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Research on the Effect of Temperature on Soil Water Movement and Parameters

Author: GaoHongBei
Tutor: ShaoMingAn
School: Northwest University of Science and Technology
Course: Environmental Science
Keywords: temperature soil water infiltration soil water conductivity thermodynamics
CLC: S152.7
Type: Master's thesis
Year: 2011
Downloads: 163
Quote: 0
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Abstract


On the basis of existing research about the effect of temperature on soil moisture movement and soil moisture-heat coupling migration, a further dicussion about the effect which was caused by the conditions involving constant temperature and the condition of existing temperature gradients on the soil water movement and the soil water movement parameters has been deployed. Some typical soils in Loess Plateau were selected as the research object. In order to complete the experiment, artifical settings was put into use to achieve different temperature conditions accroding to different experiment setting. Meanwhile, another discussion about soil moisture movement parameters’variation due to the temperature change, including soil moisture retention curve、hydraulic conductivity、soil moisture diffusivity and specific moisture capacity, was curried out on the basis of laboratory experiments and theoretical analysis. The results show that: (1) In the process of infiltration, a good result was achieved by emplying the power function fitting the effect. the effect of temperature on the wetting front distance mainly through the parameter“a”to realize , which was the coefficient in the function.The effect on infiltration rate mainly through affects the moisture absorption rate S. With the temperature rising , the rate of wetting front transport and infiltration rate will increase. the relationship between them with time and temperature can be fitted by the complex power multifunction. The wetting front transport rate and water infiltration rate of the same soil will change with the temperature change. The effect in the low temperature stage will be greater than that in the warmer stage. (2) Soil temperature has an obvious effect on soil moisture properties and soil structures. Meanwhile, the effect could be described by the soil moisture dynamic parameters changes which were caused by temperature’s alteration. During the process of the soil moisture movement the changes of the soil moisture properties mainly act on kinetic energy and potential energy of the moisture, while the changes of soil structure mainly affect the potential energy. The soil moisture movement parameters change with the temperature varied greatly for different soil types. The effect of temperature on soil moisture movement could be ignored in sandy soil, but for clay soil, the opposite is true. (3) The mechods of soil moisture dynamics analysis and thermodynamics analysis were combined to discuss the properties of soil water movement under temperature gradients. By using this mechod, one-dimensional level function of soil moisture movement was abtained ,which was drove by matrix potential and temperature potential. Furthermore, this method can overcome the shortage of the analysis taken by dynamics method and modynamic method respectively,then get more better results.

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CLC: > Agricultural Sciences > Agriculture as the foundation of science > Soil > Soil physics > Soil moisture
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