Causes and mitigation of flooding in the Brahmaputra river basin: a systematic review

Recurrent flooding in the Brahmaputra River Basin has caused extensive loss of life and substantial economic damage. Despite its profound socio-economic and environmental implications, a comprehensive understanding of how the basin's geomorphological and hydrometeorological characteristics shape flood occurrence and how these complexities constrain early warning and management systems remains limited. This review synthesizes current knowledge on the occurrence, drivers, and mitigation of floods in the Brahmaputra River Basin. The basin's distinctive geomorphology and hydroclimatic regime create inherently favorable conditions for flooding. Active river meandering, avulsion, and rapid channel migration across the middle and lower reaches enhance flood susceptibility, whereas glaciers and snowmelt dominate hydrological processes in the upper basin, and monsoonal rainfall governs the lower basin. Flood generation arises from the interaction of extreme precipitation, antecedent hydrological conditions, and large-scale atmospheric dynamics. Although recent decades have witnessed basin-wide warming alongside declining mean rainfall, increasing rainfall variability and shifting monsoon behavior continue to amplify flood unpredictability. Despite technological progress in flood forecasting and early warning systems, their effectiveness remains constrained by sparse observations, inadequate data sharing, and limited transboundary coordination. Overall, rising temperatures, accelerated glacier melt, geomorphological dynamism, and shifting precipitation patterns collectively heighten the challenges of flood prediction and management in the Brahmaputra River Basin.