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Watersheds in ArcGIS10 using NHDPlus data and ArcHydro

Watersheds in ArcGIS10 using ArcHydro

(SOURCE:  Arc Hydro Tools 2.0 - Tutorial)

Download & Install ArcHydro tools for ArcGIS v. 10

ArcHydro and associated docs can be found at ftp://RiverHydraulics:river%2E1114@ftp.esri.com/ArcHydro/Setup10/

NHDPlus data download

I'm using the NHDPlus elevation data which can be downloaded from (http://www.horizon-systems.com/nhdplus/data.php or ftp://ftp.horizon-systems.com/nhdplus/).  Georgia is split into 2 regions:  the South Atlantic Gulf region, subregions 3a, 3b, and 3d, and the Mississippi region, subregion 6a.  The data are compressed, so you will need to unzip them once your download completes.  On my machine, after unzipping the files, I have the following directories:

c:\\NHDPlus\SouthAtlanticGulf\NHDPlus03\...\
c:\\NHDPlus\Mississippi\NHDPlus06\...\

The elevation models we'll be using are saved in the 'elev_unit_*' folders and are called 'elev_cm'.  Before you move on, open ArcCatalog and build pyramid files for each DEM (navigate into each of these folders, right-click on the DEM and select 'Build Pyramids') - this might take some time, but it will speed up their display in ArcMap. 

I created the folder C:\\NHDPlus\GaData in which all output will be directed.

International elevation data

SRTM 90 meter DEM:  http://srtm.csi.cgiar.org/

ArcHydro v2...

'Terrain Preprocessing'

  • Level DEM
  • DEM Reconditioning
  • Assign Stream Slope
  • Burn Stream Slope
  • Sink Preprocessing
  • Fill sinks

'Terrain Processing'

  • Flow Direction
  • Adjust Flow Direction in Lakes
  • Flow Accumulation
  • Stream Definition
  • Stream Segmentation
  • Catchment Grid Delineation
  • Catchment Polygon Processing
  • Drainage Point Processing
  •