flood analysis and evolution tropical cyclone sagar-18...
TRANSCRIPT
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
surrounding buildings
(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)
Pre event - 23 April 2018 Post event – 20 May 2018
Imagery Copyright: DigitalGlobe, Inc Imagery Copyright: DigitalGlobe, Inc
Examples of standing
water along some
road sections
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Inset 2: Situation as of 23 May 2018 – Waters have receded (Serpent)
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
Examples of standing
water along some
road sections
Waters have
completely receded
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Inset 3: Situation as of 20 May 2018 - Severely affected (Einguela 1 & 2, Quartier 1 & 4)
Pre event - 23 April 2018 Post event – 20 May 2018
Imagery Copyright: DigitalGlobe, Inc Imagery Copyright: DigitalGlobe, Inc
Water and mud
surrounding buildings
(no fence)
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Inset 3: Situation as of 23 May 2018 – Waters have receded (Einguela 1 & 2, Quartier 1 & 4)
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
surrounding buildings
(no fence)
Examples of standing
water along some
road sections
9
Inset 4: Situation as of 20 May 2018 - Partially affected (Djebel)
Pre event - 23 April 2018 Post event – 20 May 2018
Imagery Copyright: DigitalGlobe, Inc Imagery Copyright: DigitalGlobe, Inc
Examples of standing
water along some
road sections
10
Inset 4: Situation as of 23 May 2018 – Waters have receded (Djebel)
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
Examples of standing
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)
Pre event - 23 April 2018 Post event – 20 May 2018
Imagery Copyright: DigitalGlobe, Inc Imagery Copyright: DigitalGlobe, Inc
Water and mud
surrounding buildings
(other construction
material)
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Inset 5: Situation as of 23 May 2018 – Waters have receded (Oued Ambouli)
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
surrounding buildings
(other construction
material)
Examples of standing
water visible in some
areas
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Inset 6: Situation as of 20 May 2018 - Partially affected (Aeroport)
Pre event - 23 April 2018 Post event – 20 May 2018
Imagery Copyright: DigitalGlobe, Inc Imagery Copyright: DigitalGlobe, Inc
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)
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
Examples of standing water
and mud inside the airport
and surrounding areas
Waters have almost receded
only some road sections still
affected by mud
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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
T +41 22 767 4020