272-4 Evaluating the Hydrothermal Footprint of Geothermal Energy Development in Complex Rift Settings using MODFLOW 6 GWE

Abstract:

As global demand for renewable energy grows, numerical modeling is a key tool for assessing the feasibility of geothermal development. However, the potential for deep geothermal pumping to impact shallow hydrothermal resources and protected surface waters remains under-studied. We present a numerical model of a Rocky Mountain rift valley characterized by a low-enthalpy hydrothermal system. Using the MODFLOW 6 Groundwater Energy (GWE) simulator, we apply the fully coupled groundwater flow and heat transport model to a complex network of steeply dipping normal faults and shear zones. These structures act as pathways for upwelling geothermal fluids, establishing a hydraulic connection between deep production zones and the shallow subsurface. The model was calibrated against hydraulic heads, streamflow observations, well and spring temperatures, and thermal gradients. Predictive simulations of deep geothermal pumping reveal significant hydrologic and thermal impacts on the shallow system. Results show groundwater level fluctuations ranging from -1.2 m to +1.6 m, temperature shifts between -5.6°C and +8.3°C, and spring flow reductions of up to 9.6%. Simulations show tributary groundwater depletion in response to extraction, highlighting the implications for water rights administration. These findings demonstrate that in structurally controlled rift systems, the very features that make geothermal energy viable also facilitate impacts that may conflict with surface water rights. This work highlights the necessity of coupled flow and transport modeling in the permitting and long-term management of energy projects to mitigate conflicts between energy production and existing water users.

Geological Society of America Abstracts with Programs. Vol. 58, No. 5, 2026

doi: 10.1130/abs/2026AM-22631

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