Study on the estimation to the amount of evapotransplration based on changes in soil water

基于土壤水分变化估算蒸散量的研究

• 批准号: 08660182
• 负责人: TSUCHIYA Satoshi
• 金额: $ 1.47万
• 依托单位: Sizuoka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08660182/
• 关键词: soil water; unsaturated flow; evapotranspiration; soil column; 森林土壌

The amount of evapotranspiration can be evaluated mainly by two processes. One depends on the transpiration by plants which is related to the water absorbed from the soil through their roots, the other is due to direct evaporation from the ground surface. We can evaluate the water balance for a soil layr by adding ; the amount of water which infiltrates from the ground surface during rainfall, gravitational water moving down and passing through the layr, evaporation water through the ground surface and transpiration water by plant leaves. When the observed suction value at the upper and lower portions of the layr is known at each boundary of unsaturated transient flow in the soil layr, the input/output flux at the upper and lower boundary can be calculated using a physical law which is related to the soil-water flow. On the basis of this idea, an unsaturated water flow simulation is carried out to evaluate the amount of evapotranspiration by using soil suctions observed with the soil column obtained at actual forest site (Kuroboku Column) and the man made column (Sand Column) with Japanese standard sand. The analysis results are in agreement with the observed soil water fiux in both column. On the other way, we apply this idea to the actual forest site, measuring the soil suction changes at the upper layr (10cm in depth) and lower layr (40 cm in depth). Changes in the hydraulic gradient are calculated by using observed soil suction changes, and the soil water flux can be estimated with the unsaturated permeability of the site. It is necessary to measure the soil suction changes in the nearest top soil, in order to estimate direct flux from the forest land surface.

蒸散量主要通过两个过程来估算。一种依赖于植物的蒸腾作用，这种蒸腾作用与通过根部从土壤中吸收的水分有关，另一种依赖于地面的直接蒸发。评价土层水分平衡的方法是：将降雨期间从地表渗入的水量、重力水向下渗入和穿过土层的水量、地面蒸发水量和植物叶片蒸腾水量相加。当土层中非饱和瞬变流各边界上、下部的观测吸力值已知时，可利用与土壤-水流有关的物理定律计算上、下边界处的输入/输出通量。在此基础上，利用实测土柱(Kuroboku柱)和采用日本标准沙的人造柱(沙柱)观测的土壤吸力，进行了非饱和水流模拟计算蒸散量。分析结果与观测到的土壤水分流动情况基本一致。另一方面，我们将这个想法应用于实际的森林站点，测量上层(10厘米深)和下层(40厘米深)的土壤吸力变化。利用观测到的土壤吸力变化来计算水力坡度的变化，并利用场地的非饱和渗透率来估算土壤水分通量。为了估算森林地表的直接通量，有必要测量最近的表层土壤的吸力变化。

项目成果

土屋智: "土壌水分の変動から見た地表被覆の異なる土壌カラムからの蒸発量" 中部森林研究. 第45号. 237-240 (1997)

Satoshi Tsuchiya：“从土壤湿度的变化看出不同地面覆盖的土壤柱的蒸发”中部森林研究第 45 期。237-240 (1997)。

坂井 ひとみ: "林床被覆の蒸発抑制に関する評価手法とその適用事例" 中部森林研究. 47. 197-200 (1998)

酒井瞳：“森林地面覆盖蒸发抑制评价方法及其应用实例”中部森林研究47。197-200（1998）。

KASHIWABARA,Yoshiaki: "Evapration from soil column based on soil moisture changes under different ground conditions" Chubu For. Res.46. 237-240 (1997)

柏原义明：“基于不同地面条件下土壤湿度变化的土柱蒸发”Chubu For。

SAKAI,Hitomi: "Evaluation wethod and its application to the evaporation control from forest floor" Chubu For. Res.47. 197-200 (1998)

SAKAI，Hitomi：“评估方法及其在森林地面蒸发控制中的应用” Chubu For。

柏原 佳明: "土壌水分の変動からみた地表被覆の異なる土壌カラムからの蒸発量" 中部森林研究. 46. 237-240 (1997)

Yoshiaki Kashihara：“从土壤湿度波动的角度来看不同地表覆盖的土壤柱的蒸发”中部森林研究46。237-240（1997）。