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A simplified functions approach for determining soil hydraulic conductivities and water characteristics in situ
Author(s) -
Ahuja L. R.,
Green R. E.,
Chong S.K.,
Nielsen D. R.
Publication year - 1980
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr016i005p00947
Subject(s) - hydraulic conductivity , pedotransfer function , soil science , soil water , water content , thermal diffusivity , logarithm , water retention curve , drainage , environmental science , conductivity , power function , geotechnical engineering , geology , mathematics , chemistry , thermodynamics , physics , ecology , biology , mathematical analysis
The unsaturated hydraulic conductivity and the soil water content are assumed to be piecemeal power form and linear logarithmic functions of the soil water suction, respectively. The parameters of these functions are determined by an analysis of the drainage phase tensiometric data, combined with the field measured value of near saturated conductivity and one soil moisture sampling during the drainage. The unsaturated hydraulic conductivity and diffusivity are determined without the prior knowledge of the soil water characteristic, which is required for the more rigorous Darcian analysis. The method was tested on field data of four Hawaii soils and one California soil. The results, generally, were encouraging. However, in some cases there was discrepancy in the conductivity values for very small suctions, less than 20 cm, between the rigorous and the simplified methods, due probably to an error in measuring the field‐saturated conductivity or the errors of analysis and using soil core water characteristics for the very wet region in the rigorous Darcian method. The slope parameter of the water characteristic function was somewhat more sensitive to the scatter in the input data, but large errors in this function can be independently detected. Overall, the simplified method looked promising for further testing as such and in large‐area applications of the calculated soil parameters.