Momentum and Scalar Exchange Between Channels and Vegetated Banks

通道和植被银行之间的动量和标量交换

• 批准号: 0125056
• 负责人: Heidi Nepf
• 金额: $ 43.35万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-03-01 至 2006-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0125056&HistoricalAwards=false
• 关键词: Momentum; Scalar; Exchange; Between; Channels

0125056NepfWetland systems often consist of a branching network of channels cutting through regions of dense vegetation. While the channels provide most of the flow conveyance, the vegetated regions provide most of the bioremediation and particle trapping. Thus, exchange between the channel and vegetated zone may control the overall wetland function, in particular with regard to water quality and sediment trapping. A similar relationship exists between the channel and vegetated bank of a river system. Laboratory experiments will be used to quantify the exchange of momentum and mass between a channel and a zone of emergent vegetation of equal or lesser depth (a bank), and to develop a model that predicts this exchange from representative vegetation and flow parameters. In the flume model, the exchange will be observed by tracking the evolution of dye plumes released from different locations within the channel and vegetated zone. The model vegetation will be designed using geometric and dynamic similarity to real vegetation. A preliminary flow visualization study will be used to assess major mechanisms, to define ranges of behavior across different geometry, and to refine the experimental system. Subsequent detailed studies will simultaneously measure concentration and velocity to directly quantify turbulent fluxes of momentum and mass. The study will draw from existing models for floodplains, including the effects of vegetation on hydraulic roughness and floodplain geomorphology. After the completion of this project, future phases of this research will integrate the new model for exchange between channels and vegetated zones with existing models for channel flow and vegetated flow to construct a comprehensive wetland model capable of predicting wetland circulation and transport. This model will provide an important tool for managing wetland systems by enabling stake holders to predict the changes in wetland function that will arise with proposed development and land-use changes.

0125056NEPFWETLAND系统通常由切割茂密植被区域的通道的分支网络组成。 虽然通道提供大部分流量输送，但植被区域提供了大部分的生物修复和颗粒捕获。 因此，通道和植被区之间的交换可以控制整体湿地功能，特别是在水质和沉积物诱捕方面。 河流系统的通道和植被河岸之间也存在类似的关系。 实验室实验将用于量化一个通道和相等深度或较少深度的新兴植被区域之间的动量和质量交换（银行），并开发一种模型，该模型可预测从代表性的植被和流动参数中进行交换。 在水槽模型中，将通过跟踪从通道和植被区域内不同位置释放的染料羽流的演变来观察交换。 模型植被将使用与真实植被的几何和动态相似性设计。 初步可视化研究将用于评估主要机制，定义跨不同几何形状的行为范围并完善实验系统。 随后的详细研究将同时测量浓度和速度，以直接量化动量和质量的湍流。 该研究将从现有模型中汲取洪泛区，包括植被对液压粗糙度和洪泛区地貌学的影响。 该项目完成后，这项研究的未来阶段将将新的模型与植被区域之间的交换模型与现有的通道流量和植被流的模型相结合，以构建一个综合湿地模型，能够预测湿地循环和运输。 该模型将通过使赌注持有人能够预测湿地功能的变化来为管理湿地系统提供重要的工具，这将随着拟议的开发和土地利用变化而产生。