Livelihoods, Mobility, and Flood Infrastructure in the Ganges-Brahmaputra-Meghna Delta

Abstract:

Deltas are dynamic sedimentary landforms that emerge where rivers meet the sea. More than half a billion people globally reside within deltas and are exposed to coastal and river processes that continually shift land-water boundaries through sediment deposition and erosion. Humans have attempted to manage flooding and secure socioeconomic assets in deltas through the building of coastal flood control infrastructure such embankments. In the densely populated Ganges-Brahmaputra-Meghna (GBM) Delta in Bangladesh, nearly 10,000 km² of low-lying deltaplain sits on embanked land, known locally as polders. First established in the 1960’s, polders initially increased agricultural yields by protecting crops from tides and storm surges. However, recent studies reveal that widespread embanking has impacted natural system dynamics, leading to subsidence, the infilling of tidal channels, and waterlogging. The direct and indirect (via natural system feedbacks) impacts of embankments on local communities are poorly understood. In this analysis, we examine how the presence of embankments relate to the livelihood and migration activities of individuals living in southwest Bangladesh. Using retrospective life history data from 4000 households situated within the dynamic coastal zone of the GBM deltaplain, we examine temporal and spatial variability in rates of migration, participation in crop cultivation, and shifts to or away from aquaculture. We answer three primary research questions: (1) How have livelihoods and rates of migration changed over time; (2) how do patterns vary across embanked and un-embanked landscapes; and (3) how do patterns vary in conjunction with natural processes such as sediment infilling or lateral erosion of fluvio-tidal channels? These data provide insight into how flood control infrastructure, and the morphological feedbacks that result, impact human mobility and the stability of rural and coastal livelihoods.