Vertically Meandering Mountain Streams

垂直蜿蜒的山涧

• 批准号: 0620543
• 负责人: Anne Chin
• 金额: --
• 依托单位: Texas A&M Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-01 至 2009-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0620543&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.

山涧是世界上水和泥沙供应的主要来源，是向低地河流和较大水体提供水源的主要水库。这些山间溪流的特点是有大量的台阶和水池，呈现出引人注目的阶梯状纵剖面，多年来一直吸引着科学家们。近年来，光谱分析的应用发现了台阶和池的发生周期，从而表明水流和河道形态之间存在相互调节，并且在垂直维度上类似于曲流。虽然这一发现将垂直曲流的重要概念从下游河道的水池和河汊扩展到流域源头的台阶池，但台阶池河床的振荡并没有受到与水池和河汊以及曲流河流相同水平的分析。本研究将采用野外、实验室和统计相结合的方法，建立一个定量模型来描述、预测和解释有节奏的台阶池形态，并充分确立其作为山涧垂直曲流表达的意义。时间序列分析技术将应用于世界各地台阶池流的大型数据库，以开发一个可以描述和预测节奏序列的模型。还将对加利福尼亚州圣莫尼卡山脉的阶梯池河道进行调查，并与1991年建立的剖面进行比较，以评估十年时间尺度上的周期性变化。水槽实验将进一步为周期性阶梯池序列使山河水系的水流功率最小的假设提供具体的检验，从而将节奏形式与能量消耗原理联系起来。总的来说，这些结果有望证明可预测的、周期性的台阶池山河床在各种环境中发育和保存，以在高能量条件下保持平衡的通道几何形状。本研究的综合处理有望将我们对山溪垂直振荡的认识提高到几十年来众所周知的小池和水平曲流的认识。为有节奏的台阶池序列建立一个通用的预测模型，将有助于深入了解在山间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。加强对阶梯池溪流垂直模式的理解将有助于稳定的河道设计和使用阶梯池的溪流恢复，这种做法在山区和城市环境中越来越多。对陡峭的山涧进行有效的设计和管理，将减轻洪水的危害，保护下游社区的财产和生计。由于山涧是许多敏感水生物种的重要栖息地，本研究结果将对生态管理具有进一步的重要意义。