1. Arc Hydro Terrain Processing
Exercise 3
Input Data
HydroID Assignment

2. HydroID Assignment Used in this exercise Unused in this exercise
Catchment HydroID = 535 to 654 (120 Catchments)
DrainageLine HydroID = 655 to 774 (120 Drainage Lines)
AdjointCatchment HydroID = 775 to 828 (54 Adjoint Catchments)
DrainagePoint HydroID = 949 to 1068 (120 Drainage Points)
HydroID is always unique – if you create a feature class and then
delete it or overwrite it, HydroID’s are all assigned new

3. HydroID - DrainID HydroID of Catchment =
DrainID of DrainageLine and DrainagePoint

4. NextDownID NextDownID = 549 NextDownID = 557 NextDownID = 549
NextDownID of a Catchment is HydroID of next downstream Catchment

5. Tracing by NextDownID Tracing Downstream
Each catchment has only one downstream catchment (like a DEM cell)

6. Upstream Tracing using Next DownID