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   This numerical program calculates transient, confined groundwater flow
   in three dimensions based on volume maps and the current 3d region
   resolution. All initial- and boundary-conditions must be provided as
   volume maps.
   This module calculates the piezometric head and optionally the
   groundwater velocity field. The vector components can be visualized
   with paraview if they are exported with r3.out.vtk.
   The groundwater flow will always be calculated transient. If you want
   to calculate stady state, set the timestep to a large number (billions
   of seconds) or set the specific yield raster maps to zero.

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   The groundwater flow calculation is based on Darcy's law and a finite
   volume discretization. The groundwater flow partial differential
   equation is of the following form:

   (dh/dt)*S = Kxx * (d^2h/dx^2) + Kyy * (d^2h/dy^2) + Kzz * (d^2h/dz^2) +
   q
     * h -- the piezometric head im meters [m]
     * dt -- the time step for transient calculation in seconds [s]
     * S -- the specific yield [1/m]
     * b -- the bottom surface of the aquifer meters [m]
     * Kxx -- the hydraulic conductivity tensor part in x direction in
       meter per second [m/s]
     * Kyy -- the hydraulic conductivity tensor part in y direction in
       meter per seconds [m/s]
     * Kzz -- the hydraulic conductivity tensor part in z direction in
       meter per seconds [m/s]
     * q - inner source in [1/s]

   Two different boundary conditions are implemented, the Dirichlet and
   Neumann conditions. By default the calculation area is surrounded by
   homogeneous Neumann boundary conditions. The calculation and boundary
   status of single cells can be set with the status map, the following
   cell states are supportet:
     * 0 == inactive - the cell with status 0 will not be calulated,
       active cells will have a no flow boundary to an inactive cell
     * 1 == active - this cell is used for groundwater calculation, inner
       sources can be defined for those cells
     * 2 == Dirichlet - cells of this type will have a fixed piezometric
       head value which do not change over time

   The groundwater flow equation can be solved with several solvers.
   Aditionally a direct Gauss solver and LU solver are available. Those
   direct solvers only work with quadratic matrices, so be careful using
   them with large maps (maps of size 10.000 cells will need more than one
   gigabyte of ram).

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   Use this small script to create a working groundwater flow area and
   data. Make sure you are not in a lat/lon projection.

# set the region accordingly
g.region res=25 res3=25 t=100 b=0 n=1000 s=0 w=0 e=1000

#now create the input raster maps for a confined aquifer
r3.mapcalc "phead=if(row() == 1 && depth() == 4, 50, 40)"
r3.mapcalc "status=if(row() == 1 && depth() == 4, 2, 1)"
r3.mapcalc "well=if(row() == 20 && col() == 20 , -0.00025, 0)"
r3.mapcalc "hydcond=0.00025"
r3.mapcalc "syield=0.0001"
r.mapcalc  "recharge=0.0"

r3.gwflow --o -s solver=cg phead=phead status=status hc_x=hydcond hc_y=hydcond
 \
hc_z=hydcond q=well s=syield r=recharge output=gwresult dt=8640000 velocity=gwr
esult_velocity

# The data can be visulaized with paraview when exported with r3.out.vtk
r3.out.vtk -p in=gwresult,status vector=gwresult_velocity_x,gwresult_velocity_y
,gwresult_velocity_z out=/tmp/gwdata3d.vtk

#now load the data into paraview

СÐ. ТÐÐÐÐ

   [1]r.gwflow
   [2]r3.out.vtk

ÐÐТÐÐ

   Soeren Gebbert

   Last changed: $Date: 2007-07-04 02:52:35 -0500 (СÑ, 04 иÑл 2007) $

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References

   1. file://localhost/root/tmp/2/fin/r.gwflow.html
   2. file://localhost/root/tmp/2/fin/r3.out.vtk.html