Unsaturated hydraulic conductivity of disturbed and undisturbed loam soil

Abstract

The soil water content-pressure head curve [q(h)], described by van Genuchten, was used to predict some hydraulic characteristics of a Xeric torriorthent soil. Experimental data of volumetric soil water content (q) and pressure head (h) were adjusted to the model, obtaining the three independent parameters used to calculate the unsaturated soil hydraulic conductivity (K) and soil water diffusivity (D). The K(q) functions for disturbed and undisturbed soil samples were statistically different pointing to the effect of soil structure on soil water flow. For soil moisture values close to saturation, K values were ³ 0.392 and ³ 0.019 cm h -1 , for undisturbed and disturbed soils, respectively. These low values would reflect the loam texture of the soil studied. In absence of roots capable of absorbing water, a supply of more than 4 L m -2 h -1 will lead to water-logging and losses through evaporation and runoff.Additional key words: Mualem model, soil water diffusivity, soil water retention curve, van Genuchten model. Resumen Conductividad hidráulica insaturada de un suelo franco alterado e inalteradoSe ha empleado la curva carga de presión-humedad del suelo [q(h)], descrita por van Genuchten, para predecir algunas características de un suelo Xeric torriorthent. Los datos experimentales se ajustaron al modelo, obteniéndose los parámetros que se han usado para calcular la conductividad hidráulica insaturada (K) y la difusividad del agua en el suelo (D). La existencia de diferencias estadísticamente significativas entre las funciones K(q) para muestras de suelo alteradas y no alteradas, muestra el efecto de la estructura del suelo sobre el flujo de agua. Para valores de humedad del suelo próximos a la saturación, se han obtenido valores de K ³ 0,392 y ³ 0,019 cm h -1 , para muestras de suelo no alterado y alterado respectivamente. Por tanto, en ausencia de raíces capaces de absorber agua, un aporte hídrico superior a 4 L m -2 h -1 , producirá encharcamiento, pérdidas por evaporación y escorrentía.Palabras clave adicionales: curva de retención de agua en el suelo, difusividad del agua en el suelo, modelo de Mualem, modelo de van Genutchen

Effect of water harvesting techniques on hydrological processes and sediment yield in Northern Ethiopia

“…High correlation and significant factor loadings of SMC and Ks in the principal components of the hydro-meteorological and soil parameters indicated that SMC was highly influenced by the existing Ks of the soil. This was consistent with other studies that reported a positive effect of Ks on SMC (Abrisqueta et al, 2006;Schuhmann et al, 2011). Our study found that SMC and Ksat were poorly correlated, indicating that SMC is weakly associated with Ksat when the soil is saturated.…”

Effect of Anisotropy on Unsaturated Hydraulic Conductivity and SWCC of Clayey Soil (English)

“…Al-Taie (2005) [4] found that 45 days is sufficient for equilibrium to occur for most types of soil. Table (1) lists the saturated solutions used in this method and it's relative humidity and matric suction.…”

“…All the parameters that influence the soil-water characteristic curve behaviour also influence the unsaturated coefficients stated above [18]. One of the most factors that influence the soil water characteristic curve and unsaturated coefficients of permeability and diffusion is the anisotropy [1], which has been studied in this research paper.…”

Bridging hydraulic diffusivity from aquifer to particle-size scale: a study on loess sediments from southwest Hungary

“…It also plays a dominant role in predictions of water content profiles in concrete during wetting and drying conditions, in the context of forecasting the service life of concrete structures (Pradhana et al 2005, Das andKondraivendhan 2012, andreferences therein). But hydrology is the branch of scientific knowledge where hydraulic diffusivity is more extensively used, namely for prediction of natural fluid flow through rock masses (Li 1984, Delépine et al 2004, Pacheco and Alencoão 2006, Pacheco and Van der Weijden 2012, soil horizons (Appoloni et al 1990, Chen 1998, Abrisqueta et al 2006 or aquifer sediments, also known as porous media. The literature on methods for assessing hydraulic diffusivity of porous media aquifers is vast.…”