authority: folia
slug: impervious-surface
name: Impervious Surface
domain: anthroposphere
subdomain: urban
authority_id: folia:impervious-surface
aliases:
  - imperviousness
  - isa
  - impervious-cover
external_ids:
  cf_standard_name: null
canonical_units: "1"
external_validations:
  product:
    id: nlcd-impervious
    docs_url: https://www.mrlc.gov/data/type/urban-imperviousness
  product_alt:
    id: gaia-tsinghua
    docs_url: http://data.ess.tsinghua.edu.cn/
  product_alt2:
    id: hisdac-us
    docs_url: https://dataverse.harvard.edu/dataverse/HISDAC
  product_alt3:
    id: gisa-wuhan
    docs_url: http://geosimulation.cn/GISA.html
description: |
  Fraction (0-1) or percent (0-100) of a pixel covered by impervious
  artificial surfaces — roofs, asphalt, concrete, compacted material —
  through which water cannot infiltrate. Distinct from `built-up-area`:
  sparse rural settlement may register as built-up while remaining only
  partially impervious; conversely, a paved parking lot outside any
  built footprint is impervious without being "built-up" in the urban
  sense. Flagship products: NLCD Impervious (USGS / MRLC, CONUS, 30 m,
  Collection 2 annual), GAIA (Tsinghua, global annual 1985-2018, 30 m),
  HISDAC-US (Harvard Dataverse, US historical built-up surface back to
  1810), and GISA (Wuhan University, global impervious surface area
  1972-2019). Consumed by hydrology ops (stormwater runoff, SCS curve
  number), urban heat-island analyses, and CSRD / EUDR-adjacent impact
  assessments.
theme: infrastructure
consumed_by: []
produced_by: []
demos: []
status: documented
sources:
  - https://www.mrlc.gov/data/type/urban-imperviousness
  - http://data.ess.tsinghua.edu.cn/
  - https://dataverse.harvard.edu/dataverse/HISDAC
  - http://geosimulation.cn/GISA.html