Sentinel 1 SAR for Rapid Identification of Flooded Inquiries in South Kalimantan Province

An 2021-flood occurred in South Kalimantan Province caused severe moral and material losses, the destruction of nature, and weakened the wheel of the economy. Rapid identification of affected flood inundation areas spatially is essential for monitoring and assisting in the preparation of emergency responses. Spatial analysis of flood areas utilizes SAR (Synthetic Aperture Radar) images because its wavelength is able to penetrate well through clouds or hazy atmosphere. This study utilizes Sentinel-1A level GRD (Ground Range Detect) - IW (Interferometric Wide Swath Mode) images with VV and VII polarization. We used Remote Sensing Change Detection (RDCD) method and then implemented a flood threshold. Flood event verification is obtained from the crowdsourcing report of flood events through social media. Results shows that 11 districts of South Kalimantan were affected by flooding, namely Balangan Regency (3,498 ha), Banjar (47,548 ha), Barito Kuala (37,530 ha), Hulu Sungai Selatan (9,939 ha), Hulu Sungai Tengah (9,789 ha), Hulu Sungai Utara (13,002.24 ha), Tabalong (4,876 ha), Tanah Laut (25,931 ha), Tapin (15,597 ha), Banjarbaru (2,812 ha) and Banjarmasin (6,570 ha).