the rivers, it is expedient to use the calculation dependences of Chézy’s coefficient for assessing the roughness of the bottom sediment mixture, or the dependences of the form based on the field investigation data. Three models are most commonly used and based on the original formulas of Meyer-Peter and Müller (1948), Einstein (1950) and van Rijn (1984). This work deals with assessing the hydraulic resistance of the channel and improving the river sediment transport model in a simulation of riverbed transformation on the basis of previous research to verify it based on 296 field measurements on the Central-East European lowland rivers. The performed test calculations show that the modified van Rijn formula gives the best results from all the considered variants.

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Field Investigation and Rapid Deterioration Analysis of Heavy Haul Corrugation

Applied Sciences ◽

10.3390/app11146317 ◽

2021 ◽

Vol 11 (14) ◽

pp. 6317

Author(s):

Feng Jin ◽

Hong Xiao ◽

Mahantesh M Nadakatti ◽

Huiting Yue ◽

Wanting Liu

Keyword(s):

Finite Element Method ◽

Finite Element ◽

Fatigue Cracks ◽

Field Measurements ◽

Field Investigation ◽

The Finite Element Method ◽

Rail Corrugation ◽

Rapid Deterioration ◽

Heavy Haul

In this study, the rapid growth of corrugation caused by the bad quality of grinding works and their wavelength, depth, and evolution processes are captured through field measurements. The residual grinding marks left by poor grinding quality lead to further crack accumulation and corrugation deterioration by decreasing plastic resistance in rails. In this case, the average peak-to-peak values of corrugation grow extremely fast, reaching 1.4 μm per day. The finite element method (FEM) and fracture mechanics methodologies were used to analyze the development and trends in rail surface crack deterioration by considering rails with and without grinding marks. Crack propagation trends increase with residual grinding marks, and they are more severe in circular curve lines. To avoid the rapid deterioration of rail corrugation, intersections between grinding marks and fatigue cracks should be avoided.

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Measurement of unsaturated meltwater percolation flux in seasonal snowpack using self-potential

Journal of Glaciology ◽

10.1017/jog.2021.67 ◽

2021 ◽

pp. 1-16

Author(s):

Wilson S. Clayton

Keyword(s):

Method Development ◽

Water Saturation ◽

Field Measurements ◽

Time Domain Reflectometry ◽

Electrode Spacing ◽

Glacier Mass Balance ◽

Wetting Front ◽

Electrical Field Strength ◽

Water Redistribution ◽

Self Potential

Abstract This paper presents a feasibility study of in situ field measurements of unsaturated meltwater percolation flux within the vertical profile of a snowpack, using the self-potential (SP) method. On-site snowmelt column tests calibrated the SP measurements. The SP data measured electrical field strength with an electrode spacing of 20 cm, and coincident water saturation (Sw) measurements using time domain reflectometry allowed calculation of SP-modeled vertical percolation flux (qsp), expressed as Darcy velocity. The results reflected transient diurnal snowmelt dynamics, with peak flux lagging arrival of a saturation wetting front. Peak daily qsp was 60 to >300 mm d−1, whereas daily snowmelt was 20–50 mm w.e. Surface refreezing events appeared to cause upward flow, possibly representing water redistribution toward the freezing boundary. Calculated fluxes were comparable to actual fluxes, although average errors ranged from −15 to +46% compared to average of melt expected from surface energy-balance and ablation stake measurements. By advancing method development to measure unsaturated meltwater percolation flux in snowpacks this study creates opportunities to study fundamental snowmelt processes, may improve mathematical modeling and may supplement glacier mass-balance studies and studies of snowmelt interactions with avalanches, groundwater and surface water.

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Short-term velocity variations at three rock glaciers and their relationship with meteorological conditions

Earth Surface Dynamics ◽

10.5194/esurf-4-103-2016 ◽

2016 ◽

Vol 4 (1) ◽

pp. 103-123 ◽

Cited By ~ 35

Author(s):

V. Wirz ◽

S. Gruber ◽

R. S. Purves ◽

J. Beutel ◽

I. Gärtner-Roer ◽

...

Keyword(s):

