During this presentation you will discover how soil-moisture processes in the subsurface play a crucial role in the hydrological cycle and the groundwater budget. 

Understanding soil-moisture conditions in this zone is of interest in various applications in hydrology, such as land-atmospheric interaction, soil evaporation and evapotranspiration, and climate modeling, as well as emerging problems in assessing the risk of, for example, the leakage of carbon dioxide or methane from deep geological formations to the shallow subsurface that affects groundwater quality and vegetation. 

In this lecture you will learn about: 

• Relevant processes of mass, momentum, and energy transfer at the interface between a free-flow and a porous-media system 
• Conceptual modeling for coupled single-phase free flow and two-phase porous-medium flow with a detailed description of the models in the free flow and in the porous medium 
• A new coupling concept for modeling coupled porous-medium and free flow with application to evaporation and salt-precipitation processes; a comparison study will show the advantages and disadvantages in comparison with classical approaches 

Three model combinations for evaporation processes and how to use them to study the effects of various quantities and processes—a porous-medium model coupled with a laminar free-flow model, a simple boundary-layer model, and a Reynolds-averaged turbulence model that uses algebraic expressions to account for the turbulent flow behavior.