Is it Flooding?

"Is it Flooding" is a bit of a janky, demo-ready mess right now, and doesn't pass for a normal Rails app either. All queries are hand-rolled SQL, ActiveRecord isn't touched, and loading data in is a bit insane.

Dependencies

• Ruby 2.0
• Rails 4.0
• PostgreSQL 9.2
• PostGIS 2.0
• GDAL

Postgres Configuration on Mac

This application was developed on Mac OS X, using the homebrew package manager.

brew install gdal --with-postgres
# do the normal postgres setup here
brew install postgis

Data Import

The data we use is compressed in vendor/data.

• county_data.tar.bz2 is Miami-Dade County-provided data about FEMA Flood Zone designation (as "MultiPolygonZ") and elevation contours (as "MultiLineStringZ"). Right now, only the FEMA data is used because converting lines into polygons isn't trivial if you don't know GIS. These data are SQL ready to be loaded into PostGIS.

• orig_kml.tar.bz2 is the KML files the above is converted from.

• nws_precip_1day_observed_shape_20130601.tar.gz is NWS rainfall observations for the entire US. It can be loaded in with GDAL's ogr2ogr tool:

  ogr2ogr -f PostgreSQL PG:dbname=flood-dev nws_precip_1day_observed_20130601

  It should also be indexed to provide a hilariously huge speedup:

  CREATE INDEX ON nws_precip_1day_observed_20130601 (lat, lon);

Nationalizing

The rainfall data is ready for use anywhere in the US.

The FEMA flood zone data, however, is not. The application expects it to be provided as polygon data in the femafloodzone_lyr table, and queryable as such:

SELECT ogc_fid, name
FROM femafloodzone_lyr
WHERE 
  ST_Within(
    ST_PointFromText(
      'POINT(-122.0312186 37.33233141)', 4326),
    wkb_geometry)
LIMIT 5;

This query lives in app/models/flood_zone.rb, should you need to alter it.

What's Next?

There's lots of improvements that can be made. See the issues list on GitHub for a comprehensive list.

Authors

• Bryce Kerley: bkerley@brycekerley.net , https://twitter.com/bonzoesc

License

This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.