How far downstream do wildfire disturbances propagate in fluvial networks?

毁灭性的野火在美国西部和西南部的频率和严重程度都在增加。除了野火对基础设施、土壤和陆地生态系统的巨大影响外，越来越多的证据表明，野火引发的级联扰动在河流网络和流域中传播，影响水生环境中的水质和生态系统服务。然而，严重缺乏数据、建模工具和基本知识来评估下游野火干扰在河流网络中传播的程度，以及它们对水质、生态系统服务和下游水文过程（如河岸植被的洪水衰减和地下水的渗透补给）的影响程度。这项研究的首要目标是解决我们对野火影响的基本理解中的这些差距。为了实现这一目标，该项目的首席研究员（pi）建议建立、培训和维护快速反应小组（RRTs），该小组能够部署现场传感器，调查野火后对流域的干扰，并评估野火前后水质的变化。这项研究的成功完成将通过生成新的数据和建模工具来预测和评估野火对水质和水生生态系统的影响，从而造福社会。进一步的社会效益将通过学生教育和培训来实现，包括指导一名博士后，一名研究生和两名本科生。在美国，野火的频率、严重程度和范围都在增加。虽然我们目前有能力使用地面图和卫星图像以相对较高的精度绘制火灾区域及其严重程度，但我们没有可比的能力绘制河流网络和流域野火干扰的程度。该项目将解决关于野火影响的两个基本问题：1)野火干扰在河流网络中传播到下游多远；2)关键控制因素是什么？为了回答这两个问题，该项目的首席研究员（pi）建议利用欧拉监测（现场固定传感器）和拉格朗日监测（随水流移动的移动传感器）的综合优势，通过部署快速反应小组（RRTs）和原位传感器网络来调查野火前后水质的变化[例如pH值、浊度、溶解氧、溶解有机物（DOM）和营养物质（例如硝酸盐）]。RRTs收集的数据将使用GIS流域地貌数据、土地利用和土地覆盖数据、水质数据的时空统计分析和水质建模进行分析和解释。通过结合这些数据、方法和建模工具，pi希望开发一个框架来生成缩放关系，能够预测下游野火干扰在河流网络中传播的距离，以及它们对水质、生态系统服务和关键下游水文过程（如渗透、洪水衰减和地下水补给）的影响程度。该奖项由NSF/ENG/CBET部门的环境工程和环境可持续性项目共同资助。该奖项反映了美国国家科学基金会的法定使命，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。

Devastating wildfires are increasing in frequency and severity across the Western and Southwestern United States. In addition to the dramatic impacts of wildfires on infrastructure, soils, and terrestrial ecosystems, there is growing evidence that wildfires trigger cascading disturbances that propagate across fluvial networks and watersheds impacting water quality and ecosystem services in aquatic environments. However, there is a critical lack of data, modeling tools and fundamental knowledge to assess how far downstream wildfire disturbances propagate in fluvial networks and the extent to which they affect water quality, ecosystem services, and downstream hydrological processes such as flood attenuation by riparian vegetation and groundwater recharge by infiltration. The overarching goal of this research is to address these gaps in our fundamental understanding of the impact of wildfires. To advance this goal, the Principal Investigators (PIs) of this project propose to setup, train, and maintain Rapid Response Teams (RRTs) capable of deploying in-situ sensors to investigate disturbances to watersheds following wildfires and assess changes in water quality before and after wildfires. The successful completion of this research will benefit society through the generation of new data and modeling tools to predict and assess the impact of wildfires on water quality and aquatic ecosystems. Further benefits to society will be achieved through student education and training including the mentoring of a postdoctoral associate, one graduate student and two undergraduate students.In the United States, wildfires are increasing in frequency, severity, and extent. While we currently have the capability to map fire areas and their severity with relatively high accuracy using areal and satellite images, we do not have comparable capabilities to map the extent of wildfire disturbances across fluvial networks and watersheds. This project will address two fundamental questions about the impact of wildfires: 1) how far downstream do wildfire disturbances propagate in fluvial networks, and 2) what are the key controlling factors? To answer these two questions, the Principal Investigators (PIs) of this project propose to leverage the combined advantages of Eulerian monitoring (fixed sensors at a site) and Lagrangian monitoring (mobile sensors that move with a water stream) by deploying Rapid Response Teams (RRTs) and networks of in-situ sensors to investigate changes in water quality [e.g., pH, turbidity, dissolved oxygen, dissolved organic matter (DOM), and nutrients (e.g., nitrate)] before and after wildfires. The data collected by the RRTs will be analyzed and interpreted using GIS watershed geomorphology data, land use and land cover data, spatiotemporal statistical analysis of water quality data, and water quality modeling. By combining these data, methods and modeling tools, the PIs hope to develop a framework to generate scaling relationships capable of predicting how far downstream wildfire disturbances propagate in fluvial networks and the extent to which they affect water quality, ecosystem services, and critical downstream hydrological processes such as infiltration, flood attenuation and groundwater recharge.This award is jointly funded by the Environmental Engineering and Environmental Sustainability programs of the NSF/ENG/CBET Division.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.