RAPID: Impacts of an Extreme Flood on River Channel Formation and Riparian Forests

RAPID：极端洪水对河道形成和河岸森林的影响

• 批准号: 1748816
• 负责人: Robert Pavlowsky
• 金额: $ 4万
• 依托单位: Missouri State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1748816&HistoricalAwards=false
• 关键词: RAPID; Impacts; Extreme; Flood; River

The project will address the complex ways in which extreme floods impact river channel formation and stability and the structure and composition of related riparian forests. Previous studies of flood effects on river systems have focused on the history and causes of the flood, and their hydrology, with little attention to the flood impacts on riparian forest structure and the consequences of woody debris inputs on channel stability. Furthermore, the few studies that do exist have been limited to mountainous or arid regions, and their findings of limited applicability in more humid settings. More studies examining the variation of flood disturbances among different regions and within watersheds are needed to evaluate the long-term influence of floods on channel form, sediment, and forest structure, and to help predict how flood impacts can be managed in the future. The results of this study will help address U.S. Forest Service concerns over future impacts of increased flooding trends on federal facilities and the natural resources of national forests. The findings of this study will be shared during a workshop with the U.S. Forest Service, Department of Transportation, and surrounding communities. Besides benefits for natural resource management, this project will provide educational opportunities for undergraduate and graduate students in fieldwork and data analysis through the Ozarks Environmental and Water Resources Institute (OEWRI) at Missouri State University.The goal of this project is to describe and analyze how an extreme flood (greater than a 100-year return interval) has contributed to riparian forest mortality and wood recruitment along the river channel, and to identify which variables are responsible for the spatial variations in those effects. The research plan addresses five questions: (1) Was riparian tree mortality systematically related to biological variables (e.g., species, size of trees, pre-flood wood patterns)?; (2) Was mortality systematically related to hydro-geomorphic variables (e.g., valley morphology, landform, flow depth)?; (3) How much woody debris was generated and what tree or site characteristics affected the likelihood of wood transportation versus accumulation?; (4) Do forest disturbance and wood debris patterns vary with scale at different sites along a gradient of increasing drainage area?; and (5) Can aerial imagery from drones/UAVs and photogrammetry-based analysis be used to acquire accurate quantitative data regarding tree mortality and wood accumulation? This study combines field research with imagery analysis to evaluate the effects of the largest flood on record on the North Fork River in the Missouri Ozarks. The results will be combined with those from other regional studies to develop a conceptual model of geomorphic-biotic response to extreme floods in a humid forest environment. While this study focuses on the assessment of immediate effects, it will offer insights into the spatial variability of those effects and the direction of recovery which can be monitored over the next decade or longer to gain a full understanding of the recovery process. The research will inform fundamental understanding of fluvial geomorphic and biogeographic processes.

该项目将探讨极端洪水影响河道形成和稳定以及相关河岸森林的结构和组成的复杂方式。 洪水对河流系统的影响，以往的研究主要集中在历史和洪水的原因，和他们的水文，很少注意到洪水对河岸森林结构的影响和对通道稳定性的后果的木质残体输入。 此外，现有的少数研究仅限于山区或干旱地区，其研究结果在较潮湿环境中的适用性有限。 需要进行更多的研究，检查不同地区和流域内洪水干扰的变化，以评估洪水对河道形态、沉积物和森林结构的长期影响，并帮助预测未来如何管理洪水影响。 这项研究的结果将有助于解决美国林务局对未来洪水趋势增加对联邦设施和国家森林自然资源的影响的担忧。这项研究的结果将在与美国林务局，交通部和周边社区的研讨会上分享。 除了对自然资源管理的好处外，该项目将通过密苏里州州立大学的欧扎克环境和水资源研究所（OEWRI）为本科生和研究生提供实地考察和数据分析的教育机会。该项目的目标是描述和分析极端洪水如何（大于100年一遇的间隔期）对河岸森林死亡率和沿着河道木材补充量的影响，并确定哪些变量是造成这些影响的空间变化的原因。 研究计划解决了五个问题：（1）河岸树木死亡率是否与生物变量（例如，树木的种类、大小、洪水前的木材图案）; (2)死亡率是否与水文地貌变量（例如，河谷形态、地形、流深）; (3)产生了多少木质残体，哪些树木或场地特征影响了木材运输和堆积的可能性？(4)森林干扰和木材残体格局是否随流域面积增加的梯度沿着不同地点的尺度而变化？以及（5）无人机/UAV的航空图像和基于摄影测量的分析能否用于获取关于树木死亡率和木材积累的准确定量数据？ 本研究结合实地研究与图像分析，以评估有记录以来最大的洪水对密苏里州奥扎克的北福克河的影响。 这些结果将与其他区域研究的结果结合起来，以建立一个在潮湿森林环境中地貌生物对极端洪水的反应的概念模型。虽然这项研究的重点是评估直接影响，但它将深入了解这些影响的空间变异性以及未来十年或更长时间内可以监测的恢复方向，以充分了解恢复过程。 这项研究将为河流地貌和水文过程的基本理解提供信息。