Doctoral Dissertation Research: Geomorphology and Sediment Dynamics of a Tropical Montane River

博士论文研究：热带山地河流的地貌和沉积动力学

• 批准号: 1333429
• 负责人: Patricia McDowell
• 金额: $ 1.43万
• 依托单位: University of Oregon Eugene
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-08-15 至 2015-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1333429&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Research; Geomorphology; Sediment

This doctoral dissertation research project will examine bedload sediment transport of tropical montane rivers and estimate the potential impact of predicted climate change and dam development scenarios on their geomorphology. Tropical montane rivers are geomorphically dynamic and complex. They convey large-magnitude floods with the capacity to mobilize coarse bedload (gravels to large boulders) multiple times during a single rainy season. This doctoral dissertation research project will examine bedload distribution and flux, which play an important role in defining channel form in these systems and therefore are a proxy of system sensitivity. The doctoral student will pursue answers to the following research questions through an analysis of the Rio Pacuare, Costa Rica: (1) How does channel geomorphology vary going downstream in relation to local geology and sediment sources? (2) What are the sediment transport rates and annual yields of each reach? (3) Does downstream flux of bedload express local, reach, or system-wide geomorphic connectivity? (4) How will sediment flux change in response to predicted future climate change and impoundment (dam) scenarios? The Rio Pacuare is an appropriate stream for these kinds of analyses because it is free-flowing, relatively accessible, and is representative of other tropical montane rivers. The student will use innovative field techniques to map and characterize sediment and to create reach-scale sediment budgets. In addition to traditional survey methods, the Structure from Motion approach, which derives topographic data from multiple photographs, will be adapted for grain-size analysis and identification of grain mobilization to validate sediment transport estimates. Hydraulic and sediment transport models will quantify sediment flux to characterize system sensitivity to projected climate change and impoundment scenarios. Research on tropical rivers is particularly important because demands on their resources (freshwater supply, hydroelectricity, ecology, and agriculture) continue to increase steadily, but relatively little research has been done on the geomorphology of these systems. The distinctive mix of field and remote sensing techniques used in this research will overcome some of the noted challenges of tropical river research, including difficult access, high sediment flux, rapidly fluctuating flows, and large-grain mobilization. Beyond expanding basic understanding of the dynamics of fluvial geomorphology, and especially the dynamics of tropical river morphology, this project may assist in the sustainable development, management, and conservation of tropical rivers by offering fundamental information that is usable by the public, scientists, resource managers, and policy makers. As a Doctoral Dissertation Research Improvement award, this project will provide support to enable a promising student to establish an independent research career.

本博士论文研究项目将研究热带山区河流的推移质泥沙输运，并估计预测的气候变化和大坝开发方案对其地貌的潜在影响。 热带山地河流地貌动态复杂。 它们能够在一个雨季内多次运送大规模的洪水，并能够调动粗泥沙（砾石到大圆石）。 本博士论文研究项目将研究推移质分布和通量，这在定义这些系统中的通道形式中起着重要作用，因此是系统灵敏度的代理。 博士生将通过对哥斯达黎加的Rio Pacuare的分析来寻求以下研究问题的答案：（1）河道地貌如何随当地地质和沉积物来源而变化？ (2)各河段的输沙率和年产量是多少？ (3)下游推移质通量表达局部、河段或系统范围的地貌连通性吗？ (4)沉积物通量将如何变化以响应预测的未来气候变化和蓄水（大坝）情景？ Rio Pacuare河是一条适合进行此类分析的河流，因为它是自由流动的，相对容易到达，并且是其他热带山区河流的代表。 学生将使用创新的现场技术来绘制和表征沉积物，并创建达到规模的沉积物预算。 除了传统的调查方法外，还将采用从多张照片中提取地形数据的“从运动中提取结构”方法，用于粒度分析和确定颗粒移动情况，以验证沉积物运移估计数。 水力和沉积物输运模型将量化沉积物通量，以确定系统对预计气候变化和蓄水情景的敏感性。对热带河流的研究尤其重要，因为对它们的资源（淡水供应、水电、生态和农业）的需求持续稳定增长，但对这些系统的地貌学研究相对较少。 在这项研究中使用的实地和遥感技术的独特组合将克服一些热带河流研究的挑战，包括难以进入，高沉积物通量，快速波动的流量，和大颗粒的动员。 除了扩大对河流地貌动态，特别是热带河流形态动态的基本了解外，该项目还可以通过提供公众，科学家，资源管理者和决策者可用的基本信息来帮助热带河流的可持续发展，管理和保护。 作为博士论文研究改进奖，该项目将提供支持，使有前途的学生建立一个独立的研究生涯。