Symbology / Legend Order for No Value Features

[sgambrel_Bouldercounty]

Hello,

I have a web map that shows the FEMA-regulated Floodplain in my community.  In the FEMA data, there is a Zone Subtype field that is used to classify features in the commonly-used categories of Floodway / 100-Year Floodplain / 500-Year Floodplain.  This field has values for Floodway and 100-year Floodplain, but no value for 100-Year Floodplain. 

I can symbolize each of these categories distinctly, however because the 100-Year Floodplain is "No Value", it doesn't seem that I can re-order it in the legend to show up where it logically should, between Floodway and 500-Year Floodplain. 

I also do not appear to be able to suppress the "Area of Minimal Flood Hazard" - basically everything NOT regualted floodplain -  from showing up on the legend.  This does not need to be on the legend.

Is there any way to remedy this?  The current layer list / legend looks ridiculous as-is.   See the screenshot below for an illustration.   

  
Two notes:  The source of this data is a REST mapservice; I am using the "0" layer.  I don't think there's any flexibility in this.  Also, both FEMA and ESRI host this data which is somehow correctly symbolized, but I cannot use that as we have modified the FEMA data slightly, as we consider all floodplain above a certain elevation to be floodway.

 

[Laura]

I downloaded data from FEMA and used the S_FLD_HAZ_AR layer. From there you can symbolize by the field ZONE_SUBTY. Within Pro it lets me move the blank 100 yr around in the symbology placement. Maybe try using this dataset? I couldn't get the one you provided to move around in Pro either.

https://hazards.fema.gov/femaportal/NFHL/searchResulthttps:/hazards.fema.gov/femaportal/NFHL/searchR...

[sgambrel_Bouldercounty]

Hi Laura,

Sorry, got pulled away from this for a bit. 

I can symbolize just how I want in pro, but when I share it to AGO, the blank values (all of the 100-year floodplain) disappear and are left in the "other" category.  So the problem remains in ArcGIS Online with no seeming way around it.   

Map (arcgis.com)

[Laura]

Have you tried using FLD_Zone? I think you are always going to have issues unless that field is populated. You should be able to pull the same info from another field. This one does not have the no value field issue.

[sgambrel_Bouldercounty]

Unfortuantely Nope.  The commonly-used floodplain classifications don't exactly align with the FLD_ZONE Field.  Both zones A & AE can be either Floodway or 100-year Floodplain, depending on the Zone Subtype (either 1100 or no value).  Zone X is either 500-Year Floodplain or Area of Minimal Risk, depending on the Zone Subtype (either 500 or 2000).

Unfortunately I and everyone else using FEMA data need to use "No Value" to symbolize the 100-Year Floodplain.

[Laura]

We also use this for local gov. If you look at their viewer it appears they are using AE / & AE / floodway. 

https://hazards-fema.maps.arcgis.com/apps/webappviewer/index.html?id=8b0adb51996444d4879338b5529aa9c...

Could try using that layer and symbolizing by both field zone & zone subtype. 

[sgambrel_Bouldercounty]

Hi Laura,

Unfortuinately I can't use the data straight from FEMA because we modify it slightly in certain areas.  I did notice that they use the two fields together for their symbology - I'm not exactly sure why, when just the subtype will do - but maybe that's just here and not the case across the entire US... Anyway, I've tried to do that as well and the Map Viewer doesn't allow the Zone_Subtype field as an additional field to use for symbology once the Fld_Zone field is selected.

Something I should mention is that I have similar behavior in Pro, not recognizing the blank values as valid values to symbolize.  That nixes the strategy of creating a properly symbolized layer in Pro and sharing it online.    I've asked a similar question in the Pro Community.  I'm starting to think there's just something wonky / corrupt in the feature class. 

I really appreciate your attempts to help here!  Thank you!