Doctoral Dissertation Research: Investigation of Factors Controlling the Dynamics of Beach-Surface Moisture Content

海滩表面水分含量的时空变化被广泛认为是影响风成沉积物输运系统运行的关键参数，因此代表了对海岸沙丘随时间发展的关键控制。最近的一些研究已经调查了海滩表面水分含量的变化，然而，一个实用的方法来建模或模拟这些研究所揭示的相当大的空间和时间变化的表面水分仍然难以捉摸。这种变化是由一套水文，气象和沉积参数，包括降水，地下水流，毛细运输，蒸发，冷凝，土壤质地和潮汐振荡之间的复杂的相互作用控制。精确的模拟表面水分含量需要更精确的关系，描述这些控制参数之间的相互作用和它们对海滩表面水分动态的影响比目前可用。这个博士论文项目的基本目标是发展这些关系。为了实现这一目标，将进行一系列实地和实验室实验，以监测地表含水量的动态以及这些控制参数的波动。本研究的实地调查将在得克萨斯州帕德雷岛国家海滨进行，以监测控制水文和气象参数对地表含水量动态的影响。沉积物结构对海滩水文有着深远的影响，预计在具有不同沉积物特性的海滩上，所调查的关键过程的相对大小和影响将有所不同。因此，为了提高本研究的适用性，将进行一系列的实验室实验来记录沉积物质地对表面水分动态的影响。这个项目的结果将拓宽和加深我们对海滩水文的理解，特别是与海滩表面水分含量的时空动态的关系。这些知识对于提高我们预测短期和长期沙丘从风暴侵蚀中恢复的能力至关重要。此外，从这项研究中产生的地表水分动力学的基本理解将有助于广泛的重要问题，其中地表水分含量有显着的影响，如生态系统结构和发展，环境管理应用，全球气候模拟和地球大气能量通量，以及陆地水文循环。例如，这项研究有可能有助于加强与全球气候变化模型相关的降水预测，因为地表水分动态对当地气候环流模式的发展有着深远的影响。它还可能有助于编写关于沿海水资源管理问题的文献。随着人类活动对沿海水文系统的压力不断增加，对海滩水文的适当了解和认识对于考虑污染物通过土壤基质的扩散至关重要，土壤基质对含水量的时空动态非常敏感。

The spatial and temporal variability of beach surface moisture content is widely recognized as a critical parameter affecting the operation of aeolian sediment transport systems, and therefore represents a critical control on coastal dune development over time. A number of recent studies have investigated the variability of beach surface moisture content; however, a practical method to model or simulate the considerable spatial and temporal variability in surface moisture revealed by these studies remains elusive. This variability is controlled by complex interactions between a suite of hydrological, meteorological and sedimentary parameters that include precipitation, groundwater flow, capillary transport, evaporation, condensation, soil texture, and tidal oscillations. Accurate modeling of surface moisture content requires more precise relationships describing the interactions between these controlling parameters and their influence on beach surface moisture dynamics than are currently available. The fundamental goal of this doctoral dissertation project is to develop these relationships. In order to accomplish this objective, a series of field and laboratory experiments will be conducted to monitor the dynamics of surface moisture content in conjunction with fluctuations in these controlling parameters. Field investigations for this study will be conducted at Padre Island National Seashore, Texas to monitor the influence of the controlling hydrological and meteorological parameters on the dynamics of surface moisture content. Sediment texture has a profound influence on beach hydrology and it is to be expected that the relative magnitudes and influences of the key processes under investigation will vary at beaches with differing sediment characteristics. Therefore, in order to enhance the applicability of this study, a series of laboratory experiments will be conducted to document the influence of sediment texture on surface moisture dynamics. Results of this project will both broaden and deepen our understanding of beach hydrology, specifically in relation to the spatial and temporal dynamics of beach surface moisture content. This knowledge is vital to improving our ability to forecast both short and long term dune recovery from storm erosion. In addition, the basic understanding of surface moisture dynamics resulting from this study will contribute to an extensive range of important issues where surface moisture content has a significant impact, such as ecosystem structure and development, environmental management applications, global climate modeling and earth-atmosphere energy fluxes, and the terrestrial hydrologic cycle. For example, this research has the potential to contribute to enhancement of precipitation prediction associated with global climate change models, as surface moisture dynamics has a profound effect on the development local climatic circulation patterns. It may also contribute to the literature on coastal water resource management issues. With increasing anthropogenic pressure on coastal hydrological systems, proper knowledge and understanding of beach hydrology is paramount to consideration of the dispersal of contaminants through the soil matrix which is highly sensitive to the spatial and temporal dynamics of moisture content.