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通过观测田间微气象数据、土壤表层水分变化状况及荞麦作物冠层下土面蒸发等资料,引进一个表面体积含水率的函数,构建了基于表层有效土壤水分的土壤蒸发模型。该模型包含了土面蒸发的2个过程:水蒸气从土壤孔隙中扩散到地表面及水蒸气由地表面传输到大气中。模型中表层有效土壤水分参数不仅取决于表层土壤含水状况,而且受风速影响。采用波文比能量平衡法及微型蒸发器观测荞麦地实际蒸腾蒸发量及冠层下土面蒸发的变化规律,并验证模型精度。结果表明,所构建模型可以成功预测冠层下土面蒸发,其平均相对误差为13.5%。该研究对于实现土壤蒸发及作物蒸腾的分离估算,减少无效水分消耗具有重要意义。
A model of soil evaporation based on surface soil moisture was constructed by observing field micro-meteorological data, soil surface moisture and soil surface evaporation under buckwheat canopy, and introducing a function of surface water content. The model includes two processes of soil surface evaporation: water vapor diffuses from the soil pores to the surface and water vapor from the surface to the atmosphere. The surface soil available moisture parameters in the model not only depend on the surface soil moisture but also the wind speed. The changes of actual evapotranspiration of buckwheat field and soil surface evaporation under the canopy were observed by using the energy balance method of Bowen ratio and the micro-evaporator. The accuracy of the model was also verified. The results show that the constructed model can predict the soil surface evaporation under the canopy with an average relative error of 13.5%. The research is of great significance for the separation estimation of soil evaporation and crop transpiration and reduction of ineffective water consumption.