Sedimentation-induced flood risks and food security in Bangladesh’s Haor basin: a geospatial multi-index approach

Sedimentation, floodplain degradation, and altered hydrological regimes are major global challenges that undermine river basin resilience and water–food security. These pressures are most severe where upstream catchment processes and climate variability reshape downstream hydro-morphological systems. The north-eastern Haor floodplains of Bangladesh, particularly within the Om-Piyan-Dawki River system, exemplify these risks. Here, intense rainfall and runoff from Meghalaya accelerate sedimentation and flooding, with cascading impacts on agriculture, fisheries, and biodiversity. This study assesses sedimentation-induced risks to food security using a geospatial multi-index model that integrates Landsat imagery (1996–2021) with field observations. Results reveal a 904% increase in silted land and a 42% decline in water bodies, largely due to sand-dominated deposits. Wetlands, highly vulnerable to suspended sediment (>200 mg/L), expanded from 4% to 44%, severely affecting fisheries. The Sari-Gowain River’s water-carrying capacity declined threefold (2014–2018), while the Piyan River is nearing functional extinction, exacerbating biodiversity loss. Coupled with shifting rainfall patterns that aggravate flash floods, these changes reduced crop returns by 18%. The findings highlight the urgent need for integrated mitigation and adaptive management strategies to sustain ecological integrity, agricultural productivity, and water sustainability in flood-dependent systems worldwide.