Sediment Storage at the Transition Between Debris-Flow and Fluvial Processes

泥石流与河流过程过渡处的沉积物储存。 为了更好地了解沉积，保留和疏散机制和沉积物预算的强烈影响泥石流沉积的山谷，拟议的研究将表征体积，年龄和沉积物存储及其关系，以促进流域和当地的山谷特征的源头流的俄勒冈州海岸山脉。该项目将处理地貌沉积物从源流向汇的一个关键界面。现代地貌学的一个重要目标是确定控制地貌系统中通量的一阶速率定律，本项目具体解决了这个问题。为了在山区的开发和保护之间达成知情的妥协，必须了解调解森林火灾和相关泥石流等偶发干扰下游影响的自然机制。这项研究将有助于围绕太平洋西北部和其他地方的森林做法和生境进行科学和政治辩论，阐明泥石流产生的沉积物脉冲的下游衰减，并向管理人员和决策者提供这一信息。技术说明。 山溪中沉积物沉积、滞留和排泄的机制、速率和体积是什么？这些机制、速率和体积在下游如何变化？它们之间有什么关系？它们如何受到气候变化的影响？调查将包括沿泥石流和河流过程之间的过渡沿着不同位置的河流，从泥石流冲刷和沉积都很重要的山谷，到泥石流冲刷似乎不重要但泥石流沉积占主导地位的山谷，再到支流泥石流沉积仅打断河流沉积的山谷。具体的研究活动将包括：（1）利用机载激光条带测绘和地面测绘对整个水源网络的沉积物量进行测绘和测量，并利用地面测量对该方法进行测试;（2）表征和绘制存款沉积学和地层学、存款放射性碳年龄分布和斯特拉特阶地，以阐明滞留和排空机制、排空时间，以及由于气候变化而引起的变化;以及（3）分析数字高程模型（DEM）以找到存款量和特征以及山谷形态的依赖性（例如，实地地点将设在始新世砂岩地层（Tyee）下面的俄勒冈海岸山脉（OCR）的部分地区，因为先前的研究提供了地貌过程和古气候的知识;泥石流主导了将沉积物输送到上游山谷的储存;第四纪气候变化没有改变主导的地貌过程; OCR分别是开发和保护倡导者之间争论的焦点;这一领域很容易进入。

Sediment Storage at the Transition Between Debris-Flow and Fluvial Processes Project AbstractBroad Explanation. In order to better understand deposition, retention, and evacuation mechanisms and the sediment budget in valleys strongly affected by debris-flow deposition, the proposed research will characterize volumes, ages, and sedimentology of sediment storage and their relationships to contributing drainage basin and local valley characteristics in headwater streams of the Oregon Coast Range. This project will address a key interface in the source-to-sink flow of sediment off landscapes. An important goal in modern geomorphology is to determine the first-order rate laws that govern fluxes in geomorphic systems, and this projectl specifically addresses this issue. To reach an informed compromise in mountainous areas between exploitation and conservation, it is vital to understand the natural mechanisms mediating downstream effects of episodic disturbances such as forest fires and associated debris flows. The research will contribute to the scientific and political debate around forest practices and habitat in the Pacific Northwest and elsewhere by elucidating the downstream attenuation of debris-flow-derived sediment pulses and presenting that information to managers and policy-makers. Technical Description. What are the mechanisms, rates, and volumes of sediment deposition, retention, and evacuation in mountain streams, and how do these mechanisms, rates, and volumes change downstream? How are they related? How are they affected by climate change? Investigations will encompass streams at varying positions along the transition between debris-flow and fluvial processes, from valleys where both debris-flow scour and deposition are important, through valleys where debris-flow scour appears unimportant but debris-flow deposits predominate, to valleys where debris-flow deposition from tributaries merely punctuates otherwise fluvial deposits. Specific research activities will include (1) mapping and measurement of sediment volumes throughout headwater networks with airborne laser swath mapping (ALSM) and ground-based mapping and testing of the method with ground-based surveying; (2) characterization and mapping of deposit sedimentology and stratigraphy, deposit radiocarbon age distributions, and strath terraces to elucidate retention and evacuation mechanisms, evacuation times, and changes due to climate change; and (3) analysis of digital elevation models (DEMs) to find the dependence of deposit volumes and characteristics and valley morphology (e.g., strath terraces) on network structure and topography.Field sites will be in parts of the Oregon Coast Range (OCR) underlain by an Eocene sandstone formation (Tyee) because prior studies provide knowledge of geomorphic processes and paleoclimate; debris flows dominate sediment delivery to storage in headwater valleys; Quaternary climate change has not changed the dominant geomorphic processes; the OCR is the focus of debate between advocates of exploitation and conservation, respectively; and this area is readily accessible.