Simulation of paddy water temperature for advanced water management on agricultural lands

陸面大気相互作用によって形成される農耕地の熱環境は，作物の生育や収量を左右するなど農業上の重要な役割を果たしている．群落微気象モデルの農業における利用例として，イネの生育に影響を及ぼす水田水温のシミュレーションについて解説した．水田水温を推定する既存モデルをレビューするとともに，田面と群落の熱収支に基づいたモデルを紹介し，田面における熱交換係数の特性を論じた．これをもとに，水田の水深や灌漑時刻など水管理方法によって水田水温がどのように変化するのかシミュレーションを行った．その結果から，水管理方法が水田群落の熱環境に強く影響を及ぼしている可能性を示した．The thermal environment of the agricultural land formed by the interaction between the land surface and the atmosphere plays an important role in agriculture to affect growth and yield of crops. As an application example of micro-meteorological model in agriculture, a water temperature simulation of rice paddies was described. In addition to reviewing existing models estimating paddy water temperature, a model based on the energy budgets of the ground and the plant canopy was explained in detail, and the characteristics of the heat exchange coefficient on the paddy ground surface was also discussed. Based on these knowledge, it was simulated how the paddy water temperature is changed by water management such as water depth and irrigation time in paddy fields. It was suggested from the result that the water management strongly affects the thermal environment in paddy fields