I am running a hypothetical earthquake/ tsunami scenario off of Western Sumatra. Parameters are to display a 45 ft. tsunami inundation zone off of the Mentawai Islands (purple contours in images below) and a 21 ft inundation zone off of western Sumatra (brown contours). My end goal is to have one polygon to represent the entire inundation zone. I would like for this polygon to only represent areas <= 21 ft and <=45 ft for their respective areas. My dilemma being that ‘feature to polygon’ and any combination of ‘feature to raster, raster to polygon, dissolve’ does not represent my entire needed surface area, while also leaving out areas greater than the thresholds given above (areas with elevation greater than 21 ft should not be represented within the polygon).

My process so far:

Downloaded several DEM’s from USGS. Mosaic-ed DEM’s into one.

Ran focal statistics at parameters of Mean, Rectangle 25x25 feet on DEM.

Used Contour tool at base of 0; Interval of 1. Output to two polyline files – one for Mentawai Islands and one for Sumatra (purple and brown contours, respectively)

Select by attributes for <=21 feet; <=45 feet for each line dataset.

Clipped out erroneous contours leaving only the true inundation zones.

Attempted this workflow in ArcMap Desktop, full licensing level. Big surprise – it crashed when contouring DEM’s. So I started using it in ArcPro (which I know love using) at the full licensing level.

Any idea how I can turn these two polyline feature classes into one polygon data set displaying only the elevations at or below the thresholds?

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