Saltmarsh Extent and Zonation in England from 2016-2019 Aerial Imagery

Saltmarsh Extent & Zonation is a polygon data layer showing the extent of saltmarsh in England, created by the Environment Agency. The layer was mapped from aerial photography collected predominantly between 2016 and 2019, with over 95% of the national extent mapped to zonation level. The dataset was updated in 2023 and 2024 and is intended for flood and coastal risk management and ecological monitoring.

Use Cases

• Modeling coastal flood risk based on saltmarsh extent as a natural defense feature.
• Monitoring ecological community changes based on mapped zonation classes like Pioneer and Upper Marsh.
• Reporting on habitat status for regulatory frameworks like the Water Framework Directive.
• Analyzing the impact of managed realignment sites based on included sites like Medmerry and Steart.

Strengths

• Over 95% of the national saltmarsh extent has been mapped to detailed zonation level.
• Data was ground-truthed with field data collected by the Environment Agency and Natural England.
• Aerial imagery used was typically at 20 x 20 cm resolution.
• Includes saltmarsh within 63 managed realignment and regulated tidal exchange sites.

Limitations

• Description metadata is limited; actual data quality requires manual inspection after download.
• The dataset has been retired and superseded by a newer version, as noted in the description.
• Mapping methodology varies, with some areas having local outputs 'fairly simply embedded' into the national layer.

Provenance

Source

Environment Agency

Collection Method

Interpreted from aerial imagery, primarily from Regional Coastal Monitoring Programmes, and ground-truthed.

Time Range

Predominantly 2016 to 2019

Freshness

Last updated 2026-05-06 16:28:23.537709; freshness should be verified.

Geography

England