Regional Patterns of Flood Hazard in India: A Geographical Study

Flooding in India is characterised by pronounced regional contrasts produced by variations in monsoon rainfall, river-basin morphology, topography, sediment regimes, antecedent hydrological conditions, coastal processes and human modification of drainage systems. Although the Indo-Gangetic and Brahmaputra plains have traditionally been regarded as the principal flood-prone regions, recurrent floods in peninsular basins, Himalayan valleys, coastal zones and rapidly urbanising areas demonstrate that India contains multiple and increasingly interconnected flood regimes. This paper examines the regional geography of flood hazard in India through a descriptive, analytical and comparative secondary-data approach. The principal empirical basis is the Central Water Commission’s satellite-derived assessment of maximum aggregated flood-affected area for 1986–2022, supplemented by flood-forecasting records, official policy reports and peer-reviewed hydrological and geographical research. The analysis shows that 21.213 million hectares were identified within the maximum aggregated satellite-observed inundation footprint during 1986–2022. Uttar Pradesh, Bihar, Assam and West Bengal together account for approximately 58.5% of this national extent. However, absolute area alone obscures important contrasts in flood intensity, proportional spatial exposure and flood-generating processes. Himalayan-fed alluvial rivers dominate the northern and north-eastern plains, while extreme precipitation, antecedent moisture, reservoir conditions, cyclonic rainfall, urban imperviousness and short-response catchments shape hazards elsewhere. The study concludes that Indian flood hazard cannot be represented adequately through a single national flood-prone category. Region-specific, process-based mapping integrating inundation frequency, depth, duration, velocity and evolving hydroclimatic conditions is necessary for more effective flood management.