Details
| Translated title of the contribution | Measurement and simulation of nonisothermal moisture movement in water-repellent mineral soils |
|---|---|
| Original language | German |
| Pages (from-to) | 147-155 |
| Number of pages | 9 |
| Journal | Journal of Plant Nutrition and Soil Science |
| Volume | 161 |
| Issue number | 2 |
| Publication status | Published - 1998 |
Abstract
Water repellency often occurs in surface soil horizons, where the temperature may have a significant effect on water movement. Relatively few studies have been conducted to measure the effect of temperature gradients on hydraulic processes in water-repellent soils. The objective of this paper is to analyze the simultaneous impact of hydraulic and thermal gradients on water movement in unsaturated soils. Four sandy soils with organic matter contents between 1.0 and 2.4 percent were used in a laboratory column experiment. The soils had similar particle size distribution and contact angles between 25 and 111 degrees. The water repellency was measured with the "sessile drop method". The experiments were conducted with open laboratory soil columns. A ceramic plate was placed at the upper end of the soil column to allow water movement from a reservoir, the lower end was closed. The matric potential of -175 hPa at the upper part of the column was held constant. Simultaneously a constant temperature gradient of approximatly 1.1 °C/cm was applied during the nonisothermal runs. Hydraulic properties of the four soils were determined sequentially at different temperatures (5, 20 and 38°C). The time dependent volumetric water content, matric potential and temperature were measured at five positions in the column. It was found that after steady state was established the water content and matric potential profiles of the four soils differed considerably. A computer code based on the theory of Philip and De Vries (1957) was developed to simulate water and heat transport. For three soils with contact angles of 25-35, 93-108 and 109-111 degrees, respectively, the model performed well when the theoretically calculated thermal vapor diffusivity, D TV, was multiplied by a factor between two and three. For the slightly water repellent soil with a contact angle between 45 and 83 degrees, however, this factor was about seven to eight. This factor could be the result of a combined impact of the moderate water repellency and the micromorphology of the humic substance.
ASJC Scopus subject areas
- Agricultural and Biological Sciences(all)
- Soil Science
- Agricultural and Biological Sciences(all)
- Plant Science
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In: Journal of Plant Nutrition and Soil Science, Vol. 161, No. 2, 1998, p. 147-155.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Messung und Simulation der anisothermen Feuchtebewegung in benetzungsgehemmten Mineralböden
AU - Bachmann, Jörg
N1 - Copyright: Copyright 2012 Elsevier B.V., All rights reserved.
PY - 1998
Y1 - 1998
N2 - Water repellency often occurs in surface soil horizons, where the temperature may have a significant effect on water movement. Relatively few studies have been conducted to measure the effect of temperature gradients on hydraulic processes in water-repellent soils. The objective of this paper is to analyze the simultaneous impact of hydraulic and thermal gradients on water movement in unsaturated soils. Four sandy soils with organic matter contents between 1.0 and 2.4 percent were used in a laboratory column experiment. The soils had similar particle size distribution and contact angles between 25 and 111 degrees. The water repellency was measured with the "sessile drop method". The experiments were conducted with open laboratory soil columns. A ceramic plate was placed at the upper end of the soil column to allow water movement from a reservoir, the lower end was closed. The matric potential of -175 hPa at the upper part of the column was held constant. Simultaneously a constant temperature gradient of approximatly 1.1 °C/cm was applied during the nonisothermal runs. Hydraulic properties of the four soils were determined sequentially at different temperatures (5, 20 and 38°C). The time dependent volumetric water content, matric potential and temperature were measured at five positions in the column. It was found that after steady state was established the water content and matric potential profiles of the four soils differed considerably. A computer code based on the theory of Philip and De Vries (1957) was developed to simulate water and heat transport. For three soils with contact angles of 25-35, 93-108 and 109-111 degrees, respectively, the model performed well when the theoretically calculated thermal vapor diffusivity, D TV, was multiplied by a factor between two and three. For the slightly water repellent soil with a contact angle between 45 and 83 degrees, however, this factor was about seven to eight. This factor could be the result of a combined impact of the moderate water repellency and the micromorphology of the humic substance.
AB - Water repellency often occurs in surface soil horizons, where the temperature may have a significant effect on water movement. Relatively few studies have been conducted to measure the effect of temperature gradients on hydraulic processes in water-repellent soils. The objective of this paper is to analyze the simultaneous impact of hydraulic and thermal gradients on water movement in unsaturated soils. Four sandy soils with organic matter contents between 1.0 and 2.4 percent were used in a laboratory column experiment. The soils had similar particle size distribution and contact angles between 25 and 111 degrees. The water repellency was measured with the "sessile drop method". The experiments were conducted with open laboratory soil columns. A ceramic plate was placed at the upper end of the soil column to allow water movement from a reservoir, the lower end was closed. The matric potential of -175 hPa at the upper part of the column was held constant. Simultaneously a constant temperature gradient of approximatly 1.1 °C/cm was applied during the nonisothermal runs. Hydraulic properties of the four soils were determined sequentially at different temperatures (5, 20 and 38°C). The time dependent volumetric water content, matric potential and temperature were measured at five positions in the column. It was found that after steady state was established the water content and matric potential profiles of the four soils differed considerably. A computer code based on the theory of Philip and De Vries (1957) was developed to simulate water and heat transport. For three soils with contact angles of 25-35, 93-108 and 109-111 degrees, respectively, the model performed well when the theoretically calculated thermal vapor diffusivity, D TV, was multiplied by a factor between two and three. For the slightly water repellent soil with a contact angle between 45 and 83 degrees, however, this factor was about seven to eight. This factor could be the result of a combined impact of the moderate water repellency and the micromorphology of the humic substance.
UR - http://www.scopus.com/inward/record.url?scp=23644438919&partnerID=8YFLogxK
M3 - Artikel
AN - SCOPUS:23644438919
VL - 161
SP - 147
EP - 155
JO - Journal of Plant Nutrition and Soil Science
JF - Journal of Plant Nutrition and Soil Science
SN - 1436-8730
IS - 2
ER -