Need to aggregate to HUC8
The data (total N and P) is organized by ComID.
Therefore, we need to add up the value of comID to the HUC8 that comIDs are belong to.
- total N and P text file (ID: comid)
- catchment to huc12 crosswalk data: (https://www.epa.gov/waterdata/nhdplus-national-data)
- DBF file
- HUC8 boundary shapefile
- Derive a relationship table between (catchment (COMID) and HUC8) from crosswalk data above
- calculate (add up) the total N and P value by huc8 by using table above
- join the table above (calcualted table) with HUC8 boundary
2002 Nutrient Model Results by SPARROW