Preliminary Rapid Flood Assessment Lao People s Democratic Republic Update 1

Transcription

1 Preliminary Rapid Flood Assessment Lao People s Democratic Republic Update 1 2 August 2017

2 Situation Overview- SAR data over the area- Latest Acquisition SAR Image from 30 July 2017 covering the provinces of Salavan, Champasack, Attapeu, Sekong Post Event Cyclone SONCA-17 Sentinel 1 SAR image 10 m Resolution 30 July 2017 Pre Event Cyclone SONCA-17 Sentinel 1 SAR image 10 m Resolution 18 July 2017 Satellite images: Copernicus 2017/ESA Analysis: UNITAR- UNOSAT

3 Summary Situation -Findings 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 30 and July Districs analysed: - Khongxedone (Salavan Pronvince) - Kaleum, Thateng, Lamarm & Dakcheung (Sekong Province) - Sukhuma & Pathoomphone (Champasack Province) - Sanamxay & Phouvong (Attapeu Province) Rapid Flood Assessment compares 2 different situations: Post Event: After Cyclone SONCA-17 made landfall (30 July 2017) Pre Event: Before Cyclone SONCA-17 made landfall (18 July 2017) Main results / findings : As a general trend, the waters in all the analyzed districts seem to remain the same or even reced, except for the Sukhuma district where flooded agricultural areas have increased on the southeastern part of the district as of 30 July Although wet saturated soils and standing waters have been reducing in extension, they are still visible in all the analysed districts as of 30 July Some exceptions are observed in the Sekong province, as to know the waters of the Kaleum, Thateng, Lamarm & Dakcheung districts have almost completely receded.

4 Khongxedone District (Salavan Pronvince) - Situation -Findings

5 Khongxedone District (Salavan Pronvince) - Situation -Findings Khongxedone District (Salavan Pronvince) In the close up-view, a comparison between 18 July and 30 July 2017 shows that waters are receding in some areas (orange arrows). As of 30 July, agricultural areas (paddy fileds) seems to be potentially flooded. Close up-view 18 July Baseline July 2017 for Reference Close up-view 30 July 2017

6 Thateng District (Sekong Province)

7 Thateng District (Sekong Province) - Situation -Findings Thateng District (Sekong Pronvince) In the close up-view, a comparison between 18 July and 30 July 2017 indicates that waters have almost completly receded. As of 30 July, wet saturated soils are visible (orange arrows), but major flooded areas are not. Close up-view 18 July 2017 Baseline for Reference Close up-view 30 July 2017

8 Kaleum District (Sekong Province)

9 Kaleum District (Sekong Province) - Situation -Findings Kaleum District (Sekong Pronvince) In the close up-view, a comparison between 18 July and 30 July 2017 shows that the observed situations remained the same beteween both dates. No major floods are observed. The river seems to be flowing in its natural banks. Wet saturated soils are visible in the left side of the riverbak (in orange). Close up-view 18 July 2017 Baseline for Reference Close up-view 30 July 2017

10 Lamarm District (Sekong Province)

11 Lamarm District (Sekong Province) - Situation -Findings Lamarm District (Sekong Pronvince) In the close up-view, a comparison between 18 July and 30 July 2017 is visible and the two situations look quite similar between both dates. Waters receded in the southern part of the image. There are potentially wet saturated soils close to the city of Sekong. Close up-view 18 July 2017 Baseline for Reference Close up-view 30 July 2017

12 Dackcheung District (Sekong Province)

13 Dakcheung District (Sekong Province) - Situation -Findings Dackcheung District (Sekong Pronvince) In the close up-view, a comparison between 18 July and 30 July 2017 indicates the same situation in both dates. No floods observed. Close up-view 18 July 2017 Baseline for Reference Close up-view 30 July 2017

14 Sukhuma District (Champasack Province)

15 Sukhuma District (Champasack Province) - Situation -Findings Sukhuma District (Champascak Pronvince) In the close up-view, a comparison between 18 July and 30 July 2017 shows an increase of flooded agricultural areas 9km south of the Soukhouma town and as well in both river banks (orange arrows). As of 30 July 2017, waters are receding in the areas that surround the town of Sukhuma. Baseline for Reference Close up-view 18 July 2017 Close up-view 30 July 2017

16 Pathoomphone District (Champasack Province)

17 Pathoomphone District (Champasack Province) - Situation -Findings Pathoomphone District (Champasack Pronvince) In the close up-view, a comparison between 18 July and 30 July 2017 shows a decrease of flooded areas that surround the different villages. (orange arrows) As of 30 July 2017 waters are receding in some areas. Some standing waters are located in the surroudings of the villages, which might thus be affected. Baseline for Reference Close up-view 18 July 2017 Note that resolution of the image is 10m so the spectral characteristics of the satellite imagery used might underestimate flood extent areas along highly vegetated areas and built-up urban areas. Close up-view 30 July 2017

18 Sanamxay District (Attapeu Province)

19 Sanamxay District (Attapeu Province) - Situation -Findings Sanamxay District (Attapeu Pronvince) In the close up-view, a comparison between 18 July and 30 July 2017 shows a decrease of flooded agricultural areas (orange arrows). As of 18 July 2017, heavy rains might have caused inundations in the areas that surround the villages along the road 18 (road segment in the inset). Even if waters are receding, as of 30 July 2017, wet saturated soils are still visible on that date. Baseline for Reference Close up-view 18 July 2017 Note that resolution of the image is 10m so the spectral characteristics of the satellite imagery used might underestimate flood extent areas along highly vegetated areas and built-up urban areas. Close up-view 30 July 2017

20 Phouvong District (Attapeu Province)

21 Phouvong District (Attapeu Province) - Situation -Findings Phouvong District (Attapeu Pronvince) In the close up-view, a comparison between 18 July and 30 July 2017 shows a decrease of flooded agricultural areas (orange arrows). As of 18 July 2017, heavy rains might have caused inundations in the areas that surround the villages located along the road. Even if waters are receding, as of 30 July 2017, wet saturated soils are still visible on that date. Baseline for Reference Close up-view 18 July 2017 Note that resolution of the image is 10m so the spectral characteristics of the satellite imagery used might underestimate flood extent areas along highly vegetated areas and built-up urban areas. Close up-view 30 July 2017

22 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 UNITAR International Environment House Chemin des Anémones 11-13, CH-1219 Châtelaine, Geneva - Switzerland T F This presentation should not be copied or disseminated in any manner without the express permission of UNOSAT.