36 From Data to Decision: Integrating Geophysics, Data Systems, and Modeling for Aquifer Characterization in Data-Sparse Regions

Advances in data acquisition, management, and analytics are transforming water-resources research in semi-arid, data-sparse regions. This session highlights the integration of geophysics, data systems, and modeling, including AEM, legacy data digitization, and cloud platforms. Contributions demonstrate how advances in data collection, management, analysis, and modeling  approaches improve the characterization of fresh and brackish groundwater to support management, recharge, and long-term planning.

Wednesday, 20 May 2026
8:00 AM - 12:00 PM
Alvarado F

Water Rights Modeling-When the Laws of Nature are Subjugated by the Laws of Man

Paper number: 36-11
Program: Technical Sessions
Time: 11:40 AM – 12:00 PM

Authors

Abstract

The use of groundwater models for water management purposes is not new. When it is commonplace for development of sophisticated groundwater models for calculating impacts of water users under the National Environmental Protection Act (NEPA) the standards are different that when they are applied to simplified models used to determine how water is allocated to users. The purpose of this presentation is to highlight two examples of groundwater models being used to regulate water use in large basins using simplified models. In Colorado, the South Platte River model is used to provide the Colorado Water Conservation Board a tool for administering Colorado’s Doctrine of Prior Appropriation. The complex system of tributaries and alluvial aquifers is simulated with a single-layer MODFLOW model with 0.19-mile grid cells. While the model may generally depict overall flow conditions for administration of the river it is inadequate for small-scale, specific evaluations of stream-alluvial aquifer hydraulic interactions. The Nevada State Engineer’s Office recently released the Middle Humboldt River Groundwater Model, prepared by the U.S. Geological Survey for the purpose of managing curtailments of groundwater use in the basin. This six-layer model with uniform 0.38-mile grid spacing simulates a region already represented by several NEPA and consulting groundwater models. A web-based interface conveniently queries the groundwater model results for capture of Humboldt River flows. These models are meant to serve both a legal and scientific basis for the management of water rights Nevada and Colorado, which are based on the priority system of “first in time, first in right”. As such, a general model of the hydraulics of the system can identify on a large-scale basis overall water-supply availability, but it may be incapable of predicting specific impacts to stream flows from groundwater pumping in a specific well in time, location, and amount. We compared the construction of these two models, the administrative rules for which they are being applied, and ask philosophical questions about when administrative expediency outweighs the need for a state-of-the-art understanding of geologic and hydrogeologic complexities.

Geological Society of America Abstracts with Programs. Vol. 58, No. 4

doi: 10.1130/abs/2026RM-410698

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