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

世界主要河流三角洲--支持农村生计和养活全球大部分人口的农业生产热点--正面临重大的可持续性危机。这是因为他们正面临海平面上升的“淹没”威胁，这可能会对在那里生活和工作的5亿人造成严重后果。特别是，“淹没”的过程意味着三角洲正在迅速失去土地（预计到2100年，仅在南亚和东南亚的主要三角洲，就有20%的土地将因海平面上升而失去），同时加剧了洪水和土壤盐碱化的问题。这些问题正在创造一场“完美风暴”，使农业变得越来越具有挑战性，而正是在这个时候，这些丰富，肥沃的土地生产更多的粮食以支持快速增长的全球人口的压力正在增加。世界第三大三角洲，湄公河，是东南亚的稻米篮子，也是近2000万人口的家园，但由于气候变化和快速的经济发展，它正面临严重的环境风险，最明显的是在湄公河上游流域开发水电大坝，切断了三角洲的沉积物供应。因此，湄公河不仅代表了世界三角洲面临的许多问题，而且迫切需要可靠的数据来帮助制定可持续管理计划，为三角洲居民提供安全的操作空间。在我们之前的工作中，我们已经证明了三角洲内部和通过三角洲的水，沉积物和相关营养物质的流动对水稻种植策略的恢复力至关重要。沉积在三角洲的沉积物有助于抵消海平面上升，它们非常肥沃，因为它们含有丰富的营养物质（氮和磷）。该提案的重点是湄公河三角洲的许多贫困农民（超过350万农民生活在贫困线以下）依靠河流沉积物提供的免费施肥来减少他们的“投入”成本（他们的收入中用于购买和施用人工肥料以维持水稻产量的部分）。因此，在积极影响和消极影响之间存在着一种权衡，自然沉积物沉积（三角洲建设和自由施肥）与洪水过程的负面影响，导致它。随着沉积物和营养通量下降，在未来（由于上游水坝的沉积物截留），需要采取新的办法，为适应战略提供信息（如有管理的洪水），以确保脆弱社区今后能够继续可持续地耕作。在本提案中，我们将与越南合作伙伴合作，将英国在以下方面的专业知识引入其中：（i）洪水，沉积物运输和营养物通量的建模;（ii）农业生计;（iii）参与性利益相关者参与过程和（iv）社会生态系统动态，以应对这一挑战。通过汇集这些专业知识，并与我们的越南同事和利益相关者密切合作，我们将能够确定未来变化的政策相关情景，量化洪水，沉积物和营养物沉积与农业生计之间的联系，并开发新的建模工具，以评估未来环境变化时洪水和营养物供应之间的权衡。我们将能够对一种新方法进行概念验证，这种方法可以对推动生计变化的因素进行综合评估，并探索适应的影响，从而使水稻农业更加可持续地集约化。这将在一个具有全球意义的标志性三角洲内完成，为全球南方其他脆弱三角洲的类似分析提供模板。

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.