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五十年代以来,应用能量观点研究非饱和土壤(包气带)水分运动,有了很大的发展。在应用这个理论对土壤水分运动进行定量分析时,求其基本方程的解或数值解,都离不开方程中出现的几个基本参数——导水率K(θ)(又叫水力传导度或非饱和土渗透系数)、扩散率D(θ)(又叫扩散度或扩散系数)和容水度C(θ)(又叫比水容量)。而且,对于某种密度的同一种土壤,它们都不是常数,是随土壤含水率θ(体积比)而变化的。另外,研究土壤水运动,对土壤水的相对能量值(土水势)的测定也是不可缺少的资料,
Since the 1950s, the use of energy perspectives to study unsaturated soil (clad zone) water movement has made great progress. In applying this theory to the quantitative analysis of soil water movement, the fundamental equation solution or numerical solution is inseparable from several basic parameters that appear in the equation—the hydraulic conductivity K(θ) (also called hydraulic conductivity). Or unsaturated soil permeability coefficient), diffusivity D (θ) (also known as diffusion or diffusion coefficient) and water capacity C (θ) (also called specific water capacity). Moreover, for the same soil of a certain density, they are not constant and vary with the soil moisture content θ (volume ratio). In addition, to study the soil water movement, the determination of the relative energy value (earth water potential) of soil water is also indispensable data.