Temperature Effect Research On Soil Hydraulics Conductivity And Thermodynamics Parameters Of In The Mu Us Bottomland

Soil is a complex system that composed by the solid phase, liquid phase and gas phase. There are continuous transport and transformation of liquid and gas in the system, and thus it plays an important role in soil heat conduction and soil moisture solute transport. Soil hydraulic conductivity and thermodynamic parameter is the core of the above-mentioned model predictions. Due to the large day-and-night temperature difference in Mu Us Desert, the water table fallings and the ecological environment there is extremely fragile. Therefore, it has important scientific significance for the vegetation- soil- groundwater system, rational utilization of regional water resources and ecological environment protection to carry out the research of soil hydraulic conductivity and thermodynamic parameters under different temperature. Based on the theory of soil water dynamics, fluid dynamics in porous media, thermodynamics and statistics, etc. The study carries out the research of temperature effect between soil hydraulic conductivity and thermodynamic parameters using the indoor soil column test and the thermal parameter instrument Hot Disk and thermostat. The main contents are as follows:(1)The soil saturated hydraulic conductivity of bottomland at six different temperature, 6.5℃, 11℃, 22℃, 26℃, 27.5℃ and 34℃, was tested by laboratory experiments. Temperature and soil saturated hydraulic conductivity showed a good linear positive correlation, the correlation coefficient is 0.991. This is related to the physical properties of water, such as dynamic viscosity coefficient, bulk density and temperature.(2)With the increase of soil temperature in Mu Us bottomland, soil suction showed a decreasing trend, and the water capacity of soil weakened. With the increase of temperature, the saturated water content and residual water content of the soil declined, and the characteristic curve of soil moisture was down. With the increase of water content and temperature, the unsaturated permeability coefficient K(s) and diffusion rate D(s) showed a gradual increase in growth.(3)The thermal parameters of the soil at different water content were tested by Hot Disk and thermostat at five temperatures, 7℃, 12℃, 18℃, 31℃ and 36℃. And this study fitted the relevant parameters again using the Zhao Guizhang formula. The fitting degree is over 0.95. Thermal conductivity and soil temperature, and thermal conductivity and moisture content both showed a more significant positive correlation. Correlation between soil heat capacity and temperature is not too obvious, showing a small decline, but between soil heat capacity and soil water content rate showed a good positive correlation. With the increase of temperature, soil thermal diffusivity show formerly positive but latterly negative relationship, and it reached the maximum value in the volume water content of 0.18.(4)The heat conductivity test data fitting under different temperature and moisture content was used by Tarnawski empirical model, and the fitting degree was 0.953. Therefore, this correction model can be used in the forecast of soil thermal conductivity under the influence of different temperature and moisture in Mu Us bottomland.