Developing the RHESSys / ArcView
Integrated Modeling Environment
David Tenenbaum
Univ. of North Carolina-Chapel Hill
Landscape Representation
RHESSys divides the landscape into a series
of successively contained partitions
1) World
Basin
Hillslope
Zone
Patch
Stratum
2) The method for creating a
partition is determined by
the processes it will represent
3) Once landscape objects in a
partition are defined,
parameters at that level can
be calculated
Old technology: grass2world
• GRASS - a shareware raster
GIS produced by the U.S.
Army CERL
• Augmented with standalone
code for unimplemented
functions and algorithms
• Methods and results stored in
ASCII text files
Visualization of results
and comparison of
methods is AWKWARD
New Technology: RAIMEnt
•implemented in
ESRI’s ArcView
GIS using Avenue
R HESSys
A rcView
I ntegrated
M odeling
E nvironment
n
t
•Presents tightly
coupled functions
accessed using a single
graphical user interface
(GUI)
•Methods and results
stored in Shapefiles
and tables Visualization of results
and comparison of
methods is EASY
RAIMEnt Partitioning
• Specify a theme for
partitioning using a
dialog box
• Performs a raster
intersection with its
parent partition
• New partition is
produced and shown
• Method of partitioning
is stored in Partitioned
Objects Table
RAIMEnt Parameter Generation
• Specify methods
using a short string,
stored in Parameter
Generation Table
• Methods include:
– constant
– equation
– expression using
spatial data
• Results are calculated,
method stored in table
The key advantages
• ArcView Shapefile / Theme
representation links parameters
to the spatial representation of
objects for easy visualization
• Model runs managed and output
visualized on the fly
• Optimal capabilities of raster
and vector data models are used
• Storing partitioning and
parameter generation methods
inside RAIMEnt along with
results promotes the learning of
effective new methods
What RAIMEnt offers here
RAIMEnt offers an environment
where augmenting RHESSys can be
explored efficiently and effectively,
so that we can more quickly learn
new methods for the effective
representation of landscapes, and
accumulate this knowledge by
storing the methods systematically
along with their results
Development Issues
RAIMEnt as a prototype for a system for
supporting RHESSys revealed some of the
significant difficulties in doing so:
•RHESSys evolves quickly ... Parameters and
even its structure changes
•File sizes and processing time can be large
enough that the GUI is not pleasant to use
•Trying to house all the required functionality
in one package is tricky
Development Solutions
RAIMEnt as a prototype has evolved to deal
with some of these problems:
•System reads the object structure from a table,
which can be modified to reflect changes
•‘Tricks’ in coding can make handling the large
World more efficient
•Expanded capabilities through linking with
external executables (another ‘trick’).
Where To Go From Here
The key issue in developing a support system for
RHESSys is how complicated / capable it
should be:
•grass2world is very simple and easy to use but
places a significant burden on the user to know
a lot about RHESSys in creating a useful World
•RAIMEnt is too complex and difficult to use /
make work, and tries to take on a lot of that
burden, perhaps too much
From Prototype to Release
•There is a middle ground between grass2world
and what I tried to do with RAIMEnt
•By developing and enhancing this prototype I
have a clearer idea of how to write a package
that will be useful and easy to use
•There is a real demand for me to get this done
... but I still need to ask for your patience ... in a
half-baked form, I don’t think this software is
going to help anyone use RHESSys