Geology Reference
In-Depth Information
bundled with the website. Four hillslope shapes
can be represented (e.g. uniform, convex, con-
cave, S-shape). Once simulation selections are
made, and the simulations are completed, WEPP
model input files in ASCII format are available on
the website. In addition, a wide variety of detailed
graphics can be displayed ranging from climatic
inputs, plant and residue attributes as a function
of simulation time, to time-varying hydraulic and
erosion parameters and model outputs.
The well-known RUSLE erosion model (Renard
et al
., 1997; and see Chapter 8) has been set up as
a web-based application for the state of Michigan
(Ouyang & Bartholic, 2001; http://www.iwr.msu.
edu/rusle/). For this application, erosion can be
calculated for agricultural and construction land
uses. A simple graphical interface is displayed for
the user to select an individual county within the
state. Drop-down menus are then displayed for
the user to enter run identification information,
hillslope characteristics, and soil types from
NRCS databases for the selected county. For the
agricultural land-use case the user then selects
from a list of cropping rotations and tillage prac-
tices by year for up to five years. From these selec-
tions the various factors of RUSLE equations are
obtained from databases and lookup tables built
into the system. The calculation for annual ero-
sion is then completed. The
C
-factor (cover) can
also be manually set.
The Water Erosion Prediction Project Climate
Assessment Tool (WEPPCAT: http://typhoon.
tucson.ars.ag.gov/weppcat/) is a further refine-
ment of the hillslope version of WEPP in which
simultaneous assessments of climate change and
the effectiveness of end-of-field filter strips for
mitigation of erosion can be evaluated. It is an
easy-to-use, web-based system that allows users
to adjust climate inputs for user-specified climate
scenarios within the continental US. It allows the
user to modify monthly mean maximum and
minimum temperatures, the monthly mean
number of wet days, monthly mean precipitation,
and rainfall intensity in order to predict changes
in surface water runoff and erosion rates.
WEPPCAT allows the user to assess erosion
changes under a large variety of land management
alternatives. It does not require specialized scien-
tific expertise to run, and scenarios are quick and
easy to set up.
The Sediment and Erosion Control Planning,
Design and SPECification Information and
Guidance Tool (SEDSPEC; Tang
et al
., 2004) pre-
dicts small watershed peak runoff and will assist
in the design of hydrological, sediment, and ero-
sion control measures. The SEDSPEC system is
composed of a model, database, and user inter-
face. Two hydrological models (the Rational
Method and TR−55) simulate short-term peak
runoff based on site-specific hydrological soil
groups and land uses. The hydrological models
estimate peak runoff using design storm data
stored in associated databases. The DSS inte-
grates WebGIS technology to help users to esti-
mate watershed boundaries and access a spatial
database to obtain land use and hydrological soil
group data for the watershed. As the final output,
SEDSPEC calculates dimensions and costs of
hydrological, sediment and erosion control struc-
tures based on users' specifications, and provides
structure maintenance information. SEDSPEC
will provide customized drawings of the struc-
tures, and there is a limited amount of interac-
tion which allows users to determine what size
structure fits their needs.
17.5.4
Watershed model applications
Unlike the hillslope erosion models, the develop-
ment of watershed model applications is just
beginning, and to date no application is currently
available 'online' that specifically addresses ero-
sion and sediment yield. One difficulty with
watershed model applications is their need for
geospatial information (e.g. digital elevation mod-
els, soil maps, land use/land cover). Making the
geospatial information for a region locally avail-
able for an Internet application using a 2- or 3-tier
architecture would be costly (i.e. creation costs,
storage requirements, maintenance). The costs
would be considerably greater if national or inter-
national applications are desired. Requiring users
to provide their own data creates other problems
related to data quality, storage requirements,
