Arc Hydro is… a set of data models and tools that operates within ArcGIS to support geospatial and temporal data analyses.
Use Arc Hydro to delineate and characterize watersheds in raster and vector formats, define and analyze hydro geometric networks, manage time series data, and configure and export data to numerical models.
To get started with Arc Hydro, download Arc Hydro Data Model and Tools, consult Arc Hydro: GIS for Water Resources and Arc Hydro Tools Overview and Tutorial. For additional information, see the Hydro Data Model Support Page and the Center for Research in Water Resources Online Publications. For information about the licensing levels required for Arc Hydro, please see the Tools list.
Arc Hydro training:
Training: Esri offers courses for stream flooding applications, or consult our Education Gallery resources.