Satellite and GIS-Based Mapping of Inundated Areas during the September 2026 Floods in Patna and Surrounding Districts, Bihar

Satellite and GIS-Based Mapping of Inundated Areas during the September 2026 Floods in Patna and Surrounding Districts, Bihar Vishal Kumar* This paper presents a satellite and GIS-oriented assessment of the major flood event that affected Patna and surrounding districts of Bihar in September 2026. The River Ganga crossed historical high flood levels at Gandhi Ghat and other stations, inundating extensive low-lying diara and floodplain areas. Using the standard remote-sensing workflow employed by scientists (Sentinel-1 SAR change detection, optical water indices, and DEM-derived terrain parameters), the study describes how inundated zones are identified and analysed. Key inundation patterns are concentrated along the Ganga corridor, particularly in Danapur, Maner, Fatuha, Barh, Mokama and downstream reaches towards Bhagalpur. Integration of flood extent with slope, curvature and land-use layers enables quantitative exposure assessment. The paper provides a practical GIS methodology that can be reproduced in Google Earth Engine and desktop GIS software. * Department of Geography, Central University of South Bihar, Gaya, India, Email: [email protected]