Splitting Catchments after generation

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10-02-2014 01:12 PM
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ShaneWarner
New Contributor

Ultimately, I'm trying to generate catchment polygons and stream lines for about 25 small watersheds that are linked to each other in attributes, where the stream segments are linked to each other with a nextDown attribute. I've gone through the basic process in ArcHydro and created this, but I've just realized that I need to calibrate results to stream gauge stations which are not located at the outflow of the watershed or a stream junction. Therefore, I'm trying to figure out how to split a generated catchment at the gaging point (which I did by adding a pour point at the station and calculating the sub watershed and then using Union with the original catchments) but I'm now stuck at trying to regenerate the linking attributes to properly account for the new catchment. I've assigned HydroIDs to the new features (split catchment and split stream segment) with the command from Attribute Tools, but when I try to run the Find Next Downstream Line it runs properly but ignores the inserts (I assume because they haven't been incorporated into the underlying node network).

Is there any way to create new nodes to include these new features, or am I approaching it totally wrong and there's some other (earlier in the process) way to do this?

Any help would be greatly appreciated, and I can provide more details/screenshots if needed.

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MarkBoucher
Regular Contributor II

If you have a stream gage location you want to calibrate to, it seems that you could do a separate watershed delineation just for that point. Then after calibration, use the parameters you  used for that watershed in the greater model. This would help you avoid having to shoehorn the gage point into the current model.

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