Geology Reference
In-Depth Information
Problems involving heat also require an equation, similar to the solute transport
equation, but now in terms of temperature. This model is referred to as a
heat transport model
. Finally, a
deformation model
combines a groundwater
flow model with a set of equations that describe aquifer deformation. All of
the models start with the basic equations of groundwater flow.
Models may be subdivided into those describing porous media and those
describing fractured media. Large number of models have come up to resolve
diverse type of hydrogeological problems. Some most widely used models
are:
Physical Scale Model:
is made from the same material as those of the
natural system. Sand Models have been used for different types of
hydrogeological studies such as dispersion, artificial recharge and seawater
intrusion etc.
Analog Model:
may be developed using electric circuits or viscous fluid
flow as the governing equations of groundwater flow through porous media
is similar to electricity through conductor. Two-dimensional groundwater
flow can be analogous to the flow of a viscous fluid between two very
closely spaced parallel plates. The model is known as Hele-Shaw model.
Fate and Transport Models:
simulate the movement and chemical alteration
of contaminants as they move with groundwater through the subsurface.
These models require the development of a calibrated groundwater flow
model or, at a minimum, an accurate determination of the velocity and
direction of groundwater flow, which has been based on field data. Fate and
transport models are used to simulate the following processes:
Movement of contaminants by advection and diffusion,
Spread and dilution of contaminants by dispersion,
Removal or release of contaminants by sorption, or desorption, of
contaminants onto, or from, subsurface sediment or rock, or
Chemical alteration of the contaminant by chemical reactions, which may
be controlled by biological processes, or physical chemical reactions.
In addition to a thorough hydrogeological investigation, the simulation of
fate and transport processes requires a complete characterization of the
following:
Horizontal and vertical distribution of average linear groundwater velocity
(direction and magnitude) determined by a calibrated groundwater flow
model or through accurate determination of direction and rate of
groundwater flow from field data,
Boundary conditions for the solute,
Initial distribution of solute (initial conditions),
Location, history and mass loading rate of chemical sources or sinks,
Effective porosity,
Soil bulk density,
