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重要作用。由于植物茎尾流的影响和由此产生的复杂水动力结构，植被的存在增强了溶质在植被内的混合和扩散。因此，模拟有植被存在时的流动和污染物运输对于理解冠层内溶质混合和扩散以及环境流动至关重要。植被环境流系统对淡水生态和生物多样性具有重要意义。环境流动系统中的土壤、沉积物床、植被和生物的组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控制着影响污染运输和命运的物理、化学和生物过程。水的动态运动和与植被的相互作用在决定环境流动系统中污染物的混合和分散中起着关键作用。植物群落对这些流动系统的流体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，使悬浮物质落到流域的床层。植被生长和枯死的季节变化影响着这些系统的性能。然而，在植被环境流动系统中污染物的来源和命运方面仍然存在关键的知识空白。主要目的是利用实验室研究和我们的行业合作伙伴诺福克河信托公司收集的实地数据，确定和量化控制污染物运输和命运的关键机制。该项目还将使用物理和现场数据来开发和验证数值模型，以模拟溶质和微塑料与植被流动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被淡水流动系统中污染物运输的动力学。因此，该项目将通过了解和量化植被流中的污染运输和命运，为环境保护和综合流域管理提供一个阶段性的变化，并在淡水系统面临相当大的污染压力时产生重要影响。该项目将进行以实验室为基础的物理模拟测量和实地数据收集，以了解河流和湿地中污染物运输的动态。我们将利用沃里克水实验室的世界级实验设施，创造一个相互作用的中生态河流和湿地环境。荧光示踪以及新型颗粒染色技术将与平面激光诱导荧光（PLIF）一起应用，目的是识别和量化污染物的潜在物理传输机制以及水力条件对污染物传输和命运的影响。植被对（河流和湿地）水流和污染物特征的影响将通过基于Reynolds平均Navier-Stokes （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输运粒子模型。数值模型将根据实验数据进行验证，并进行情景模拟。

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.