土壤水分运动是水文过程中的重要组成部分.熵概念将土壤水分运动的物理意义和统计学意义统一起来,并逐渐被应用于研究土壤水分的运动.但初始条件和边界条件对土壤水分运动熵演变的影响没有被充分考虑,简单地将熵演变看做单调增加过程.研究探讨了土壤水分的入渗过程和再分布过程在不同初始条件、边界条件影响下的信息熵演变特征.结果表明:1)不同土壤水分运动方式下,信息熵演变过程所呈现的特征曲线类型差异显著,初始含水率均匀、下边界无界的入渗过程和再分布过程,其熵演变分别以线性和对数形式单调增加.2)受初始条件和边界条件的影响,信息熵演变特征曲线的一致性和特征曲线类型都将发生改变,熵减小过程也会发生,进而导致系统的熵演变过程呈现多样化和复杂化.因此,运用熵理论研究土壤水分运动需要充分考虑水分运动方式、初始条件和边界条件对系统熵演变的综合影响.这样既能体现熵理论从统计学机理角度阐述土壤水分的动态变化,克服物理模型因测定水力学参数而大量耗时的不足,又能保证结果具有较高精度.

Soil water movement is an important part of hydrological processes. Entropy concept connected the physical meaning and statistical meaning of soil moisture transportation; and it is used to study the soil moisture transportation in recent years. However, many studies did not fully consider the effect of initial and boundary conditions on entropy evolution of soil water movement; they simply consider the entropy evolution as a linearly increase process. In this study, we investigate information entropy evolution characteristics in soil water infiltration and redistribution processes with constraints of initial conditions and boundary conditions. The results are as follows. (1) Information entropy evolution exhibit different characteristics in soil water infiltration and redistribution process. The former generally shows a linear increase trend while the latter shows a logarithmic increase trend. (2) Affected by the initial and boundary conditions, the information entropy evolution characteristic curve continuity, consistency and characteristic curve types will change; entropy decreases process will occur, leading to diversification of entropy production. Therefore, it is one-sided to simply consider soil water movement as the process of increasing entropy, and the influences of the initial conditions, boundary conditions and soil moisture transportation types on entropy evolution needs to fully consider. Only in this way, we can not only keep the advantages of simulating soil moisture dynamics on the basis of statistical mechanics and time saving compared with physical model by measuring the hydraulic parameters, but also to ensure that the results have a high accuracy.