نتایج جستجو برای: environment unsaturated and hydraulic conductivity. then

تعداد نتایج: 16901497  

ژورنال: علوم آب و خاک 2013
سید محمدعلی زمردیان, , پویان باقری , ,

Hydraulic conductivity is an important parameter in the design of geotechnical structures such as earth dam, floor construction, retaining walls and environmental structures. In unsaturated soils, hydraulic conductivity is a function of moisture content and soil water suction i.e. soil moisture characteristic curve. In this study, the values of unsaturated hydraulic conductivity in two soil typ...

2009
D. D. Bosch

Steady-state and transient one-dimensional unsaturated flow in vertically stratified porous media are examined. Saturated hydraulic conductivity and the alpha parameter of the exponential hydraulic conductivity function were assumed to vary from soil layer to soil layer. The use of effective unsaturated hydraulic conductivity to compute matric potential in the soil profile is demonstrated. Resu...

2008
M. Berli A. Carminati T. A. Ghezzehei

[1] Prediction of water flow and transport processes in soils susceptible to structural alteration such as compaction of tilled agricultural lands or newly constructed landfills rely on accurate description of changes in soil unsaturated hydraulic conductivity. Recent studies have documented the critical impact of aggregate contact characteristics on water flow rates and pathways in unsaturated...

2003
Kai Schwaerzel Heiko P. Bohl

A simple method for the installation of groundwater lysimeters in peat soils was developed which reduces both time and financial effort significantly. The method was applied on several sites in the Rhinluch, a fen peat land 60 km northwest of Berlin, Germany. Over a two-year period, upward capillary flow and evapotranspiration rates under grassland with different groundwater levels were measure...

2009
Luis Guarracino Leonardo B. Monachesi

In this study we determine constitutive relations (relations between saturation, hydraulic conductivity and pressure head) for unsaturated fractured rocks using a computational procedure that mimics the laboratory technique of measurement. Isotropic three-dimensional rock samples with random vertical and horizontal fractures are computationally constructed. Each fracture is conceptualized as a ...

Journal: :تحقیقات مهندسی کشاورزی 0
بهزاد قنبریان علویجه دانشجوی دکتری دانشکده آب و خاک پردیس کشاورزی و منابع طبیعی دانشگاه تهران عبدالمجید لیاقت دانشیار گروه آبیاری و آبادانی دانشکده آب و خاک پردیس کشاورزی و منابع طبیعی دانشگاه تهران سمانه سهرابی دانشجوی کارشناسی ارشد گروه مهندسی آب دانشکده کشاورزی دانشگاه تبریز

soil hydraulic properties such as saturated and unsaturated hydraulic conductivity play an important role in environmental research. since direct measurement of these soil hydraulic properties is time-consuming and costly, indirect methods such as pedotransfer functions and artificial neural networks (ann) were developed based on readily available parameters. in this study, the use of ann to pr...

2000
Marcel G. Schaap Feike J. Leij

variables as input (e.g., Rawls and Brakensiek, 1985; Ahuja et al., 1989; Vereecken et al., 1989; Schaap et In many vadose zone hydrological studies, it is imperative that the al., 1998). Far fewer alternatives exist for unsaturated soil’s unsaturated hydraulic conductivity is known. Frequently, the Mualem–van Genuchten model (MVG) is used for this purpose behydraulic conductivity. Although som...

2005
C. Fallico

Papers published in Hydrology and Earth System Sciences Discussions are under open-access review for the journal Hydrology and Earth System Sciences Abstract In the context of studies aiming at the estimation of effective parameters for unsaturated zone modelling, this work tackles the problem of experimental data quality, considering the large collection of data gathered at an experimental sit...

2009
Y. J. Cui A. M. Tang C. Loiseau P. Delage Yu-Jun Cui

Highly compacted sand-bentonite mixtures are often considered as possible engineered barriers in deep high-level radioactive waste disposals. In-situ, the saturation of these barriers from their initially unsaturated state is a complex hydro-mechanical coupled process in which temperature effects also play a role. The key parameter of this process is the unsaturated hydraulic conductivity of th...

ژورنال: علوم آب و خاک 2012
حجت امامی, , محمدرضا نیشابوری, , مهدی شرفا, ,

Direct measurement of soil unsaturated hydraulic conductivity (K(h) or K(θ)) is difficult and time-consuming, and often in many applied models, predicting hydraulic conductivity is carried out according to measurements of soil retention curve and saturated hydraulic conductivity (Ks). However, using KS as a matching point in many procedures may result in over-estimation of unsaturated hydraulic...

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