Vertically Meandering Mountain Streams

垂直蜿蜒的山涧

• 批准号: 1145469
• 负责人: Anne Chin
• 金额: $ 10.26万
• 依托单位: University of Colorado at Denver
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2013-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1145469&HistoricalAwards=false
• 关键词: Vertically; Meandering; Mountain; Streams

Mountain streams are major sources of the world's water and sediment supply, serving as the primary reservoirs feeding into lowland rivers and larger water bodies. These mountain streams, which are characterized by a preponderance of steps and pools, exhibit a striking, staircase-like longitudinal profile that has intrigued scientists for many years. Recently, the application of spectral analysis has identified periodicities in the occurrence of steps and pools, thereby suggesting a mutual adjustment between flow and channel morphology, and an analogy to meandering in the vertical dimension. Although this finding extends the fundamentally important concept of vertical meandering from pools and riffles in downstream channels to step-pools in headwater areas of river basins, the oscillations in the step-pool streambed have not been subjected to the same level of analysis as those in pools and riffles and the meandering river. Using a combination of field, laboratory, and statistical methods, this research will develop a quantitative model to describe, predict, and explain the rhythmic step-pool morphology, and to fully establish its significance as an expression of vertical meandering in mountain streams. Time-series analytic techniques will be applied to a large database of step-pool streams from around the world to develop a model that can describe and predict the rhythmic sequences. Step-pool channels in the Santa Monica Mountains of California will also be surveyed and compared to profiles constructed in 1991 to assess change in the periodic character over decadal timescales. Flume experiments will further provide specific tests for the hypothesis that periodic step-pool sequences minimize stream power in the mountain river system, thus linking the rhythmic form to principles of energy expenditure. Collectively, these outcomes are expected to demonstrate that predictable, periodic step-pool mountain streambeds develop and are preserved in a wide range of environments to maintain equilibrium channel geometries under high energy conditions.The comprehensive treatment undertaken in this study is expected to elevate our understanding of the vertical oscillations in mountain streams toward that of riffle-pools and horizontal meandering well known for decades. Developing a general predictive model for rhythmic step-pool sequences will give insight into the underlying processes operating in mountain streams. Linking the repetitive step-pool form to principles of energy expenditure will enhance our understanding of river behavior in general. Enhanced understanding of the vertical patterns in step-pool streams will assist stable channel design and stream restoration using step-pools, a practice that is increasing in mountain and urban settings. Effective design and management of steep mountain streams will mitigate flood hazards and protect property and livelihood in downstream communities. Because mountain streams are important habitats for many sensitive aquatic species, results of this study will have further important implications for ecological management.

山脉溪流是世界水和泥沙供应的主要来源，是流入低地河流和较大水体的主要水库。这些以阶梯和水池为主的山间溪流，呈现出引人注目的阶梯式纵向轮廓，多年来一直吸引着科学家的兴趣。最近，频谱分析的应用识别了阶梯和水池出现的周期性，从而提出了水流和河道形态之间的相互调节，并在垂直方向上类似于蜿蜒。尽管这一发现将重要的垂直游荡概念从下游河道的水池和冲沟扩展到了流域源头地区的阶梯水池，但阶梯水池河床中的振荡并没有得到与水池、冲沟和蜿蜒河流中的振荡相同水平的分析。本研究将采用野外、实验室和统计学方法相结合的方法，开发一个定量模型来描述、预测和解释有节奏的阶梯滩形态，并充分确立其作为山间溪流垂直曲折表现形式的意义。时间序列分析技术将被应用于来自世界各地的台阶池流的大型数据库，以开发能够描述和预测节奏序列的模型。加州圣莫尼卡山脉的阶梯水池水道也将被调查，并与1991年建造的剖面进行比较，以评估十年时间尺度上周期性的变化。水槽实验将进一步为周期性阶跃水池序列将山区河流系统中的水流功率降至最低这一假设提供具体的测试，从而将节奏形式与能量消耗原则联系起来。总而言之，这些结果有望证明，在高能条件下，可预测的周期性阶跃池山地河床在广泛的环境中发育并被保存，以保持平衡的河道几何形状。本研究采取的综合处理措施有望提高我们对山区河流垂直振荡的理解，使我们对几十年来众所周知的冲积池和水平曲折现象的理解有所提高。开发一个有节奏的阶梯池序列的通用预测模型将使我们深入了解在山区溪流中运行的潜在过程。将重复的阶梯池形式与能量消耗原理联系起来，将增强我们对河流行为的总体理解。加强对阶梯水池溪流垂直模式的了解，将有助于稳定的渠道设计和使用阶梯水池的溪流恢复，这种做法在山区和城市环境中正在增加。对陡峭的山溪进行有效的设计和管理将减轻洪水灾害，保护下游社区的财产和生计。由于山地溪流是许多敏感水生物种的重要栖息地，本研究的结果将对生态管理具有进一步的重要意义。