scholarly journals Characterization of stony soils' hydraulic conductivity using laboratory and numerical experiments

2015 ◽  
Vol 2 (2) ◽  
pp. 1103-1133
Author(s):  
M. Pichault ◽  
E. Beckers ◽  
A. Degré ◽  
S. Garré
Keyword(s):  
Hydraulic Conductivity ◽  
Water Flow ◽  
Numerical Experiments ◽  
Saturated Hydraulic Conductivity ◽  
Rock Fragments ◽  
Hydraulic Behaviour ◽  
Unsaturated Hydraulic Conductivity ◽  
The One ◽  
The Impact

Abstract. Determining soil hydraulic properties is of major concern in various fields of study. Though stony soils are widespread across the globe, most studies deal with gravel-free soils so that the literature describing the impact of stones on soil's hydraulic conductivity is still rather scarce. Most frequently, models characterizing the saturated hydraulic conductivity of stony soils assume that the only effect of rock fragments is to reduce the volume available for water flow and therefore they predict a decrease in hydraulic conductivity with an increasing stoniness. The objective of this study is to assess the effect of rock fragments on the saturated and unsaturated hydraulic conductivity. This was done by means of laboratory and numerical experiments involving different amounts and types of coarse fragments. We compared our results with values predicted by the aforementioned models. Our study suggests that considering that stones only reduce the volume available for water flow might be ill-founded. We pointed out several drivers of the saturated hydraulic conductivity of stony soils, not considered by these models. On the one hand, the shape and the size of inclusions may substantially affect the hydraulic conductivity. On the other hand, the presence of rock fragments can counteract and even overcome the effect of a reduced volume in some cases. We attribute this to the creation of voids at the fine earth-stone interface. Nevertheless, these differences are mainly important near to saturation. However, we come up with a more nuanced view regarding the validity of the models under unsaturated conditions. Indeed, under unsaturated conditions, the models seem to represent the hydraulic behaviour of stones reasonably well.

scholarly journals Characterization of stony soils' hydraulic conductivity using laboratory and numerical experiments

SOIL ◽  
2016 ◽  
Vol 2 (3) ◽  
pp. 421-431 ◽  
Author(s):  
Eléonore Beckers ◽  
Mathieu Pichault ◽  
Wanwisa Pansak ◽  
Aurore Degré ◽  
Sarah Garré
Keyword(s):  
Hydraulic Conductivity ◽  
Water Flow ◽  
Predictive Models ◽  
Laboratory Experiments ◽  
Saturated Hydraulic Conductivity ◽  
Experimental Conditions ◽  
Rock Fragments ◽  
Unsaturated Hydraulic Conductivity ◽  
The One ◽  
The Impact

Abstract. Determining soil hydraulic properties is of major concern in various fields of study. Although stony soils are widespread across the globe, most studies deal with gravel-free soils, so that the literature describing the impact of stones on the hydraulic conductivity of a soil is still rather scarce. Most frequently, models characterizing the saturated hydraulic conductivity of stony soils assume that the only effect of rock fragments is to reduce the volume available for water flow, and therefore they predict a decrease in hydraulic conductivity with an increasing stoniness. The objective of this study is to assess the effect of rock fragments on the saturated and unsaturated hydraulic conductivity. This was done by means of laboratory experiments and numerical simulations involving different amounts and types of coarse fragments. We compared our results with values predicted by the aforementioned predictive models. Our study suggests that it might be ill-founded to consider that stones only reduce the volume available for water flow. We pointed out several factors of the saturated hydraulic conductivity of stony soils that are not considered by these models. On the one hand, the shape and the size of inclusions may substantially affect the hydraulic conductivity. On the other hand, laboratory experiments show that an increasing stone content can counteract and even overcome the effect of a reduced volume in some cases: we observed an increase in saturated hydraulic conductivity with volume of inclusions. These differences are mainly important near to saturation. However, comparison of results from predictive models and our experiments in unsaturated conditions shows that models and data agree on a decrease in hydraulic conductivity with stone content, even though the experimental conditions did not allow testing for stone contents higher than 20 %.

scholarly journals Evolution of Hydraulic Conductivity of Unsaturated Compacted Na-Bentonite under Confined Condition—Including the Microstructure Effects

