scholarly journals Water retention curve and hydraulic conductivity function of highly compressible materials

2007 ◽  
Vol 44 (10) ◽  
pp. 1200-1214 ◽  
Author(s):  
Serge-Étienne Parent ◽  
Alexandre Cabral ◽  
Jorge G. Zornberg
Keyword(s):  
Hydraulic Conductivity ◽  
Water Retention ◽  
Void Ratio ◽  
Silty Sand ◽  
Water Retention Curve ◽  
Volume Changes ◽  
Retention Curve ◽  
Conductivity Function ◽  
K Function ◽  
Compressible Materials

A model capable of describing the suction-induced consolidation curve (void ratio function) and water retention curve (WRC) of highly compressible materials (HCM) is developed, validated, and finally applied to describe the WRC of deinking by-products (DBP). DBP are a highly compressible by-product of paper recycling used in geoenvironmental applications. Validation is conducted by modelling the WRC and the void ratio function for a well documented silty sand from Saskatchewan, Canada. The WRC and void ratio function were used to predict its hydraulic conductivity function (k-function). The water content, suction, and volumetric deformation data of DBP are obtained using an experimental technique that allows determination of the WRCs of HCMs that is suitable for prediction of the DBP k-function. The results show that volumetric water contents are underestimated if volume changes are not accounted for, leading to inaccuracies in the WRCs, thus inaccurately predicted k-functions. It is shown that the newly developed model is better suited for HCMs than currently available models, in particular for HCMs that continue to undergo significant volume changes when the applied suction exceeds the air-entry value.

scholarly journals Comparison of different estimation procedures for the hydraulic properties of horticultural substrates by One-Step technique

2013 ◽  
Vol 44 (2s) ◽  
Author(s):  
Carlo Bibbiani ◽  
Carlo A. Campiotti ◽  
Luca Incrocci ◽  
Alberto Pardossi
Keyword(s):  
Hydraulic Conductivity ◽  
Hydraulic Properties ◽  
Water Retention ◽  
Water Retention Curve ◽  
Step Method ◽  
Retention Curve ◽  
Van Genuchten Model ◽  
One Step ◽  
Conductivity Function ◽  
The One

The improved iterative method for the simultaneous determination of the hydraulic properties of growing media from One-Step experiment by Bibbiani, is performed and compared with simplified equations by Valiantzas and Londra. Brooks and Corey equation for water retention, and Kozeny power equation for hydraulic conductivity characterized the hydraulic properties of the porous media. The iterative procedure is applied on pure peat, pumice, and their mixes. The One- Step method has been previously optimized: processing the mean cumulative outflow curves recorded versus time, an estimation of diffusivity, and therefore of the hydraulic functions, is derived. Estimated water retention curve is compared with nine experimental data, and with the estimation of the Van Genuchten model, via the RETC code. Bibbiani’s and Van Genuchten’s models overlap except for the “very wet” range near saturation, whereas the Valiantzas and Londra’s procedure didn’t get satisfactory results. In regard to diffusivity, a good similarity between Bibbiani’s and Van Genuchten-Mualem’s curves can be assessed, while Valiantzas and Londra’s procedure generally results in higher values. Due to the lack of estimation of the water retention curve, Valiantzas and Londra’s procedure fails to estimate the hydraulic conductivity function, whereas Bibbiani’s and Van Genuchten-Mualem’s curves match together in most cases.

Determination of the Soil-Water Retention Curve and the Hydraulic Conductivity Function Using a Small Centrifuge

2011 ◽  
Vol 34 (5) ◽  
pp. 103590
Author(s):  
L. D. Suits ◽  
T. C. Sheahan ◽  
Rodrigo Martins Reis ◽  
Wagner Nogueira Sterck ◽  
Artur Bastos Ribeiro ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Water ◽  
Water Retention ◽  
Water Retention Curve ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
Retention Curve ◽  
Conductivity Function

scholarly journals Water retention and transfer properties of a Green roof volcanic substrate

2020 ◽  
Vol 195 ◽  
pp. 03011
Author(s):  
Filip Stanic ◽  
Pierre Delage ◽  
Yu Jun CUI ◽  
Emmanuel DE LAURE
Keyword(s):  
Hydraulic Conductivity ◽  
Water Retention ◽  
Green Roof ◽  
Water Retention Curve ◽  
Retention Curve ◽  
Column System ◽  
Paris Area ◽  
Conductivity Function ◽  
Transfer Properties

