A critical evaluation of the variability induced by different mathematical equations on hydraulic conductivity determination using disc infiltrometer

The subject of the contribution is the evaluation of the influence of the conventional tillage and reduced tillage technology of soil processing on the infiltration properties of the soil in the Větřkovice area. Field experimental work at the area was carried out in the years 2013–2015 on Cambisol district medium-heavy clayey soil. The research was conducted on sloping erosion-endangered blocks of arable land sown with spring barley. The areas were chosen each year in the way that one of the experimental areas was handled by conventional tillage technologies and the other by reduced tillage technologies. Intact soil samples were taken into Kopecký’s cylinders in the three landscape positions, at a depth of 10 cm (representing topsoil) and 30 cm (representing subsoil). The cumulative infiltration was measured using a mini-disc infiltrometer near the consumption points. The Zhang method (1997), which provides an estimate of the unsaturated hydraulic conductivity K(h), was used for the evaluation of the infiltration tests of the mini-disc infiltrometer. The soil profile processed by conventional tillage showed a higher degree of compaction. The bulk density was between 1.10–1.67 g.cm-3, compared to the land processed by the reduced tillage technology, where the values were between 0.80–1.29 g.cm-3. Unsaturated hydraulic conductivity values were about one‑third higher within the reduced tillage technology soil processing.

Download Full-text

Characterization of the field saturated hydraulic conductivity on a hillslope: measurement techniques, data sensitivity analysis and spatial correlation modelling

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-2-1247-2005 ◽

2005 ◽

Vol 2 (4) ◽

pp. 1247-1298 ◽

Cited By ~ 4

Author(s):

C. Fallico ◽

E. Migliari ◽

S. Troisi

Keyword(s):

Sensitivity Analysis ◽

Hydraulic Conductivity ◽

Spatial Correlation ◽

Unsaturated Zone ◽

Measurement Errors ◽

Measurement Techniques ◽

Saturated Hydraulic Conductivity ◽

Spatial Correlation Structure ◽

Disc Infiltrometer ◽

Data Sensitivity

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 site equipped for unsaturated zone hydraulic monitoring in the alluvial basin of a Calabrian river, in the South of Italy. Focusing attention on field saturated hydraulic conductivity, the in-site measurement techniques by tension disc and pressure ring infiltrometers are considered, pointing out the main indications for the correct use of each measuring approach; laboratory techniques are also considered. Statistical data analysis showed that the measurements performed by tension disc infiltrometer supplied values of hydraulic conductivity which are on average lower and more homogeneous than the values provided by the other measurement techniques considered. Sensitivity analysis was then carried out by Monte Carlo simulation on the parameter sampling achieved by field measurement techniques in order to evaluate the influence of any possible small measurement errors on the data. Sensitivity analysis showed that both ring and disc infiltrometer are tools reliable enough for the in situ measurements of field saturated hydraulic conductivity. Finally, after a data merging procedure giving origin to different sets of data, the spatial correlation structure of field saturated hydraulic conductivity is investigated, using well-known geostatistical techniques.

Download Full-text

An improved disc infiltrometer method for calculating soil hydraulic properties

Canadian Journal of Soil Science ◽

10.4141/s03-065 ◽

2004 ◽

Vol 84 (3) ◽

pp. 265-273

Author(s):

Xuzhang Xue, Renduo Zhang ◽

Shengxiang Gui

Keyword(s):

Hydraulic Conductivity ◽

Hydraulic Properties ◽

Piecewise Linear Approximation ◽

Large Field ◽

Improved Method ◽

Soil Hydraulic Properties ◽

Capillary Length ◽

Highly Nonlinear ◽

Soil Hydraulic ◽

Disc Infiltrometer

The disc infiltrometer has been established as a field device for in situ measurements of unsaturated infiltration under tensions. Several methods have been developed for calculating hydraulic properties based on infiltration data from the disc infiltrometer. The method by Zhang (1998) has the advantage in using infiltrometer data measured in a relatively short time period to estimate soil hydraulic properties. In this study, we improved this method by replacing the piecewise linear approximation of hydraulic conductivity function (K(h )), which results in overestimated macroscopic capillary length, with the exponential form of K(h). An efficient and accurate iteration procedure was introduced to solve the highly nonlinear equations of the improved method. An experiment was conducted in a large field to measure infiltration processes at various locations with different sizes of disc infiitrometers under different tensions. Based on the infiltration data, the improved method and three other methods in the literature were utilized to estimate soil hydraulic conductivities at different tensions and macroscopic capillary length. Compared with the three methods, the proposed method provided more accurate and stable estimations of the hydraulic conductivity and macroscopic capillary length, using infiltration data collected at short experiment periods within 20 min. Key words: Soil hydraulic conductivity, disc infiltrometer, infiltration rate

Download Full-text

Electron Microscopy of Metal-Matrix Composites

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069016 ◽

1970 ◽

Vol 28 ◽

pp. 404-405

Author(s):

A. Lawley ◽

M. R. Pinnel ◽

A. Pattnaik

Keyword(s):

Electron Microscopy ◽

Metal Matrix Composites ◽

Metal Matrix ◽

Critical Evaluation ◽

Elastic Behavior ◽

Matrix Composites ◽

Directionally Solidified ◽

Fracture Characteristics ◽

Broad Program

As part of a broad program on composite materials, the role of the interface on the micromechanics of deformation of metal-matrix composites is being studied. The approach is to correlate elastic behavior, micro and macroyielding, flow, and fracture behavior with associated structural detail (dislocation substructure, fracture characteristics) and stress-state. This provides an understanding of the mode of deformation from an atomistic viewpoint; a critical evaluation can then be made of existing models of composite behavior based on continuum mechanics. This paper covers the electron microscopy (transmission, fractography, scanning microscopy) of two distinct forms of composite material: conventional fiber-reinforced (aluminum-stainless steel) and directionally solidified eutectic alloys (aluminum-copper). In the former, the interface is in the form of a compound and/or solid solution whereas in directionally solidified alloys, the interface consists of a precise crystallographic boundary between the two constituents of the eutectic.

Download Full-text