Geology Reference
In-Depth Information
Fraction of organic carbon in soils,
Density of fluid,
Viscosity of fluid,
Longitudinal and transverse dispersivity,
Diffusion coefficient,
Chemical decay rate or degradation constant,
Equations describing chemical transformation processes, if applicable,
and
Initial distribution of electron acceptors, if applicable.
Mathematical Models:
are used to simulate the components of the conceptual
model and include a single equation or set of governing equations that
presents the processes occurring (e.g. groundwater flow, solute transport,
etc.). The mathematical models rely upon the solution of the basic equations
of groundwater flow, heat flow and mass transport. The simplest mathematical
model of groundwater flow is Darcy's law. Darcy's law is an example of an
Analytical Model.
Analytical Models:
Analytical models are an exact solution of a specific,
greatly simplified, groundwater flow or transport equation. The equation is
a simplification of more complex three-dimensional groundwater flow or
solute transport equations. Prior to the development and widespread use of
computers, there was a need to simplify the three-dimensional equations
because it was not possible to easily solve these equations. Specifically,
these simplifications resulted in reducing the groundwater flow to one
dimension and the solute transport equation to one or two dimensions. This
resulted in changes to the model equations that include one-dimensional
uniform groundwater flow, simple uniform aquifer geometry, homogeneous
and isotropic aquifers, uniform hydraulic and chemical reaction properties,
and simple flow or chemical reaction boundaries. Analytical models are
typically steady state and one-dimensional, although selected groundwater
flow models are two dimensional (e.g. analytical element models), and some
contaminant transport models assume one-dimensional groundwater flow
conditions and one-, two- or three-dimensional transport conditions. Well
hydraulics models, such as the Theis or Neumann methods, are examples of
analytical one-dimensional groundwater flow models. Because of the
simplifications inherent with analytical models, it is not possible to account
for field conditions that change with time or space. This includes variations
in groundwater flow rate or direction, variations in hydraulic or chemical
reaction properties, changing hydraulic stresses, or complex hydrogeologic
or chemical boundary conditions.
Numerical Models:
Numerical models are capable of solving the more
complex equations that describe groundwater flow and solute transport. These
equations generally describe multi-dimensional groundwater flow, solute
transport and chemical reactions, although there are one-dimensional
