Search results for "HYDRAULIC CONDUCTIVITY"

INVESTIGATIONS ON INFILTRATION METHODS FOR AN IMPROVED SOIL HYDRAULIC CHARACTERIZATION

2020

Determining hydraulic properties of a loam soil by alternative infiltrometer techniques

2015

Testing infiltrometer techniques to determine soil hydraulic properties is necessary for specific soils. For a loam soil, the water retention and hydraulic conductivity predicted by the BEST (Beerkan Estimation of Soil Transfer parameters) procedure of soil hydraulic characterization was compared with data collected by more standard laboratory and field techniques. Six infiltrometer techniques were also compared in terms of saturated soil hydraulic conductivity, Ks. BEST yielded water retention values statistically similar to those obtained in the laboratory and Ks values practically coinciding with those determined in the field with the pressure infiltrometer (PI). The unsaturated soil hyd…

DETERMINING THE SATURATED HYDRAULIC CONDUCTVITY OF A LOAM SOIL WITH DIFFERENT INFILTROMETER TECHNIQUES

2015

The saturated soil hydraulic conductivity, Ks, is one of the most important soil hydraulic properties since it controls many hydrological processes. This hydrodynamic parameter depends on soil texture and structure and it is very difficult to measure. Infiltrometer techniques are becoming very popular to determine Ks in the field but testing alternative approaches is necessary for specific soil types. For a loam soil, the estimated Ks values with six infiltrometer techniques were compared. The so-called BEST procedure of soil hydraulic characterization, the pressure infiltrometer (PI), single head experiments with both the tension infiltrometer (TI) and the mini disk infiltrometer (MDI), th…

Does short-term potassium fertilization improve recovery from drought stress in laurel?

2014

Xylem hydraulic conductance varies in response to changes in sap solute content, and in particular of potassium (K(+)) ion concentration. This phenomenon, known as the 'ionic effect', is enhanced in embolized stems, where it can compensate for cavitation-induced loss of hydraulic conductance. Previous studies have shown that in well-watered laurel plants (Laurus nobilis L.), potassium concentration of the xylem sap and plant hydraulic conductance increased 24 h after fertilization with KCl. The aim of this work was to test whether water-stressed laurel plants, grown under low potassium availability, could recover earlier from stress when irrigated with a KCl solution instead of potassium-fr…

Management scenarios preventing salinization under irrigation with saline water.

2006

Management scenarios aimed at optimizing irrigation in a Sicilian vineyard characterized by a cracking clay soil irrigated with saline water were explored for seven soil profiles (Baglio 1-Baglio 7), by using the simulation model soil-water-atmosphere-plant environment (SWAP), which accounts for shrinkage and cracking. Accurate prediction of water content, theta, was obtained for the seven profiles by expressing the soil hydraulic properties according to the Brutsaert retention equation coupled with the hydraulic conductivity model proposed by Gardner (B-G model). A satisfactory prediction of the electrical conductivity of saturated extract (ECsat) ad was obtained using for the dispersivity…

Field and Numerical Tests of the Two-Ponding Depth Procedure for Analysis of Single-Ring Pressure Infiltrometer Data

2013

Abstract The two-ponding depth (TPD) analysis procedure of single-ring infiltrometer data can yield invalid results, i.e., negative values of the field-saturated soil hydraulic conductivity or the matric flux potential, denoting failure of the two-level run. The objective of this study was to test the performance of the TPD procedure in analyzing the single-ring infiltrometer data of different types of soils. A field investigation carried out in western Sicily, Italy, yielded higher failure rates (40%) in two clay loam soils than in a sandy loam soil (25%). A similar result, i.e., fine-textured soils yielding higher failure rates than the coarse-textured one, was obtained using numerically …

Soils with Specific Features

2016

This chapter deals with some specific features of soil that are relevant for interpretation of infiltration experiments. Infiltration in water repellent soils is first examined. After summarizing the causes of hydrophobicity, phenomena associated to infiltration in water repellent soil, including reduced infiltration rates and irregular wetting front advance, are illustrated. The Water Drop Penetration Time (WDPT), the Molarity of an Ethanol Droplet (MED) and the Repellency tests for quantitative assessment of soil water repellency are presented. Particular attention is given to estimation of subcritical soil water repellency by means of soil sorptivity measurements conducted with infiltrat…

Using the single-ring infiltrometer method to detect temporal changes in surface soil field-saturated hydraulic conductivity

2004

Abstract Determining temporal changes in field-saturated hydraulic conductivity ( K fs ) is important for understanding and modelling hydrological phenomena at the field scale. Little is known about the sensitivity of temporal change estimates to the method used for measuring K fs . The objective of this study was to compare temporal changes in K fs obtained in the surface layer of a clayey soil using two application procedures of the single-ring infiltrometer method. Rings installed permanently at the beginning of a 1.5-year study period (permanent sites, PSs, sample size N =16) and rings installed immediately before conducting the infiltrometer measurement (non-permanent sites, NPSs, N =1…

Testing laboratory methods to determine the anisotropy of saturated hydraulic conductivity in a sandy–loam soil

2009

Abstract Anisotropy, a (the log of the ratio of horizontal to vertical conductivity, log 10 ( K h / K v )), of saturated soil hydraulic conductivity, K s , affects transport processes in soil but is not routinely measured, probably because practical and validated methods are lacking. The objective of this investigation was to determine the effects of different constant-head laboratory and sampling procedures on anisotropy of saturated hydraulic conductivity measurements. The sequence of K s measurements was varied (vertical conductivity, K v , first, then horizontal, K h , second and vice versa) for an experimental set-up considering five variables: 1) water ponding type (Mariotte or siphon…

Using the simplified falling head technique to detect temporal changes in field-saturated hydraulic conductivity at the surface of a sandy loam soil

2007

Abstract Determining temporal changes in field-saturated hydraulic conductivity ( K fs ) is important for understanding and modeling hydrological phenomena at the field scale. Little is known about temporal variability of K fs values measured at permanent sampling points. In this investigation, the simplified falling head (SFH) technique was used for an approximately 2-year period to determine temporal changes in K fs at 11 permanent sampling points established at the surface of a sandy loam soil. Additional K fs measurements were obtained by the single-ring pressure infiltrometer (PI) technique to also compare the SFH and PI techniques. The lowest mean values of K fs , M ( K fs ), were det…