The Significance of Grain Size and Pore Water Content for the Interstitial Fauna of Sandy Beaches

Oikos ◽  
1967 ◽  
Vol 18 (2) ◽  
pp. 311 ◽  
Author(s):  
Bengt-Owe Jansson
Keyword(s):  
Grain Size ◽  
Water Content ◽  
Pore Water ◽  
Sandy Beaches ◽  
Interstitial Fauna

A new approach to the stability analysis of thawing slopes

1980 ◽  
Vol 17 (4) ◽  
pp. 607-612 ◽  
Author(s):  
Luis E. Vallejo
Keyword(s):  
Stability Analysis ◽  
Water Content ◽  
Pore Water ◽  
Active Layer ◽  
Necessary Conditions ◽  
Mass Movements ◽  
New Approach ◽  
Pore Water Pressures ◽  
The Stability ◽  
Excess Pore

A new approach to the stability analysis of thawing slopes at shallow depths, taking into consideration their structure (this being a mixture of hard crumbs of soil and a fluid matrix), is presented. The new approach explains shallow mass movements such as skin flows and tongues of bimodal flows, which usually take place on very low slope inclinations independently of excess pore water pressures or increased water content in the active layer, which are necessary conditions in the methods available to date to explain these movements.

scholarly journals Snow dielectric properties: from DC to microwave X-band

1994 ◽  
Vol 19 ◽  
pp. 92-96 ◽  
Author(s):  
TH. Achammer ◽  
A. Denoth
Keyword(s):  
Grain Size ◽  
Dielectric Properties ◽  
Water Content ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Frequency Range ◽  
Snow Density ◽  
Cold Room ◽  
X Band ◽  
Grain Size And Shape

Broadband measurements of dielectric properties of natural snow samples near or at 0°C are reported. Measurement quantities are: dielectric permittivity, loss factor and complex propagation factor for electromagnetic waves. X-band measurements were made in a cold room in the laboratory; measurements at low and intermediate frequencies were carried out both in the field (Stubai Alps, 3300 m; Hafelekar near Innsbruck, 2100 m) and in the cold room. Results show that in the different frequency ranges the relative effect on snow dielectric properties of the parameters: density, grain-size and shape, liquid water content, shape and distribution of liquid inclusions and content of impurities, varies significantly. In the low-frequency range the influence of grain-size and shape and snow density dominates; in the medium-frequency range liquid water content and density are the dominant parameters. In the microwave X-band the influence of the amount, shape and distribution of liquid inclusions and snow density is more important than that of the remaining parameters.

scholarly journals Field Test Research on Red Clay Slope under Atmospheric Action

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Kaisheng Chen
Keyword(s):  
Internal Friction ◽  
Water Content ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Red Clay ◽  
Failure Characteristics ◽  
Clay Slopes

By embedding water content sensors and pore water pressure sensors inside the red clay slope on-site in Guiyang, Guizhou, shear tests were performed on soil samples at different depths of the slope under different weather. The changes of water content, pore water pressure, and shear strength index of the slope inside the slope under the influence of the atmosphere were tracked and tested, and the failure characteristics and evolution of the red clay slope were analyzed. It is believed that the depth of influence of the atmosphere on red clay slopes is about 0.7 m, rainfall is the most direct climatic factor leading to the instability of red clay slopes, and the evaporation effect is an important prerequisite for the catastrophe of red clay slopes. The cohesion and internal friction angle of the slope soil have a good binary quadratic function relationship with the water content and density. The water content and density can be used to calculate the cohesion and internal friction angle. Failure characteristics of red clay slopes: the overall instability failure is less, mainly surface failure represented by gullies and weathering and spalling, and then gradually evolved into shallow instability failure represented by collapse and slump. The damage evolution law is as follows: splash corrosion and surface corrosion stage⟶ fracture development stage⟶ gully formation stage⟶ gully development through stage⟶ local collapse stage⟶ slope foot collapse stage.

