Unsaturated hydraulic properties from upward flow into soil cores
Unsaturated hydraulic properties from upward flow into soil cores
复制标题
DOI：
10.2136/sssaj1996.03615995006000020009x
复制
发表时间：
1996-03-01
影响因子：
2.9
通讯作者：
Hills, RG
中科院分区：
文献类型：
--
作者：
Hudson, DB;Wierenga, PJ;Hills, RG
确定土壤非饱和水力特性的常用方法是耗时的，并且测量仅限于相对潮湿的土壤条件。本研究发展了一种估算土壤水力特性的瞬时向上入渗法。该过程包括将精心控制的水流量泵入最初干燥的土壤芯的底部。由于非饱和核心缓慢地吸收水，用张力计测量土壤水势，并且可选地，用时域反射仪测量土壤含水量。不饱和Bow程序不需要多孔板，因为使用了Bur边界。在7.6 cm直径、7.6 cm高的岩心上施加约0.76 cm d（-1）的通量60 h，使含水量从初始干燥状态（约-7500 kPa）增加到几乎饱和。Levenberg-Marquardt逆参数估计程序结合一维数值模型的实验弓系统，估计土壤水力特性从收集的水势数据，使用Eve不同的方法。同时估计了货车van Schchten持水关系和货车Schchten-Mualem或坎贝尔导水率关系中的参数。最好的方法（最低RMSE），估计所有参数的保水关系[phi（m）（θ）]和水力传导率关系[K（θ）]产生类似的水力性质的关系，为四个相同的填充芯的壤土细砂。
Common methods for determining unsaturated hydraulic properties of soils are time consuming and measurements are restricted to relatively moist soil conditions. This study developed a transient upward infiltration procedure for estimating soil hydraulic properties. The procedure involves pumping a carefully controlled water flux into the bottom of an initially dry soil core. As the unsaturated core slowly absorbs water, soil water potentials are measured with tensiometers, and, optionally, soil water contents are measured with time domain reflectometry. No porous plates are required for this unsaturated Bow procedure because a Bur boundary is used, Applied fluxes of approximately 0.76 cm d(-1) for 60 h to 7.6 cm diam, by 7.6 cm high cores increased the water content from an initial dry state (approximately - 7500 kPa) to almost saturation. A Levenberg-Marquardt inverse parameter estimation procedure was combined with a one-dimensional numerical model of the experimental Bow system to estimate the soil hydraulic properties from the collected water potential data using Eve different methods. Parameters in the van Genuchten water retention relationship and the van Genuchten-Mualem or the Campbell hydraulic conductivity relationships were simultaneously estimated, The optional water content data was combined with the water potential data to provide initial estimates of water retention parameters. The best method (lowest RMSE) that estimated all parameters in the water retention relationship [phi(m)(theta)] and the hydraulic conductivity relationship [K(theta)] produced similar hydraulic property relationships for four identically packed cores of a loamy fine sand.