Available with Spatial Analyst license.
Creates a raster layer of upstream or downstream distance, or weighted distance, along the flow path for each cell.
A primary use of the Flow Length function is to calculate the length of the longest flow path within a given basin. This measure is often used to calculate the time of concentration of a basin. This is done using the Upstream option. The function can also be used to create distance-area diagrams of hypothetical rainfall and runoff events using the weight raster as an impedance to movement downslope.
This is a global raster function.
The value type for the Flow Length output raster layer is floating point.
Flow Direction Raster
The input raster that shows the direction of flow out of each cell.
The flow direction raster can be created by running the Flow Direction function.
Direction of Measurement
The direction of measurement along the flow path.
An optional input raster for applying a weight to each cell.
If no weight raster is specified, a default weight of 1 will be applied to each cell.