Environmental effects on the structure of polychaete feeding guilds on the beaches of Sepetiba Bay, south-eastern Brazil

2012 ◽  
Vol 93 (4) ◽  
pp. 973-980 ◽  
Author(s):  
Gustavo Mattos ◽  
Ricardo S. Cardoso ◽  
André Souza Dos Santos
Keyword(s):  
Grain Size ◽  
Sandy Beach ◽  
Sandy Beaches ◽  
Feeding Guilds ◽  
Feeding Guild ◽  
Beach Sediment ◽  
Sepetiba Bay ◽  
Importance Index ◽  
Eastern Brazil ◽  
Macrofauna Communities

Several studies have been conducted to explain patterns of the abundance, richness and diversity of sandy-beach macrofauna; however, such analyses have ignored the overall functional structure of macrofauna communities. Few studies have examined polychaete feeding guilds on sandy beach environments. To examine the effects of environmental factors on polychaete feeding guilds on sandy beaches, 12 sandy beaches from five islands in Sepetiba Bay were sampled. A total of 24 polychaete morphospecies, grouped among 21 families, were identified in these sandy beaches. The polychaete species were classified into 10 feeding guilds, and the SDT guild (suspended-deposit feeders, discretely motile, with tentacles) was the most abundant feeding guild, with 34.2% of total number of organisms. The highest trophic importance index and index of trophic diversity values were recorded on the sheltered beaches. A canonical correspondence analysis showed that the exposure rate, beach length, and grain size of the beach sediment significantly affected the polychaete feeding guild distribution and abundance. We can conclude that sheltered beaches have a higher diversity of feeding guilds than exposed beaches and that the biological descriptors of the feeding guilds are directly associated with the grain size of the sediment.

scholarly journals Physical Processes in Temperate Glaciers

1976 ◽  
Vol 16 (74) ◽  
pp. 151-158 ◽  
Author(s):  
L. Lliboutry
Keyword(s):  
Grain Size ◽  
Liquid Phase ◽  
Water Content ◽  
Past History ◽  
Salt Content ◽  
Physical Processes ◽  
The Past ◽  
Glacier Ice ◽  
History Of

AbstractIn a temperate glacier ice the water content results from the past history of the ice, and the temperature adjusts itself to the appropriate value. Results obtained by the Laboratoire de Glaciologie are summarized. Several facts seem to prove some migration of the liquid phase and a coalescence of liquid inclusions. The enthalpy flux is calculated, but it cannot be proved that a spontaneous gathering together of liquid inclusions could occur. The water-rich, small grain-size layers should come from the lowering of the viscosity when the water content increases, as discovered by Duval. The form of Weertman’s sliding law without cavitation can be derived from simple dimensional considerations. Numerically, it cannot account for high sliding velocities, for which subglacial cavitation must be introduced. The cavities are infilled with more stagnant regelation ice than water. Two subglacial hydraulic regimes are distinguished: autonomous and interconnected. The effect which the salt content may have on cavitation is estimated.

scholarly journals Integrated Geological, Hydrogeological, and Geophysical Investigations of a Barchan Sand Dune in the Eastern Region of Saudi Arabia

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 682
Author(s):  
Mohammed Benaafi ◽  
Sherif M. Hanafy ◽  
Abdullatif Al-Shuhail ◽  
Ammar El-Husseiny ◽  
Jack Dvorkin
Keyword(s):  
Grain Size ◽  
Saudi Arabia ◽  
Water Content ◽  
Sand Dune ◽  
Sand Dunes ◽  
Homogeneous Medium ◽  
Eastern Region ◽  
Large Area ◽  
Electrical Resistivity Survey ◽  
Dune Crest

