日本地球惑星科学連合2021年大会

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[E] ポスター発表

セッション記号 A (大気水圏科学) » A-GE 地質環境・土壌環境

[A-GE27] 地質媒体における流体移動、物質移行 及び環境評価

2021年6月3日(木) 17:15 〜 18:30 Ch.05

コンビーナ:斎藤 広隆(東京農工大学大学院農学研究院)、加藤 千尋(弘前大学農学生命科学部)、小島 悠揮(岐阜大学工学部)、濱本 昌一郎(東京大学大学院農学生命科学研究科)

17:15 〜 18:30

[AGE27-P15] Seasonal Variation of the Effect of Ridge Orientation on Water and Temperature Distribution Inside Ridges

*増本 啓人1、窪田 新太郎2、斎藤 広隆3 (1.東京農工大学農学部、2.東京農工大学大学院農学専攻、3.東京農工大学大学院農学研究院)

キーワード:HYDRUS 2D、地表面エネルギー収支、蒸発フラックス、畝の向き

The recent rapid climate change in Japan and globally, as well as the declining birthrate, aging population, and rapid increase in population, have required changes in the production environment of agriculture, which is the foundation of our lives. For example, sustainable development of agriculture in arid and semi-arid regions is required, and optimization of water use efficiency is essential for its establishment.

In the energy balance of the land surface, the radiation from the sun to the surface is divided into evaporation, atmospheric temperature rise, and subsurface temperature rise, respectively. Moisture transfer can be classified into two major categories: transfer as liquid water and transfer as water vapor (Philip and de Vries, 1957). As for the calculation of moisture and heat balance considering water vapor transfer under non-isothermal conditions, the unsaturated soil water flow and solute transport program HYDRUS-1D (Šimůnek, et al., 2005) has been used to analyze liquid water, water vapor, and heat transfer in one dimension (Saito et al., 2006).

For more practical analysis, it is necessary to consider the external environment in terms of topographical and meteorological conditions. However, there is a lack of quantification of the effects of topographical conditions on the couple movement of liquid water, water vapor, and heat through the soil. In addition, there is a need for research on the land surface balance, moisture, and heat transfer that considers land surface structures and solar movement.

The purpose of this study was to investigate the seasonal variation in the effects of topographical conditions, such as the direction of ridges and other structures, on the moisture and temperature distribution in a soil profile.

In this study, we set up a test site at FM Fuchu (35.68°N, 58m above sea level) in the TUAT campus. Three rows of ridges were made so that the slopes of the ridges faced north-south and east-west directions. Thermocouples, soil moisture sensors, potential sensors, and heat flux panels were inserted in the ridges. The temporal changes of soil temperature, volumetric water content, water pressure, and heat flux were recorded from each sensor. Various soil hydraulic and thermal parameters were determined based on the basic soil experiment. Numerical analysis was performed using modified HYDRUS 2D (Šimůnek, et al., 2014).

In terms of moisture distribution, the entire ridge was drier in summer than in winter, with rapid drying occurring in a smaller area near the surface of the slope that was exposed to the sun for a longer period of time. In summer, the soil temperature was higher in the whole rows, although there were differences depending on the orientation of the rows. The effect of topographical conditions such as the orientation of ridges and other structures on the moisture and temperature distribution varies seasonally. The moisture and temperature distribution in the rows did not fluctuate in winter when seasonal radiation is lower suggesting that because of the lack of exposure to the sun, the orientation of the rows is likely to affect the moisture and temperature distribution inside the rows.