I am new to Arc Hydro (AH), and have been working to Identify Sinks in the landscape. I encountered several issues, so I wanted to share my methods in hope this saves someone else the time I spent trying to figure this out. I started my project with raw Lidar and processed it using Quick Terrain Modeler, which resulted in 10 subset DEMs in a .tif file format for just one county. I did not mosaic the subsets, because I later learned that a county-level DEM is far too large to process in AH. Many of these tips were compiled from the AH Tutorial found online, Geonet AH Problem Solvers, and the developers of AH. I used ArcMap 10.4.
*before starting make sure you have downloaded the correct version of AH for your system, and make sure your computer has the hardware/software needed for this level of geoprocessing. You will need a Spatial Analyst license.
1) Create a folder on your local machine, i.e., C:\GIS\project *When using AH, always work on the local machine, keep names and pathways short and simple.
2) Open ArcMap, select My Template/Blank Map, and designate geodatabase for this map, i.e., C:\GIS\project\project.gdb
7) Set Target Locations AH toolbar > ApUtilities > Set Target Locations > ApUtilitiesConfig > OK > make sure this location is correct AH toolbar > ApUtilities > Set Target Locations > HydroConfig > OK > make sure this location is correct *Rasters should go into a folder (no .gdb) and Vectors go into a .gdb
😎 Add your DEM raster to the map, build pyramids if prompted.
9) Save map File > Save As > navigate to C:\GIS\project and save map, i.e., project.mxd
10) Preprocess the DEM if necessary. The raster format that I found to be most useful included: a small raster (columns and rows < 10,000x10,000), integer (not floating point), GRID format, defined Z coordinate system, and NoData values converted to "0". I started with a 32-bit, floating point, .tif raster, so I had to preprocess the raster before running it in AH: a) Original DEM Float to Integer Spatial Analyst > Math > Int Output Location: C:\GIS\project *I added "i" to the end of the file name, so I knew which raster this was from the others, i.e., "projecti.tif" b) DEM .tif to GRID Conversion > to Raster > Raster to Other Format Output Location: C:\GIS\project c) Define Projection Input: DEM GRID in an integer format (from previous step) Open coordinate system list, Spatial Reference Properties > select Z Coordinate System tab > select NAVD88 > double- click NAVD88 > Vertical Coordinate System Properties window will open > and change Linear Unit Name: centimeters > Apply > OK > OK > OK *This step changes the coordinate system of the input file and does not create an output. d) Raster Calculator, convert NoData to "0" Spatial Analyst > Map Algebra > Raster Calculator Use this equation for the raster: Con(IsNull("inputraster"),0,"inputraster") Output: C:\GIS\project\projectc *I added a "c" to the end of the name, so I knew this is the calculated version of the raster.
11) Remove the other files that may have been added to your map except for "projectc" file (this should be the raster that is: integer, GRID, defined projection, and NoData=0). It wouldn't hurt to save your map again, and clean your temp folder one last time before running AH.
I followed all of the above steps, and still could not get a successful output with Sink Evaluation and the issue turned out to be my computer's graphic/video card. It worked perfectly once I ran it on a more robust machine.