1r3.gwflow(1) Grass User's Manual r3.gwflow(1)
2
6 r3.gwflow - Numerical calculation program for transient, confined
7 groundwater flow in three dimensions
8
10 raster3d, voxel
11
13 r3.gwflow
14 r3.gwflow help
15 r3.gwflow [-ms] phead=string status=string hc_x=string hc_y=string
16 hc_z=string [q=string] s=string [r=string] output=string [veloc‐
17 ity=string] dt=float [maxit=integer] [error=float] [solver=name]
18 [relax=float] [--overwrite] [--verbose] [--quiet]
19 Flags:
21 -m
22 Use G3D mask (if exists)
23 -s
25 Use a sparse linear equation system, only available with iterative
26 solvers
27 --overwrite
29 Allow output files to overwrite existing files
30 --verbose
32 Verbose module output
33 --quiet
35 Quiet module output
36 Parameters:
38 phead=string
39 The initial piezometric head in [m]
40 status=string
42 The status for each cell, = 0 - inactive, 1 - active, 2 - dirichlet
43 hc_x=string
45 The x-part of the hydraulic conductivity tensor in [m/s]
46 hc_y=string
48 The y-part of the hydraulic conductivity tensor in [m/s]
49 hc_z=string
51 The z-part of the hydraulic conductivity tensor in [m/s]
52 q=string
54 Sources and sinks in [m^3/s]
55 s=string
57 Specific yield in 1/m
58 r=string
60 Recharge raster map in m^3/s
61 output=string
63 The piezometric head result of the numerical calculation will be
64 written to this map
65 velocity=string
67 Calculate the groundwater distance velocity vector field and write
68 the x, y, and z components to maps named name_[xyz]. Name is base‐
69 name for the new raster3d maps
70 dt=float
72 The calculation time in seconds
73 Default: 86400
74 maxit=integer
76 Maximum number of iteration used to solver the linear equation sys‐
77 tem
78 Default: 100000
79 error=float
81 Error break criteria for iterative solvers (jacobi, sor, cg or
82 bicgstab)
83 Default: 0.0000000001
84 solver=name
86 The type of solver which should solve the symmetric linear equation
87 system
88 Options: gauss,lu,cholesky,jacobi,sor,cg,bicgstab,pcg
89 Default: cg
90 relax=float
92 The relaxation parameter used by the jacobi and sor solver for
93 speedup or stabilizing
94 Default: 1
95
97 This numerical program calculates transient, confined groundwater flow
98 in three dimensions based on volume maps and the current 3d region res‐
99 olution. All initial- and boundary-conditions must be provided as vol‐
100 ume maps.
101 This module calculates the piezometric head and optionally the ground‐
102 water velocity field. The vector components can be visualized with
103 paraview if they are exported with r3.out.vtk.
104 The groundwater flow will always be calculated transient. If you want
105 to calculate stady state, set the timestep to a large number (billions
106 of seconds) or set the specific yield raster maps to zero.
107
109 The groundwater flow calculation is based on Darcy's law and a finite
110 volume discretization. The groundwater flow partial differential equa‐
111 tion is of the following form:
112 (dh/dt)*S = Kxx * (d^2h/dx^2) + Kyy * (d^2h/dy^2) + Kzz * (d^2h/dz^2) +
114 q
115 h -- the piezometric head im meters [m]
117 dt -- the time step for transient calculation in seconds
119 [s]
120 S -- the specific yield [1/m]
122 b -- the bottom surface of the aquifer meters [m]
124 Kxx -- the hydraulic conductivity tensor part in x direc‐
126 tion in meter per second [m/s]
127 Kyy -- the hydraulic conductivity tensor part in y direc‐
129 tion in meter per seconds [m/s]
130 Kzz -- the hydraulic conductivity tensor part in z direc‐
132 tion in meter per seconds [m/s]
133 q - inner source in [1/s]
135 Two different boundary conditions are implemented, the Dirichlet and
136 Neumann conditions. By default the calculation area is surrounded by
137 homogeneous Neumann boundary conditions. The calculation and boundary
138 status of single cells can be set with the status map, the following
139 cell states are supportet:
140 0 == inactive - the cell with status 0 will not be calu‐
142 lated, active cells will have a no flow boundary to an
143 inactive cell
144 1 == active - this cell is used for groundwater calcula‐
146 tion, inner sources can be defined for those cells
147 2 == Dirichlet - cells of this type will have a fixed
149 piezometric head value which do not change over time
150 The groundwater flow equation can be solved with several solvers. Adi‐
151 tionally a direct Gauss solver and LU solver are available. Those
152 direct solvers only work with quadratic matrices, so be careful using
153 them with large maps (maps of size 10.000 cells will need more than one
154 gigabyte of ram).
155
157 Use this small script to create a working groundwater flow area and
158 data. Make sure you are not in a lat/lon projection.
159 # set the region accordingly
160 g.region res=25 res3=25 t=100 b=0 n=1000 s=0 w=0 e=1000
161 #now create the input raster maps for a confined aquifer
162 r3.mapcalc "phead=if(row() == 1 && depth() == 4, 50, 40)"
163 r3.mapcalc "status=if(row() == 1 && depth() == 4, 2, 1)"
164 r3.mapcalc "well=if(row() == 20 && col() == 20 , -0.00025, 0)"
165 r3.mapcalc "hydcond=0.00025"
166 r3.mapcalc "syield=0.0001"
167 r.mapcalc "recharge=0.0"
168 r3.gwflow --o -s solver=cg phead=phead status=status hc_x=hydcond
169 hc_y=hydcond \
170 hc_z=hydcond q=well s=syield r=recharge output=gwresult dt=8640000
171 velocity=gwresult_velocity
172 # The data can be visulaized with paraview when exported with
173 r3.out.vtk
174 r3.out.vtk -p in=gwresult,status vector=gwresult_velocity_x,gwre‐
175 sult_velocity_y,gwresult_velocity_z out=/tmp/gwdata3d.vtk
176 #now load the data into paraview
177
180 r.gwflow
181 r3.out.vtk
182
184 Soeren Gebbert
185 Last changed: $Date: 2007-07-04 09:52:35 +0200 (Wed, 04 Jul 2007) $
187 Full index
189 © 2003-2008 GRASS Development Team
191GRASS 6.3.0 r3.gwflow(1)