Under The Condition Of Snow Cover Soil Water Thermal Migration Patterns

Heilongjiang Province, the cold winter, the average temperature of minus 20 degrees Celsius,and the temperature difference is larger between day and night. Winter snowfall, snowcovered farmland for a long time,which also provides a source of water for the spring crop growth.The snow has the characteristic of high heat conductivity weak, high reflectivity and heat capacity which influence the change of soil temperature and moisture content. Study on the relationship among the transfer rules of soil moisture under snow-covered,the parameters of soil water movement and water content is of great importance for the natural water circulation.Due to the outdoor temperature is low in the freezing period, the moisture in the soil did not transfer and deep soil remained constant, so the existence of snow provides a certain amount of water resources guarantee for the spring agricultural production,The change of soil temperature also provides a corresponding research idea for the research of Engineering Mechanics and engineering of frost heave.Through application of optimization algorithm and the computer programming determine the method of soil water movement parameter,which can overcome the spatial variability of soil properties and make the research model precision is guaranteed.This study has high theoretical significance on the soil moisture movement model and soil water movement parameter optimization algorithm model,and also has strong practical significance for the agricultural production and the analysis of soil properties, etc.Therefore, the main research contents of this paper,materials and methods, the main conclusions are summarized as follows :(1)Surface soil profile soil temperature higher than the temperature of the snow-covered soil without snow cover, no snow-covered soil can absorb solar radiation due to energy exchange, so as time goes on, the surface temperature with atmospheric temperature variations changes.Natural snowfall, snow compaction, soil profiles thick snow surface temperature remained basically unchanged. Natural snowfall, snow cover, snow compaction can maintain the soil temperature, depth ranges remain for 100 cm, 100 cm profile after exceeding the temperature of each cell is basically consistent with no change(2)The PSO algorithm into the seasonal migration of moisture in permafrost research, so we propose a new seasonal frozen soil water movement parameter identification methods. The establishment of a parameter identification model based on PSO algorithm to achieve the optimal seasonally frozen water movement parameters, model has been optimized diffusion rate and soilhydraulic conductivity.By optimizing the model to calculate the soil conductivity water rates and expansion rate is consistent with the measured values of the overall trend, the analysis found that the measured value is ignored by the soil bulk density varies with space, so the optimization model is more suitable for determining the field soil water movement parameters. Parameter model to simulate soil volumetric water content using the optimized with high accuracy, absolute maximum error analog value and the real value of each point is only 2.57%, the maximum relative error is only 5.53%, the average relative error is only 2.51%,so Seasonal Frozen Soil moisture migration model shows a good simulation can establish migration of moisture, and can reflect the PSO algorithm can better water movement parameter optimization seasonally frozen ground. The research results has important theoretical and practical significance,which guided the farmland irrigation and drainage, soil evaporation and groundwater recharge and plant root zone soil moisture movement.(3) The basic equations are derived cylindrical coordinates and spherical coordinates the movement of soil moisture and surface fluxes derived zero flux surface, the surface flux method,flux method of positioning operation process. Combed the one-dimensional soil water movement equation of three equations solved by finite difference. Equations of motion under the snowcovered soil moisture conditions for solving differential, the appropriate method to solve the equations into a form of catch-up, using MATLAB to solve the equation, the results show that :the water transport model built there can be a good simulation plot snow-covered soil moisture conditions under boundary conditions.