Collaborative Research: Unlocking The Seismic Signature Of Rivers

合作研究：解锁河流的地震特征

• 批准号: 1148488
• 负责人: Noah Finnegan
• 金额: $ 17.61万
• 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: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2015-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1148488&HistoricalAwards=false
• 关键词: Collaborative; Research; Unlocking; Seismic; Signature

Gravel and cobble transport by rivers governs channel change, and is therefore of great importance to geomorphologists and river engineers. The most commonly used approaches to estimating bedload transport rates are empirically calibrated relationships based on flume experiments. However, it is difficult to assess how effectively such relationships predict transport rates during extreme events in large rivers because quantitative measures of bedload transport are labor intensive and, at high flows, often dangerous to obtain. For logistical reasons, most bedload studies have been carried out in small mountain streams. Particle impacts on the river bed transfer momentum, which in turn generates elastic (seismic) waves. Therefore, seismology (the study of elastic waves in the Earth) can potentially constrain bedload transport rates in rivers. Taking advantage of a well-instrumented catchment with independent constraints on when and at what rate sediment moves in the channel, we will deploy an array of seismometers to test theoretical predictions for the generation of seismic waves from bedload sediment impacts with the bed during transport. Understanding more clearly when and at what rate coarse sediment moves in river channels is essential for planning infrastructure in and adjacent to rivers (e.g., bridges, dams, roads). Approaches to predicting coarse sediment transport are typically developed in controlled settings and can be inaccurate in large floods, when it is most critical to be able to predict sediment movement. Using a novel application of an existing science (seismology), we are developing an approach to measuring bedload transport in large rivers without requiring the deployment of any instrumentation in the river. This work has the potential to greatly improve our capacity to cheaply, safely, and efficiently monitor sediment movement in rivers while simultaneously advancing understanding of the processes influencing bedload transport rates in rivers. Additionally, this project will have an outreach component in which an undergraduate geology class will conduct a sediment transport monitoring exercise using the approach developed here.

河流的砾石和卵石运移控制着河道的变化，因此对地貌学家和河流工程师来说是非常重要的。估算推移质输沙率最常用的方法是基于水槽试验的经验校正关系。然而，很难评估这种关系在大型河流极端事件期间预测输沙率的有效性，因为推移质输沙量的定量测量是劳动密集型的，而且在高流量时，往往很难获得。出于后勤方面的原因，大多数泥沙研究都是在山间小溪中进行的。颗粒对河床的冲击传递动量，进而产生弹性(地震)波。因此，地震学(研究地球上的弹性波)可能会限制河流的推移质输移率。利用一个仪器齐全的集水区，对泥沙在河道中移动的时间和速度有独立的约束，我们将部署一组地震仪，以测试推移质泥沙在运输过程中与河床碰撞产生地震波的理论预测。更清楚地了解粗泥沙在河道中移动的时间和速度，对于规划河流内和邻近河流的基础设施(如桥梁、大坝、道路)至关重要。粗泥沙运移的预测方法通常是在受控环境下开发的，在大洪水中可能不准确，而此时能够预测泥沙运动是最关键的。利用现有科学(地震学)的一种新应用，我们正在开发一种测量大型河流推移质输运的方法，而不需要在河流中部署任何仪器。这项工作有可能极大地提高我们廉价、安全和有效地监测河流泥沙运动的能力，同时促进对影响河流推移质输沙率的过程的了解。此外，该项目将有一个外展部分，其中一个本科生地质学课程将使用这里开发的方法进行泥沙输送监测练习。