Pore Water Pressure ◽

Water Pressure ◽

Ground Surface ◽

Climatic Conditions ◽

Water Infiltration ◽

High Temporal Resolution ◽

Rock Glacier ◽

Short Term ◽

Rock Glaciers ◽

Velocity Variations

Abstract. In recent years, strong variations in the speed of rock glaciers have been detected, raising questions about their stability under changing climatic conditions. In this study, we present continuous time series of surface velocities over 3 years of six GPS stations located on three rock glaciers in Switzerland. Intra-annual velocity variations are analysed in relation to local meteorological factors, such as precipitation, snow(melt), and air and ground surface temperatures. The main focus of this study lies on the abrupt velocity peaks, which have been detected at two steep and fast-moving rock glacier tongues ( ≥  5 m a−1), and relationships to external meteorological forcing are statistically tested.The continuous measurements with high temporal resolution allowed us to detect short-term velocity peaks, which occur outside cold winter conditions, at these two rock glacier tongues. Our measurements further revealed that all rock glaciers experience clear intra-annual variations in movement in which the timing and the amplitude is reasonably similar in individual years. The seasonal decrease in velocity was typically smooth, starting 1–3 months after the seasonal decrease in temperatures, and was stronger in years with colder temperatures in mid winter. Seasonal acceleration was mostly abrupt and rapid compared to the winter deceleration, always starting during the zero curtain period. We found a statistically significant relationship between the occurrence of short-term velocity peaks and water input from heavy precipitation or snowmelt, while no velocity peak could be attributed solely to high temperatures. The findings of this study further suggest that, in addition to the short-term velocity peaks, the seasonal acceleration is also influenced by water infiltration, causing thermal advection and an increase in pore water pressure. In contrast, the amount of deceleration in winter seems to be mainly controlled by winter temperatures.

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Estimation of energy dissipation in step-pool reaches of mountain river - a field investigation

10.22541/au.163769134.49556278/v1 ◽

2021 ◽

Author(s):

Abbas Torabizadeh ◽

Hamid-Reza Ghafouri ◽

Mohamadreza Majdzadehtabatabai ◽

Ahmad Tahershamsi

Keyword(s):

Energy Dissipation ◽

Field Measurements ◽

Step Length ◽

Field Investigation ◽

Mountain River ◽

Mountainous Areas ◽

Flow Conditions ◽

Effective Parameters ◽

Mountain Rivers ◽

Height Difference

The bed of the step-pool rivers is adapted to the flow conditions in terms of the topographic position and the steep slope of the path in such a way to dissipate the water energy, along the river. The beds of these rivers is sinusoidal like the meander rivers. However, as the river banks are mostly rocky in mountainous areas and the erosion in these areas is less, the bed fluctuation of these reaches is mainly vertical. When the water flow streams from the step crest into the pool, most of the water energy dissipates. In addition to the height difference, other factors contribute to the energy dissipation in the step pool reaches. The present study examines the energy dissipation by determining its effective factors, including step height (H), step length (L), hydraulic radius (R), sediment material diameter (d84), velocity in the step (V), etc. by field measurements in three reaches of mountain rivers. In the same vein, an equation is provided to estimate energy dissipation in the step pool reaches, by considering measurable effective parameters.

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METHODUCAL APPROACH AND ASSESSMENT OF NOISE IMPACT OF RAIL TRANSPORT ON THE BASIS OF THE USE OF RISK ASSESSMENT METHODOLOGY

Hygiene and Sanitation ◽

10.18821/0016-9900-2017-96-7-675-681 ◽

2019 ◽

Vol 96 (7) ◽

pp. 675-681 ◽

Cited By ~ 1

Author(s):

Olga I. Kopytenkova ◽

D. E. Kurepin ◽

K. B. Fridman ◽

E. B. Kuznetsova

Keyword(s):

Extreme Values ◽

Residential Buildings ◽

Traffic Noise ◽

Calculated Data ◽

Ground Surface ◽

Field Measurements ◽

Railway Transport ◽

Sound Levels ◽

Age Related ◽

Zone Of Influence

The paper presents the results of measurement, prediction and assessment of noise in the territory in the zone of the influence of the railway transport. The railway transport is established to be a source of excess acoustic impact on the environment within the area of sanitary break (100 m). The dependence of the change in noise levels from freight trains at a distance of 100 m from the source and up to 30 m from the ground surface was revealed. Equivalent sound levels in octave bands for the railway section of the model are calculated. Based on the results of field measurements and calculated data, the identification of indices of risk for adverse reactions in the population living in the zone of influence of the Railways was executed. The paper presents results of the calculation of the probability of occurrence of complaints on excessive noise and the likelihood of irritation at the noise, and the results of the calculation of risk indices of pathologies of the nervous and cardiovascular systems. The research made it possible to identify the regulatory documentation discrepancy in the definition of the health gap between the line source traffic noise and residential buildings. Field measurements and executed on their basis their modeling of the noise propagation (without obstacles) have shown that on the boundary of the regulatory sanitary protection zone (100m) in the congested section of the railway the noise level of 60-62 dBA is maintained. The risk of irritation to the noise and the likelihood of complaints is assessed as “acceptable”. The risk of pathology of the cardiovascular system is evaluated as “low”. At a distance of 50 m (65 dBA) with bearing in mind age-related changes after 70 years of exposure the risk reaches of extreme values - 0,935. Construction sites located less than 100 m from the railway were shown to fall into the zone of acoustic discomfort. There was substantiated the necessity of resolving differences in regulatory documentation by harmonizing sanitary and technical groups documents regulating methods of measurement, prediction and evaluation of sound levels on the territories in the zone of influence of the Railways.

