I'm trying to delineate all river basins on a global 1/16 degree grid. The algorithm that the Basin tool in the Spatial Analyst Toolbox works well (fast) except it doesn't know how to handle the International Dateline (-180/180 degree line). See example image below...

It is important that I process the entire globe at once because I need each basin to have a unique identifier. Can anyone suggest a way of doing this? I'd be open to modifying the Basin tool script if necessary and if I can get my hands on it.

I'm using ArcInfo 10.0 and all standard python tools.

Arctic Basins showing break at International Dateline

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    You can obtain unique identifiers even when you process the world in pieces. Just add a large constant to each piece (varying from piece to piece) in order to make the identifiers unique. When you mosaic the results, merely retain the smallest identifier at each cell. – whuber Jan 6 '13 at 17:09

You can use archydro tools. This tool will create unique identifier for each basin.

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    Thanks @prasad, hopefully this works (it should). I discovered that the Flow Direction Raster that I was given was created using the "Force" option which goes out of its way to insure the boundary is padded by zeros. So this may be the problem of the flow direction and not basins. – sea_hydro Jan 6 '13 at 16:24

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