Large wood in low-gradient floodplain rivers: Spatial distribution, physical controls, and geomorphic effects

该项目将促进对美国东南部沿海平原河流中大型木材（LW）动态的理解。LW（河内原木）提供了许多好处，影响沉积物的运输、河道的形式和水生生态系统的功能。以往大多数关于LW的研究都是在小溪流中进行的，通常是在山区或砾石河床中。本项目将研究沿海平原相对较大、坡度较缓、河床较细的河流中LW的分布、流动性和影响。研究结果将对该地区的森林和河流管理产生影响，该地区的LW曾经非常丰富，但由于人类活动而减少。该项目还将通过一项新的公民科学倡议，与北卡罗莱纳州的河流守护者组织合作实施，在学生培训和教育公众关于LW的好处方面提供好处。本研究旨在描述低梯度洪泛平原河流中大型木材（LW）的空间分布特征，对LW的吸收和运输的物理控制，以及LW对河道过程和形态的影响。长期以来，LW（通常定义为长度至少为1米，直径至少为10厘米，位于活动河道中的木片）一直被认为是河流系统中物理和生态过程的重要驱动因素。然而，大多数关于河流中LW的知识是基于对陡峭水源集水区的中小型河流的研究，例如在美国西部的山区。因此，有必要系统地分析低梯度洪泛平原河流的LW动态及其对地貌过程的影响。研究将通过野外测量和遥感研究河段尺度和区域尺度的降水空间分布，通过统计模拟研究降水增加的物理控制，通过偶发和连续跟踪研究降水输送，通过物理模拟研究降水对河道过程和形态的影响及其物理驱动因素。这些结果将有助于理解河流系统的物理和生态耦合动力学。更广泛的影响包括在少数民族服务机构培训学生，向国家土地和水资源管理机构传播研究成果，以及一项新的公民科学倡议，收集河流中生物多样性的数据，并向公众宣传生物多样性的好处。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project will advance understanding of the dynamics of large wood (LW) in Coastal Plain rivers of the Southeastern US. LW (logs within rivers) provides many benefits, affecting the transport of sediment, the form of river channels, and the functioning of aquatic ecosystems. Most previous research on LW has been conducted in small streams, often in mountainous regions, or in gravel-bedded rivers. This project will examine the distribution, mobility, and effects of LW in relatively large, gently sloped, and fine-bedded rivers of the Coastal Plain. The results will have implications for forest and river management in this region, where LW was once abundant but has been reduced because of human activities. The project will also provide benefits in terms of student training and in educating the public about the benefits of LW through a new citizen-science initiative that will be implemented in collaboration with Riverkeeper organizations across North Carolina.The proposed research seeks to characterize the spatial distribution of large wood (LW) in low-gradient floodplain rivers, the physical controls on LW recruitment and transport, and the effects of LW on channel process and form. LW (generally defined as pieces of wood at least 1 m in length and 10 cm in diameter, located in the active channel) has long been recognized as a significant driver of physical and ecological processes in river systems. Nevertheless, most knowledge of LW in rivers is based on studies of small to medium-sized rivers in steep headwater catchments, such as in the mountains of the western United States. There is therefore a need for a systematic analysis of LW dynamics and their influence on geomorphic processes in low-gradient floodplain rivers. The research will investigate the spatial distribution of LW at reach and regional scales through field measurements and remote sensing, the physical controls on LW recruitment through statistical modeling, LW transport through episodic and continuous tracking, and the effects of LW on channel process and form and the physical drivers of those effects through physically based modeling. The results will contribute to the understanding of coupled physical and ecological dynamics in river systems. Broader impacts include training of students at a Minority Serving Institution, dissemination of research results to state land- and water-management agencies, and a new citizen-science initiative to collect data on LW in rivers and to educate the public about the benefits of LW.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.