Efficient measurement of unsaturated hydraulic conductivity using a wetting front advancing method

2010 ◽  
pp. 689-694 ◽  
Author(s):  
X Li ◽  
L Zhang ◽  
D Fredlund
Keyword(s):  
Hydraulic Conductivity ◽  
Wetting Front ◽  
Unsaturated Hydraulic Conductivity ◽  
Efficient Measurement

Simulating transient infiltration in unsaturated soils

1998 ◽  
Vol 35 (6) ◽  
pp. 1093-1100 ◽  
Author(s):  
J R McDougall ◽  
I C Pyrah
Keyword(s):  
Hydraulic Conductivity ◽  
Unsaturated Soils ◽  
Flow Model ◽  
Unsaturated Flow ◽  
Surface Region ◽  
Infiltration Rate ◽  
Soil Suction ◽  
Wetting Front ◽  
Near Surface ◽  
Unsaturated Hydraulic Conductivity

Transient responses to various infiltration events have been examined using an unsaturated flow model. Numerical simulations reveal a range of infiltration patterns which can be related to the ratio of infiltration rate to unsaturated hydraulic conductivity. A high value of this ratio reflects a prevailing hydraulic conductivity which cannot readily redistribute the newly infiltrated moisture. Moisture accumulates in the near-surface region before advancing down through the soil as a distinct wetting front. In contrast, low values of the ratio of rainfall to unsaturated hydraulic conductivity show minimal moisture accumulation, as the relatively small volumes of infiltrating moisture are readily redistributed through the soil profile.Key words: numerical modelling, infiltration, unsaturated soil, soil suction, groundwater.

Wetting front advancing column test for measuring unsaturated hydraulic conductivity

2009 ◽  
Vol 46 (12) ◽  
pp. 1431-1445 ◽  
Author(s):  
X. Li ◽  
L. M. Zhang ◽  
D. G. Fredlund
Keyword(s):  
Hydraulic Conductivity ◽  
Large Scale ◽  
Soil Column ◽  
Measurement Range ◽  
Wetting Front ◽  
Time Saving ◽  
Steady State Method ◽  
Unsaturated Hydraulic Conductivity ◽  
Soil Wetting ◽  
Wetting Process

Unsaturated hydraulic conductivity is the primary soil parameter required when performing seepage analyses for unsaturated–saturated soil systems. Unsaturated hydraulic conductivity is also one of the most difficult parameters to measure because of the time involved and the limited suction measurement range (e.g., 0∼1500 kPa in a test using the steady-state method). In this study, a new wetting front advancing method was developed for measuring unsaturated hydraulic conductivity. The wetting front advancing method simulates and monitors a soil wetting process through a large-scale soil column. A new interpretative procedure was developed to calculate the unsaturated hydraulic conductivity based on the monitored water content, suction, and wetting front advancing velocity. The proposed technique is used to measure the unsaturated hydraulic conductivities of five soils, which vary from gravel to clay. The results indicate that the proposed technique is time-saving (i.e., requires several days for a complete test) and is applicable over wide ranges of suctions and unsaturated hydraulic conductivities. The measured unsaturated hydraulic conductivity using the wetting front advancing method is similar to that obtained using the instantaneous profile method, with the latter covering narrower ranges of soil suction and hydraulic conductivity.

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