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 219
Author(s):  
Tian Chen ◽  
Mao Du ◽  
Qiangling Yao
Keyword(s):  
Hydraulic Conductivity ◽  
Network Evolution ◽  
Saturated Hydraulic Conductivity ◽  
Constitutive Relationship ◽  
Pore System ◽  
Compacted Bentonite ◽  
Hydraulic Behaviour ◽  
Unsaturated Hydraulic Conductivity ◽  
Microstructure Effects ◽  
Microstructure Effect

Compacted bentonite is envisaged as engineering buffer/backfill material in geological disposal for high-level radioactive waste. In particular, Na-bentonite is characterised by lower hydraulic conductivity and higher swelling competence and cation exchange capacity, compared with other clays. A solid understanding of the hydraulic behaviour of compacted bentonite remains challenging because of the microstructure expansion of the pore system over the confined wetting path. This work proposed a novel theoretical method of pore system evolution of compacted bentonite based on its stacked microstructure, including the dynamic transfer from micro to macro porosity. Furthermore, the Kozeny–Carman equation was revised to evaluate the saturated hydraulic conductivity of compacted bentonite, taking into account microstructure effects on key hydraulic parameters such as porosity, specific surface area and tortuosity. The results show that the prediction of the revised Kozeny–Carman model falls within the acceptable range of experimental saturated hydraulic conductivity. A new constitutive relationship of relative hydraulic conductivity was also developed by considering both the pore network evolution and suction. The proposed constitutive relationship well reveals that unsaturated hydraulic conductivity undergoes a decrease controlled by microstructure evolution before an increase dominated by dropping the gradient of suction during the wetting path, leading to a U-shaped relationship. The predictive outcomes of the new constitutive relationship show an excellent match with laboratory observation of unsaturated hydraulic conductivity for GMZ and MX80 bentonite over the entire wetting path, while the traditional approach overestimates the hydraulic conductivity without consideration of the microstructure effect.

scholarly journals The impact of different tillage treatments on hydraulic conductivity of loamy soil

2012 ◽  
Vol 60 (5) ◽  
pp. 109-114 ◽  
Author(s):  
Ivana Kameníčková ◽  
L. Larišová ◽  
A. Stoklásková
Keyword(s):  
Hydraulic Conductivity ◽  
Conventional Tillage ◽  
Saturated Hydraulic Conductivity ◽  
Water Infiltration ◽  
Reduced Tillage ◽  
Loamy Soil ◽  
Double Ring ◽  
Unsaturated Hydraulic Conductivity ◽  
The Impact

Water infiltration into the soil profile, surface runoff and soil erosion in arable lands depend on the conditions of the top layer. The tillage treatment of the top layer plays a key role in changes of the hydro-physical properties, mainly saturated hydraulic conductivity Ks of the surface layer. The aim of this study was to asses the impact of different tillage treatments on hydraulic conductivity in the locality Bohaté Málkovice. Field experimental works in this area were performed in 2009 and were repeted in 2011 on Haplic Chernozem, medium heavy loamy soil. The experimental area was divided into two parts; top layer of these plots was cultivated by applying conventional and reduced tillage treatment. Both these plots were sown with spring barley (Hordeum vulgare). For the field measurement of water infiltration into the soil was used double-ring infiltrometer (2009, 2011) and Minidisk infiltrometer (2011). Near the point were the infiltration was measured, the soil samples were always collected for laboratory determination of basic physical properties of soil (bulk density, porosity, initial and saturated water content, aeration of the soil) and saturated hydraulic conductivity Ks. For laboratory determination of Ks was used permeameter with constant gradient.For evaluation of saturated hydraulic conductivity Ks using the double-ring infiltration method was used Philip’s three-parameter equation and for evaluation of unsaturated hydraulic conductivity K(h) using Minidisk infiltrometer was used Zang’s method. After two years of using repeatedly applied different tillage treatments was significantly influenced saturated hydraulic conductivity Ks. The Ks value increased approximately six times for reduced tillage and more than three times for conventional tillage. Laboratory determined average values of Ks were compared with the average estimates of Ks from infiltration tests. The results were burdened by a number of errors (compaction, preferential flow). These mean values were higher for conventional and reduced tillage. Unsaturated hydraulic conductivity K(−2cm) for reduced tillage was higher, for conventional tillage decreased approximately three times.

