Estimating Air-Water Hydraulic Conductivity Using Soil-Water Characteristic Curve

2006 ◽  
Author(s):  
T. Nishimura ◽  
Y. Murasawa ◽  
T. Okami
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Water ◽  
Characteristic Curve ◽  
Soil Water Characteristic Curve ◽  
Water Hydraulic

scholarly journals Effects of Temperature Change on the Soil Water Characteristic Curve and a Prediction Model for the Mu Us Bottomland, Northern China

Water ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1235
Author(s):  
Xiaoying Qiao ◽  
Shaoyang Ma ◽  
Guixing Pan ◽  
Guanglu Liu
Keyword(s):  
Hydraulic Conductivity ◽  
Prediction Model ◽  
Soil Water ◽  
Direct Measurement ◽  
Empirical Formula ◽  
Characteristic Curve ◽  
Soil Column ◽  
Distribution Model ◽  
Undisturbed Soil ◽  
Soil Water Characteristic Curve

The soil-water characteristic curve (SWCC) is the basis for obtaining the hydraulic conductivity parameters of a soil as well as for using soil water and heat transport models. At present, the curve can be obtained by two methods: by direct measurement and by empirical formula. Direct measurement is both difficult and time-consuming. By contrast, fitting the SWCC with a suitable empirical formula is stable and convenient. The van Genuchten (VG) model has the advantage of universal applicability due to its use of a statistical aperture distribution model for estimating hydraulic conductivity. This study selected the Mu Us Bottomland as a study area. Data on the water content and water potential of undisturbed soil from this site were obtained with a Ku-pF instrument and a self-designed soil column experiment with temperature settings of 13 °C, 18 °C, 23 °C, 27 °C, and 30 °C. The variation of four main parameters in the VG model with temperature was analyzed based on thermodynamic theory and considering the effect of temperature on soil capillary pressure via its effects on surface tension and contact angle. A prediction model for the soil-water characteristic curve of the Mu Us Bottomland was then constructed, and its applicability was further analyzed. The temperature dependence of the SWCC demonstrated here provides an important scientific basis for agricultural production, farmland water conservancy, and the design of soil and water conservation engineering projects.

Assessment of the hydraulic characteristics of unsaturated base-course materials: a practical method for pavement engineers

2003 ◽  
Vol 40 (1) ◽  
pp. 121-136 ◽  
Author(s):  
J Côté ◽  
J -M Konrad
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Water ◽  
Characteristic Curve ◽  
Practical Method ◽  
Hydraulic Characteristics ◽  
Soil Water Characteristic Curve ◽  
Uniform Dispersion ◽  
Distribution Index ◽  
Graded Material ◽  
Base Course

This paper presents the results of a comprehensive laboratory investigation program on the influence of the properties of fines particles on the hydraulic characteristics of granular base-courses. The soil-water characteristic curve and the hydraulic conductivity were determined for three types of well-graded crushed aggregates (granite, limestone, and schist) with different amounts of fines (3.5–12.5%). A porosity model that considers the uniform dispersion of fines is proposed for well-graded material. Empirical relationships have been developed between the hydraulic parameters (i.e., the saturated hydraulic conductivity, the air entry value, the pore-size distribution index, the fines fraction porosity) and their specific surface area. A methodology is proposed for the assessment of the saturated and unsaturated hydraulic characteristics of base-course materials.Key words: pavement, drainage, base-course, fines, soil-water characteristic curve, hydraulic conductivity.

How to predict hydraulic conductivity of unsaturated soils from an incomplete soil water characteristic curve?

2020 ◽  
Author(s):  
Xingwei Ren ◽  
Qidong Fang ◽  
Xiaojun Chen
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Water ◽  
Unsaturated Soils ◽  
Characteristic Curve ◽  
Ground Surface ◽  
Experimental Conditions ◽  
Flow Process ◽  
Soil Water Characteristic Curve ◽  
Wide Range ◽  
Extensive Experimental Data

<p>Unsaturated soils are those in which pore is filled partially with water and partially with air. They are the most relevant porous medium to human activities, and cover almost all the soils near the ground surface. Hydraulic conductivity (HC) is one of the most important and useful properties of unsaturated soils in numerous studies, including governing flow process, settlement of soil foundations, migration of groundwater and gas hydrate. Unfortunately, direct measurement of HC for unsaturated soils is very difficult with high uncertainty due to its nature of complexity and limited experimental conditions. Thus, indirect estimation of HC from soil water characteristic curve (SWCC) becomes an alternative way and being widely used all over the world.</p><p>Because of the difficulty to reach high suction at the residual state of unsaturated soils, however, the SWCC obtained by laboratory experiments is often incomplete, which will lead to an unreliable estimation of hydraulic conductivity. However, no study has been published on how to estimate hydraulic conductivity of unsaturated soils with incomplete SWCC. In response to this situation, an innovative method was proposed based on the classical van Genuchten model and Mualem model. The proposed method was evaluated by extensive experimental data from existing literature and proved to have an excellent performance in predicting a complete SWCC for a wide range of soils. Also, it exhibits certain superiority in predicting hydraulic conductivity. The limitations of the proposed method were comprehensively discussed, and its corresponding improvement strategies were also addressed. This paper presents a practical way to obtain a more reliable hydraulic conductivity from incomplete SWCC.</p>

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