Converting a NEXRAD Rainfall Map into a Flood Inundation Map by ...

component and for integration purposes. Besides having access to all thehydrologic elements represented in HEC-HMS, Arc Hydro also needs to selectonly some of the hydrologic elements. In particular Arc Hydro needs to clearlyrecognize those HydroJunctions associated with Flow Change Location Points. Toaccomplish this, the Schematic Nodes representing flow change points (reachentry points of external source hydrographs) have been attributed with theModelCode (HMSCode in this case) and populated with the corresponding namein HEC-HMS (see Figure 4.16). By doing so, the application, DSS2GDB, canquery the relationship “HydroJunctionHasSchematicNode” and select thoseNodes inputting a runoff hydrograph for the reach. In short, the hydrologic nodeshave been stored in the Arc Hydro SchemaNode feature class, and related toHydroJunctions at the appropriate locations on the stream network based on arelationship class that extends Arc Hydro’s content. Only the HydroJunctionfeatures corresponding to flow change points have been labeled with HMSCodesto recognize which are exchange points and which are not.Figure 4.16 ModelCodes Populated under the SchematicNode Topology116