Investigating The Role Of Bedrock River Meandering In The Formation Of Unpaired Strath Terraces

研究基岩河蜿蜒在不成对地层阶地形成中的作用

• 批准号: 1049889
• 负责人: Noah Finnegan
• 金额: $ 24.63万
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-05-01 至 2015-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1049889&HistoricalAwards=false
• 关键词: Investigating; Role; Bedrock; River; Meandering

River incision into bedrock sets the pace of landscape evolution in most settings and is the mechanism by which tectonic signals are communicated to the landscape. Consequently, a mechanistic understanding of river incision is important for many practical problems (e.g., river restoration, habitat stability) as well as for addressing intellectual questions such as how will a landscape respond to an increase in tectonic uplift rate or annual precipitation? In the past decade, recognition of the importance of bedrock river incision has led to an explosion of research on this topic, and substantial progress has been made in understanding river incision processes. However, most efforts have treated rivers one-dimensionally. Hence, how a river erodes laterally in a valley is largely unknown. Consequently, features such as bedrock (strath) terraces, which illustrate the alternating dominance of lateral and vertical incision over geologic time-scales, remain enigmatic. A deeper understanding of how bedrock terraces form would illuminate lateral erosion mechanics and would help answer a century-old question in Geomorphology, how and why do rivers form terraces in bedrock? This project, which combines numerical modeling, analysis of high resolution topographic data, and field work focused on the Smith River in Oregon and on the Pescadero Creek watershed in California, will test hypotheses related to how and why rivers move laterally across bedrock, and the consequences of this for where and when terraces form.Broader Significance: Through better understanding of processes of lateral bedrock erosion, we can test the plausibility that bedrock rivers might record climatic or tectonic events when they create terraces. This is of fundamental scientific value because the record rivers leave in the landscape is one of the few direct clues that we have to understand how landscapes respond to shifting climates. This research will also foster invaluable scientific training for a PhD student, an undergraduate research assistant, and an entire undergraduate geology class that will be involved in field-testing the hypotheses articulated in the proposal.

河流对基岩的切割在大多数情况下决定了景观演化的速度，也是构造信号与景观沟通的机制。 因此，对河流下切的机械理解对于许多实际问题（例如，河流恢复，栖息地稳定），以及解决智力问题，如如何将一个景观响应构造抬升率或年降水量的增加？ 在过去的十年中，认识到基岩河流下切的重要性，导致了对这一主题的研究爆炸，并在了解河流下切过程中取得了实质性进展。 然而，大多数努力都是从一维的角度来对待河流的。 因此，河流如何在山谷中横向侵蚀在很大程度上是未知的。因此，基岩（斯特拉特）阶地等特征仍然是个谜，这些特征说明了横向和垂直切割在地质时间尺度上的交替优势。 更深入地了解基岩阶地是如何形成的，将有助于阐明侧向侵蚀力学，并有助于回答地貌学中一个百年的问题，即河流如何以及为什么在基岩中形成阶地？ 该项目结合了数值模拟、高分辨率地形数据分析和实地工作，重点关注俄勒冈州的史密斯河和加州的佩斯卡德罗溪流域，将测试与河流横向穿越基岩的方式和原因相关的假设，以及这种情况对梯田形成的地点和时间的影响。通过更好地了解横向基岩侵蚀过程，我们可以测试基岩河流在形成阶地时可能记录气候或构造事件的可能性。 这具有基本的科学价值，因为河流在景观中留下的记录是我们了解景观如何应对气候变化的少数直接线索之一。 这项研究还将促进宝贵的科学培训博士生，本科研究助理，和整个本科地质类，将参与实地测试的假设中阐述的建议。