The impervious surface ratio is a key environmental indicator measuring the percentage of land covered by artificial impervious surfaces (buildings, roads, parking lots, industrial areas, infrastructure). It reflects the degree of soil sealing, a process that impairs the soil's capacity to absorb water, support vegetation, filter pollutants, and sustain biodiversity.
Soil sealing is one of the most irreversible forms of land consumption: a sealed soil completely loses its ecosystem functions. In Europe, artificial sealing affects approximately 4–5% of total land area and continues to expand with urbanisation. Locally, high impermeability values translate to increased flood risk, reduced groundwater recharge, urban heat island effects, and habitat loss for flora and fauna.
Important note: this indicator is inverted — a lower value corresponds to better conditions.
The impervious surface ratio is calculated from the CLC layer (integrated Corine Land Cover), by summing the area covered by impervious land use classes and dividing by total land hectares within the analysed area:
impermeability (%) = (ha impervious classes / total land ha) × 100Unit: percentage (%)
| Code | Name | Provider | Resolution | Availability |
|---|---|---|---|---|
WRD_ESAWC_99 | ESA World Cover | ESA | 10 m | 2020–2021 |
WRD_IOBSV_99 | Impact Observatory LULC | Impact Observatory | 10 m | 2017–present |
WRD_S2SCL_99 | Sentinel-2 SCL | ESA/Copernicus | 20 m | 2017–present |
WRD_GDYXX_99 | Google Dynamic World | 10 m | continuous | |
WRD_OSMRD_99 | OSM Roads | OpenStreetMap | vector | continuous update |
WRD_CLCBB_99 | CLC Backbone | EEA | 100 m | 2012–2018 |
WRD_CORIN_99 | Corine Land Cover | EEA | 100 m | 1990–2018 |
WRD_DLFXX_99 | Dominant Leaf Type | Copernicus | 10 m | annual |
WRD_EUCRP_99 | European Crop Map | JRC | 10 m | annual |
| Indicator | Unit | Range | Inverted |
|---|---|---|---|
impermeability | % | [0, 20, 40, 60, 80, 100] | Yes |
Inverted = Yes: a lower value indicates better conditions (less artificial soil sealing).
| Level | Impermeability (%) | Ecological Interpretation |
|---|---|---|
| E (Excellent) | 0 – 20 | Predominantly natural territory, permeable soil with intact ecosystem functions |
| D (Good) | 20 – 40 | Low urbanisation, dominant vegetation cover, good water infiltration capacity |
| C (Moderate) | 40 – 60 | Moderate urbanisation, growing hydraulic risk, reduction of ecosystem services |
| B (Low) | 60 – 80 | High sealing, peri-urban or industrial areas, ecosystem functions severely impaired |
| A (Critical) | 80 – 100 | Nearly fully impervious territory, maximum flood risk, absence of natural habitats |
impermeability
(%)The impervious surface ratio indicates the percentage of land covered by impervious surfaces (buildings, roads, parking lots, industrial areas). Calculated from the CLC layer by summing impervious classes and dividing by total land hectares. Integrates ESA World Cover, Impact Observatory, Sentinel-2 SCL, Google Dynamic World, OSM Roads, CLC Backbone, Corine, Dominant Leaf Type and European Crop Map.