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USGS - science for a changing world

Groundwater Modeling

A hydrologic model is a simplified conceptual and computer model used to simulate and predict the movement and use of water. It takes into account various or all components of the landscape, aquifer system, and water cycle and provides a framework to organize data, knowledge, and understanding of hydrologic systems. Models can provide insights that water-resource managers need to plan effectively for future water demands and to answer scientific and management questions.

California Groundwater Model Archive

The USGS models shown on this site are in the public domain, and are freely available. They are based on MODFLOW and other public-domain USGS software. Links to publications and web resources associated with each model are shown in the table next to the model map. The associated model files for some of these models are currently available via links in this table; if a link is not available, and you would like to receive the model files, please contact Steve Phillips at

Click on a model on the map or in the list for detailed information and data downloads.


Model Development
Model developed, but no simulation of alternative water-use/management scenarios. Indicates type(s) of model(s) developed.
Modeling with Scenarios
Modeling/assessment of alternative water-use/management scenarios.
Uncertainty Analysis
Parameter: Model parameter estimation with automated techniques; in some reports, also includes sensitivity analysis, correlation analysis, and/or parameter uncertainty analysis.
Prediction: Model-prediction uncertainty analysis.
Modeling coupled with optimization to identify "best" management plans.
Climate Change Analysis
Study included assessment of impacts of climate change using down-scaled climate-model projections.
Advanced Analyses
Modeling combined with advanced tools such as stochastic optimization, multi-objective analysis, economics, etc. For a study with advanced analyses, the type of analysis is noted.
Sustainability Indicator(s) Modeled (from CA's Sustainable Groundwater Management Act)
LVL – Changes in groundwater levels
STOR – Changes in groundwater storage
SEA – Seawater intrusion
SUB – Subsidence
SW/GW – Surface water / groundwater interactions
  • drn - drain
  • strm - stream/spring
  • lak - lake/reservoir
  • hab - habitat impacts
WQ – Water quality