GCRF Living Deltas Hub River deltas comprise only 1% of global landscapes, yet support over half a billion people.  Deltas are tightly coupled social-ecological systems (SESs), but human exploitation, environmental degradation and threats from climate change increasingly threaten these delicate interfaces between land and water.  The intractable development challenge addressed by this bid is how to avoid the collapse of South and SE Asian deltas as functioning, highly productive social-ecological systems in the face of human development and the projected consequences of climate change. The proposed Living Deltas Hub focuses on the delta SESs of three major rivers in South and Southeast Asia: the Red River and Mekong (Vietnam) and Ganges-Brahmaputra-Meghna (GBM: Bangladesh, India). Deltas form part of wider river basins and so the Hub will also engage with other riparian country researchers, in Thailand, Cambodia, Laos and Myanmar. The stakes for the project are clear: 70% of the Mekong delta is highly vulnerable to flooding with 7 million people at risk.  Sea level rise in Bangladesh could displace between 3 and 13 million by 2100. SE-Asian mega-deltas produce 88% of the world's rice, but the 98cm of sea level rise predicted under IPCC AR5 (2014) would render 16% of arable land in Bangladesh and 25% in Vietnam unusable by 2100.  Upstream damming and sediment retention is also a major threat, with resulting delta subsidence putting 12 million people in 23 Asian cities at risk from water inundation.  As human impacts increase, the need for locally-rooted sustainable development strategies underpinned by traditional knowledge becomes ever greater. The GCRF Living Deltas Hub will co-develop the transdisciplinary frameworks needed to understand delta SESs, and will work with delta-dwellers and policymakers to develop solutions that can help realise the UN Sustainable Development Goals (SDGs) in delta contexts. The Hub is novel - no other existing or previous international delta initiative has specifically addressed the SDGs by co-creating new natural and cultural heritage understandings of deltas. It is timely, as it addresses the crucial challenges of SE Asian delta degradation early in the lifespan of the SDGs and so contributes to the development of SDG monitoring and planning - globally and regionally, as well as in country contexts.  The Hub is innovative as it emphasizes transdisciplinary integration of the earth and life sciences, social sciences, humanities and arts, to address these common challenges The Hub will operate on a model of 'equitable partnership', involving delta-dwellers and the research community in developing knowledge and policy for better delta futures. The Hub comprises six innovative work packages co-developed with Global South partners and research institutes addressing specific in-country and delta-scale needs. Its new knowledge will serve to build capacity and shape policy at local, national, regional and global levels. The Hub will have lasting impact through improved livelihoods and more resilient communities, sustainable management and conservation, improved monitoring of SDG indicators and better policies for sustainable development.  The Hub brings together a transdisciplinary team of experts and practitioners from Global 'North' and 'South'. Hub strengths are in: coupled human and natural systems analyses; demography and international development; natural hazard modelling and coastal resilience; environmental monitoring and modelling; policy and practice of resource management, hazard, risk and resilience; SDG-focused analyses of delta systems and their vulnerability to hazards; justice and governance; behavioral finance; delta nutrition and food security; and gender-sensitive research.   Working together with stakeholders from delta countries, the research team have the knowledge, expertise and track record to build new understandings of delta change, new partnerships, and new solutions. The Global Challenges Research Fund (GCRF) supports cutting-edge research to address challenges faced by developing countries. The fund addresses the UN sustainable development goals. It aims to maximise the impact of research and innovation to improve lives and opportunity in the developing world.