Bangladesh - Satellite Detected Water Extent in Chittagong District, Chittagong Division

This map illustrates satellite-detected surface water extent in the District of Cox's Bazar, Chittagong Division, located in the southeastern part of Bangladesh after the tropical cyclone Mora-17 using a Sentinel-1 satellite image acquired on the 30 May 2017. A total of 23,058 ha surface waters were observed. In many zones, the affected lands are mainly agricultural. The analysis of this image reveals also that about 234 km of roads mainly tertiary roads seem to be potentially affected. The population exposure analysis using WorldPop data shows that ~267,000 people are potentially affected by floods within map extent. This is a preliminary analysis and has not yet been validated in the field. Please send ground feedback to UNITAR - UNOSAT.

This map illustrates satellite-detected surface water extent in the central and southern parts of Bangladesh using a Sentinel-1 satellite image acquired on the 22 August 2017. In the analysed area; 608,747 ha of lands are likely affected. These lands are mainly cropland irrigated and rainfed areas and estimated to 475,000 ha. The population exposure analysis using WorldPop data shows that ~6,400,000 people are potentially affected by floods in the analysed zone: ~2,300,000 are located in Chittagong Division and ~2,170,000 in Dhaka Division. Please note that for visualization purposesanalyzed area is wider than the extent of this map. This is a preliminary analysis and has not yet been validated in the field. Please send ground feedback to UNITAR-UNOSAT.

**UNOSAT code: FL20200713BGD** This map illustrates satellite-detected surface waters over Chittagong, Dhaka, Mymensingh and Sylhet Divisions of Bangladesh as observed from a Sentinel-1 image acquired on 20 July 2020 due to the current monsoon rains. Within the analyzed area of about 14,250 km2, a total of about 7,120 km2 of lands appear to be flooded. Based on WorldPop population data and the detected surface waters, about 6,700,000 people area potentially exposed or living close to flooded areas. This is a preliminary analysis and has not yet been validated in the field. Please send ground feedback to UNITAR - UNOSAT. Important Note: Flood analysis from radar images may underestimate the presence of standing waters in built-up areas and densely vegetated areas due to backscattering properties of the radar signal.

**UNOSAT code: FL20210729BGD** This map illustrates satellite-detected surface waters in Chittagong division, Bangladesh as observed from a Sentinel-1 image acquired on 30 July 2021 at 05:33 local time Within the analyzed area of about 18,700 km2 and, about 852 km2 of lands appear to be flooded. The water extent appears to have decreased of about 18km2 since 27 July 2021. Based on Worldpop population data and the detected surface waters in the analyzed area, the potentially exposed population is mainly located in the district of Cox's Bazar with ~425,000 people, Chittagong with ~392,300 people. This is a preliminary analysis and has not yet been validated in the field. Please send ground feedback to United Nations Satellite Centre (UNOSAT). Important note: Flood analysis from radar images may underestimate the presence of standing waters in built-up areas and densely vegetated areas due to backscattering properties of the radar signal.

**UNOSAT code: FL20210729BGD** This map illustrates satellite-detected surface waters in Chittagong division, Bangladesh as observed from a Sentinel-1 image acquired on 11 August 2021 at 05:48 local time. Within the analyzed area of about 18,700 km2 and, about 754 km2 of lands appear to be flooded. The water extent appears to have decreased of about 119 km2 since 8 August 2021. Based on Worldpop population data and the detected surface waters in the analyzed area, the potentially exposed population is mainly located in the district of Chittagong with ~ 342,690 people. and Cox's Bazar with ~ 244,000 people. This is a preliminary analysis and has not yet been validated in the field. Please send ground feedback to United Nations Satellite Centre (UNOSAT). Important note: Flood analysis from radar images may underestimate the presence of standing waters in built-up areas and densely vegetated areas due to backscattering properties of the radar signal.

This map illustrates satellite-detected surface water extent in the central and northern parts of Bangladesh using a Sentinel-1 satellite image acquired on the 22 August 2017. The total analysed area is about 4,284,431 ha. In this analysed area; 1,099,369 ha (39%) of lands are likely affected. These lands are mainly cropland irrigated and rainfed areas and estimated to 1,039,350 ha. The population exposure analysis using WorldPop data shows that ~10,000,000 people are potentially affected by floods in the analysed zone: ~5,400,000 are located in Dhaka Division and ~2,750,000 in Rajshahi Division. Please note that for visualization purposes the analyzed area is wider than the extent of this map.This is a preliminary analysis and has not yet been validated in the field. Please send ground feedback to UNITAR-UNOSAT.