Evaluation of Van Genuchten-Mualem Relationships to Estimate Unsaturated Hydraulic Conductivity at Low Water Contents

1995 ◽  
Vol 31 (11) ◽  
pp. 2659-2668 ◽  
Author(s):  
Raziuddin Khaleel ◽  
John F. Relyea ◽  
James L. Conca
Keyword(s):  
Hydraulic Conductivity ◽  
Unsaturated Hydraulic Conductivity ◽  
Water Contents

scholarly journals Scaling the Hydraulic Functions of A Water Repellent Sandy Soil

2014 ◽  
Vol 28 (3) ◽  
pp. 349-358 ◽  
Author(s):  
Heiner Stoffregen ◽  
Gerd Wessolek
Keyword(s):  
Numerical Simulation ◽  
Hydraulic Conductivity ◽  
Sandy Soil ◽  
Water Retention ◽  
High Spatial Resolution ◽  
Water Repellent ◽  
Soil Cores ◽  
Initial Water ◽  
Unsaturated Hydraulic Conductivity ◽  
Water Contents

Abstract The heterogeneity of both unsaturated hydraulic conductivity and water retention was measured with a high spatial resolution on a transect using an evaporation method. Fifteen undisturbed 100 cm3 soil cores were taken on a transect every 10 cm from the topsoil of a water repellent sandy site. Five dynamic water retention curves and four unsaturated conductivity curves were determined for each core. We conducted measurements without further saturation in the laboratory in order to achieve field-like conditions. The initial water contents were heterogeneous, indicating different hysteretic conditions and water repellent areas. The scattering of the water retention curves was high, while the heterogeneity of unsaturated conductivity curves was unexpectedly low. Two scaling approaches were used to describe the heterogeneity: one with and one without considering hysteresis. The concept of scaling applies well to describing the heterogeneity of both hydraulic functions. Including hysteresis leads to similar results than excluding hysteresis. The distribution of the hydraulic conductivity and the water retention were independent from each other. The results give important information for numerical simulation of the water flow with heterogeneous hydraulic functions.

A sensitivity analysis of the Jackson method of predicting unsaturated hydraulic conductivity

Soil Research ◽  
1992 ◽  
Vol 30 (3) ◽  
pp. 285 ◽  
Author(s):  
HP Cresswell
Keyword(s):  
Sensitivity Analysis ◽  
Hydraulic Conductivity ◽  
Water Content ◽  
Volumetric Water Content ◽  
Small Range ◽  
Matric Potential ◽  
Unsaturated Hydraulic Conductivity ◽  
Moisture Characteristic ◽  
Intended Use ◽  
Water Contents

An assessment is made of the sensitivity of the unsaturated hydraulic conductivity predictions from the Jackson model to changes in the measured moisture characteristic and matching factor hydraulic conductivity inputs. The model is shown to be sensitive to the volumetric water content corresponding to the matching factor hydraulic conductivity as well as to the 0 to -1.0 kPa matric potential section of the moisture characteristic input. The significance of this sensitivity is dependent on intended use of the data. Where accurate conductivity prediction is required over a small range of water contents near saturation, the moisture characteristic input used with this model should include measured points between 0 and 1.0 kPa matric potential.

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