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Identification of effective process formulations for evaporation of water from bare soil

确定裸土水分蒸发的有效工艺配方

基本信息

批准号：
215627694
负责人：
Professor Dr. Wolfgang Durner
金额：
--
依托单位：
Institut für Geoökologie
依托单位国家：
德国
项目类别：
Research Units
财政年份：
2012
资助国家：
德国
起止时间：
2011-12-31 至 2014-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/215627694?language=en
关键词：
Identification effective process formulations evaporation

项目摘要

Describing the evaporative movement of soil water towards the soil-atmosphere interface with one-dimensional effective continuum-scale process models can be a valid approach under some conditions, but may lead to erroneous flow predictions under certain circumstances. The aim of this subproject is to explore validity limits of the Richards equation for describing bare soil evaporation in particular during stage-two evaporation, where the soil's unsaturated hydraulic conductivity and vapor diffusion in soil dominate the evaporation process. To analyze limitations arising from neglect of coupled heat and water vapor flow processes and to assess the importance of using a correct hydraulic conductivity function for liquid phase flow, we will evaluate data from a variety of evaporation scenarios by inverse modeling with effective process models. Scenarios cover experiments under transient conditions and include flow interruptions to study dynamic effects. Data will be provided by virtual realities obtained by comprehensive forward modeling by SP2, small lysimeter experiments under laboratory and field conditions, and a joint lysimeter experiment (SP3). In the inverse evaluations, we will start with the full Philip-de Vries model and extensions for non-equilibrium water flow and simplify it stepwise towards the Richards equation in order to assess which model complexity is necessary to adequately describe the measurement data. Our particular interest lies in (i) identifying the relative contributions of liquid and vapor water flow to the total water flow near the surface, (ii) determining the time at which evaporation shifts from stage-one to stage-two, (iii) determining the position of the vaporization plane during stage-two evaporation, and (iv) quantifying the range of conditions where effective process descriptions can be used in practical situations to correctly predict the water fluxes to the atmosphere.

用一维有效的连续尺度过程模型描述土壤水分向土壤-大气界面的蒸发运动在某些条件下是有效的方法，但在某些情况下可能导致错误的流动预测。该子项目的目的是探索理查兹方程的有效性限制，特别是在第二阶段的蒸发，土壤的非饱和导水率和蒸汽在土壤中的扩散占主导地位的蒸发过程中描述裸土蒸发。为了分析忽略耦合的热和水蒸气流动过程所产生的局限性，并评估使用正确的水力传导率函数的液相流的重要性，我们将评估各种蒸发情况下的数据，通过逆建模与有效的过程模型。方案涵盖瞬态条件下的实验，包括研究动态效应的流量中断。数据将通过SP2的综合正演模拟、实验室和现场条件下的小型蒸渗仪实验以及联合蒸渗仪实验（SP3）获得的虚拟现实提供。在逆向评估中，我们将从完整的Philip-de弗里斯模型和非平衡水流扩展模型开始，逐步简化为理查兹方程，以评估模型复杂性对充分描述测量数据是必要的。我们特别感兴趣的是（i）确定液体和蒸汽水流对表面附近总水流的相对贡献，（ii）确定蒸发从第一阶段转移到第二阶段的时间，（iii）确定第二阶段蒸发期间蒸发平面的位置，以及（iv）量化在实际情况中可以使用有效的工艺描述来正确地预测到大气中的水通量的条件的范围。