Evaporation from heterogeneous surfaces at the field-plot scale: effect of lateral heat and water fluxes in soil and atmosphere

由于土壤结构的局部变化（压实的轮轨）或由于局部灌溉（滴灌），农田中可能存在湿斑。常用的估算蒸发的方法假设蒸发面的横向范围很大，因此可以忽略气流和土壤中的热量和蒸汽的横向平流。对于本项目所考虑的斑块尺度，我们假设土壤和空气中的侧向热量和质量通量可能影响湿斑块的蒸发速率。为了研究这些影响，我们将在室外条件下的一个地块上进行实验，我们将监测湿斑的表面温度和微渗计的蒸发速率，其中有和没有湿斑，以及与周围土壤隔热或不隔热。在进行这些实验的同时，还将进行模拟研究，其中将考虑土壤和空气流动中的侧向热通量和水通量。为支持其他子项目，将在人工搭建的异质土槽中进行入渗、蒸发和盐示踪试验。

Wet patches in agricultural fields may exist due to local variations in soil structure (compacted wheel tracks) or due to local irrigation (drip irrigation). Commonly used approaches to estimate evaporation assume that the lateral extent of the evaporating surface is large so that the lateral advection of heat and vapor in the air stream and in the soil can be neglected. For the scales of patches that are considered in this project, we postulate that lateral heat and mass fluxes in both the soil and the air may influence the evaporation rate from wet patches. In order to investigate these effects, we will carry out experiments at a field plot under outdoor conditions in which we will monitor the surface temperature of wet patches and the evaporation rate of micro-lysimeters with and without patches and which are or are not thermally insulated from the surrounding soil. The experiments will be accompanied by simulation studies in which lateral heat and water fluxes in both the soil and the air flow will be considered. To support other subprojects, infiltration, evaporation and salt tracer experiments will be carried out in an artificially constructed heterogeneous soil tank.