Develop tool to allocate Census Block/Tract values to FMA boundaries

[russellgould]

Develop tool to allocate values to from Census spatial data to FMA boundaries using an area-weighted proportioning approach.

This will initially be developed using spatial queries in PostGres and PostGIS.

Output may be a lookup table that ties Census Tract ID's to Fire Management Areas and would include a value that represents the area Census Tracts that overlap a coincident Fire Management Area boundary.

[rcallihan]

Simple workflow for creating a table with the area weightings:

Target = FMA Source = Census Blocks (Only those that intersect with FMA's)

1) Calculate Area on the Target Data

2) Spatial Union the Target and Source Data

3) Calculate Area on the Union Layer

4) Aggregate (via sum) area value using by on Target ID AND Source ID.

5) Calc "Summed Source Area / Target Area"

[rcallihan]

Here's the methodology from a past HO project using PG queries. This should work for us as well.

https://github.com/hackoregon/urbandev-etl/blob/master/convert/POSTGIS_AREAL_INTERPOLATION_README.md

[sky-t]

Task list for next week:

• [x] grab census tract shapes from ryan's repo and put up on EC2

• [x] individually try to write query/queries in postgres to create FMA-census block table

[sky-t]

This task is now complete. The lookup tables are: fcb_proportion and fmac_proportion