Coastal SEES Collaborative Research: Multi-scale modeling and observations of landscape dynamics, mass balance, and network connectivity for a sustainable Ganges-Brahmaputra delta

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River deltas around the world are in a state of modest to severe decline, primarily in response to anthropogenic activities such as the damming of rivers, extensive embankment systems, groundwater and gas extraction, and intense land-use pressures. These settings are also among the world's most physically dynamic, being impacted by sea-level rise and subsidence, river flooding, channel erosion, and storms. Such vulnerabilities are further magnified in highly populated delta systems, notably the large mega-deltas that rim Asian coasts in politically sensitive regions from Pakistan to China. These environments suffer not only from having more humans, infrastructure, and livelihoods in peril, but also from the anthropogenic strain that large populations place on physical and ecological support systems. In Bangladesh and West Bengal, India, the Ganges-Brahmaputra-Meghna delta (GBMD) may well be the prime example as the world's largest and most densely populated delta system, hosting 150 million people in an area the size of Louisiana. In this Coastal SEES project, a diverse group of scholars with expertise across several earth-science and engineering disciplines are brought together to answer questions about the fate and future sustainability of the GBMD and its human population. Specifically, is there sufficient river sediment available for the delta to keep pace with sea-level rise to 2100? How does the delta's network of river and tidal channels effectively distribute water and sediment across the region? How are human activities affecting this channel-network system, and what are the subsequent repercussions on human infrastructure? How can research-based knowledge developed in response to these questions help with planning and decision making for a sustainable GBMD and deltas elsewhere? To address these questions, the project combines innovative quantitative tools (numerical modeling, network and connectivity analysis) with new and existing observational data to analyze the coupled human-natural system and long-term sustainability of the GBMD. Specifically, team members will (i) develop a detailed mass balance for delta-wide sediment dispersal; (ii) quantitatively analyze the connectivity of the delta-system network that disperses this sediment; (iii) integrate this knowledge through numerical modeling at local to global scales; (iv) use observational data of landscape and channel dynamics to understand coupled land-sea interactions; (v) evaluate the quality of regional soil and water resources and their links with physical and anthropogenic processes; (vi) assess the impact of these delta dynamics on the human environment and transportation, and finally (vii) disseminate this knowledge through a variety of educational activities and opportunities for students, researchers, and professionals. Team members have collaborated extensively with local entities and universities in Bangladesh; through these contacts the knowledge developed in this project will reach relevant stakeholder communities. Findings are especially urgent to guide large-scale engineering efforts underway to improve the Bangladesh coastal-zone stability. Final products will provide a grounded, integrated, and multidisciplinary view of how the world's largest delta works and its plausible responses to environmental change in the coming century.Some of the international activities in this project are partially supported by a small contribution from the OISE Global Venture Fund.