CNH-L: Socioecological System Dynamics Related to Livelihood, Human Migration, and Landscape Evolution

这个跨学科的研究项目将研究在人口密集的河流三角洲中河流和海岸过程、景观动态、人类活动和移民之间的关系。它将加强对物理和人类系统动力学之间的尺度和联系的理解，包括这些系统之间的复杂反馈回路。该项目将确定这些关系是如何随着时间的推移而变化的，它将为人类变化的河流流量或土地改造可能影响未来系统相互作用的方式提供新的见解。该项目将产生一系列在基础研究和应用研究背景下具有未来价值的多样化产品，包括关于移民、生计活动、土地利用和生活在不断变化的海岸线上的社区的适应的数据；详细描述了陆地-水治理在塑造河流三角洲当代和历史社会生物物理动态方面的作用，以及在土地不断被创造和破坏的环境中出现的移民和景观模式的开源计算机模型。该项目将为研究生提供宝贵的跨学科教育和培训机会。与研究相关的其他教育活动将涉及美国和孟加拉国类似地区的学生。河流三角洲是一个复杂的系统，面临着在不断变化的环境中平衡可持续发展、资源利用和土地安全的挑战。随着不断变化的景观动态创造（有时也破坏）土地和经济机会，洪水和土地保有权冲突的风险加剧，迫使社区动荡和移民。调查人员将采用跨学科的方法，将家庭和社区一级的调查、定性访谈、沉积学和地球化学实地数据的收集、景观和制度变化的时间序列分析以及情景建模结合起来。他们将把社会科学和地球科学中已建立的经验方法与计算模型结合起来，研究生活在低洼三角洲河道沿岸的农村社区的人类活动和环境变化的耦合动力学，在那里，沉积物的沉积和侵蚀创造了不断变化的景观。调查人员将把重点放在人口流动上，作为这些耦合动态中人类方面的关键过程。它们将把不同类型的移徙定性为对环境和社会经济压力的反应，以及对与不断变化的环境条件有关的机会的反应。还将评估移徙对生计活动的影响，而生计活动又通过土地使用影响自然环境。在物理系统方面，沉积物运输以及沉积和侵蚀速率将是一个中心焦点，因为预计农业和家园土地的产生或破坏将强烈影响迁移动态，特别是在气候制度变化产生不可预测的降水和洪水模式的情况下。关于变化的生物物理景观和人类活动的观测数据将整合到基于耦合剂和沉积物运输模型中，以探索迁移作为对气候压力的潜在适应和脆弱人群恢复力的来源的作用。虽然项目的大部分将集中在孟加拉国恒河-布拉马普特拉河-梅克纳河三角洲生物物理系统和人类系统之间的动态相互作用，但项目发现将与世界上其他人口密集的三角洲相关，包括美国南部的密西西比河三角洲。该项目由美国国家科学基金会自然与人类系统耦合动力学（CNH）计划支持。

This interdisciplinary research project will examine the relationships among river and coastal processes, landscape dynamics, and human activities and migration in a densely populated river delta. It will enhance understanding of the scales and associations among physical and human system dynamics, including complex feedback loops among those systems. The project will identify how these relationships shift over time, and it will provide new insights regarding the ways in which variable river discharge or land modifications by humans may influence system interactions in the future. The project will yield a diverse set of products that will have future value in both basic and applied research contexts, including data about migration, livelihood activities, land-use, and adaptation from communities living on a shifting coastline; detailed characterization of the role of land-water governance in shaping both contemporary and historical social-biophysical dynamics within river deltas, and open-source computer models of migration and landscape patterns that emerge in an environment where land is constantly created and destroyed. The project will provide valuable interdisciplinary education and training opportunities for graduate students. Other educational activities related to the research will involve students in comparable regions of the U.S. and Bangladesh.River deltas are complex systems facing the challenge of balancing sustainable development, resource use, and land security in a continually shifting environment. As land and economic opportunities are created (and sometimes destroyed) through evolving landscape dynamics, risks from floods and conflicts over land tenure are intensified, forcing community upheaval and migration. The investigators will use an interdisciplinary approach that integrates household- and community-level surveys, qualitative interviews, collection of sedimentological and geochemical field data, time-series analyses of landscape and institutional change, and scenario modeling. They will combine established empirical methods in the social sciences and the earth sciences with computational modeling to study coupled dynamics of human activity and environmental change in rural communities living along channels in a low-lying delta, where sediment deposition and erosion create a constantly changing landscape. The investigators will focus on population movement as a crucial process on the human side of these coupled dynamics. They will characterize different types of migration as responses to environmental and socioeconomic stress and to opportunities related to changing environmental conditions. The impacts of migration on livelihood activities, which in turn affect the physical environment through land use, also will be assessed. With respect to physical systems, sediment transport, and the rates of deposition and erosion will be a central focus, because the creation or destruction of agricultural and homestead land are expected to strongly affect migration dynamics, particularly as changing climatic regimes produce unpredictable precipitation and flooding patterns. Observational data about the changing biophysical landscape and human activity will be integrated in coupled agent-based and sediment transport models to explore the role of migration as a potential adaptation to climatic stress and as a source of resilience in vulnerable populations. Although the bulk of the project will focus on dynamic interactions among biophysical and human systems in the Ganges-Brahmaputra-Meghna Delta of Bangladesh, project findings will have relevance for other densely settled deltas around the world, including the Mississippi River delta of the southern U.S. This project is supported by the NSF Dynamics of Coupled Natural and Human Systems (CNH) Program.