Estimating unsaturated hydraulic conductivity from tension disc infiltrometer data in the areas with high water table

One of the essential requirements in agriculture, environment, engineering and irrigation and drainage system design is to use a functional and effective method to estimate the unsaturated soil hydraulic properties. Tension disc infiltrometers are becoming increasingly popular devices for in situ measurement of the unsaturated hydraulic properties of soil. This study mainly aims to estimate unsaturated Hydraulic conductivity from tension disc infiltrometer data in the areas with high water table. For this purpose, a physical model was developed to simulate groundwater flow and apply different water tables. The unsaturated hydraulic conductivity was measured through tension disc infiltrometer in four modes of drainage (no water) and at water tables of 60, 45 and 30 cm below soil level and 6 suctions of zero, 3, 6, 9,12 and 15 cm. Each mode was tested three times which resulted in a total of 12 tests. In order to analyze the results, the method proposed by Logsdon and Jaynes , which is a non-linear regression method, was used. The results show that rising water levels, hydraulic conductivity is estimated to be more, indicating that tension disc infiltrometer should be used cautiously to estimate unsaturated hydraulic conductivity especially in lower suctions (zero, 3 and 6).