FOR 1083:  Multi-Scale Interfaces in Unsaturated Soil (MUSIS)

• Subject Area: Geosciences
• Term: from 2008 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 66234063

Water distribution and dynamics within the unsaturated zone determine energy balance and key mass fluxes at the land-atmosphere interface at scales ranging from soil profile to continental response. Soil water redistribution and exchanges such as infiltration and evaporation at the interface with the atmospheric boundary layer above, or drainage and recharge with groundwater below often involve displacement of fluid fronts across soil layers and through heterogeneous boundaries. Current modelling concepts are inadequate for describing such complex displacement processes through naturally-heterogeneous soils with highly non-linear flow mechanisms involved, thus limiting their predictive capabilities simply because water-air interfaces may form a stable displacement front or may split into fingers and preferential flow domains, leading to vastly different patterns of water distribution and associated transport pathways.
The central working hypothesis is that small-scale physics of moving water-air interfaces within heterogeneous soil structures and interplay among competing driving forces give rise to a wide array of macroscopic patterns of water and gas dynamics not captured by standard continuum models. The primary objective of this Research Unit is to characterise and quantify characteristic patterns of water and gas distributions as a function of
(1) structural properties at a hierarchy of spatial scales ranging from the pore scale to the field and
(2) external driving forces.
We approach this challenge with a broad range of complementary methods integrating innovative experimental tools, theoretical considerations and modelling concepts. Water and gas displacement dynamics are analysed at a broad range of length scales, ranging from pore to plot scale, in order to develop criteria for different displacement regimes and their incorporation into improved quantitative predictive tools of exchange processes in the upper vadose zone of the biosphere. The new insights and improved predictive tools are considered to be critical for addressing key environmental and societal questions as for example quantification of terrestrial carbon fluxes, land-atmosphere exchange processes for climate models, more realistic estimates of transport behaviour for contaminant transport in the subsurface and improved natural hazard risk assessments.

• DFG Programme: Research Units
• International Connection: Switzerland

Projects

• Characteristics of displacement fluid fronts - from rapid interfacial jumps to steady capillary flows (Applicant Or, Dani )
• Coordination (Applicant Neuweiler, Insa )
• Development of flow and transport models and effective parameters for flow with dynamic boundary conditions (Applicant Neuweiler, Insa )
• DNS-LES pore scale simulation of thermal multi-component, multi-phase flow including radiative heating (Applicant Krafczyk, Manfred )
• Dynamics and morphology of displacement fronts across textural and wettability discontinuities (Applicant Or, Dani )
• Evaporation from heterogeneous surfaces at the field-plot scale: effect of lateral heat and water fluxes in soil and atmosphere (Applicant Vanderborght, Jan )
• Identification of effective process formulations for evaporation of water from bare soil (Applicant Durner, Wolfgang )
• Modeling and analysis of the movement of fluid-fluid interfaces ín porous media coupled with free flow (Applicant Helmig, Rainer )
• Non-equilibrium processes during infiltration into structured soil (Applicant Vogel, Hans-Jörg )

• Spokesperson: Professorin Dr. Insa Neuweiler