Slope, elevation and area calculation in DEM

06-11-2016 02:05 PM
New Contributor

Hi guys,

I have an assignment to hand in at uni and I have come to a point where I don't know which method to use to complete it and I receive no guidance from my tutors. As I am new to GIS I can't make heads from tails so I would immensely appreciate your help.

Here goes:

I have a DEM of the German alpine area as well as several vector files pertaining to land use, streets, railways etc. I need to determine which areas can count as "alps" based on the criteria elevation (between 600 and 800 m NN), percentage rise of the slope (above 18%) and at least 5 hectares big. I get the general idea that I first have to calculate or classify these numbers and then find a way (perhaps by converting into a vector file?) of excluding everything that doesn't fulfill these. I have looked around arcGIS, have watched several videos and even looked at the slope and reclassify tool, but I feel very uncertain as to whether I am doing the right thing. When it comes to finding out a certain elevation, the tool that seems most plausible to me is reclassify, whereby it looks as though you can manipulate the data. Should I just do that? Should I just create new elevation classes according to my needs? Would that not mess with the underlying data?

As you see, I really need a guiding hand.

Thanks for your help!


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1 Reply
Occasional Contributor II

1. Use the CON tool so that only those elevation that fits your criteria will be included in the output. = map1

2. using map1, use the SLOPE tool. = map2

3. using map2, use the CON tool again to select only those that are > 18%. = map3

4. convert map3 to a polygon (RASTER to POLYGON Tool) and select only those that are >= 5 ha.

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