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I've been using Arc Hydro for the last 7 years to determine catchment characteristics. I'm currently setting up a new model to determine structure locations along a proposed railway alignment. This is the largest study area I've ever had to process and currently its failing when I try to generate the Flow Accumulation Grid. My Flow Direction Grid for the study area has 863 398 034 cells.

I'm looking for advice in how to successfully generate my Flow Accumulation Grid. If ArcGIS can't handle such large DEM's will GRASS be able to process such a large DEM and generate a ArcGIS GRID as an output that I could use for further processing of catchment characteristics.

migrated from stackoverflow.com May 28 '13 at 14:03

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  • How big is the file? ArcGIS is 32 bit, so it's going to die around 2 GB. – DPierce May 28 '13 at 14:46
  • GRASS GIS has large file support, even on 32bit systems, so no barrier to be expected here. See also here for an overview about grasswiki.osgeo.org/wiki/Hydrological_Sciences (list of functionality, check especially out r.watershed). – markusN May 28 '13 at 18:52
  • Would it be possible to separate your grid into multiple smaller watersheds for separate processing? You could identify them by first resampling the DEM to a coarser resolution, recomputing flow directions, and calculating the watersheds. – whuber Nov 11 '15 at 15:16

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