Doctoral Dissertation Research: Geomorphic and Anthropogenic Controls on Baseflow Discharge of Southern Blue Ridge Mountain Streams

基流是指在降水和融雪事件之间持续的径流，来自地下水库，如基岩、腐泥岩、冲积层或土壤。由于基流在河流生态和淡水供应方面极其重要，迫切需要了解流域物理特性和基流之间的关系，以及人类土地利用对这些物理特性的影响方式。地形和土地利用分别对基流有很大的影响，但它们的相对影响和相互作用尚不清楚。以往的研究表明，关于流域森林覆盖是增加还是减少基流流量，以及这些问题与流域规模的关系，仍然是水文科学中一个尚未解决的重大问题。该项目将评估地形和土地利用对蓝岭山脉南部基流的作用，强调以下目标：1)评估流域森林覆盖和基流之间的关系，2)确定地形和土地利用对基流的相对影响，以及3)利用地理信息系统模型预测径流对未来土地利用变化的响应。将使用数字地形和土地覆盖数据的地理信息系统分析来描述北卡罗来纳州和佐治亚州的小田纳西河流域的子盆地。至少35条溪流将用连续水位记录器进行测量，基流流量值将根据土地利用和地形特征进行计算。随后的地理信息系统建模将能够预测基流对该区域进一步土地利用变化的响应，并将指导发展规划，以鼓励对基流水量影响最小的增长情景。几十年来，淡水保护一直处于全球问题的前沿，随着人口和工业对水资源的需求增长，其紧迫性不断增加。通过地下通道进入河流系统的污染物在基流期间最为集中，对于维持公共健康、水生生物完整性和经济增长来说，更坚定地了解水量控制是至关重要的。该项目的成果将在许多领域产生重大意义，从水文学和地貌学理论的发展到保护敏感水生物种的充足供水。开发和测试模拟能力以估计径流对土地利用变化的反应，将有助于进一步的研究和正在进行的监测和管理议程。识别控制水量的关键地形和土地利用特征，将有利于可持续发展规划、野生动物保护、水资源管理、公共卫生和工业，并将促进和改善未来的环境研究。

Baseflow refers to streamflow sustained between precipitation and snowmelt events, contributed from subsurface reservoirs such as bedrock, saprolite, alluvium, or soil. Because baseflow is extremely important in the context of stream ecology and freshwater supply, a critical need exists to understand the relationships between basin physical properties and baseflow, as well as the ways in which human land use affects these physical properties. Topography and land use, separately, have been demonstrated to exert strong influence on baseflow, but their relative influences and interaction remain unclear. Previous studies have demonstrated inconsistent results as to whether watershed forest cover increases or decreases baseflow discharge, and how such issues relate to watershed scale remains a major unresolved problem in the hydrologic sciences. This project will assess the roles of topography and land use on baseflow in the southern Blue Ridge Mountains, emphasizing the following objectives: 1) assessment of the relationship between basin forest cover and baseflow, 2) determination of the relative influences of topography and land use on baseflow, and 3) prediction of streamflow response to future land-use change using GIS modeling. Sub-basins of the Little Tennessee River basin in North Carolina and Georgia will be characterized using GIS analysis of digital terrain and land-cover data. At least 35 streams will be instrumented with continuous stage recorders, from which baseflow discharge values will be derived and related to land-use and topographic characteristics. Subsequent GIS modeling will allow prediction of baseflow response to further land-use change in the region and will guide development planning to encourage growth scenarios imparting minimal impact on baseflow water quantity.Adequate freshwater protection has been at the forefront of global issues for decades, and its urgency continues to increase, as water resource demands grow with population and industry. Contaminants entering stream systems via subsurface pathways are most highly concentrated during baseflow, and a firmer understanding of controls on water quantity is imperative to sustaining public health, aquatic biotic integrity, and economic growth. Results from this project will be significant in many realms, from advancement of hydrologic and geomorphic theory to protection of adequate water supply for sensitive aquatic species. The development and testing of modeling capabilities to estimate streamflow response to land use change will assist further research and ongoing monitoring and management agendas. The identification of key topographic and land-use characteristics exerting control on water quantity will benefit sustainable development planning, wildlife protection, water resources management, public health, and industry, and will facilitate and improve future environmental research.