Doctoral Dissertation Research: Characterizing Spatial Patterns of River Morphology and Hydraulics: Remote Mapping and Geostatistical Modeling of a Dynamic Fluvial System

河道及其所输送的水和沉积物之间的非线性相互作用，在一系列空间和时间尺度上形成了广泛的过程和形式。长期以来，提取这种复杂性的尝试一直受到天然河流中发现的不均匀条件和河道形态的双重作用的阻碍，河道形态既是流动和沉积物运输过程的结果，也是对其的控制。同样，传统的方法强调横断面平均值的预测，没有解决深度和速度在河段内和河段之间的二维空间变化，尽管它们在河道形态和泥沙运输之间的关系中起着基本作用。由于难以以足够的精度和经济性测量河道和洪泛区地形，对这些重要的相互作用进行表征和建模的努力受到了阻碍。本博士论文的研究目标是：发展用于表征河流形态和水力学空间格局的遥感和地质统计方法；将这些技术应用于黄石国家公园的原始流域；并将观测到的地形和水流形态与泥沙运移和河道变化联系起来。这项研究产生的技术创新包括一种灵活的、基于物理的河流遥感方法，以及一种专门的地质统计框架，用于获得改进的河道形式表示和河段尺度空间结构的定量描述。该项目的现场部分包括详细的地形调查和空间分布的水流深度、流速和河床物质粒度的测量。为了提供这些密集的野外站点的背景资料，将使用1949年至2004年期间的遥感时间序列数据来绘制水深变化，记录河道平台和谷底土地覆盖的变化，并估计沉积物转移的长期速率。该项目将引入一种全新的、独特的空间视角，使地貌学理论超越对单个剖面的平均深度和速度的一维预测，从而实现对这些水力量的可变性和空间模式的参数化建模。所开发的技术也将有助于在扩大的尺度范围内检查河道形态和沉积物运输之间的关系。这些工具对河流恢复特别有用，因为有效的监测和适应性管理对项目的成功至关重要，但往往受到收集基本现场数据的困难和缺乏客观标准来评估“增加地貌复杂性”等模糊目标进展的影响。

Non-linear interactions among river channels and the water and sediment they convey result in a broad spectrum of process and form across a range of spatial and temporal scales. Attempts to distill this complexity have long been stymied by the non-uniform conditions found in natural rivers and by the dual role of channel morphology as both a consequence of and a control on flow and sediment transport processes. Similarly, traditional approaches emphasizing the prediction of cross-sectional averages have not addressed two-dimensional spatial variations of depth and velocity within and among reaches, despite their fundamental role in the relationship between channel morphology and sediment transport. Efforts to characterize and model these important interactions have been hindered by the difficulty of measuring channel and floodplain topography with sufficient precision and economy. The goals of this doctoral dissertation research are to: develop remote sensing and geostatistical methods for characterizing spatial patterns of river morphology and hydraulics; apply these techniques to a pristine watershed in Yellowstone National Park; and relate the observed patterns of topography and flow to sediment transport and channel change. The technical innovations resulting from this study include a flexible, physics-based approach to remote sensing of rivers and a specialized geostatistical framework for obtaining improved representations of channel form and quantitative descriptions of reach-scale spatial structure. The field component of the project involves detailed topographic surveys and spatially distributed measurements of flow depth and velocity and bed material grain size in several stream reaches at a range of discharges. To provide context for these intensive field sites, a time series of remotely sensed data spanning the period from 1949 to 2004 will be used to map variations in water depth, document changes in channel planform and valley floor land cover, and estimate long-term rates of sediment transfer. This project will introduce a new, distinctly spatial perspective that will allow geomorphic theory to move beyond one-dimensional prediction of mean depths and velocities for individual cross-sections to parametric modeling of the variability and spatial pattern of these hydraulic quantities. The techniques developed will also facilitate examination of the relationship between channel morphology and sediment transport across an expanded range of scales. These tools will be particularly useful for river restoration, where effective monitoring and adaptive management are critical to project success but are often compromised by the difficulty of collecting even basic field data and by the lack of objective criteria for assessing progress toward such nebulous goals as "increased geomorphic complexity.'"