Upscaling the coupled water flow and heat transfer in the subsurface – Comparison between numerical and field data

The simultaneous movement of liquid water, water vapor, and heat in the vadose zone plays a critical role in the overall water and energy balance of the near surface environment. Moisture near the soil surface is influenced by evaporation, precipitation, liquid water flow, and water vapor flow, most of which are strongly coupled. The demand for mathematical models that take into account spatial and temporal scales for the shallow soil are now-a-days more imperative given that: (a) the critical role that such processes play in the global water and energy balance; (b) the interplay between spatial and temporal scales in the near surface region is not well understood. The new contributions in this paper are: the coupled model is revisited and some modifications are proposed aiming to represent the surface/subsurface interaction more accurately; the spatial upscaled coupled model is presented. The models are validated by comparing numerical results between the fine-scale and upscaled models and data for both,...