Karst Conduit Hyporheic Zone Exchange

岩溶导管潜流区交换

• 批准号: 1141768
• 负责人: John Wilson
• 金额: $ 26.15万
• 依托单位: New Mexico Institute of Mining and Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-03-01 至 2018-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1141768&HistoricalAwards=false
• 关键词: Karst; Conduit; Hyporheic; Zone; Exchange

Karst Conduit Hyporheic Zone ExchangeJohn L. Wilson, New Mexico Institute of Mining and TechnologyThis project will attempt to measure, for the first time, hyporheic exchange at the margin of a karst conduit (cave below the water table). Hyporheic exchange in surface streams is a relatively new field, but related publications are growing exponentially as the implications for flow contaminant transport, residence time distributions, biogeochemistry and biology are realized. One definition of the hyporheic zone is the subsurface volume where water enters from the stream, travels through the subsurface, and returns to the stream. Hyporheic zones in streams exist at a variety of nested spatial and temporal scales whether there is net gain, net loss, or even no net exchange along the course. The fundamental fluid dynamics of karst conduits are not different from streams, and karst conduits have the same features that cause hyporheic flow in fluvial systems. This project will investigate whether, as with streams, hyporheic exchange occurs in karst conduits, regardless of larger-scale net exchange with the aquifer. Karst-conduit hyporheic exchange, and related biogeochemical processing, then becomes a fundamental component of the karst water cycle. The project will be conducted in a phreatic conduit field site in the unconfined Floridan Aquifer; additionally there will be a nearby air-filled analog site that was exposed to similar processes at some time in the geologic past. Cores will be taken from the phreatic and analog sites. Porosity, permeability, and petrophysical measurements will be used a proxy indicators of past conduit hyporheic flow. The core holes at the phreatic site will be equipped with multilevel samplers and injectors, and a series of dye traces will be conducted to observe karst-conduit hyporheic flow. Modeling will be used throughout the project, first to help plan the field work and then to synthesize the data. Results from the data and models will give insights into the temporal and spatial scales of hyporheic flow. The project will end with modeling as a predictive tool to generalize our results.Karst aquifers supply water to 25% of the United States, and almost all water to some regions, e.g. 90% of Florida's population. New mathematical models and field studies will be used to illuminate a previously unrecognized process, karst hyporheic exchange at the margin of a flowing karst conduit, in which the conduit and surrounding karst rock matrix exchange water with consequences for karst chemistry and biology. As does hyporheic exchange in surface streams, karst hyporheic exchange may impact water supply, water quality, and ecology, and will be of interest to environmental agencies and interest groups at the local, state and federal level.

岩溶管道低渗带交换。威尔逊，新墨西哥州采矿和技术研究所该项目将首次尝试测量岩溶管道（地下水位以下的洞穴）边缘的潜流交换。 表面流中的潜流交换是一个相对较新的领域，但随着对流动污染物输运、停留时间分布、生物地球化学和生物学的认识，相关出版物呈指数增长。 潜流区的一个定义是地下体积，水从溪流进入，穿过地下，然后返回溪流。 河流中的潜流区存在于各种嵌套的空间和时间尺度上，无论是沿程有净增益、净损失，还是甚至没有净交换沿着。 岩溶管道的基本流体动力学与河流没有不同，岩溶管道具有引起河流系统中的潜流的相同特征。 本项目将调查是否与溪流一样，在岩溶管道中发生潜流交换，而不考虑与含水层的大规模净交换。 岩溶-管道潜流交换及相关的地球化学过程成为岩溶水循环的基本组成部分。 该项目将在非封闭的Floridan含水层的潜水管道现场进行;此外，附近将有一个充气模拟现场，在地质过去的某个时间暴露于类似的过程。 岩心将取自潜水和模拟现场。 孔隙度、渗透率和岩石物理学测量将被用作过去管道潜流的替代指标。 潜水点的岩心孔将配备多级采样器和注入器，并将进行一系列染色示踪，以观察岩溶管道潜流。 建模将在整个项目中使用，首先帮助规划现场工作，然后综合数据。 从数据和模型的结果将提供洞察的时间和空间尺度的潜流。 岩溶含水层为美国25%的地区供水，并且几乎所有的水都供应给某些地区，例如佛罗里达90%的人口。 新的数学模型和实地研究将被用来阐明一个以前未被认识的过程，在流动的岩溶管道，管道和周围的岩溶岩石基质交换水与岩溶化学和生物学的后果的边缘岩溶潜流交换。 正如地表溪流中的潜流交换一样，岩溶潜流交换可能会影响供水、水质和生态，并将引起地方、州和联邦一级环境机构和利益集团的兴趣。