EarthCube GEO Domain Workshop Proposal: Envisioning a Digital Crust for Simulating Continental‐ Scale Subsurface Fluid Flow in Earth System Models

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In order to advance the understanding of the critical zone and deeper crust and to better couple the exchange of mass and energy between the surface and the subsurface, this project will hold 3-day workshop to develop a long?]term vision of a digital representation of the continental crust of N. America and design concepts for prototype data model(s). The digital catalog of crustal structure, composition and permeability (as well as parameters from which permeability could be inferred) define the mechanisms by which to integrate vast amounts of dcisparate data types and to construct a coherent, 3D picture of subsurface structure and material properties, so that we can begin to represent subsurface fluid flow in Earth system models and elucidate its critical controls in the evolution of the Earth system from the past to the present and the future.Fluid circulation in the subsurface, from the critical zone to the deeper crust, plays an essential role in surface, near-surface, and crustal dynamics. In the critical zone (50m), soil water is a ecologic filter and niche differentiator where energy is abundant, explaining patterns in plant distribution globally and locally; and shallow groundwater is a primary source for rivers, lakes andwetlands in dry seasons and regions, thereby sustaining and modifying land and aquatic ecosystems, influencing water quality, and buffering against droughts and temperature extremes. Deeper in the crust (1km), the large sedimentary formations and fractured rocks hold the fresh?]water aquifers that support major societies in arid and semi-arid regions. In the deeper crust (1km), fluid flow affects diagenesis, hydrocarbons, ore deposits, faulting, earthquakes, and geothermal fields and involves water, gas and hydrocarbon flow. What are the flow paths through the soils and rocks? How fast are the flows and how long are the residence times? And how will they respond to changes in climate and land surface drivers? The answers depend on a quantitative description of the subsurface flow fields, driven by the hydraulic gradient but strongly controlled by the permeability of the Earth?fs material. Creating a digital catalogue by which to reconstruct this poorly sampled region of the planet will enable multiple aspects of the Earth sciences to advance transformatively.