RELEASE.TXT

                           MODPATH Version 7 Release Notes

     This file describes changes introduced into MODPATH version 7 with 
each official release; these changes may substantially affect users. 

NOTE: Any use of trade, product or firm names is for descriptive purposes 
      only and does not imply endorsement by the U.S. Government.
      

o Version 7.1.000  September 26, 2016

This version is the initial public release.

Users should be aware of the following limitations of this version related to 
particle tracking with unstructured grids:

1. MODPATH supports rectangular-based quad-refined unstructured grids that have 
   refinement both horizontally as well as vertically from layer to layer. However,
   the maximum refinement level contrast between adjacent grid cells must not 
   be greater than 1. That means that any grid cell can be connected to either 0, 1,
   or 2 grid cells across any adjacent horizontal face, or 0, 1, or 4 grid cells
   across the top or bottom face. These types of unstructured grids commonly are
   referred to as smoothed quadtree or quadpatch grid.
   
2. MODFLOW-USG simulations intended for use with MODPATH-7 should always use ghost 
   nodes to minimize the effects of flow oscillations from cell to cell. 
   
3. Although ghost nodes greatly reduce flow oscillations, significant flow oscillations
   often are present in the vertical direction in the immediate vicinity of internal
   sources and sinks even when ghost nodes are used. At the present time, we recommend
   that the same plan view unstructured grid be used for all model layers to avoid
   the problem with vertical flow oscillations.
   
4. For unstructured grid simulations based on MODFLOW-USG, this version of MODPATH currently 
   is restricted to grids that have square grid cells in plan view. Particle tracking
   simulations based on traditional structured grid MODFLOW simulations are not affected 
   by this limitation.