Evaluating the hydraulic conductivity at three different scales within an unconfined sand aquifer at Lachenaie, Quebec

2005 ◽  
Vol 42 (4) ◽  
pp. 1212-1220 ◽  
Author(s):  
Robert P Chapuis ◽  
Véronique Dallaire ◽  
Denis Marcotte ◽  
Michel Chouteau ◽  
Nelson Acevedo ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Scale Effect ◽  
Large Scale ◽  
Scale Effects ◽  
Pumping Test ◽  
Field Variable ◽  
Small Scale ◽  
Sand Aquifer ◽  
Variable Head ◽  
A Site

This paper presents the evaluation of scale effects for the hydraulic conductivity, k, of a sand. Data were obtained using several methods at a site that was densely instrumented with piezometers within an area of about 100 m × 100 m. The 3.1–3.6 m thick sand deposit rests on a thick, nonfissured Champlain Sea clay deposit. At the small scale, local k values were obtained from the grain-size curves of sand samples and also from ground-penetrating radar surveys. At the intermediate scale, k values were obtained from field variable-head tests using piezometers. At the large scale, k values were obtained from pumping-test drawdowns in steady-state conditions. In this sand aquifer, the careful evaluations at three scales gave similar narrow distributions for the hydraulic conductivity, and therefore no scale effect is evidenced.Key words: hydraulic conductivity, sand, scale effect, gradation, monitoring well, pumping.

scholarly journals Assessment of the heterogeneity of hydraulic properties in gravelly outwash plains: a regionally scaled sedimentological analysis in the Munich gravel plain, Germany

2020 ◽  
Vol 28 (8) ◽  
pp. 2657-2674
Author(s):  
Markus Theel ◽  
Peter Huggenberger ◽  
Kai Zosseder
Keyword(s):  
Spatial Distribution ◽  
Hydraulic Conductivity ◽  
Large Scale ◽  
Regional Scale ◽  
Pumping Test ◽  
Small Scale ◽  
Significant Heterogeneity ◽  
Conductivity Distribution ◽  
Braided Rivers ◽  
Sedimentary Deposits

AbstractThe favorable overall conditions for the utilization of groundwater in fluvioglacial aquifers are impacted by significant heterogeneity in the hydraulic conductivity, which is related to small-scale facies changes. Knowledge of the spatial distribution of hydraulically relevant hydrofacies types (HF-types), derived by sedimentological analysis, helps to determine the hydraulic conductivity distribution and thus contribute to understanding the hydraulic dynamics in fluvioglacial aquifers. In particular, the HF-type “open framework gravel (OW)”, which occurs with the HF-type “bimodal gravel (BM)” in BM/OW couplings, has an intrinsically high hydraulic conductivity and significantly impacts hydrogeological challenges such as planning excavation-pit drainage or the prognosis of plumes. The present study investigates the properties and spatial occurrence of HF-types in fluvioglacial deposits at regional scale to derive spatial distribution trends of HF-types, by analyzing 12 gravel pits in the Munich gravel plain (southern Germany) as analogues for outwash plains. The results are compared to the reevaluation of 542 pumping tests. Analysis of the HF-types and the pumping test data shows similar small-scale heterogeneities of the hydraulic conductivity, superimposing large-scale trends. High-permeability BM/OW couples and their dependence on recognizable discharge types in the sedimentary deposits explain sharp-bounded small-scale heterogeneities in the hydraulic conductivity distribution from 9.1 × 10−3 to 2.2 × 10−4 m/s. It is also shown that high values of hydraulic conductivity can be interpolated on shorter distance compared to lower values. While the results of the HF-analysis can be transferred to other fluvioglacial settings (e.g. braided rivers), regional trends must be examined with respect to the surrounding topography.

scholarly journals Micromechanical study of potential scale effects in small-scale modelling of sinker tree roots

2021 ◽  
Author(s):  
Xingyu Zhang ◽  
◽  
Matteo Ciantia ◽  
Jonathan Knappett ◽  
Anthony Leung ◽  
...  
Keyword(s):  
Particle Size ◽  
Large Scale ◽  
Scale Effects ◽  
Distinct Element ◽  
Scaling Law ◽  
Scale Model ◽  
Small Scale ◽  
Tree Roots ◽  
Scale Modelling ◽  
Element Method

