Dear colleagues,

We  are  sending  you a copy of our now  user  friendly  (we
hope!) shallow slope stability models, SHALSTAB TOOLS. It as
been written as an ArcView extension, coupled with a C++ DLL
for  Windows (95/98/NT). If you are to use the attached file
you  will  need  to  have ArcView 3.1 a or  higher  on  your
machine. The memory requirements are those of arcview.  ESRI
recommends   32Mb,  but  as  usual  the  more  the   better.
Similarly,  you  will  need a fair  amount  of  disk  space,
depending  on  the size of your data. 100Mb should  do,  but
once  again, the more the better. For detail ArcView  system
specifications refer to:

http: //www.esri.com/software/arcview/system.html

If  you  do  not  have ArcView, you can obtain  a  one-month
evaluation copy by filling out the forms found at:

http: //www.esri.com/software/arcview/evalcd_order.html

This  is  a  "beta" version which means you might  run  into
"bugs" or other types of problems. We hope you will try  and
report   back   any  difficulties  so  that  we   can   make
improvements upon its formal release. There are  still  some
imperfections,  but we feel the program is  ready  for  some
serious  testing. Please send all feedback to  Dino  Bellugi
(dino@geomorph.berkeley.edu).

The  creation  of  this software has been supported  by  the
California Department of Forestry and Fire Protection  (CDF)
and  by  Stillwater Sciences (Berkeley). We will  eventually
make    the    program   available   at   our    web    site
(http://socrates.berkeley.edu/~geomorph/) and it  will  also
be available from CDF.

We  include  two  trial  data sets,  one  from  the  Redwood
tributary of the Noyo River in Northern California  and  the
other  from out study site near Coos Bay Oregon. The Redwood
data set is typical of current technology: 10 m grid derived
from  the USGS 7.5' quadrangle (generated using the TOPOGRID
function  in  ArcInfo). The landslide coverage (shallow.shp)
came  from  a map by John Coyle based exclusively on  aerial
photographs,  and  consequently it  has  typical  errors  of
misidentification and location that will  occur  when  using
aerial  photographs.  The Coos Bay  topography  was  created
using  airborne laser altimetry with a data density of about
2.5  m.  Dave Montgomery (see Montgomery et al.,  in  press,
GEOLOGY),  mapped the landslides (slides.shp) in the  field.
It is a very accurate map.

An  explanation  of SHALSTAB is available  in  the  Tutorial
included with the model as well as on our web site,  and  we
recommend you review it. Please keep in mind that it is also
a  work  in progress and may not be aligned with the current
version  of  the  software (file and menu  names  might  not
match).  Also  there is a report by Dietrich and  Montgomery
(1998) available at the NCASI web page discussing SHALSTAB (
http://www.ncasi.org ).

An  important feature of the TOOLS is that you can  run  the
model as cohesionless (SHALSTAB) or spatially fixed cohesion
and  soil  depth  (SHALSTABco). The default values  are  the
standard  values  we  used and strongly  recommend  (but  of
course   do   explore  what  happens  as  you   vary   these
parameters).

If  you have landslide data digitized you can examine  model
performance  using  the  SHALtest tool  by  looking  at  the
stability pattern relative to the landscape and relative  to
a biased random model of landslide
occurrence. You can also examine the values of landslide (or
landscape)stability relative to the theory using a  plot  of
area  and  slope (as illustrated in Dietrich et  al.,  1992,
Geology) and in the 1998 report cited above.

Through this testing you may be able to reject the model  or
optimize the parameters such that you have the smallest area
that  successfully identifies the location of  most  of  the
landslides (a manuscript by
Dietrich  et  al.  that  is in review which  describes  this
approach can be made available upon request).

We  welcome all comments and hope to have the final  release
in the next few months. We will notify you when that occurs.

Thanks,

Bill Dietrich

