Flood Analysis and Evolution Tropical Cyclone Sagar-18...

24 May 2018

Flood Analysis and Evolution

Tropical Cyclone Sagar-18

Djibouti

Planet Image collected on 20 May 2018

Copyright: © 2018 Planet

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UNITAR – UNOSAT, following the request of UNOCHA Djibouti , has performed a flood analysis

to illustrate the potential impact in the wake of Tropical Cyclone Sagar-18 over the city of

Djibouti.

For this flood analysis UNOSAT has used cloud-free satellite imagery over the area pre and post

event.

• Pre event: WorldView-2 from 23 April 2018 (50 cm resolution)

• Post event: WorldView-2 from 20 May 2018 (50 cm resolution)

• Post event: Pleiades from 23 May 2018 (50 cm resolution)

As observed from the satellite image from 20 May 2018, the city of Djibouti has been severely

affected by flash floods and heavy rains.

UNOSAT analysis illustrates the potential satellite detected water extent within the city of

Djibouti and classifies the areas as:

- Severely affected: as of 20 May 2018, water and mud are visible on 80% of the roads and

streets analysed, surrounding the nearby buildings almost completely. (Insets: 1, 3 & 5)

- Partially affected: as of 20 May 2018, water and mud are visible in some sections of the

roads and streets, surrounding the nearby buildings only partially. (Insets: 2, 4 & 6)

- Possibly affected: as of 20 May 2018, no visible evidence of water and mud.

In order to visualize the evolution of the situation and how the water has receded, we have

included some examples (Insets: 1-6) extending until 23 May 2018.

The findings are illustrated in the following pages.

This is a preliminary analysis and has not yet been validated in the field. Please send ground

feedback to UNITAR – UNOSAT.

SUMMARY & OVERVIEW MAP

DjiboutiSeverely affected by

the floods

BalbalaPartially affected by

the floods

INSET 1

INSET 2

INSET 3

INSET 4

INSET 5

INSET 6

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Inset 1: Situation as of 20 May 2018 - Severely affected (Marabout & Heron)

Pre event - 23 April 2018 Post event – 20 May 2018

Imagery Copyright: DigitalGlobe, Inc Imagery Copyright: DigitalGlobe, Inc

Water and mud

surrounding buildings

(protected by fences)

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Inset 1: Situation as of 23 May 2018 – Waters have receded (Marabout & Heron)

Post event - 20 May 2018 Post event – 23 May 2018

Imagery Copyright: © CNES 2018 – Distribution Airbus Defence and Space/ SPOT Image Imagery Copyright: DigitalGlobe, Inc

Water and mud


(protected by fences)

Examples of

standing water along

some road sections

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Inset 2: Situation as of 20 May 2018 - Partially affected (Serpent)



Examples of standing

water along some

road sections

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Inset 2: Situation as of 23 May 2018 – Waters have receded (Serpent)




water along some

road sections

Waters have

completely receded

7

Inset 3: Situation as of 20 May 2018 - Severely affected (Einguela 1 & 2, Quartier 1 & 4)



Water and mud


(no fence)

8

Inset 3: Situation as of 23 May 2018 – Waters have receded (Einguela 1 & 2, Quartier 1 & 4)



Water and mud


(no fence)


water along some

road sections

9

Inset 4: Situation as of 20 May 2018 - Partially affected (Djebel)




water along some

road sections

10

Inset 4: Situation as of 23 May 2018 – Waters have receded (Djebel)




water along some

road sections

Waters have almost

receded only some road

sections still affected

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Inset 5: Situation as of 20 May 2018 - Severely affected (Oued Ambouli)



Water and mud


(other construction

material)

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Inset 5: Situation as of 23 May 2018 – Waters have receded (Oued Ambouli)



Water and mud


(other construction

material)


water visible in some

areas

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Inset 6: Situation as of 20 May 2018 - Partially affected (Aeroport)



Examples of standing water

and mud inside the airport

and surrounding areas

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Inset 6: Situation as of 23 May 2018 – Waters have receded (Aeroport)



Examples of standing water

and mud inside the airport

and surrounding areas

Waters have almost receded

only some road sections still

affected by mud

Palais des Nations, CH-1211

Geneva 10, 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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UNITAR Operational Satellite Application Programme (UNOSAT)

Contact information:

www.unitar.org/unosat

[email protected]

T +41 22 767 4020

Flood Analysis and Evolution Tropical Cyclone Sagar-18...

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