26 July 2017

Preliminary Rapid Flood Assessment

Viet Nam

SAR Image from 25 July 2017 covering the provinces of Thua Thien – Hue, Da Nang and Quang Nam

Situation Overview- SAR data over the area- Latest Acquisition

Satellite images:© Copernicus 2017/ESAAnalysis: UNITAR- UNOSAT

Pre Event Cyclone

SONCA-17

Sentinel 1 SAR image

10 m Resolution

18 July 2017

Post Event Cyclone

SONCA-17

Sentinel 1 SAR image 10

m Resolution

25 July 2017

Previous Flood Event

Sentinel 1 SAR image

10 m Resolution

18 December 2016

1 December 2016

UNOSAT Rapid Flood Assessment

Purpose of the flood rapid assessment is to give a quick overview of the magnitude and severity of the event.

Rapid Flood Assessment was conducted over the area covered by the Sentinel-1 image acquired on 25 July 2017.

Provinces analysed: Thua Thien Hue, Da Nag and Quang Nam. Only Thua Thien Hue, Da Nag provinces were in the trajectory

of the cyclone SONCA-17

Rapid Flood Assessment compares 3 different situations:

• Post Event: After Cyclone SONCA-17 made landfall (25 July 2017)

• Pre Event: Before Cyclone SONCA-17 made landfall (18 July 2017)

• During previous flood event: Major floods that took place in Viet Nam last December (1 & 18 December 2016)

Main results / findings :

• No major floods were observed inside the provinces analysed

• No overflowing rivers

• Wet agricultural soils are observed as of 25 July 2017, specially in the province of Quang Nam, but there is not a clear

indication of floods

Summary– Situation -Findings

Thua Thien Province

As of 25 July 2017 wet agricultural soils are observed north of the

city of Hue in comparison with the image acquired on 18 July

2017. The Song Ngur Ha river has no visible overflow in the image

acquired after the Cyclone SONCA-17.

Thua Thien – Hue Province – Situation -Findings

25 July 2017

18 July 2017

18 December 2016

Thua Thien Province

In comparison with the image acquired last year on 18 December

2016, not major floods are visible in the image of 25 July 2017.

25 July 2017

18 July 2017

18 December 2016

Da Nang Province

As of 25 July 2017 wet agricultural soils are observed south of the

city of Da Nang in comparison with the image acquired on 18 July

2017. Wet agricultural soils are located in the sourthen part of the

river Song Cam Le. The Song Cam Le river has no visible

overflow as of 25 July 2017.

Da Nang Province – Situation -Findings

25 July 2017

18 July 2017

18 December 2016

Da Nang Province

Similar situation observed in comparison with the image acquired

as of 1 December 2016. No major floods are observed in the

province of Da Nang, only wet saturated soilds in the southern part

of the Song Cam Le river.

25 July 2017

18 July 2017

1 December 2016

Quang Nam Province

As of 25 July 2017 wet agricultural soils are clearly observed south and

north of the Vinh Cura Dai river and the land that remains in the braided

river. The Vinh Cura Dai river has no visible overflow in the image

acquired as of 25 July 2017. This province was not in the trajectory of

the cyclone SONCA -17. Wet agricultural soils are observed as a

consequence of period of heavy rains.

Quang Nam Province – Situation -Findings

25 July 2017

18 July 2017

1 December 2016

Quang Nam Province

The southeastern part of Quang Nam Province and the coast (not

observed in this image) was flooded last year, as of 1 December 2016.

In observed area, wet agricultural soils are visible as of 25 July 2017,

north of the Vinh Cura Dai river and in the land that remains inside the

braided river (bar).

UNITAR

International Environment House

Chemin des Anémones 11-13,

CH-1219 Châtelaine,

Geneva - Switzerland

T +41 22 917 8400

F +41 22 917 8047

www.unitar.org

United Nations Institute for Training and Research

Institut des Nations Unies pour la Formation et la Recherche

Instituto de las Naciones Unidas para Formación Profesional e Investigaciones

Учебньıй и научно-исследовательский институт

Организации Объединенньıх Наций

معهد األمم المتحدة للتدريب والبحث联合国训练研究所

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