Satellite-Detected Flood Extent in Bangladesh Divisions, May 2022

A map from 26 May 2022 shows satellite-detected surface waters in Sylhet, Mymensingh, Dhaka, and Chattogram Divisions, Bangladesh. It was produced by the United Nations Satellite Centre (UNOSAT) using Sentinel-1 radar imagery and an automated machine learning analysis. The analysis estimates about 6,800 km² of land was flooded, affecting approximately 5,400 km² of cropland and 1,270 km² of herbaceous wetland.

Use Cases

• Mapping flood extent and severity based on satellite-detected surface waters.
• Estimating agricultural damage based on flooded cropland area.
• Assessing population exposure to flooding based on WorldPop data integration.
• Validating flood models with observed satellite data from a specific event.

Strengths

• Covers an analyzed area of about 16,000 km².
• Quantifies flooded land (6,800 km²), cropland (5,400 km²), and herbaceous wetland (1,270 km²).
• Includes population exposure estimates for specific districts (e.g., ~1.7 million in Sunamganj).
• Uses Sentinel-1 radar data, which can penetrate cloud cover.

Limitations

• Description metadata is limited; actual data quality requires manual inspection after download.
• The analysis is preliminary and has not been validated in the field.
• Flood analysis from radar images may underestimate water in built-up and densely vegetated areas.

Provenance

Source

United Nations Satellite Centre (UNOSAT)

Collection Method

Automated analysis with a machine learning method applied to Sentinel-1 radar imagery.

Time Range

26 May 2022

Freshness

Last updated 2026-05-23 09:27:21.113580; freshness should be verified.

Geography

Sylhet, Mymensingh, Dhaka, and Chattogram Divisions, Bangladesh