Modelling Pollution Transport in Vegetated Flow Environment

植被通常存在于环境流域(如溪流、河流、湿地和河口)，通过提供氧气和降低悬浮泥沙浓度，在维持水质方面发挥着重要作用。由于植物茎尾迹和由此产生的复杂的水动力结构的影响，植被的存在加强了植被内的溶质混合和扩散。因此，模拟有植被的水流和污染物运移对于理解溶质混合和冠层内的扩散以及环境流是至关重要的。植被环境流系统对于淡水生态和生物多样性具有重要意义。在环境流系统中，土壤、沉积物、植被和生物的结合可以促进水的处理和溶质和固体污染的去除。水-植被-土壤之间的相互作用支配着影响污染转移和命运的物理、化学和生物过程。水体运动的动力学及其与植被的相互作用在决定污染物在环境流系统中的混合和扩散中起着关键作用。植物群落对这些流动系统的流体动力学和性能有显著的影响，因为它们产生流动阻力，改变速度场，影响混合特性，使悬浮物质能够落到流动区域的床上。植被生长和枯萎的季节变化影响这些系统的性能。然而，在植被环境流动系统中污染物的来源和去向方面仍然存在关键的知识空白。主要目的是利用我们的行业合作伙伴诺福克河信托公司收集的实验室研究和现场数据来识别和量化控制污染物迁移和去向的关键机制。本项目还将利用物理和现场数据开发和验证数值模型，以模拟溶质和微塑料与植物水流和沉积物床的相互作用。该项目提供的新见解将使人们能够理解植物淡水流动系统中污染物传输的动态。因此，该项目将通过了解和量化植被覆盖的河流中的污染迁移和归宿，为环境保护和流域综合管理带来阶段性的变化，并在淡水系统面临相当大的污染压力时产生重要影响。该项目将进行基于实验室的物理模型测量和现场数据收集，以了解河流和湿地中污染物的迁移动态。我们将使用沃里克水实验室的世界级实验设施来创造一个相互作用的河流和湿地环境。应用荧光示踪和新型颗粒染色技术，以及平面激光诱导荧光(PLIF)，目的是识别和量化污染物的基本物理传输机制和水力条件对污染物传输和归宿的影响。植被对河流和湿地中水流和污染物特性的影响将通过基于雷诺平均纳维斯托克斯(RANS)和大涡模拟(LES)方法的数值模型来模拟。我们将建立刚性和柔性植被的标量运移的粒子模型。数值模型将根据实验数据进行验证，并将进行情景建模。

Vegetation is often present in environmental flow domains (e.g. streams, rivers, wetlands, and estuaries), playing an important role in maintaining the water quality by providing oxygen and reducing the suspended sediment concentration. The presence of vegetation enhances solute mixing and diffusion within the vegetation due to the effects of the plant stem wake and the resulting complex hydrodynamic structure. Hence, modeling the flow and pollutant transport in the presence of vegetation is vital for understanding solute mixing and the diffusion within a canopy, and environmental flows.Vegetated environmental flow systems are significantly important for freshwater ecology and biodiversity. The combination of soil, sediment bed, vegetation, and organisms in environmental flow systems can facilitate treatment of water and removal of solute and solid pollution. It is the interplay between water-vegetation-soil that governs the physical, chemical and biological processes influencing pollution transport and fate. Dynamics of water movement and the interactions with vegetation plays a key role in determining the mixing and dispersion of pollutants in environmental flow systems. Plant communities have a prominent effect on the hydrodynamics and performance of these flow systems, as they generate flow resistance, changes the velocity field, and affect mixing characteristics, enabling suspended material to fall to the bed of the flow domain. Seasonal variation in vegetation growth and die-back influences the performance of these systems. However, critical knowledge gaps remain in sources and fate of pollutants in vegetated environmental flow systems.The main aim is to identify and quantify key mechanisms that govern the transport and fate of pollutants using laboratory studies and field-based data collected by our industry partner, Norfolk Rivers Trust. This project will also use the physical and field-based data to develop and validate numerical model to simulate the interaction of solute and microplastics with vegetated flows and sediment bed. The new insights offered by this project will enable understanding the dynamics of pollutant transport in vegetated freshwater flow systems. Hence this project will provide a step change in environmental protection and integrated catchment management by understanding andquantifying the pollution transport and fate in vegetated flows, and significantly, be influential at a time of considerable pollution stress on freshwater systems.This project will undertake laboratory-based physical modelling measurements and fieldwork data collection to understand the dynamics of pollutant transport in rivers and wetlands. We will create an interacting mesocosm river and wetland environments using the world class experimental facility at Warwick Water Laboratory. Fluorometric tracing along with novel particle staining techniques will be applied, alongside planar laser-induces fluorescence (PLIF) with the aim of identifying and quantifying underlying physical transport mechanisms of pollutants and the impact of hydraulic conditions on the transport and fate of the pollutant.The effects of vegetation on the flow (in rivers and wetlands) and pollutant characteristics will be modelled by developing numerical models based on the Reynolds averaged Navier-Stokes (RANS) and large eddy simulation (LES) method. We will develop particle model of scalar transport for both rigid and flexible vegetation. The numerical model will be validated against experimental data and scenario modelling will be performed.