Obtaining inundation boundaries from Depth (Max) vs Depth Max Extent (Max)

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Obtaining inundation boundaries from Depth (Max) vs Depth Max Extent (Max)

Suzanne
I wish to obtain inundation boundaries for areas above a certain depth threshold (e.g., 0.5 ft). In RAS Mapper the Inundation Boundary results layer does not allow me to set a threshold other than zero default. It appears I can get a boundary from the Depth layer setting a value of 0.5 for the Polygon Boundary at Value field, or from the Depth Max Extent layer which requires setting the Polygon Boundary value and a Threshold Depth parameter. Is there a difference between the results from these two methods? I would really appreciate a clear explanation of the difference in the rasters produced from Depth (Max) vs. Depth Max Extent (Max).

Also, it seems that once I have created an polygon boundary using the Depth Max Extent layer, it will not let me recompute it for a different depth threshold whether I edit the parameters of the existing layer or add a new layer? How can I get multiple layers to show boundary for different minimum depth thresholds?

I am working in HEC-RAS 5.0.3 with a 1D/2D model.

Thank you
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Re: Obtaining inundation boundaries from Depth (Max) vs Depth Max Extent (Max)

DS_ras
Use the "Wet Cells" option, Maximum, and set threshold depth. Another option is to save your Depth Max as a raster based on terrain, and use GIS to show only depths >0.5ft. You may be able to do this directly in RASMapper using categories in display options. I don't see "Depth Max Extent" option in 5.0.7.

I have also experienced the lack of recomputing problem. Try deleting the layer in RASMapper AND the created maps out of the folder the original version was saved to, that may allow you to recompute.