Sustainable Intensification of Rice Agriculture in Vulnerable Mega-Deltas: A Global Challenge

The world's major river deltas - hotspots of agricultural production that support rural livelihoods and feed much of the global population - are facing a major sustainability crisis. This is because they are under threat from being 'drowned' by rising sea levels, with potentially severe consequences for the 500 million people who live and work there. In particular, the process of 'drowning' means that deltas are rapidly losing land (up to 20% of land is projected to be lost to sea-level rise by 2100 in the major deltas of south and southeast Asia alone), while simultaneously exacerbating problems of flooding and soil salinization. These problems are creating a 'perfect storm' that makes agriculture increasingly challenging, at precisely the time when the pressure is increasing for these rich, fertile, landscapes to produce more food to support rapidly growing global populations.

The world's third largest delta, the Mekong, is SE Asia's rice basket and home to almost 20 million people, but it is being exposed to severe environmental risks as a result of climate change and rapid economic development, most notably from the development of hydropower dams in the Mekong's catchment upstream which are cutting off the supply of sediment to the delta. The Mekong is therefore not only representative of many of the issues facing the world's deltas, but reliable data are urgently needed to help inform the sustainable management plans required to provide a safe operating space for the delta's inhabitants. In our prior work we have demonstrated that flows of water, sediment and associated nutrients within and through deltas are critical to the resilience of rice cultivation strategies. The sediments that are deposited in the delta help to offset sea level rise and they are very fertile because of the abundant nutrients (nitrogen and phosphorous) they contain. The key issue that is the focus of this proposal is that many of the Mekong delta's poor farmers (over 3.5 million farmers live below the poverty line) rely on the free fertilisation provided by river sediment deposition to reduce their 'input' costs (the portion of their income that is spent on purchasing and applying artificial fertiliser to maintain rice production). There is therefore a trade-off between the positive effects (delta building and free fertilisation) of natural sediment deposition versus the negative effects of the flooding process that causes it. As sediment and nutrient fluxes decline in the future (as a result of sediment trapping by dams upstream), new approaches are needed to inform adaptation strategies (such as managed flooding) to ensure that vulnerable communities can continue to farm sustainably in the future.

In this proposal we will collaborate with Vietnamese partners to bring UK expertise in (i) the modelling of floods, sediment transport and nutrient fluxes; (ii) agricultural livelihoods; (iii) participatory stakeholder engagement processes and (iv) social-ecological systems dynamics to bear on this challenge. By bringing together this blend of expertise and working closely with our Vietnamese colleagues and stakeholders we will be able to define policy relevant scenarios of future change, quantify the links between flooding, sediment and nutrient deposition and agricultural livelihoods, and develop new modelling tools that will be able to evaluate the trade-offs between flooding and nutrient supply as the future environment changes. We will be able to concept-proof a new approach that can deliver an integrated assessment of the factors driving changes to livelihoods and explore the effects of adaptations that could enable more sustainable intensification of rice agriculture. This will be done within a globally significant, iconic, delta, providing a template for similar analyses in other vulnerable deltas in the Global South.

The deltas of the global south are the world's rice baskets but they are under environmental stress as a consequence of rising sea levels: 20% of agricultural land will be lost by 2100 in the deltas of south and southeast Asia alone, bringing attendant problems of flooding and saline intrusion. The major drivers of sea-level rise are anthropogenic climate change, land subsidence caused by groundwater and hydrocarbon extraction, and anthropogenic interventions (such as damming) on the rivers that feed deltas, which reduces the supply of nutrient rich sediments. The significance of the latter point is that the technological development of rice agriculture in poor countries is typically low, with the largest cost being artificial fertilisation (~40-50% of total costs). Rice production has been stimulated by water management infrastructure that protects against floods, but this same infrastructure prevents the input of nutrient inputs associated with flood-induced sediment deposition. Hence there are trade-offs between nutrient-rich sediment delivery to support agricultural production, sediment deposition to mitigate sea-level rise, and the negative impacts (e.g., crop damage, infrastructure damage, loss of property and threat to livestock and human life) of damaging floods. The links between these tradeoffs and agricultural livelihoods and their evolution under environmental change remains unclear. In this proposal we will build sustainable collaborations with our Vietnamese partners to bring UK expertise in (i) the modelling of floods, sediment transport and nutrient fluxes; (ii) agricultural livelihoods; (iii) participatory stakeholder engagement processes and (iv) social-ecological systems dynamics to bear on this challenge. The work plan will generate an integrated modelling tool that will be tested and implemented against a range of policy-relevant scenarios established as part of our work, providing a strong foundation to assess optimal management strategies.

This proposal will result in the establishment and development of a novel international collaboration that will bring together a range of experts with complementary expertise to address the challenge of understanding how environmental change impacts the sustainability of rice cultivation within a highly vulnerable mega-delta. We anticipate that this will benefit the following groups:

1. National and district actors in the water and agricultural sector. Our in-country partners (IPSARD, Can Tho, SIWRR) will leverage their networks of contacts to invite representatives from key policy making bodies, notably the Ministry of Natural Resources and Environment (MONRE), Ministry of Agriculture and Rural Development (MARD), and Vietnamese National Environment Agency to attend and participate in our stakeholder workshops.
2. Multilateral organisations and their bilateral counterparts/NGOs. Here we will engage primarily with our project partner (UN FAO), but also through our existing networks the Mekong River Commission (MRC), who are the transnational body responsible for sustainable development in the Mekong basin. Given our focus on understanding how upstream damming may affect agriculture in the delta, MRC will be pivotal for their perspective on basin-wide management options, while FAO offer a broader international perspective for other vulnerable deltas.
3. Affected communities / households: We will engage with local community institutions and community members through the social surveys conducted in the main research programme, giving a direct voice and participation in outcomes.
4. Organisations focused on agricultural research We will engage closely throughout with our Project Partner, the International Rice Research Institute (IRRI) to ensure that our work on the impacts of nutrient loadings can be disseminated to potential beneficiaries within and beyond Vietnam.
5. The Mekong delta is home to twenty million people. Their security in terms of space, water supply and political stability are conditional on the integrity of the delta in the next 100 years and beyond.

The two main ways in which we will engage with end-users are embedded within the main work plan via the policy analysis report and stakeholder workshops that we will produce as an output from the core research programme. However, an additional key method will be the production of a final policy brief (produced in collaboration with Southampton's dedicated knowledge transfer team, PublicPolicy@Southampton) which will summarise the main implications of our work for agriculture within the VMD. We will disseminate this policy brief (which will be published electronically and in hard form with versions in English and Vietnamese) back through the individuals and groups that we encounter through the work, as well as the broader set of individuals/organisations identified by the stakeholder analysis phase.

Some of the benefits from the advances we will make in this project will be of value within the next 10 years whereas the impacts on health, economic growth, social cohesion and political stability extend over time-scales of decades to one hundred years, but these are the appropriate planning time horizons. The UK will also benefit from improved forward planning and targeting of overseas aid to delta regions and provision of new technical solutions to sustainable delta management.