When testing an 1:N geotechnical structure in the centrifuge, it is desirable to choose a large scale factor (N) that can fit the small-scale model in a model container and avoid unwanted boundary effects, however, this in turn may cause scale effects when the structure is overscaled. This is more significant when it comes to small-scale modelling of sinker root-soil interaction, where root-particle size ratio is much lower. In this study the Distinct Element Method (DEM) is used to investigate this problem. The sinker root of a model root system under axial loading was analysed, with both upward and downward behaviour compared with the Finite Element Method (FEM), where the soil is modelled as a continuum in which case particle-size effects are not taken into consideration. Based on the scaling law, with the same prototype scale and particle size distribution, different scale factors/g-levels were applied to quantify effects of the ratio of root diameter (𝑑𝑟) to mean particle size (𝐷50) on the root rootsoil interaction.

scholarly journals Tidal spaces: choreographies of remembrance and forgetting

2020 ◽  
pp. 147447402091890
Author(s):  
Laura Bissell
Keyword(s):  
United Kingdom ◽  
Large Scale ◽  
Collaborative Work ◽  
Small Scale ◽  
Personal Memory ◽  
Community Groups ◽  
Tidal Zone ◽  
Community Work ◽  
The United Kingdom ◽  
A Site

This article explores the potential of tidal spaces to perform acts of remembrance and forgetting. Using oceanographer Rachel Carson’s The Edge of the Sea to contextualise tidal spaces, this analysis will discuss how constantly shifting and eroding coastlines act as a site for writing, rewriting and performing acts of cultural and personal memory. The concept of tidal choreographies will be introduced via two contemporary works performed on shorelines: 14-18 NOW’s Pages of the Sea, a large-scale public memorial performed on multiple beaches across the United Kingdom on Remembrance Sunday 2018; and Chloe Smith’s Tidal, an intergenerational, participatory, community work which was performed on the shore at Berwick-upon-Tweed in 2015. I will offer reflections on my own collaborative work Tide Times created with Tim Cooper to explicate ideas of the potential of tidal spaces (in this case a tidal island) further. In explicating various artworks which explore ideas of remembrance using tidal spaces, this article will also acknowledge the forgetting that is implicit in performing these actions. The markings in the sand are washed away, community groups that participate in the performance disperse and detritus left is eroded by the elements. What can the legacy of commemorations traced in such a transient and precarious space as a tidal zone be? This article argues that while shorelines provide sites for large and small-scale acts of public remembering, they are simultaneously acts of forgetting as the twice-daily tides cause inevitable erasure.

Investigation on Size Effect of Cantilever Carbon Nanotube

2012 ◽  
Vol 586 ◽  
pp. 3-9
Author(s):  
Ying Jing Liang ◽  
Qiang Han
Keyword(s):  
Carbon Nanotube ◽  
Scale Effect ◽  
Scale Effects ◽  
Elastic Shell ◽  
Small Radius ◽  
Small Scale ◽  
Moment Theory ◽  
Concentrated Load ◽  
Small Scale Effect ◽  
Analytical Expressions

Nonlocal elastic shell model based on the semi-moment theory is developed and applied to investigate the small scale effect on the bending problem of the cantilever carbon nanotube (CNT) with a vertical concentrated load applied at its tip. The small-scale effect is taken into account and is incorporated in the formulation. Analytical expressions of the stress are derived for the nonlocal elastic bending problem. It is obvious to observe significant small-scale effects on the stress resultants. The smaller the radius is, the more obvious the scale effect appears. The numerical results show that the scale effect cannot be ignored for CNTs of small radius.

scholarly journals LARGE VERIFICATION TESTS ON ROCK SLOPE STABILITY

1988 ◽  
Vol 1 (21) ◽  
pp. 157
Author(s):  
J.W. Van der Meer ◽  
K.W. Pilarczyk
Keyword(s):  
Large Scale ◽  
Scale Effects ◽  
Rock Slope Stability ◽  
Small Scale ◽  
Rock Slopes ◽  
Ripple Formation ◽  
Scale Test ◽  
Gravel Beaches ◽  
The Stability ◽  
Large Scale Tests

A number of large scale tests on stability of rock slopes and gravel beaches is described and compared with small scale test results. The following topics are treated: the stability of a rock armour layer, the profile formation of a berm breakwater, the profile formation of gravel beaches, including ripple formation, and reflection and overtopping on rock slopes. The general conclusion is that scale effects could not be found.

