DOI: 10.6084/m9.figshare.28681502
title: High-resolution estimates of the US population in high fluvial flood hazard areas

description: This dataset, called FloodPop, contains estimates of the population and housing in high flood hazard areas in the contiguous US at the Census block, tract, county, and state levels as well as classified building footprints and validation data. The dataset corresponds with the forthcoming manuscript entitled “High-resolution estimates of the US population in high fluvial flood hazard areas”. 

Note: The folders building_footprints.gdb, building_footprints_df, and validation/ buildings_w_lu.gdb contain modified building footprints from Overture Maps (https://overturemaps.org/), including information from OpenStreetMap (https://www.openstreetmap.org/), USA Structures, the National Structure Inventory, and the US release of Microsoft Building footprints. The data in building_footprints.gdb, building_footprints_df, and validation/buildings_w_lu.gdb are made available under the Open Database License (ODbL) v1.0 (https://opendatacommons.org/licenses/odbl/1-0/), while the rest of the repository is made available under the CC BY 4.0 license (https://creativecommons.org/licenses/by/4.0/) .

Contents

fp_summaries: FloodPop results in tabular and geospatial formats. Each file in this folder has columns from the original census dataset at the corresponding spatial scale and similar added columns.

Files
• blocks_by_state.gdb: An Esri file geodatabase containing a feature class of FloodPop results at the Census block level for each state. State abbreviations are at the beginning of the feature class name.
• cartographic.gdb: An Esri file geodatabase containing feature classes representing cartographic tract, county, and state level FloodPop estimates. The feature classes should be used for visualization but not used for analysis.
• summaries.gdb: An Esri file geodatabase containing feature classes representing tract, county, and state level FloodPop estimates. The feature classes can be used for analysis.
• summary_csvs: Comma Separated Value (CSV) files containing FloodPop estimates for Census blocks, tracts, counties, and states. This folder also contains a CSV (state_res_or_not_summary.csv) that summarizes the sources of building classifications by state, parsing out the count and area of buildings for residential (res_or_not = 1), non-residential (res_or_not = 0), and unknown (res_or_not = -1) buildings.

Added columns
For files in the fp_summaries folder, estimates of the population, total housing units, and occupied housing units were appended to census data boundaries. Census variables “p1_001n” (total population), “h1_001n” (total housing units), and “h1_002n” (occupied housing units) were added to all census boundaries. Then, columns were added for each census variable intersecting each scenario of estimated flood hazard (SFHA, best-available SFHA, and either SFHA). Lower and upper bounds were calculated for population and occupied housing units but not for total housing units as block-level counts for total housing units did not have privacy noise added. Columns related to population use the prefix “pop_”, total housing units uses “tot_hu_”, and occupied housing units uses “occ_hu_”. An example of the naming convention for population estimate columns is below, and this was replicated for total housing units (without upper and lower bounds) and occupied housing units:
• pop_sfha: Estimated population within the FEMA Special Flood Hazard Area (SFHA).
• pop_sfha_low: Lower bounds (90% CI) of estimated population within the FEMA Special Flood Hazard Area (SFHA).
• pop_sfha_high: Upper bounds (90% CI) of estimated population within the FEMA Special Flood Hazard Area (SFHA).
• pop_best_sfha: Estimated population within the FEMA SFHA (if mapped by FEMA) or the estimated SFHA (if not mapped by FEMA).
• pop_best_sfha_low: Lower bounds (90% CI) of estimated population within the FEMA SFHA (if mapped by FEMA) or the estimated SFHA (if not mapped by FEMA).
• pop_best_sfha_high: Upper bounds (90% CI) of estimated population within the FEMA SFHA (if mapped by FEMA) or the estimated SFHA (if not mapped by FEMA).
• pop_either_sfha: Estimated population within either the FEMA SFHA or estimated SFHA.
• pop_either_sfha_low: Lower bounds (90% CI) of estimated population within either the FEMA SFHA or estimated SFHA.
• pop_either_sfha_high: Upper bounds (90% CI) of estimated population within either the FEMA SFHA or estimated SFHA.

Additional columns for block-level results
• out_sfha_area: Building footprint area (m2) that does not intersect the SFHA.
• within_sfha_area: Building footprint area (m2) that intersects the SFHA.
• ratio_area_sfha: The ratio of total building footprint area that intersects the SFHA.
• out_est_sfha_area: Building footprint area (m2) that does not intersect the estimated SFHA.
• within_est_sfha_area: Building footprint area (m2) that intersects the estimated SFHA.
• ratio_area_est_sfha: The ratio of total building footprint area that intersects the estimated SFHA.
• out_best_sfha_area: Building footprint area (m2) that does not intersect the best-available SFHA.
• within_best_sfha_area: Building footprint area (m2) that intersects the best-available SFHA.
• ratio_area_best_sfha: The ratio of total building footprint area that intersects the best-available SFHA.
• out_either_sfha_area: Building footprint area (m2) that does not intersect either SFHA.
• within_either_sfha_area: Building footprint area (m2) that intersects either SFHA.
• ratio_area_either_sfha: The ratio of total building footprint area that intersects either SFHA.
• ci_low: Lower bounds estimate (90% CI) of block population.
• ci_high: Upper bounds estimate (90% CI) of block population.
• ci_low_hu: Lower bounds estimate (90% CI) of block occupied housing units.
• ci_high_hu: Upper bounds estimate (90% CI) of block occupied housing units.

validation: Folder containing geodatabases used for the presented validation exercises that focus on Mecklenburg County, NC, Miami-Dade County, FL, and Sacramento, CA. 
• buildings_w_lu.gdb: Modified Overture Maps building footprints for the validation area with land use classifications from local datasets.
• input_cities.gdb: Parcels with classified land use from local datasets.
• sj_cities.gdb: Parcels that intersect modified Overture Maps building footprints for the validation area.
• validation_blocks.gdb: FloodPop estimates for census blocks that intersect modified Overture Maps building footprints for the validation area.

building_footprints.gdb: An Esri file geodatabase containing classified building footprint feature classes for each state used to create FloodPop estimates. Each footprint contains information on building classification, presence within the SFHA, estimated SFHA, and FEMA study footprint, and Census block. State abbreviations are at the beginning of the feature class name.

building_footprint_dfs: Folder containing a tabular version (Parquet format) of building footprints for each state. State abbreviations are at the beginning of the file name.