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Studies on the development of model to estimate the soil moisture with AMeDAS data

利用AMeDAS数据估算土壤湿度模型的开发研究

基本信息

批准号：
63560248
负责人：
NAKAYAMA Keiichi
金额：
$ 1.09万
依托单位：
Chiba University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-63560248/
关键词：
Soil moisture Evapotranspiration Capillary rise Water balance

项目摘要

The studies were conducted to develop the model to estimate the soil moisture in the root zone by using only AMeDAS data of the meteorological agency. The model is based on the water balance of the root zone and is composed by some submodels which are connected with the terms of the water balance. The outline and the experimental results on adaptability of the model are summarized as follows:Submodel to estimate the evapotranspiration was constructed by combining the Priestley Taylor method to estimate the potential evapotranspiration and the formula to calculate the net radiation from the duration of sunshine. Furthermore, to estimate the actual evapotranspiration from any surface moisture condition, the complementary relationship was available with the pan evaporation.Submodel to estimate the capillary rise was constructed by using the Darcy's law which has the unsaturated hydraulic conductivity of concerned soil and the hydraulic gradient. The hydraulic gradient was calculated by the difference of hydraulic potential between the center of the root zone and the depth of 100 cm from the center of the root zone. The hydraulic potential at the depth of 100 cm from the center of the root zone was assumed as the potential corresponded to the field capacity of the soil.Method for estimating the outflow from the root zone after the heavy rain is composed of the surface runoff and the percolation at bottom of the root zone. In this work, we could propose the method to calculate on the basis of the assumption that the soil moisture in the root zone was corresponded to the field capacity when the zero-flux layer arrived at the bottom of the root zone.Through the experiments on the adaptability of the model at the loose sloping field,the ridging field and etc., we found out that the model represented the soil moisture in the root zone fairly well.

研究的目的是开发模型，仅使用气象机构的AMeDAS数据来估计根区的土壤水分。该模型以根区水分平衡为基础，由若干与水分平衡条件相联系的子模型组成。主要内容和适应性试验结果如下：结合Priestley-Taylor方法估算潜在蒸散量和由日照时数计算净辐射的公式，建立了蒸散估算子模型。此外，为了估算任意地表水分条件下的实际蒸散量，利用蒸发皿蒸发量的互补关系，利用达西定律建立了估算毛管上升量的子模型，该模型包含了土壤的非饱和导水率和水力梯度。根据根区中心与距根区中心100 cm深度处的水势差计算出水力梯度。以根区中心100cm处的土壤水势为土壤田间持水量，用根区地表径流和根区底部渗漏量估算暴雨后根区的出流量。本文提出了在零通量层到达根区底部时，根区土壤水分与田间持水量相对应的假设计算方法，通过对模型在松坡地、起垄田等地的适应性试验，结果表明，该模型较好地反映了根区土壤水分状况。