Location: Sustainable Agricultural Water Systems Research
Project Number: 2032-13220-002-036-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Apr 1, 2026
End Date: Mar 31, 2028
Objective:
The main objectives of this research are 1) to enhance and adapt 3D structural and probabilistic geological models (e.g., T-PROGS and GemPy) to represent hydrofacies in mountain block systems under limited data conditions, 2) to develop a conceptual model of mountain-block hydrogeology that captures key surface–subsurface processes and structural controls on recharge and connectivity to Central Valley aquifers, and 3) to evaluate the potential of Hillslope Managed Aquifer Recharge (Hillslope-MAR) to enhance recharge and mitigate groundwater depletion and land subsidence in the Central Valley.
Approach:
This research will develop a three-dimensional conceptual and computational framework to characterize mountain-block hydrology and its contribution to groundwater recharge in the Central Valley. First, 3D structural and probabilistic geological models (e.g., T-PROGS and GemPy) will be enhanced to represent hydrofacies in mountain block systems. These models will integrate geologic maps, borehole logs, geophysical surveys, and prior studies to characterize fractured bedrock, weathered regolith, and mountain-front alluvial deposits. To address limited subsurface data, stochastic approaches will generate multiple 3D realizations of hydrofacies and fracture networks, explicitly capturing structural uncertainty.
A conceptual model of mountain-block hydrogeology will then be developed to identify structural controls on recharge and groundwater flow toward the valley. Inverse modeling will be applied across stochastic realizations, integrating environmental tracers, isotopic data, and GRACE observations to constrain recharge rates, travel times, and subsurface connectivity. This analysis will identify preferential flow pathways linking mountain recharge zones to deeper Central Valley aquifers and establish a physically consistent framework for recharge dynamics.
To simulate system behavior, a stochastic, process-based modeling framework will couple computationally efficient KINEROS2, HYDRUS, and MODFLOW to represent surface runoff, vadose - zone flow, and groundwater dynamics across mountain-to-basin gradients. Simulations will evaluate responses to varying hydroclimatic conditions, including shifts in precipitation and extreme events (e.g., atmospheric rivers), and assess how recharge pulses and pressure propagation through fracture networks influence basin groundwater systems.
Finally, Hillslope Managed Aquifer Recharge (Hillslope-MAR) will be evaluated as a strategy to enhance mountain-derived recharge and mitigate groundwater depletion and land subsidence. Scenario-based simulations will assess how targeted land management or engineered infiltration affects recharge magnitude, timing, and connectivity to basin aquifers. Emphasis will be placed on the role of subsurface structure in controlling Hillslope-MAR effectiveness, particularly its capacity to promote deep recharge and transmit hydraulic signals through mountain block pathways.