National Structures Inventory¶

The National Structure Inventory (NSI) is a system of databases containing structure inventories of varying quality and spatial coverage. The purpose of the NSI databases is to facilitate storage and sharing of point-based structure inventories used in the assessment and analysis of natural hazards. Flood risk is the primary usage, but sufficient data exists on each structure to compute damages and life safety risk due to other hazard types. This document describes the NSI data structure and the processes utilized to produce the 2022 NSI base data.

The National Structure Inventory Base layer was created and is maintained by the U.S. Army Corps of Engineers (USACE). The USACE base data layer was created to simplify the GIS pre-processing workflow for the USACE Modeling Mapping and Consequence center, but the data has gone on to see use in a variety of USACE, FEMA, and other agency applications. The NSI is a repository of point structure inventories with a structured RESTful API service, and the inventory contains a series of required attributes or fields that describe each point in the inventory.

Table of Public Fields¶

Structure Processing and Valuation¶

The National Structure Inventory (NSI) involves several key processes for managing and analyzing structures:

• Structure Placement and Aggregation: Initially, structure locations are based on source data such as parcel centroids or business addresses. The NSI Generator refines these locations by aligning structures with building footprints within the same parcel. Commercial structures outside their original parcel are relocated based on distance and use code similarity. Structures are placed in unpaired footprints until all footprints are matched. Stacked structures are partially or completely merged based on their occupancy type, with residential units combined as multi-family structures if stacked. Commercial structures are merged only if they share the same occupancy type and similar characteristics, like number of stories and construction material.

• Population Distribution: The NSI-2022 estimates population levels for 2020 using data from 2010 block information and 2020 county data. This population is distributed to structures according to housing units and block-level estimates. For commercial structures, worker population estimates are derived from the U.S. Census Bureau’s LEHD database.

• Structure Valuation: Depreciated replacement values for structures are estimated based on a dollar per square foot metric, with depreciation at 1% per year for the first 20 years. Content values are calculated using specific ratios tied to occupancy types.

Occupancy Type¶

Occupancy types help determine structure valuation and damage criteria. They are based on FEMA definitions with further classification.

Main Data Sources¶

Citation¶

U.S. Army Corps of Engineers (Year). National Structure Inventory (NSI) Base Data. U.S. Army Corps of Engineers. URL or DOI.

Earth Engine Snippet¶

The datasets are available by state using the two alphabet state abbreviation for example, for WYOMING (WY)

var nsi_wy = ee.FeatureCollection('projects/sat-io/open-datasets/NSI/nsi_2022_WY');

Sample Code: https://code.earthengine.google.com/?scriptPath=users/sat-io/awesome-gee-catalog-examples:global-utilities-assets-amenities/NSI

License¶

The National Structure Inventory (NSI) from the U.S. Army Corps of Engineers (USACE) has a licensing structure that allows for public access to its primary fields, as these fields are curated to have less restrictive license agreements.

Provided by: USACE

Curated in GEE by: Samapriya Roy

Keywords: Buildings, Structures Inventory, US

Last updated: 2024-08-07

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