② Mathematical model for migration of pollutes in groundwater
This evaluation is based on the iterative calculation function of Modflow software
of Visual Modflow and MT3DS module.
I. Flow mathematical model
For heterogeneous, isotropic, three-dimensional spatial structures and unsteady
groundwater flow systems, the following definite solutions of differential equations
can be used for description:
S
@h
@t ¼
@
@x K x
@h
@x
À
Á þ
@
@y K y
@h
@y
þ
@
@z K z
@h
@z
x; y; z 2 X; t ! 0
hðx; y; z; tÞ t¼0 ¼
j
h 0
x; y; z 2 X; t ! 0
h ¼ h 1
x; y; z 2 C 1 ; t ! 0
K n
@h
@~ n C 2
j ¼ qðx; y; tÞ
x; y; z 2 C 2 ; t ! 0
8
> > > <
> > > :
where X—vadose region; h—head (m); K—permeability coefficient (m/d); K n —
Normal permeability coefficient of boundary surface (m/d);
S—storage coefficient; h 0 —initial head (m); C 0 —upper boundary of vadose region;
C1—water level boundary of vadose region;
C 2 —flow boundary of vadose region; ñ—normal direction of boundary surface; q
(x, y, z, t)—unit discharge of Neumann boundary condition (m
3 /d m), the inflow is
positive, the outflow is negative, and the confining boundary is 0.
II. Mathematical model of solute migration
The migration and transformation process of pollutants in groundwater is extremely
complicated. There are convection and dispersion, as well as chemical and biochemical effects such as ion exchange, chemical reaction and microbial degradation
that may absorb solid particles. We only consider convection and dispersion herein.
The three-dimensional solute migration with convection and dispersion can be
described by the definite solution of the following differential equation:
Hydrogeological conditions
1. Field survey and investigation
2. Indoor and outdoor test
(experiment)
Site pollution characteristics
Hydrogeological parameters
Related parameters of solute
transport
3. Numerical modeling
Groundwater flow model
Solute transport model
Analysis of effectiveness and
rationality of existing monitoring wells
Fig. 5.79 Technical route for numerical simulation analysis
5.5 North China
313
This evaluation is based on the iterative calculation function of Modflow software
of Visual Modflow and MT3DS module.
I. Flow mathematical model
For heterogeneous, isotropic, three-dimensional spatial structures and unsteady
groundwater flow systems, the following definite solutions of differential equations
can be used for description:
S
@h
@t ¼
@
@x K x
@h
@x
À
Á þ
@
@y K y
@h
@y
þ
@
@z K z
@h
@z
x; y; z 2 X; t ! 0
hðx; y; z; tÞ t¼0 ¼
j
h 0
x; y; z 2 X; t ! 0
h ¼ h 1
x; y; z 2 C 1 ; t ! 0
K n
@h
@~ n C 2
j ¼ qðx; y; tÞ
x; y; z 2 C 2 ; t ! 0
8
> > > <
> > > :
where X—vadose region; h—head (m); K—permeability coefficient (m/d); K n —
Normal permeability coefficient of boundary surface (m/d);
S—storage coefficient; h 0 —initial head (m); C 0 —upper boundary of vadose region;
C1—water level boundary of vadose region;
C 2 —flow boundary of vadose region; ñ—normal direction of boundary surface; q
(x, y, z, t)—unit discharge of Neumann boundary condition (m
3 /d m), the inflow is
positive, the outflow is negative, and the confining boundary is 0.
II. Mathematical model of solute migration
The migration and transformation process of pollutants in groundwater is extremely
complicated. There are convection and dispersion, as well as chemical and biochemical effects such as ion exchange, chemical reaction and microbial degradation
that may absorb solid particles. We only consider convection and dispersion herein.
The three-dimensional solute migration with convection and dispersion can be
described by the definite solution of the following differential equation:
Hydrogeological conditions
1. Field survey and investigation
2. Indoor and outdoor test
(experiment)
Site pollution characteristics
Hydrogeological parameters
Related parameters of solute
transport
3. Numerical modeling
Groundwater flow model
Solute transport model
Analysis of effectiveness and
rationality of existing monitoring wells
Fig. 5.79 Technical route for numerical simulation analysis
5.5 North China
313