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GIS to calculate slope lengths   Angela Moore Feb 18, 2005
Re: GIS to calculate slope lengths   Angela Moore Feb 18, 2005
Re: GIS to calculate slope lengths   Jarlath ONeil-Dunne Feb 18, 2005
Re: GIS to calculate slope lengths   Angela Moore Feb 18, 2005
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Subject GIS to calculate slope lengths 
Author Angela Moore 
Date Feb 18, 2005 
Message Hi,

We don't have 3D analyst, but the city has given us a DEM for our 280 acre campus and they processed it to give us files with the elevation data, the aspect, the slope, and maybe one other file. (I guess we can't work with the TIN with only Spatial Analyst?).

Anyway, we are doing an estimate of soil erosion from our campus and need the slope length for the soil loss equation (l). I have the equation to convert L and S values to the composite LS factor, but I am having trouble figuring out exactly *how* to get the slope length. We are working on a 5 ft grid spacing, and it seems lame for us to just fudge the slope length with crude rise/run calculations by hand!

I went to this website:

-www.cwu.edu/~rhickey/slope/slope.html

but sadly I don't have a clue about how to implement the coding or if I even have the right tools to do that. I am still a newbie user myself, unfortunately! This is for a student research project and we want to present the results, but it isn't high powered super research. Thanks for any suggestions! 
   
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Subject Re: GIS to calculate slope lengths 
Author Angela Moore 
Date Feb 18, 2005 
Message Just to clarify, we have ArcMap 9.0 with the Spatial Analyst extension but we do not have 3D analyst. 
   
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Subject Re: GIS to calculate slope lengths 
Author Jarlath ONeil-Dunne 
Date Feb 18, 2005 
Message Hands down Bob Hickey's method of calculating LS is the best. However it is extremely computationally intensive (may take several days) and requires that you have ArcInfo with ArcWorkstation and a license for GRID (Spatial Analyst) installed. The file is an AML so at the ArcWorkstation prompt you have to type "&RUN" followed by the name of the AML file (see ArcDoc for help). It will then give you a series of prompts. There are other ways to calculate LS that you may find easier, but I was not happy with the results.
http://skagit.meas.ncsu.edu/~helena/gmslab/erosion/usle.html 
  Jarlath O'Neil-Dunne
UVM Spatial Analysis Lab 
   
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Subject Re: GIS to calculate slope lengths 
Author Angela Moore 
Date Feb 18, 2005 
Message Thanks! I have ArcGIS Desktop (vs. workstation), but I assume that I can run this from the command line option in there as well? I do have Spatial Analyst, but no other extensions.

I will try to search the help documentation for more info on the AML stuff, but do I basically just need to save the downloaded code with some specific extension that I can then run as a program inside of ArcMap? This is clearly a powerful program, but it really is hard to find out how to get from Point A to Point B sometimes...!!