Dear all,
I was trying to calculate slope in gradients for the Himalayan region using spatial analysis tool in ArcGIS, but my values are not matching with global mode and Indian region which are ranges 0 to 0.1 (Sitharam et al. 2014) (my values are 0 to 10.44).
As per slope formula in ArcGIS... slope percent = (rise/run)*100
Rise/Run (Gradient)=slope percent/100
then I got the values 0 to 10.44. I have tried from degrees to rise/run also, no use.
Could you please any one suggest me where I was doing a mistake or any suggestions.
Dear Pudi,
Check whether Sitharam et al. 2014 used the same DEM resolution you use. It seems that your slope range is correct if you have 10 or 30 m DEM resolution.
Using higher DEM resolution (90, 270 or 1000 m) slope range will be lower than yours.
Thank you, Sir.
You are right, I am using 30 m DEM. My problem is
I would like to use Allen& Wald (2009) Slope-Angle model for Vs30. In this case, my slope values are not coming under that model values. In that model higher gradient value is 0.138 but I got 10.2.
Thanks,
Ramesh Pudi
You are right. Himalayan region is so high and very active seismically, Based on Wald-Allen ranges maybe you poorly describe your region. This is depends on the total number of slope pixels in the image lower than 0.138.
You consider each slope pixel higher than 0.138 the equivalent velocity Vs >760 and B site class.
This is another difference between my suggested model and Wald-Allen slope-velocity ranges. Try to use my suggested formula.
Let me know, slope range in your study area?
Ok, thank you.
I am using your formula only but just was trying to correlate with that model also.
Slope range is 0 to 84 degrees.
- Badges
- Science topic
- Similar topics
- Agricultural Science
- Agronomy