Momentum and Scalar Exchange Between Channels and Vegetated Banks

0125056Nepf湿地系统通常由一个分支网络的渠道切割通过茂密的植被地区。 虽然通道提供了大部分的流动输送，但植被区域提供了大部分的生物修复和颗粒捕集。 因此，通道和植被区之间的交换可以控制整个湿地功能，特别是在水质和沉积物截留方面。 类似的关系存在于河流系统的河道和植被岸之间。 实验室实验将用于量化通道和相等或更小深度的紧急植被区（银行）之间的动量和质量交换，并开发一个模型，从代表性的植被和流量参数预测这种交换。 在水槽模型中，将通过跟踪从通道和植被带内不同位置释放的染料羽流的演变来观察交换。 将利用与真实的植被的几何和动态相似性来设计模型植被。 初步的流动可视化研究将用于评估主要机制，以确定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通量。 这项研究将借鉴现有的洪泛区模型，包括植被对水力糙率和洪泛区地貌的影响。 在本研究完成后，未来的研究阶段将整合新的渠道和植被区之间的交换模型与现有的渠道流量和植被流量模型，以构建一个综合的湿地模型，能够预测湿地循环和传输。 该模型将为管理湿地系统提供一个重要工具，使利益相关者能够预测拟议的开发和土地使用变化将引起的湿地功能变化。

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.