NEW EQUATIONS FOR THE DETERMINATION OF SOIL SATURATED HYDRAULIC CONDUCTIVITY USING THE VAN GENUCHTEN MODEL PARAMETERS AND EFFECTIVE POROSITY

2013 ◽  
pp. n/a-n/a ◽  
Author(s):  
Vassilis G. Aschonitis ◽  
Vassilis Z. Antonopoulos
Keyword(s):  
Hydraulic Conductivity ◽  
Effective Porosity ◽  
Saturated Hydraulic Conductivity ◽  
Model Parameters ◽  
Van Genuchten Model

Modelling the saturated hydraulic conductivity of soils amended with different biochars

2020 ◽  
Author(s):  
Boguslaw Usowicz ◽  
Jerzy Lipiec
Keyword(s):  
Hydraulic Conductivity ◽  
Organic Carbon ◽  
Statistical Model ◽  
Water Retention ◽  
Saturated Hydraulic Conductivity ◽  
Carbon Accumulation ◽  
Water Retention Curve ◽  
Satellite Monitoring ◽  
Model Parameters ◽  
Retention Curve

<p>Soil organic carbon accumulation is central to the improvement of many soil properties and functions. Biochar use and management could be particularly beneficial for soils with low organic carbon content. It's known that many of soils in the world intrinsically exhibit little ability to retain water and nutrients due to their texture and mineralogy. Also, acquiring biomass for other than agricultural purposes can reduce the organic carbon accumulation and worsens the soil quality. Adding biochar to the soil can affect saturated hydraulic conductivity, water holding capacity and reduce soil erosion and mineral fertilization. It has been shown that saturated hydraulic conductivity depends on type of feedstock and pyrolysis temperatures used for biochar production and application dose but the results are inconsistent. Therefore, in order to explain the different biochar impacts, we propose in this study the use the physical-statistical model of B. Usowicz for predicting the saturated hydraulic conductivity using literature data for various soils amended with biochars (from woodchip, rice straw and dairy manure), pyrolyzed at 300, 500 and 700 °C.  </p><p>Soil with biochar and pores between them can be represented by a pattern (net) of more or less cylindrically interconnected channels with different capillary radius. When we view a porous medium as a net of interconnected capillaries, we can apply a statistical approach for the description of the liquid or gas flow. The soil and biochar phases and their configuration is decisive for pore distribution and the course of the water retention curve in this medium. The physical-statistical model considers the pore space as the capillary net that is represented by parallel and serial connections of hydraulic resistors in the layer and between the layers, respectively. The polynomial distribution was used in this model to determine probability of the occurrence of a given capillary configuration. Capillary size radii and the probability of occurrence of a given capillary configuration were calculated based on the measured water retention curve and saturated water content. It was found a good agreement between measured and the model-predicted hydraulic conductivity data for the biochar amended soils. It indicates that the used variables and model parameters to predict the saturated hydraulic conductivities of the soils were chosen correctly. The different types and pyrolysis temperatures of biochars affected the soil water retention and the equivalent length of the capillaries that characterize the pore tortuosity in the soil.</p><p> </p><p>Acknowledgements. Research was conducted under the project “Water in soil - satellite monitoring and improving the retention using biochar” no. BIOSTRATEG3/345940/7/NCBR/2017 which was financed by Polish National Centre for Research and Development in the framework of “Environment, agriculture and forestry” - BIOSTRATEG strategic R&D programme.</p>

scholarly journals Hydraulic Characteristics of Tuff (Scoria) used as a Container Medium

1992 ◽  
Vol 117 (3) ◽  
pp. 415-421 ◽  
Author(s):  
R. Wallach ◽  
F.F. da Silva ◽  
Y. Chen
Keyword(s):  
Hydraulic Conductivity ◽  
Natural Material ◽  
Model Parameters ◽  
Retention Data ◽  
Reliable Prediction ◽  
Unsaturated Hydraulic Conductivity ◽  
Different Types ◽  
The Media ◽  
Conductivity Curve

For effective management of irrigation and fertilization, a complete understanding of the hydraulic properties of container media is essential. This study was conducted to test the applicability of an existing predictive model for calculating the unsaturated hydraulic conductivity K(h) of tuff (Scoria, granulated volcanic ash). Two texturally different types of tuff as well as five fractions (0-1, 1-2, 2-4, 4-8, and > 8 mm), obtained from the natural material by sieving, were investigated. A 0- to 1-mm fraction of quartz sand was also tested and compared to the corresponding fraction of tuff. Water retention curves 0(h) (main drying and primary wetting scanning curves) of the media were measured over a 0- to 120-cm suction range, which covers the range of horticultural interest. The saturated hydraulic conductivity K was measured after the determination of the range of validity of Darcy's law. The model parameters were determined by curve-fitting of the measured retention data, and the K(h) relationship was obtained by multiplying the calculated relative hydraulic conductivity curve K,(h). The model prediction of K(h) was validated following direct and indirect approaches. The results showed that a reliable prediction of the unsaturated hydraulic conductivity of coarsely textured container media consisting of tuff is possible using a model commonly used for regular soils.

scholarly journals Comparison of pedotransfer functions for the determination of saturated hydraulic conductivity coefficient

2017 ◽  
Vol 28 (1) ◽  
pp. 25-30 ◽  
Author(s):  
Marek Ryczek ◽  
Edyta Kruk ◽  
Magdalena Malec ◽  
Sławomir Klatka
Keyword(s):  
Hydraulic Conductivity ◽  
Direct Methods ◽  
Laboratory Method ◽  
Saturated Hydraulic Conductivity ◽  
Pedotransfer Functions ◽  
United States Bureau ◽  
Empirical Methods ◽  
Mean Values ◽  
Bureau Of Reclamation

Abstract On one hand, direct methods of measurement of saturated hydraulic conductivity coefficient are time consuming, and on the other hand, laboratory methods are cost consuming. That is why the popularity of empirical methods has increased. Their main advantages are speed of calculations and low costs. Comparison of various empirical methods (pedotransfer functions) for the determination of saturated hydraulic conductivity coefficient was the purpose of this work. The methods used were Shepard’s, Hazen’s, USBR (United States Bureau of Reclamation), Saxton et al.’s, Kozeny–Carman’s, Krüger’s, Terzaghi’s, Chapuis’s, Sheelheim’s, Chapuis’, and NAVFAC (Naval Facilities Engineering Command) methods. Calculations were carried out for the soil samples of differential texture. The obtained results shows the methods used for the determination of permeability coefficient differ considerably. Mean values obtained by analysed methods fluctuated between 0.0006 and 12.0 m·day−1. The results of calculations by the chosen methods were compared with the results of the laboratory method. The best compatibility with laboratory method was obtained by using the Terzaghi method.

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