Special variation of unsaturated hydraulic conductivities in a crop field based on soil surface temperature measurements using a UAV

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K05827
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 41030:Rural environmental engineering and planning-related
• Research Institution: Mie University
• Principal Investigator: SAKAI Masaru 三重大学, 生物資源学研究科, 准教授 (70608934)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 土中・水分熱移動 / 地表面熱収支 / 蒸発散 / 地表面温度 / 数値シミュレーション / UAV / 赤外放射温度計 / 空間分布

Outline of Final Research Achievements

Using a UAV equipped with an infrared thermography camera, we were able to observe surface temperatures reflecting variations in soil moisture content in a field. A coupled numerical simulation program of a soil moisture and heat transfer model and a surface energy balance model was developed. The unsaturated hydraulic conductivity of a soil was estimated by applying the developed program that reflects meteorological conditions to the observed surface temperatures. UAV measurement is limited in number of observations. Numerical experiment showed a possibility of estimating hydraulic conductivity over a wide pressure head range by observing surface temperature on wet and dry soil days.

Free Research Field

土壌物理学

Academic Significance and Societal Importance of the Research Achievements

気候変動にともなう厳しい気象条件の元，持続可能な作物生産を行うには，土壌水分量の把握が重要である．特に，今後農地の集約化が進められ大規模化した時，圃場内の水分の空間的なばらつきが顕在化し，従来の土壌水分センサーによる点的な観測だけでは不十分となることが予想される．
土壌内部の水分量変化を予測する手法の一つに数値シミュレーションが挙げられるが，不飽和透水係数の原位置での面的な決定が必要であり，土壌物理学にとっても残された最大の課題である．赤外線サーモグラフィカメラを搭載したUAVで観測した圃場の土壌面温度から透水係数の空間分布を推定する上で，本研究成果は非常に有用である．