Geology Reference
In-Depth Information
8.3.2 RUSLE2 implementation
and lessons learned
desired. In RUSLE2 inappropriate changes are
controlled by three mechanisms. The first is the
user interface, which is very user-configurable.
This allows more complicated inputs or outputs
to be removed from the visible set, simplifying
the model to a degree matching the user's inter-
ests and abilities. Since in the RUSLE2 calcula-
tion engine a parameter that is not needed is not
calculated, removing unnecessary parameters
also accelerates calculations. The second control
mechanism is called access control, which limits
what the user is allowed to see or edit. Access
must be granted to the user by a higher-level user,
providing a very flexible control structure that
can be modified as a user is trained and needs
greater control over the program. The third con-
trol mechanism is protection of specific records
or groups of records within the database. For
example, records created by a user with a high
access level can only be edited and re-saved by a
user with that access level or a higher one in the
same access chain. Other users can edit the
record, but can only save it as another record,
over which they can exert control. As a result,
once NRCS creates and locks a record, they can
distribute it with the confidence that it cannot be
modified by less knowledgeable users.
(i) RUSLE2 websites
There are two 'official'
RUSLE2 web sites: an ARS site, http://www.ars.
usda.gov/Research/docs.htm?docid
6010, and an
NRCS site, http://fargo.nserl.purdue.edu/rusle2_
dataweb/RUSLE2_Index.htm. Both sites offer the
same model, but with different databases, per-
mission (access) levels, and templates. The ARS
site provides a minimal database and access lev-
els that allow scientists and engineers to see and
change more parameters. The NRCS site includes
much more extensive databases, and templates
including a wide variety of additional tools, but
the permissions for database manipulation are
more restricted. The USDA-NRCS website is the
single national point of delivery for the NRCS-
approved RUSLE2 management templates and
database components. Both websites contain doc-
umentation and training materials.
The NRCS website is remotely maintained
and kept current by the NRCS database manager,
who posts frequent database updates, revised
soils data in RUSLE2 format, and updates to the
24,000
=
management templates. Although the
current version installer is posted for download-
ing and installation by private sector users, the
NRCS has recently begun using an automatic
software installation process for new releases of
RUSLE2. This minimizes the amount of support
time necessary to remove and install RUSLE2 on
NRCS field office computers.
+
(iii) RUSLE2 database development and manage-
ment
RUSLE2 is supported by databases that
store factor data and data entered by users. The
climatic data are held in a location/climate
description stored in the database, as are the soil
data in their own separate description. These can
then be accessed for re-use simply by calling for
them by name. The most extreme example of this
approach is in the management descriptions.
A management description is a list of the field
operations and associated dates, including what
vegetation is planted or residue added (if any).
These field operation, vegetation, and residue
descriptions are each stored in their own named
database descriptions for potential re-use by other
managements, which in turn can also be stored.
Database development began in early 2000
with the designation of a USDA-NRCS National
Database Manager or 'czar' who was given the
(ii) RUSLE2 interface: plasticity and security
An internal NRCS oversight and evaluation
review of RUSLE1 implementation uncovered
significant differences in soil loss estimates from
RUSLE1 across county lines in adjacent states
and regions due to a lack of consistent RUSLE1
databases within NRCS. With this past experi-
ence in mind, RUSLE2 was implemented with a
hierarchical approach that allows users to see and
change only those factors they fully understand.
In RUSLE1, any user could change any parameter,
sometimes leading to a very unlikely combina-
tion of inputs that gave them the output they