In arid countries such as Saudi Arabia, aeolian sand often covers a large area of the country. Understanding the variations of sand properties in dunes, including grain size, sorting, mineral composition and water content, can be important for groundwater recharge, environmental, and construction applications. Earlier studies examined properties of sand dunes by collecting samples from the surface. This study aims to investigate variations of sand properties within a Barchan sand dune in the coastal area of Saudi Arabia, by collecting samples and measurements from two vertically drilled boreholes up to the ground water level; one drilled in the dune crest and another one in the limb. Representative samples were collected and analyzed for their texture parameters, water content, and mineralogy. Electrical resistivity survey data was also acquired to map water content variation in the dune limb, and for comparison with well bore data. The reported results show no vertical variations in grain size or sorting in the dune crest. In contrast, the upper 0.5 m of the dune limb shows a relatively poorer sorting than found in deeper parts of the dune. Laterally, no variations in minerology were observed between crest and limb sands while grain size tended to be slightly coarser in the dune limb compared to the crest. Regarding the water content, it was found to vary vertically, probably due to previous cycles of rainfall infiltration through the sand body. Such observed variation in water content is consistent with the measured resistivity profile which could clearly identify the water table and areas with higher water content. This study concludes that beyond the upper 0.5 m, the Barchan sand dune body can be treated as a homogeneous medium in terms of mineralogy and sorting while grain size increases slightly toward the limb side.

Aspects of the behaviour of compacted clayey soils on drying and wetting paths

2002 ◽  
Vol 39 (6) ◽  
pp. 1341-1357 ◽  
Author(s):  
Jean-Marie Fleureau ◽  
Jean-Claude Verbrugge ◽  
Pedro J Huergo ◽  
António Gomes Correia ◽  
Siba Kheirbek-Saoud
Keyword(s):  
Water Content ◽  
Pore Water ◽  
Unsaturated Soils ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Dry Density ◽  
Clayey Soils ◽  
Maximum Dry Density ◽  
Optimum Water Content ◽  
Optimum Water

A relatively large number of drying and wetting tests have been performed on clayey soils compacted at the standard or modified Proctor optimum water content and maximum density and compared with tests on normally consolidated or overconsolidated soils. The results show that drying and wetting paths on compacted soils are fairly linear and reversible in the void ratio or water content versus negative pore-water pressure planes. On the wet side of the optimum, the wetting paths are independent of the compaction water content and can be approached by compaction tests with measurement of the negative pore-water pressure. Correlations have been established between the liquid limit of the soils and such properties as the optimum water content and negative pore-water pressure, the maximum dry density, and the swelling or drying index. Although based on a limited number of tests, these correlations provide a fairly good basis to model the drying–wetting paths when all the necessary data are not available.Key words: compaction, unsaturated soils, clays, drying, wetting, Proctor conditions.

scholarly journals Temporal isotope changes in wet snow layers in association with mass exchange between snow particles and liquid water in between the particles

2005 ◽  
Vol 40 ◽  
pp. 128-132 ◽  
Author(s):  
S. Hashimoto ◽  
S. Zhou ◽  
M. Nakawo ◽  
M. Shimizu ◽  
N. Ishikawa
Keyword(s):  
Melting Point ◽  
Water Content ◽  
Pore Water ◽  
Mass Exchange ◽  
Liquid Water ◽  
Closed System ◽  
Temporal Change ◽  
Field Observations ◽  
Isotope Concentration ◽  
Wet Snow

AbstractWe carried out snow-pit observations at Nagaoka, Niigata prefecture, Japan, where the snow layers were at the melting point. It was observed that the water content in the snowpack was nearly constant at approximately 10%, and the coarsening rate of snow particles was about 0.4×10–3mm3 h–1, which was in the range between the rate for dry snow and that for snow soaked in water. The isotope change of snow particles by melting and freezing in a closed system under isothermal conditions at 0˚C was modeled. The temporal change in isotope concentration was calculated for wet snow layers, based on the fractionation between snow particles and liquid water in between the particles, in association with the coarsening of snow particles. The results compared well with field observations. These results suggest that the isotope concentration of the pore water that flows downward from the surface contributed significantly to the isotope change of snow particles.

Sign in / Sign up

Export Citation Format

Share Document