Doctoral Dissertation Research: Hydro-Ecological Linkages in Urbanizing Watersheds: A Process-Based Assessment of Land-Use Change Impact on Nitrogen Export

陆水界面，特别是河岸交错带，在流域氮循环中起着重要的作用。 由于土地利用变化可以显著改变其处理或保留氮的能力，因此了解高地氮输送与生态交错带处理之间的联系对于土地利用变化影响评估至关重要。 本博士论文研究项目将探讨河岸带和河流在氮的保留、转化和流动中的作用。 学生将研究河岸和河流处理的作用，土地利用的空间布局的影响，以及基于遥感的聚合程序的发展。 该研究方法将把联合收割机水文生态建模与遥感和实地测量相结合，以便在一系列空间和时间尺度上处理相关过程和相关模式。 区域水文生态模拟系统（RHESSys）是一个水文生态流域模型，将在地理信息系统内与溪流流量和水质模型相结合。 河流模型将得到加强，以考虑河流-地下水的相互作用和相关的氮处理在潜流区，地下流动路径的河流水与地下水混合。 模型的开发和应用将以已建立的RHESSys应用程序以及作为巴尔的摩生态系统研究长期生态研究站点（BES-LTER）活动的一部分收集的遥感数据和实地数据为基础。 将开展更多的实地活动，以支持模拟活动，包括实地实验和河流监测。了解水文和地球化学循环之间的联系是全球变化科学的一个重要研究挑战。 在多个时空尺度上耦合水文学和地球化学是应对这一挑战的关键途径。 这项研究将有助于弥合这一差距，在科学的理解，提供了一个多学科的，基于过程的方法，调查氮输出流域。 这项研究应能增进人们对水和地球化学循环之间的时空联系及其在控制人类活动对生态系统功能的影响方面的作用的普遍了解。 增强后的模式对可能将其用于水资源和土地资源管理的从业人员也具有直接价值。 这项研究将建立在既定的研究努力，并将与教育和社区外展活动，包括使用高中学生和社区成员作为志愿者数据收集者。 博士生将协助感兴趣的学生使用他们和其他人在科学博览会项目中收集的数据。 作为博士论文研究改进奖，该奖项还将提供支持，使有前途的学生建立一个强大的独立的研究生涯。

The terrestrial-aquatic interface, in particular the riparian ecotone, plays an important role in watershed nitrogen cycling. Because land-use change can significantly alter its capacity to process or retain nitrogen, understanding the linkages between upland nitrogen delivery and ecotone processing is crucial for land-use change impact assessments. This doctoral dissertation research project will address the role of the riparian zone and the stream in the retention, transformation and mobilization of nitrogen. The student will examine the role of riparian and in-stream processing, the effect of spatial arrangement in land use, and the development of remote sensing-based aggregation procedures. The research approach will combine hydro-ecological modeling with remote sensing and field measurements, allowing for addressing relevant processes and related patterns across a range of spatial and temporal scales. The regional hydro-ecological simulation system (RHESSys), a hydro-ecological watershed model, will be coupled within a geographic information system (GIS) to a flow and water quality model for streams. The stream model will be enhanced to account for stream-groundwater interactions and associated nitrogen processing in the hyporheic zone, the subsurface flowpath where stream water mixes with subsurface water. Model development and application will be based on an established RHESSys application and on remote sensing data and field data collected as part of activities at the Baltimore Ecosystem Study Long Term Ecological Research site (BES-LTER). Additional field campaigns will be conducted in support of the modeling activities, including field experiments and stream monitoring.Understanding the linkages between hydrologic and biogeochemical cycling is an important research challenge in global change science. Coupling hydrology and biogeochemistry across multiple spatial-temporal scales is a key approach for meeting this challenge. This study will help bridge this gap in scientific understanding by providing a multidisciplinary, process-based approach for investigating nitrogen export from watersheds. The study should enhance general understanding of spatial-temporal linkages in the landscape between water and biogeochemical cycling and their role in controlling human-induced impacts on ecosystem functioning. The enhanced model should also be of direct value to practitioners who might use it for water- and land-resource management. The research will build on established research endeavors and will integrate with educational and community outreach activities, including the use of high school students and community members as volunteer data collectors. The doctoral candidate will assist interested students in using data they and others collect in science fair projects. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.