Geomorphic effects and distribution of anthropogenic debris in urban streams

城市的溪流中充满了垃圾：从塑料包装纸到汽车轮胎，从购物车到建筑垃圾。这些垃圾会使当地环境恶化，对人类健康构成风险，需要反复的志愿者清理工作，并且可能是湖泊，海洋和海岸线中发现的塑料和微塑料的重要来源。然而，目前，我们对垃圾如何在城市河流中移动和储存，以及它如何与沿着的沉积物，木材和工程结构相互作用的了解很少。 这个项目试图解决两个基本问题：（1）是什么控制了垃圾在流中的位置？以及（2）是什么控制着垃圾对通道形式和功能的影响？ 由于垃圾的形状和材料特性多种多样，其行为方式可能无法通过现有的沉积物迁移模型预测或解释。通过测量垃圾在城市溪流中的实际行为，这项研究将改进这些模型，并推进有关溪流和河流中物质物理行为的科学。研究结果对指导城市垃圾管理和环境清理与恢复工作具有重要意义。该项目还将在社区节日和环境活动中为公众以及本科生和研究生提供教育机会。该项目旨在通过调查对垃圾分布的控制及其产生的变化，量化城市河流中垃圾或人为碎片的地貌影响。地貌评估，包括量化的人为宏观碎片（5厘米），在一个广泛的，多城市集流达到将量化其分布内和跨城市流达到其与其他流元素的相互作用。延时摄影和对大型碎片、河床地形和沉积物大小的重复调查将量化碎片的流动性和地貌变化，作为地貌和水文的函数。水槽实验将查明碎片特性和物体之间的相互作用对人为碎片的迁移机制和地貌影响的影响。该项目中的实地和实验室工作将为人们对材料特性如何影响河流系统中物体的地貌功能的普遍理解提供信息。该奖项反映了NSF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。

Urban streams are full of garbage: from plastic wrappers to car tires, from shopping carts to construction debris. This garbage degrades the local environment, poses risks to human health, requires repeated volunteer clean up efforts, and may be a significant source of the plastics and microplastics found in lakes, oceans, and coastlines. Yet currently, we have a poor understanding of how garbage moves through and is stored within urban streams, and how it interacts with sediment, wood, and engineered structures along the way. This project seeks to address two fundamental questions: (1) what controls where garbage is found in streams? and (2) what controls what garbage does to channel form and function? With its wide variety of shapes and material properties, garbage is likely to behave in ways that are not predicted or explained by existing models of sediment transport. By measuring how garbage actually behaves in urban streams, this research will improve these models and advance science about the physical behavior of materials in streams and rivers. The results of this research will be useful for guiding litter management in cities and environmental clean-up and restoration efforts. The project will also provide educational opportunities for the public at community festivals and environmental events, as well as undergraduate and graduate students. This project aims to quantify the geomorphic effects of garbage, or anthropogenic debris, in urban streams, by investigating the controls on its distribution and the changes that it produces. Geomorphic assessments, including quantification of anthropogenic macro-debris (5 cm), conducted in an extensive, multi-city set of stream reaches will quantify its distribution within and across urban stream reaches and its interaction with other stream elements. Time lapse photography and repeat surveys of large debris, streambed topography, and sediment size will quantify debris mobility and geomorphic change as a function of geomorphology and hydrology. Flume experiments will identify the effects of debris properties and interactions among objects on the transport mechanics and geomorphic effects of anthropogenic debris. The field and laboratory work in this project will inform generalizable understanding of how material properties influence the geomorphic function of objects in fluvial systems.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.