scholarly journals SCALE EFFECT IN LABORATORY DETERMINATION OF THE PROPERTIES OF COMPLEX CARBONATE RESERVOIRS

2020 ◽  
Author(s):  
Kamensky IP ◽  
Sudad H Al-Obaidi ◽  
Khalaf FH
Keyword(s):  
Scale Effect ◽  
Large Scale ◽  
Scale Effects ◽  
Rock Properties ◽  
Flow Capacity ◽  
Core Study ◽  
Porosity And Permeability ◽  
Relationship Of ◽  
The Relationship

As it is well known that, formation porosity and permeability are fundamental rock properties. Porosity is a measure of the storage capacity of the rock and permeability is a measure of rock flow capacity. In this study the relationship of the scale effect with the features and type of the capacitive structure of complex reservoirs is shown. The characteristic conditions for the manifestation of large-scale effects in determining porosity and permeability are analyzed. Also in this work the influence of the scale effect on the representativeness of laboratory determinations of flow- storage capacitance (FSC) properties is shown. The relationship between the values of porosity and permeability with the object of the core study has been established.

scholarly journals Effects of clouds on the UV Absorbing Aerosol Index from TROPOMI

2020 ◽  
Vol 13 (12) ◽  
pp. 6407-6426
Author(s):  
Maurits L. Kooreman ◽  
Piet Stammes ◽  
Victor Trees ◽  
Maarten Sneep ◽  
L. Gijsbert Tilstra ◽  
...  
Keyword(s):  
Large Scale ◽  
Scale Effects ◽  
Cloud Model ◽  
Structural Features ◽  
Homogeneous Distribution ◽  
Small Scale ◽  
Retrieval Models ◽  
Cloud Models ◽  
Absorbing Aerosols ◽  
Aerosol Index

Abstract. The ultraviolet (UV) Absorbing Aerosol Index (AAI) is widely used as an indicator for the presence of absorbing aerosols in the atmosphere. Here we consider the TROPOMI AAI based on the 340 nm/380 nm wavelength pair. We investigate the effects of clouds on the AAI observed at small and large scales. The large-scale effects are studied using an aggregate of TROPOMI measurements over an area mostly devoid of absorbing aerosols (Pacific Ocean). The study reveals that several structural features can be distinguished in the AAI, such as the cloud bow, viewing zenith angle dependence, sunglint, and a previously unexplained increase in AAI values at extreme viewing and solar geometries. We explain these features in terms of the bidirectional reflectance distribution function (BRDF) of the scene in combination with the different ratios of diffuse and direct illumination of the surface at 340 and 380 nm. To reduce the dependency on the BRDF and homogenize the AAI distribution across the orbit, we present three different AAI retrieval models: the traditional Lambertian scene model (LSM), a Lambertian cloud model (LCM), and a scattering cloud model (SCM). We perform a model study to assess the propagation of errors in auxiliary databases used in the cloud models. The three models are then applied to the same low-aerosol region. Results show that using the LCM and SCM gives on average a higher AAI than the LSM. Additionally, a more homogeneous distribution is retrieved across the orbit. At the small scale, related to the high spatial resolution of TROPOMI, strong local increases and decreases in AAI are observed in the presence of clouds. The BRDF effect presented here is a first step – more research is needed to explain the small-scale cloud effects on the AAI.

scholarly journals Non-Repeatability, Scale- and Model Effects in Laboratory Measurement of Impact Loads Induced by an Overtopped Bore on a Dike Mounted Wall

2019 ◽  
Author(s):  
Maximilian Streicher ◽  
Andreas Kortenhaus ◽  
Corrado Altomare ◽  
Steven Hughes ◽  
Krasimir Marinov ◽  
...  
Keyword(s):  
Large Scale ◽  
Scale Effects ◽  
Vertical Wall ◽  
Scale Factor ◽  
Scale Model ◽  
Small Scale ◽  
Length Scale ◽  
Force Measurements ◽  
Impact Forces ◽  
Small Scale Model

Abstract Overtopping bore impact forces on a dike mounted vertical wall were measured in similar large-scale (Froude length scale factor 1-to-4.3) and small-scale (Froude length scale factor 1-to-25) models. The differences due to scale effects were studied, by comparing the up-scaled force measurements from both models in prototype. It was noted that if a minimum layer thickness, velocity of the overtopping flow and water depth at the dike toe were maintained in the small-scale model, the resulting differences in impact force due to scale effects are within the range of differences due to non-repeatability and model effects.

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