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Flood Zone Determinations & Building Footprints

Question asked by sweaters1 on Feb 13, 2017
Latest reply on Feb 13, 2017 by sweaters1

Using ArcGIS Desktop 10.1

 

We recently had building footprint polygons mapped for all structures in our community.

 

Now, we'd like to identify which flood zone each building rests within.

 

This is a rather simple spatial join task for those building entirely within a certain flood zone. However, the difficulty we're encountering occurs when a flood zone boundary line transects a building to any degree.

 

The floodplain rule is ... if a flood zone boundary line touches a building to any degree, then that building is considered entirely within the higher regulated flood zone.

 

In the attached example, flood zones AE-6 & AE-7 are on either side of the black flood zone boundary line.

 

Of these two flood zones, the AE-7 flood zone is the higher regulated.

 

Six buildings (shown as selected) are at least partially transected by the flood zone boundary line, and thus should all be identified as resting within the AE-7 flood zone.

 

What's the best way to have buildings straddling any flood zone boundary line to be identified as being in the higher regulated flood zone?

 

Ideally, one task would:

  • Associate the flood zone for buildings wholly contained within any flood zone, and
  • Associate the higher regulated flood zone for any building transected by a flood zone boundary line.

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