Evaluation of the Tortuosity Parameter for Forest Soils to Predict Unsaturated Hydraulic Conductivity

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概要

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• In order to accurately predict the unsaturated hydraulic conductivity for forest soils, we evaluated the tortuosity parameter for forest soils and investigated the relationships between the tortuosity parameter and parent materials and soil sampling depths. Undisturbed forest soil samples were taken from three parent material types: the granite group, Mesozoic-Paleozoic, and Quaternary. Samples taken from layers corrcsponding to the A-horizon were categorized as topsoil and others as subsoil. After retention parameters were fitted, the tortuosity parameter was optimized using the Mualem-van Genuchten conductivity model. No signif-icant differences were found in the average values of the tortuosity parameter among depths or among parent materials. Optimized values of the rortuosity parameter varied from 3.20 to - 5.23 with a high frequency in the range of about 0 to - 2. The average value was - 0.94. This means that, for most forest soils, the predicted hydraulic conductivity tends to be underestimated when the most common value (0.5) of the tortuosity parameter is used. Modifying this parameter value to - 0.77, as explained in this study, corrected the underestimation tendency and reduced prediction errors. When the unsaturated hydraulic conductivity for forest soils is predicted from water retention, the tortuosity parameter should thus be modified to an appropriate value for more accurate prediction.

• 一般社団法人日本森林学会の論文
• 2001-08-16

著者

• SHINOMIYA Yoshiki

  Shikoku Research Center, Forestry and Forest Products Research Institute

• Takahashi Kazunobu

  Faculty Of Agriculture Tokyo University Of Agriculture And Technology:tokyo Metropolitan Government

• Kobiyama Masato

  Faculty of Agronomy, Federal University of Parana

• Kubota Jumpei

  Faculty of Agriculture, Tokyo University of Agriculture and Technology

• Shinomiya Yoshiki

  Shikoku Research Center Forestry And Forest Products Research Institute

• Kubota Jumpei

  Faculty Of Agriculture Tokyo University Of Agriculture And Technology

• Kobiyama Masato

  Faculty Of Agronomy Federal University Of Parana

関連論文

• Numerical calculation of secondary discharge peak from a small watershed using a physically based watershed scale infiltration simulation
• Evaluation of the Tortuosity Parameter for Forest Soils to Predict Unsaturated Hydraulic Conductivity
• Numerical experiments of watershed-scale soil water movement and bedrock infiltration using a physical three-dimensional simulation model

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