Description: : : This grid describes the direction of flow from each pixel to its steepest downslope neighbor. In the case of a maintained depression, flow directions are referred to as undefined. If a cell has the same change in elevation values in multiple directions, and is part of a sink, the flow direction value for that cell is coded as the sum of those directions. Generated from the filled DEM using the 'flowdirection' function. Each cell is assigned a code (value) that defines the direction water will flow from the cell. There are eight possible flow directions: east (1), southeast (2), south (4), southwest (8), west (16), northwest (32) north (64), and northeast (128).