scholarly journals Predicting the impact of biochar on the saturated hydraulic conductivity of natural and engineered media

2021 ◽  
Vol 295 ◽  
pp. 113143
Author(s):  
Yudi Yan ◽  
Seyyed Ali Akbar Nakhli ◽  
Jing Jin ◽  
Godfrey Mills ◽  
Clinton S. Willson ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Saturated Hydraulic Conductivity ◽  
The Impact

Gobernanza económica europea y modelo territorial de distribución del poder

2013 ◽  
pp. 153-191
Author(s):  
Ainhoa LASA LÓPEZ
Keyword(s):  
European Union ◽  
The European Union ◽  
European Level ◽  
Euro Pean ◽  
Economic Constitution ◽  
The One ◽  
The Impact ◽  
The Relationship ◽  
The Ideal

LABURPENA: Artikulu honetan, Europar Batasuneko botere-artikulazio berriak erkidegotan osatutako Espainian zer eragin daukan aztertuko dugu. Europa mailako politika-ekonomia erlazioak funtsezko bi koordenatu izan behar ditu ezinbestean. Alde batetik, Europako konstituzio-ordena ez dela gizartearen konstituzionalismoaren koordenatuetan ernatutako ordenaren berdina. Bestetik, Europako konstituzio ekonomikoa Europa bat egiteko proiektuak berarekin dakartzan aldaketa berriak gorpuzteko eremua dela. Izan ere, funtsean, Europako konstituzio ekonomikoa plataforma ezin hobea delako boterearen artikulazioa berria nola artikulatu asmatzeko, Europa guztirako. RESUMEN: el objetivo de este artículo es analizar el impacto que tiene la nueva articulación del poder en la Unión Europea en el Estado español de las autonomías. La relación política-economía a nivel europeo debe tener en cuenta dos coordenadas fundamentales. Por una parte, la consideración del orden constitucional europeo como un orden distinto al gestado bajo las coordenadas del constitucionalismo social. Por otra, la caracterización de la constitución económica europea como ámbito de materialización de las nuevas transformaciones que incorpora el proyecto de integración europeo. Fundamentalmente, porque la constitución económica europea representa la plataforma idónea desde la que dilucidar la nueva articulación del poder desde el espacio supranacional europeo. ABSTRACT: The aim of this paper is to analyse the impact of the new articula tion of power in the European Union in the Spanish state of autonomies. The relationship between politics and economy at European level must take into consideration two fundamental coordinates. On the one hand, the Euro pean constitucional system appears as a system opposite to that of social constitutionalism. Moreover, the characterization of the European economic constitution as a field of realization of the new transformations incorporated by the European project. Specially, because this represents the ideal platform in order to analyse the new articulation of power from European supranational space.

Unsaturated hydraulic conductivity in limestone dolines: Influence of vegetation and rock fragments

Geoderma ◽  
2008 ◽  
Vol 145 (3-4) ◽  
pp. 288-294 ◽  
Author(s):  
Xiao-Yan Li ◽  
Sergio Contreras ◽  
Albert Solé-Benet
Keyword(s):  
Hydraulic Conductivity ◽  
Rock Fragments ◽  
Unsaturated Hydraulic Conductivity

Historical development of soil-water physics and solute transport in porous media

2007 ◽  
Vol 7 (1) ◽  
pp. 59-66 ◽  
Author(s):  
D.E. Rolston
Keyword(s):  
Porous Media ◽  
Hydraulic Conductivity ◽  
Solute Transport ◽  
Soil Water ◽  
20Th Century ◽  
Water Flow ◽  
Unsaturated Soils ◽  
Transport Processes ◽  
Transport In Porous Media ◽  
Unsaturated Hydraulic Conductivity

The science of soil-water physics and contaminant transport in porous media began a little more than a century ago. The first equation to quantify the flow of water is attributed to Darcy. The next major development for unsaturated media was made by Buckingham in 1907. Buckingham quantified the energy state of soil water based on the thermodynamic potential energy. Buckingham then introduced the concept of unsaturated hydraulic conductivity, a function of water content. The water flux as the product of the unsaturated hydraulic conductivity and the total potential gradient has become the accepted Buckingham-Darcy law. Two decades later, Richards applied the continuity equation to Buckingham's equation and obtained a general partial differential equation describing water flow in unsaturated soils. For combined water and solute transport, it had been recognized since the latter half of the 19th century that salts and water do not move uniformly. It wasn't until the middle of the 20th century that scientists began to understand the complex processes of diffusion, dispersion, and convection and to develop mathematical formulations for solute transport. Knowledge on water flow and solute transport processes has expanded greatly since the early part of the 20th century to the present.

