I know of a few people who worked on maps in Houston (and helped some out in minor ways), but AFAIK there wasn't one single map that "won out".
I was the one who created the Cajun Navy's crowd-sourced rescue mapping strategy, though, while helping out with the 2016 Louisiana floods, so I can give a little insight.
At first, I just saw that people were posting requests for rescue in various Facebook groups and becoming quickly buried under requests by others. So I spent a lot of time combing through the posts and adding the details to a spreadsheet, which I then posted on Batchgeo for rescuers to use.
After that, I started working with the people from one of the Facebook groups who had set up a Google Form for submitting rescue requests, and ended up periodically copying requests over from there.
We also had another form for updates regarding a specific request, and were fielding phone calls from people about it as well.
For Houston or Louisiana? The map I linked (and the bulk of my comment) are about what we did in Louisiana last year. I'm not completely in the know regarding Houston.
Sorry. The map you linked is very similar to the map we used for the Houston/Galveston/Orange areas. The people needing rescue were tagged as in your map and useful info about each location was available, in the map we used, on the left sidebar.
I was the one who created the Cajun Navy's crowd-sourced rescue mapping strategy, though, while helping out with the 2016 Louisiana floods, so I can give a little insight.
At first, I just saw that people were posting requests for rescue in various Facebook groups and becoming quickly buried under requests by others. So I spent a lot of time combing through the posts and adding the details to a spreadsheet, which I then posted on Batchgeo for rescuers to use.
After that, I started working with the people from one of the Facebook groups who had set up a Google Form for submitting rescue requests, and ended up periodically copying requests over from there.
We also had another form for updates regarding a specific request, and were fielding phone calls from people about it as well.
The original map is actually still up here if interested: https://batchgeo.com/map/984218ef8a04f3587f6e723561501e89