How do you determine slope from a DEM?
grid values
One can calculate a simple slope in either the north-south or east west
direction, and use a maximum or average slope.
For a 20 unit cell spacing that's 3/40 (7.5%) for EW and (12.5%) for NS.
Or calculate a minimum adjacent cell and get the slope from the center cell
where the slope gradient here is (7-3)/28 = 14%or from the min to the max
Or even use a least square approach to "fitting" a surface to the 9 points in the 3x3 neighborhood (computationally expensive, however). Gee, I can't draw that....can you?
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