The MODFLOW 6 Modular Hydrologic Model

Monday, December 3, 2018: 10:20 a.m.
N109 (Las Vegas Convention Center)
Christian D. Langevin, Ph.D. , Office of Groundwater, U.S. Geological Survey, Reston, VA
Joseph Hughes, Ph.D. , Office of Groundwater, U.S. Geological Survey, Reston, VA
Alden M. Provost , U.S. Geological Survey, Reston, VA
Richard Niswonger , USGS, Menlo Park, CA
Sorab Panday , GSI Environmental, Herndon, VA

MODFLOW 6 is the latest core release of the U.S. Geological Survey’s modular hydrologic model. MODFLOW 6 synthesizes many of the recent MODFLOW advances into a single program and provides an object-oriented framework for adding new types of models and packages. The first release of MODFLOW 6 contains the Groundwater Flow (GWF) Model, which combines most of the capabilities of MODFLOW-2005, MODFLOW-NWT, MODFLOW-USG, and MODFLOW-LGR. The GWF Model supports both structured and unstructured grids, with the capability to remove thin or inactive cells from the simulation. When thin cells are removed from the simulation, the model automatically connects overlying and underlying cells. The GWF Model includes a new formulation, called XT3D, for representing full, three-dimensional anisotropic groundwater flow and for improving the flow approximation for certain grid types. The GWF Model in MODFLOW 6 contains the six, traditional MODFLOW stress packages (Well, Drain, River, General-Head Boundary, Recharge, and Evapotranspiration) and four advanced hydrologic stress packages (Multi-Aquifer Well, Streamflow Routing, Lake, and Unsaturated Zone Flow). MODFLOW 6 also includes a new and generalized way to move water between these hydrologic stress packages. This new capability can be used to route water from drains into a stream, for example, or to send rejected infiltration into a nearby lake. The object-oriented framework also makes it possible to tightly couple any number of parent, child, and grandchild models, or to couple an unstructured GWF Model of a shallow aquifer with a deep aquifer GWF Model that uses a regular grid. Future plans for MODFLOW 6 include the addition of a new subsidence package, variable-density groundwater flow, and transport.

Christian D. Langevin, Ph.D., Office of Groundwater, U.S. Geological Survey, Reston, VA
Christian Langevin is a hydrologist with the U.S. Geological Survey Office of Groundwater in Reston, Virginia. He is the author of the SEAWAT computer program for MODFLOW/MT3DMS-based simulation of variable-density groundwater flow and solute transport. His work centers on SEAWAT development and its application to a wide range of coastal groundwater problems.

Joseph Hughes, Ph.D., Office of Groundwater, U.S. Geological Survey, Reston, VA
Dr. Hughes is a hydrologist in the USGS Office of Groundwater

Alden M. Provost, U.S. Geological Survey, Reston, VA
Alden Provost is a hydrologist with the U.S. Geological Survey. He is a coauthor of the variable-density ground-water flow and transport simulator SUTRA.

Richard Niswonger, USGS, Menlo Park, CA

Sorab Panday, GSI Environmental, Herndon, VA
Dr. Sorab Panday is a Principal Engineer at GSI Environmental with over 27 years of experience in directing, managing, developing, troubleshooting and reviewing flow and transport models for subsurface contamination evaluations, groundwater/surface-water interactions, and water resource management. He has developed several of the industry’s state-of-the-art water resource modeling codes and is the lead author on MODFLOW-USG, an unstructured-grid version of MODFLOW released by the USGS.