AZHU8 Topographic Roughness Index

The Topographic Roughness Index (TRI) of AZ HUC8 watersheds generated using a custom R script utilizing the package terra. TRI is defined as the square root of the summation of the difference between the eight neighboring cells and the center cell squared, in a DEM 3x3 focal neighborhood. Put simply, it is a unitless index of surface roughness which incorporates change in surface elevation in all directions, unlike slope which is unidirectional.