Flood inundation mapping and monitoring in Kaziranga National Park, Assam using Sentinel-1 SAR data

Abstract

Satellite-based flood assessment for extent and severity is very crucial input before, during, and after a flood event has occurred. Though optical remote sensing data has been widely used for flood hazard mapping, Synthetic Aperture Radar (SAR) data is preferred for detecting inundated areas and providing reliable information during a flood event due to its capability to operate in all weather and day/night time. Availability of cloud-free optical images during monsoon over north eastern India is a rarity. SAR data also has the advantage of detecting inundation under vegetated areas due to its penetration capabilities and sensitivity to soil moisture. The present study is an attempt to use SAR data for flood monitoring of the Kaziranga National Park (KNP) during monsoon, 2017. Every year, animals are washed away by floods and most of them migrate to higher grounds in order to escape from the rising water levels. Flooding events are common in the study area during the monsoon season due to high rainfall and its close proximity to the Brahmaputra River. Dual polarized (VV and VH) Sentinel-1 SAR images obtained for the entire monsoon period in 2017 were used to create inundation maps of the KNP. Two flood waves were observed in July and August, the second of which is considered to be one of the worst flooding events inundating most areas of the park. The use of SAR data for monitoring of flood events can be very crucial for identifying locations for building animal shelters and finding routes for rescue and relief operations during the disaster.

Operational Flood Mapping Using Multi-Temporal Sentinel-1 SAR Images: A Case Study from Bangladesh

“…The actual flooded area was more from satellite image estimates which differed from officially reported areas [80]. Although real-time flood monitoring plays a vital role in relief operations [81,82], flood maps also play an important role in decision-making, planning, and implementing flood management options [83]. Most of the studies have published their flood mapping results ten years after a flood event [32].…”

Using MODIS/Terra and Landsat imageries to improve surface water quantification in Sylhet, Bangladesh

“…Thanks to the open data policy of Sentinel-1 (Torres et al 2012), this problem could be mitigated in the future while using frequent Sentinel-1A/B constellation with 6-day revisit, or even shorter if both ascending and descending passes are included. SAR images will provide faster inundation assessment (Borah et al 2018) with high accuracy (Huang et al 2018). Sentinel-1 SAR will enormously increase the efficiency in water identification (Palmer and Ruhi 2018).…”

Observatoires et Infrastructures de Données Géographiques (IDG) pour le suivi spatiotemporel et environnemental des territoires.

“…Ces observatoires sont des fournisseurs de données à références spatiales dont la clientèle reste principalement institutionnelle (Noucher et Gautreau, 2013 ; Georis-Creuseveau, 2014) mais aussi d'autres IDG. Leur usage, pour certaines applications et notamment le suivi, l'analyse et la cartographie des aléas hydrologiques, reste parfois problématique pour l'utilisateur final (Borah et al, 2018 ;Chung et al, 2015 ;Dao et Liou, 2015 ;Demir et Krajewski, 2013 ;Frazier et al, 2003 ;Hoque et al, 2011 ;Jain et al, 2005 ;Khan et al, 2011 ;Revilla-Romero et al, 2015 ;Sun et al, 2018 ;Wang et Xie, 2018). L'acquisition des données satellitaire, qui est basée sur des paramètres instrumentaux de capteurs numériques (optique, radar, résolutions…) et un protocole d'acquisition (héliosynchronisme, fauchée, période de revisite…), est aussi limitée par une sensibilité aux nuages (données optiques), à la topographie ou au vent de surface (données radar) et pour un horaire de revisite quasi fixe (tout type d'image).…”