This paper presents a novel method for the estimation of soil water diffusivity that solves the nongravitational Richards equation using the variation in the boundary of the advancing wetting front. The solution is based on the principle of stationary action. The position of the wetting front is determined from the continuity of water content at the wetting front interface, as the underlying physical principles of this area are well known and thus it can be described using relatively few assumptions. This also eliminates the need for the Boltzmann-transformation, which is commonly required in traditional methods. The Brooks-Corey empirical water diffusion function is used to analytically determine the significant parameters of diffusivity. The soil water diffusivities of 15 soil samples matched well with their measured soil–water diffusivities, thereby confirming the reliability of the method. All of the measurements required for using this method are rapidly and easily obtained, and the experimental apparatus is simple and inexpensive. Compared with other methods, this novel method is more accurate and convenient for use in laboratories for measuring the soil hydraulic properties.

本文提出了一种估计土壤水分扩散率的新方法，该方法利用前进湿锋边界的变化来求解非引力理查兹方程。该解决方案基于静止作用原理。润湿前沿的位置由润湿前沿界面处含水量的连续性确定，因为该区域的基本物理原理是众所周知的，因此可以使用相对较少的假设来描述。这也消除了传统方法中通常需要的玻尔兹曼变换的需要。Brooks-Corey 经验水扩散函数用于分析确定扩散率的重要参数。15个土壤样品的土壤水分扩散率与其测量的土壤-水分扩散率非常吻合，从而确认该方法的可靠性。使用这种方法所需的所有测量值都可以快速轻松地获得，并且实验装置简单且便宜。与其他方法相比，这种新方法在实验室测量土壤水力特性时更加准确和方便。