Porosity plays a clearly important role in geology. It controls fluid storage in aquifers, oil and gas fields and geothermal systems, and the extent and connectivity of the pore structure control fluid flow and transport through geological formations, as well as the relationship between the properties of individual minerals and the bulk properties of the rock. In order to quantify the relationships between porosity, storage, transport and rock properties, however, the pore structure must be measured and quantitatively described. The overall importance of porosity, at least with respect to the use of rocks as building stone was recognized by TS Hunt in his “Chemical and Geological Essays” (1875, reviewed by JD Dana 1875) who noted:

> “Other things being equal, it may properly be said that the value of a stone for building purposes is inversely as its porosity or absorbing power.”

In a Geological Survey report prepared for the U.S. Atomic Energy Commission, Manger (1963) summarized porosity and bulk density measurements for sedimentary rocks. He tabulated more than 900 items of porosity and bulk density data for sedimentary rocks with up to 2,109 porosity determinations per item. Amongst these he summarized several early studies, including those of Schwarz (1870–1871), Cook (1878), Wheeler (1896), Buckley (1898), Gary (1898), Moore (1904), Fuller (1906), Sorby (1908), Hirschwald (1912), Grubenmann et al. (1915), and Kessler (1919), many of which were concerned with rocks and clays of commercial utility. There have, of course, been many more such determinations since that time.

There are a large number of methods for quantifying porosity, and an increasingly complex idea of what it means to do so. Manger (1963) listed the techniques by which the porosity determinations he summarized were made. He separated these into seven methods for …

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Characterization and Analysis of Porosity and Pore Structures

Soil structure as an indicator of soil functions: A review

Drop impact onto surfaces has long been a popular and important subject of experimental, numerical and theoretical studies to explain phenomena observed both in nature and in many engineering applications. Progress in understanding and describing the hydrodynamics involved in drop impacts has been rapid in recent years, due partly to the availability of high-speed cameras, but also because of accompanying advances in theoretical and numerical approaches. Thus, for simple surfaces, i.e. smooth surfaces of uniform chemistry, the outcome of a drop impact can be well predicted over a large range of impact parameters, including quantitative values of spread dynamics and splash characteristics. This article comprehensively reviews the present level of understanding for such impact situations. However many practical applications involve impacts onto surfaces of higher complexity, either morphologically or chemically, involving textured or porous surfaces or surfaces with non-uniform wettability characteristics. This expands greatly the parameter space for which descriptions of the impact must be found and the present understanding is significantly more rudimentary compared to drop impacts onto simple surfaces. In this review such impacts are discussed by considering effects introduced by morphological changes to the surface and by changes of the wettability. Comparisons to corresponding impacts onto simple surfaces are drawn to underline the additional physical mechanisms that must be considered.

Drop collisions with simple and complex surfaces

Severe soil erosion challenges exist in China as a result of long-term human related activities and its erosion-prone land forms and climate. Anthropogenic forces that alter the physical landscape ...

https://tandfonline.com/doi/pdf/10.1080/24749508.2017.1301053

Impact of soil erosion and degradation on water quality: a review

Comparisons of pore size distribution: A case from the Western Australian gas shale formations

Characterizing anisotropy and heterogeneity of soil surface microtopography using fractal models

The spatial variability of mechanical resistance to penetration (PR) and gravimetric moisture (GM) was studied at a depth of 0-0.40 m, in a ferralsol cropped with corn, and under conventional tillage in Ilha Solteira, Brazil (latitude 20°17′S, and longitude 52°25′W). The purpose of this study was to analyse and to try explaining the spatial variability of the mentioned soil physical properties using geostatistics. Soil data was collected at points arranged on the nodes of a mesh with 97 points. Geostatistics was used to analyse the spatial variability of PR and GM at four depths: 0-0.1, 0.1-0.2, 0.2-0.3 and 0.3-0.4 m. PR showed a higher variability of data, with coefficients of variation of 52.39, 30.54, 16.91, and 15.18%, from the surface layers to the deepest layers. The values of the coefficients of variation for GM were lower: 9.99, 5.13, 5.59, and 5.69%. Correlation between GM and PR for the same soil layers was low. Penetration resistance showed spatial structure only in the 0.30-0.40 m layer, while gravimetric moisture showed spatial structure at all depths except for 0-0.10 m. All the models of fitted semivariograms were spherical and exponential, with ranges of 10-80 m. Data for the variable 'GM' in the 0.20-0.30 and 0.30-0.40 m layers revealed a trend in data attributed to the occurrence of subsurface water flow. © 2005 Elsevier B.V. All rights reserved.

Spatial variability of soil water content and mechanical resistance of Brazilian ferralsol

Multifractal characterization of saprolite particle-size distributions after topsoil removal

Rainfall changes the physical state, pore system geometry, and structure of soils. Characterization of the soil pore system provides a realistic base to understand the retention and movement of water in soil. The objective of this work was to estimate multifractal parameters from Hg injection porosimetry data on the uppermost soil surface layer as affected by simulated rainfall. Soil aggregates were sampled at the 0- to 2-cm depth in a loamy soil, both on a recently tilled soil surface and on its disturbed counterpart after 260-mm cumulative rainfall. Pore size distributions (PSDs) were determined by Hg intrusion porosimetry from 0.005- to about 100-μm pore diameters on 10 samples per surface stage. The rainfall reduced aggregate pore volume, showing significant differences between the pore space of the reference and the disturbed soil surfaces. A multifractal analysis was performed by means of scaling of the moments ranging from 10 < q < 10 for all PSDs. Mean values of the entropy dimension, D1, and correlation dimension, D 2, in the aggregate set sampled after rain disturbance were lower than those of the reference stage; however, mean values of the difference Δ(D1 - D2), the Holder exponent of order zero, α0, and widths of the left (α0 - αq+) and right (αq - α0) hand sides of the singularity spectra f(α) after rainfall action were higher than those of the initial soil surface. Entropy dimension, D1, and the width of the left (α0 αq+) hand side of the f(α) spectra best discriminated between PSDs of the reference initial soil surface vs. soil surface disturbed by rain.

E. Vidal Vázquez

Papers

Characterizing anisotropy and heterogeneity of soil surface microtopography using fractal models

Spatial variability of soil water content and mechanical resistance of Brazilian ferralsol

Multifractal characterization of saprolite particle-size distributions after topsoil removal

Multifractal analysis of pore size distributions as affected by simulated rainfall

Assessing soil particle-size distribution on experimental plots with similar texture under different management systems using multifractal parameters