Mechanism of Evapotranspiration from Forest Floor based on Soil Moisture Changes and its Evaluation Method

基于土壤水分变化的林地蒸散机理及其评价方法

• 批准号: 10660141
• 负责人: TSUCHIYA Satoshi
• 金额: $ 2.37万
• 依托单位: Shizuoka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10660141/
• 关键词: Evapotranspiration; Soil Column; Soil Moisture; Forest; Richards式; 体積含水率; 土壤水分; 林床面; ソイルカラム; リイルカラム; 土壌水分フラックス

This paper examines possible evaluations on the amount of evapotranspiration separately, based on evaporation experiments with an undisturbed soil column.To evaluate the amount of water movement during infiltrating and drying, experiments were performed by using a Kuroboku column picked out under undisturbed conditions on the forest. In the experiments, the pressure heads changes and water balance of the soil column were measured. In comparison with the measured and evaluated amount of water through the upper and lower boundary, the two were in close agreement. To estimate the surface evaporation and the water uptake by pseudo-root system separately, pressure heads in the undisturbed soil column with inserting pseudo-roots on the side were measured. In consequence, the sum of the decrease of volumetric water content in each layer was in good agreement with the loss in weight of the soil column. Evaporation from the top surface of the column was evaluated as the amount of the decrease o … More f volumetric water content in the 1st layer. Water uptake by pseudo-roots was evaluated as a sum of the decrease of volumetric water content from 2nd to 6th layers of the column. Secondly, evaporation from the top surface obtained by solving Richards' equation with the unsaturated flow analysis, was evaluated as the water flux through the top boundary of the column. Water uptake by pseudo-roots was calculated as the difference in the flux between upper and lower layer at the boundary. The sum of estimated amount of evaporation and water uptake by pseudo-roots was in good agreement with the loss in weight of the soil column. Finally, the unsaturated flow analysis applied to the soil moisture changes measured in the southwest slope of Mt. Fuji. As a result, the transpiration rate was evaluated 1.7 mm/day on the average. The evaporation rate from forest floor was evaluated 1.0 mm/day on the average, and the evapotranspiration rate by trees was estimated 2.7 mm/day by adding transpiration rate and evaporation rate. Less

本文基于原状土柱的蒸发实验，分别探讨了对蒸散量的可能评估。为了评估渗透和干燥过程中的水分运动量，使用在森林原状条件下挑选的黑木柱进行了实验在实验中，测量了土柱的压力水头变化和水平衡，与测量和评估的通过上边界和下边界的水量进行比较，估算出的结果非常一致。分别测量了表面蒸发量和假根系统的吸水量，并测量了侧面插入假根的原状土柱的压力水头，各层体积含水量的减少总和吻合良好。土柱顶部表面的蒸发量被评估为第一层体积含水量的减少量的总和。这第二层到第六层的体积含水量的减少，通过通过不饱和流动分析求解理查兹方程获得的顶部表面的蒸发被评估为通过柱顶部边界的水通量。假根计算为边界处上层和下层之间的通量差，估计的蒸发量和假根吸水量的总和与土柱的重量损失非常一致。这对富士山西南坡土壤湿度变化进行非饱和流分析，结果，蒸腾速率平均为 1.7 毫米/天，森林地面蒸发速率为 1.0 毫米/天。平均，通过添加蒸腾速率和蒸发速率，估计树木的蒸散速率为 2.7 毫米/天。

项目成果

柏原佳明、土屋智、逢坂興宏: "土壌カラムにおける蒸発量と擬似根系による水分吸収量の分離"中森研. 48巻. 191-194 (2000)

Yoshiaki Kashihara、Satoshi Tsuchiya 和 Okihiro Osaka：“土壤柱蒸发与假根系统吸水的分离” Nakamori Lab. 48. 191-194 (2000)