The water retention curve and the hydraulic conductivity function of a volcanic coarse granular material used as a substrate in an urban green roof in the Paris area was carried out on a newly developed device, in which low suctions were controlled. In the same cell, a hanging column system was used for controlling smaller suctions (up to 32 kPa) and the axis translation technique for larger suctions (up to 50 kPa). Water exchanges were monitored in connected tubes by using a high accuracy differential pressure transducer. The step changes in suction were also used to determine the hydraulic conductivity function by means of Gardner’s method, accounting for the impedance effects due to the high air entry value ceramic porous disk with Kunze and Kirkham’s method. van Genuchten and Brooks and Corey models were used for the water retention curve, but the hydraulic conductivity functions derived from these expressions appeared to lead to a significant under-estimation, confirming the need of operational and simple device for the experimental determination of the hydraulic conductivity function.

scholarly journals Determination of the Soil Water Retention Curve Using the Flow Pump

2015 ◽  
Vol 68 (2) ◽  
pp. 207-213
Author(s):  
Luciana Portugal Menezes ◽  
Waldyr Lopes Oliveira Filho ◽  
Cláudio Henrique Carvalho Silva
Keyword(s):  
Soil Water ◽  
Water Retention ◽  
Unsaturated Flow ◽  
Silty Sand ◽  
Water Retention Curve ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
Retention Curve ◽  
Flow Problems ◽  
Flow Pump

AbstractReliable measurements of the Soil Water Retention Curve, SWRC, are necessary for solving unsaturated flow problems. In this sense, a method to obtain the SWRC of a silty sand using a flow pump, as well as details about procedures and some results, are herein presented. The overall conclusion is that the new method is very convenient, fully automated, and produces reliable results in a fast and easy way, making the technique very promising.

scholarly journals Simultaneous Determination of Water Retention Curve and Unsaturated Hydraulic Conductivity of Substrates Using a Steady-state Laboratory Method

HortScience ◽  
2010 ◽  
Vol 45 (7) ◽  
pp. 1106-1112 ◽  
Author(s):  
Paraskevi A. Londra
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Hydraulic Conductivity ◽  
Water Retention ◽  
Water Pressure ◽  
Pressure Head ◽  
Laboratory Method ◽  
Water Retention Curve ◽  
Retention Curve ◽  
Unsaturated Hydraulic Conductivity

For effective irrigation and fertilization management, the knowledge of substrate hydraulic properties is essential. In this study, a steady-state laboratory method was used to determine simultaneously the water retention curve, θ(h), and unsaturated hydraulic conductivity as a function of volumetric water content, K(θ), and water pressure head, K(h), of five substrates used widely in horticulture. The substrates examined were pure peat, 75/25 peat/perlite, 50/50 peat/perlite, 50/50 coir/perlite, and pure perlite. The experimental retention curve results showed that in the case of peat and its mixtures with perlite, there is a hysteresis between drying and wetting branches of the retention curve. Whereas in the case of coir/perlite and perlite, the phenomenon of hysteresis was less pronounced. The increase of perlite proportion in the peat/perlite mixtures led to a decrease of total porosity and water-holding capacity and an increase of air space. Study of the K(θ) and K(h) experimental data showed that the hysteresis phenomenon of K(θ) was negligible compared with the K(h) data for all substrates examined. Within a narrow range of water pressure head (0 to –70 cm H2O) that occurs between two successive irrigations, a sharp decrease of the unsaturated hydraulic conductivity was observed. The comparison of the K(θ) experimental data between the peat-based substrate mixtures and the coir-based substrate mixture showed that for water contents lower than 0.40 m3·m−3, the hydraulic conductivity of the 50/50 coir/perlite mixture was greater. The comparison between experimental water retention curves and predictions using Brooks-Corey and van Genuchten models showed a high correlation (0.992 ≤ R2 ≤ 1) for both models for all substrates examined. On the other hand, in the case of unsaturated hydraulic conductivity, the comparison showed a relatively good correlation (0.951 ≤ R2 ≤ 0.981) for the van Genuchten-Mualem model for all substrates used except perlite and a significant deviation (0.436 ≤ R2 ≤ 0.872) for the Brooks-Corey model for all substrates used.

Evolution of isochoric water retention curve with void ratio

2020 ◽  
Vol 122 ◽  
pp. 103536 ◽  
Author(s):  
Amin Pasha ◽  
Arman Khoshghalb ◽  
Nasser Khalili
Keyword(s):  
Water Retention ◽  
Void Ratio ◽  
Water Retention Curve ◽  
Retention Curve
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