What is it?
The USGS releases multiple versions of MODFLOW. There is a core MODFLOW version (currently MODFLOW-6) that is under active development and is often the most widely used and most thoroughly tested version. MODFLOW-2005 (the previous core version) is still actively maintained and supported. Advanced MODFLOW versions include specialized MODFLOW variants and versions of MODFLOW that use newer formulations. These advanced MODFLOW versions are also available from the USGS.There have been six major releases of the core MODFLOW version: MODFLOW-84, MODFLOW-88, MODFLOW-96, MODFLOW-2000, MODFLOW-2005, and MODFLOW 6. With MODFLOW-2000, the part of the code that solves the groundwater-flow equation became the Groundwater Flow (GWF) Process. Although additional processes have been developed for MODFLOW, the GWF Process remains a core process on which other MODFLOW simulation capabilities are built. The primary change in MODFLOW-2005 from MODFLOW-2000 is the approach used by MODFLOW-2005 for managing internal data. MODFLOW 6 is the newest core version and uses a new format for input of model data. It was written from scratch using an object-oriented design, and is an entirely new version of MODFLOW. MODFLOW 6 presently supports one type of process model — the GWF Model. Other models may be added in the future, such as a groundwater transport model, a surface-water model, and a pipe network model, for example.
Core Versions
- MODFLOW-6: current core version
- MODFLOW-2005: previous core version
- MODFLOW-2000: previous core version
MODFLOW Variants - Newer, specialized, or advanced versions of MODFLOW for use by experienced modelers
- MODFLOW-NWT: implementation of a Newton-Raphson formulation to improve solution of unconfined groundwater-flow problems.
- MODFLOW-USG: implementation of a node-based approach to simulate groundwater flow and tightly coupled processes using a control volume finite-difference formulation in unstructured grids (The IGW-NET platform currently only supports structured grids in MODFLOW-USG).
Additional USGS version overview info
Supported Flow Packages
IGW-NET allows the user to run conceptual models with one of four flow packages across five MODFLOW versions including:MODFLOW-6
- Node Property Flow (NPF)
MODFLOW-USG
- Layer Property Flow (LPF)
- Block Centered Flow (BCF)
MODFLOW-NWT
- Upstream Weighting Flow (UPW)
MODFLOW-2005
- Layer Property Flow (LPF)
- Block Centered Flow (BCF)
MODFLOW-2000
- Layer Property Flow (LPF)
- Block Centered Flow (BCF)
Supported Solvers
IGW-NET allows the user to run conceptual models with one of nine solver packages across five MODFLOW versions including:MODFLOW-6
- Integrated Model Solution (IMS6)
MODFLOW-USG
- Sparse Matrix Solver (SMS)
MODFLOW-NWT
- Newton-Raphson Solver (NWT)
MODFLOW-2005
- Preconditioned Conjugate Gradient Method Solver (PCG)
- Preconditioned Conjugate Gradient Solver with Improved Nonlinear Control Solver(PCGN)
- Geometric MultiGrid Solver (GMG)
- Strongly Implicit Procedure Solver (SIP)
- Direct Solver (DE4)
MODFLOW-2000
- Slice-Successive Over Relaxation Solver (SSOR or SOR)