Impact of an Exponential Profile of Saturated Hydraulic Conductivity within the ISBA LSM: Simulations over the Rhône Basin

2006 ◽  
Vol 7 (1) ◽  
pp. 61-80 ◽  
Author(s):  
B. Decharme ◽  
H. Douville ◽  
A. Boone ◽  
F. Habets ◽  
J. Noilhan
Keyword(s):  
High Resolution ◽  
Hydraulic Conductivity ◽  
Land Surface ◽  
Large Scale ◽  
Saturated Hydraulic Conductivity ◽  
Rooting Depth ◽  
Surface Model ◽  
Low Resolution ◽  
The Impact ◽  
Hydrological Applications

Abstract This study focuses on the influence of an exponential profile of saturated hydraulic conductivity, ksat, with soil depth on the water budget simulated by the Interaction Soil Biosphere Atmosphere (ISBA) land surface model over the French Rhône River basin. With this exponential profile, the saturated hydraulic conductivity at the surface increases by approximately a factor of 10, and its mean value increases in the root zone and decreases in the deeper region of the soil in comparison with the values given by Clapp and Hornberger. This new version of ISBA is compared to the original version in offline simulations using the Rhône-Aggregation high-resolution database. Low-resolution simulations, where all atmospheric data and surface parameters have been aggregated, are also performed to test the impact of the modified ksat profile at the typical scale of a climate model. The simulated discharges are compared to observations from a dense network consisting of 88 gauging stations. Results of the high-resolution experiments show that the exponential profile of ksat globally improves the simulated discharges and that the assumption of an increase in saturated hydraulic conductivity from the soil surface to a depth close to the rooting depth in comparison with values given by Clapp and Hornberger is reasonable. Results of the scaling experiments indicate that this parameterization is also suitable for large-scale hydrological applications. Nevertheless, low-resolution simulations with both model versions overestimate evapotranspiration (especially from the plant transpiration and the wet fraction of the canopy) to the detriment of total runoff, which emphasizes the need for implementing subgrid distribution of precipitation and land surface properties in large-scale hydrological applications.

scholarly journals Effects of oil field brine wastewater on saturated hydraulic conductivity of smectitic loam soils

2016 ◽  
Vol 96 (4) ◽  
pp. 496-503 ◽  
Author(s):  
Nathan E. Derby ◽  
Francis X.M. Casey ◽  
Thomas M. DeSutter
Keyword(s):  
Hydraulic Conductivity ◽  
Water Flow ◽  
Great Plains ◽  
Crop Production ◽  
Saturated Hydraulic Conductivity ◽  
Oil Field ◽  
Oil Well ◽  
High Sodium ◽  
Saturated Water ◽  
Western North Dakota

Spills of brine wastewater produced during oil well drilling are occurring more frequently in the Great Plains, resulting in crop production loss on affected soil. Remediation requires removal of salt from the topsoil, which might be accomplished by leaching to subsurface horizons or subsurface drains. A laboratory study determined the effects of brine on saturated hydraulic conductivity (Ks) of four nonimpacted surface soils from western North Dakota, USA. Repacked soil cores were subjected to saturated water flow, followed by one pore volume of brine. Subsequent saturated water flow leached brine from the soil and reduced Ks as much as 97% (0.086–0.003 cm h−1) within 24 h. Effluent total dissolved solids (TDS) approached 250 000 mg L−1 then declined (5 mg L−1) with continued leaching, but Ks did not increase. Removal of soluble salts during leaching increased the relative sodium concentrations (ESP > 55), causing clay swelling/dispersion and reduced Ks. Postbrine gypsum application (11.2 Mg ha−1) to replace exchangeable sodium with calcium did not improve Ks. This evidence suggests that if subsurface drainage is used for reclaiming brine-impacted soils that special attention be given to where dispersion/swelling is occurring, leaching water quality, and closely positioning calcium amendments within the high sodium zones.

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