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Transformations and nitrate sources in an agricultural watershed(Quanshui River, China): An investigation using hydrogeochemistry, isotopes, and a Bayesian model

10.5194/egusphere-egu21-3618 ◽

2021 ◽

Author(s):

Mingda Cao

Keyword(s):

Surface Water ◽

Bayesian Model ◽

Field Investigation ◽

Climatic Conditions ◽

Agricultural Watershed ◽

Agricultural Activities ◽

Transformation Mechanism ◽

Chemical Fertilizers ◽

Nitrate Sources ◽

The Difference

The spatiotemporal changes of nitrate in agricultural watersheds are of global concern. Although numerous studies have explained the source and transformation mechanism of nitrate in groundwater and surface water, the transformation mechanism in groundwater remains poorly understood because of different hydrogeological and climatic conditions. Based on a field investigation and sampling, this study revealed the sources and transformation mechanism of nitrogen in surface water and groundwater in a karst agricultural watershed by comprehensively using water chemistry data, isotope components, and a Bayesian model (simmr). The results indicated that:1)Local agricultural activities have controlled the changes of &#948;15N-NO3-, &#948;18O-NO3- and &#948;15N-NH4+ in groundwater. The difference is that the concentration of NO3- is significantly affected by rainfall. However, the contribution of rainfall to groundwater NO3- is relatively small (<9%), indicating that there is a dual influence mechanism of leaching in the watershed that controls the concentration of groundwater NO3-, while agricultural activities control its isotope changes;2)The study observed that after fertilization, due to the influence of ammonia volatilization and nitrification, &#948;15N-NO3-, &#948;18O-NO3- in groundwater showed a simultaneous decrease, while &#948;15N-NH4+ showed an increasing trend, which may be due to the result of incomplete nitration of NH4+ in the vadose zone;3)According to the calculation results of the simmr model, in the two main fertilization periods in October 2018 and April 2019, the contribution of chemical fertilizers to groundwater NO3-reached the peak value(65% and 69%), which is in line with the seasonal variations of &#948;15N-NO3-, &#948;18O-NO3-and &#948;15N-NH4+;4)The surface water in the watershed is mainly supplied by groundwater, and the contribution of chemical fertilizers to surface water NO3- is generally higher than that of groundwater. This may be caused by the drainage of rice fields containing chemical fertilizers into the river.

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Novel Approach to Estimate Water Saturation Behind Casing Using Carbon Oxygen Data: Challenges and a Case Study in Abu-Dhabi Onshore Reservoirs

10.2118/203433-ms ◽

2020 ◽

Author(s):

Ahmed S Abdel Aziz ◽

Fathy El Wazeer ◽

Richard Odom ◽

Sanjeev Malalur

Keyword(s):

Water Saturation ◽

Abu Dhabi ◽

Novel Approach

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Apparent Permeability Model for Gas Transport in Multiscale Shale Matrix Coupling Multiple Mechanisms

Energies ◽

10.3390/en13236323 ◽

2020 ◽

Vol 13 (23) ◽

pp. 6323

Author(s):

Xiaoping Li ◽

Shudong Liu ◽

Ji Li ◽

Xiaohua Tan ◽

Yilong Li ◽

...

Keyword(s):

Pore Size ◽

Water Distribution ◽

Gas Transport ◽

Water Saturation ◽

Gas Permeability ◽

Apparent Permeability ◽

Permeability Model ◽

Proposed Model ◽

Irreducible Water Saturation ◽

The Impact

Apparent gas permeability (AGP) is a significantly important parameter for productivity prediction and reservoir simulation. However, the influence of multiscale effect and irreducible water distribution on gas transport is neglected in most of the existing AGP models, which will overestimate gas transport capacity. Therefore, an AGP model coupling multiple mechanisms is established to investigate gas transport in multiscale shale matrix. First, AGP models of organic matrix (ORM) and inorganic matrix (IOM) have been developed respectively, and the AGP model for shale matrix is derived by coupling AGP models for two types of matrix. Multiple effects such as real gas effect, multiscale effect, porous deformation, irreducible water saturation and gas ab-/de-sorption are considered in the proposed model. Second, sensitive analysis indicates that pore size, pressure, porous deformation and irreducible water have significant impact on AGP. Finally, effective pore size distribution (PSD) and AGP under different water saturation of Balic shale sample are obtained based on proposed AGP model. Under comprehensive impact of multiple mechanisms, AGP of shale matrix exhibits shape of approximate “V” as pressure decrease. The presence of irreducible water leads to decrease of AGP. At low water saturation, irreducible water occupies small inorganic pores preferentially, and AGP decreases with small amplitude. The proposed model considers the impact of multiple mechanisms comprehensively, which is more suitable to the actual shale reservoir.

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