Presampling - Field Sampling: Principles and Practices in Environmental Analysis - page 78

combined with topography, soil type, and contaminant concentration can be combined on
one map of the field. This combined picture produces an informative map of the area
[18]. The most common computer software used for GIS is called Arc View. There is
other software that will do the same things, and all should be investigated before deciding
on a system to use. Note that even if you do not intend to start your own GIS you may
need some or all of the software to view and work with GIS produced by local, state, and
national governments.
3.16. MODELING
Data collected during sampling, or obtained by analysis of samples or from other sources
will be useful in building a model of the field and how it will react in the future. We can
think of this as a model of the field before sampling is started. It can also be a dynamic
model that will allow calculation of the expected future characteristics of the field. These
models can be very effective in explaining what is happening, in deciding where to
sample, what to analyze a sample for, and what type of follow-up sampling will be
needed.
Modeling requires a model. This can be a simple physical model or a complex
computer simulation. A physical model can provide information about many aspects of
the field but will have limited predictive capability. A complex computer simulation can
be used to predict the course of the work and will also allow changes in the inputs to
explore various situations that may occur in the future. It will also allow changes in the
model as more data become available.
Modeling is another component of the sampling plan that needs to be explored at this
time.
3.17. PERMITTING
In many instances it will be necessary to have permits for a sampling and remediation
plan. These will generally not be needed when sampling farm fields for such things as
plant nutrients. Sampling for toxic or dangerous materials or other situations may require
permits, however. Permits can be of many different kinds; earth disturbance, erosion and
sedimentation control, water obstruction and encroachment, and various permits
associated with landfills are a few examples of activities that may require a permit.
Permitting is a state activity, thus different states require different permits. One state may
require a permit for an activity while another does not. It is best to go to the state or local
Environmental Protection Agency office and check to see what may be needed in this
regard.
3.18. RESOURCES
Commercial and governmental sources of the equipment, supplies, computer software,