Geology Reference
In-Depth Information
is included especially to dispel the notion that
RUSLE2 is difficult and complicated to use. The
other examples represent two common uses of
RUSLE2. The second example compares manage-
ment alternatives on a single field, as would prob-
ably be done by a conservation planner working
with an agricultural producer. The third example
demonstrates planning to meet a specific sedi-
ment delivery target on a construction site. In
both of these latter cases the figure will appear
relatively complex, but this complexity was added
so that specific features could be highlighted.
In this access level and view, the user has no
way of directly modifying any of the inputs except
slope length and steepness. Everything else must
be selected from pre-defined descriptions in the
database, presumably placed there by someone
with the training and knowledge to do so. Most
users are not long satisfied with so little flexibil-
ity. For example, they may want to be able to see
the impact of a complex slope shape rather than
being forced to assume a uniform slope. This
increased power comes at the cost of increased
complexity, as the user must now be faced with a
user template allowing them to enter length and
steepness values for the slope segments. This
constant desire for more power and flexibility
results in what the RUSLE2 development team
calls 'template creep', which is the tendency of
user templates to become increasingly complex
over time in order to provide additional power.
The RUSLE2 complexity that some users com-
plain of is not built into the RUSLE2 program,
but rather exists because other users who devel-
oped that user template thought those entries
and outputs were necessary.
Finally, notice that Plate 5 shows the inputs
and results in metric units, while the values
shown in Plate 4 were in Imperial units. This
demonstrates some of the additional flexibility of
the RUSLE2 interface, which allows for any
desired mixing and matching of units, and also
for selecting the desired units within a system
(e.g. cm or mm for height).
(i) Example 1. Very simple view One of the
complaints sometimes lodged against RUSLE2
is that it is too complex and difficult for a nov-
ice user. As described in the sections above, the
complexity the user sees in RUSLE2 is totally
controlled by what the user asks to see and how
they ask to see it. The calculations are exactly
the same for a simple view (Plate 5) as for a
more complex one, except that fewer calcula-
tions may be needed because fewer outputs are
requested. The user views are completely user-
configurable, so there is an infinite number of
possible views, not just some pre-specified sim-
ple, medium and complex views. The RUSLE2
screen capture (Plate 5) shows one of the sim-
pler views, which could be used by someone
with a minimal understanding of soil erosion.
In order to get an erosion and sediment delivery
result, the user need only select a location (cli-
mate), a soil, and a management from pre-exist-
ing lists in the database. They then enter a slope
length and steepness (which assumes a uniform
slope), and can immediately see the resulting
erosion and sediment delivery. If desired, this
view also allows the user to select from pre-de-
fined contour or cross-slope tillage systems, to
put in pre-defined vegetated barriers on or at the
bottom of the slope, or to see what happens if
pre-defined terrace systems are installed. If the
trainer or program supplier believes that even
these few conservation practices will not be
understood by the target user, even these entries
associated with Step 5 in the view above may be
easily removed.
(ii) Example 2. Agricultural conservation plan-
ning The RUSLE2 screen capture shown earlier
in Plate 4 presents the results of conservation
planning on a hypothetical field. In this view the
field is defined as having a single climate, soil,
and uniform slope. Each line in the table then
represents a single RUSLE2 erosion calculation,
using the climate, soil and topography defined
above, and combining it with a unique combina-
tion of contouring, terraces and cropping sequence
to yield erosion, fuel use, and Soil Conditioning
Index (SCI) results. In order from the top of the
table, the lines represent: (1) corn with moldboard
ploughing in the fall and disking in the spring,
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