Slope Discretization in Land Use/Soils/Slope Definition

[Motaleb Hossain]

Dec 29 (18 hours ag

Dear ArcSWAT & SWAT CUP Users

I want to know how many slope classes should I select as a multiple slope in Slope Discretization and what will be the upper limit of slope calsses. In my SWAT project the Watershed Slope Stats are Min: 0.00, Max: 177.0, Mean: 34.3 St. Dev: 25.3

Waiting for your cordial response.

Regards

Hossain

[Amol Patil]

Hi Hossain

As per my experience there are maximum 5 slope classes one can mention in ArcSWAT for Slope definition. 

I dont know it exactly but this is what I have tried in arcGIS 10.1. 

Open a separate map window and add your DEM layer on  map window. 

Then go to    Spatial Analysis Tools>> Surface>> Slope   and create an  slope map of your DEM by checking option Percent Rise. 

Then you will get a newly created slope raster with same statistics you mentioned earlier. 

Now the next step is  right click on this Slope raster and go to Properties >> Symbology. In left pane you will see an option "classified" -- select it. Now in right pane under classified tab you can select no of classes, further more you should select button classify in front of it. Here you can select different classification methods to decide the range of each class. 

By trying different methods and no of classes, you can decide how many classes are sufficient with which ranges so that you can qualitatively represent distribution of slope in your study area. 


Amol Patil