Collaborative Research: Geophysical characterization of a karst aquifer using dynamic recharge events

合作研究：利用动态补给事件对岩溶含水层进行地球物理表征

• 批准号: 1740526
• 负责人: Andrew Luhmann
• 金额: $ 48.05万
• 依托单位: New Mexico Institute of Mining and Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-04-01 至 2018-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1740526&HistoricalAwards=false
• 关键词: Collaborative; Research; Geophysical; characterization; karst

Karst aquifers are important water resources, providing water for up to a quarter of the world?s population. These aquifers are complex hydrogeologic systems, where flow and transport predominantly occur through preferential flow paths or conduits that range in size from cm-scale openings to passages much larger than required for human access (caves). Despite their hydrologic importance, the location of karst conduits and characteristics of the larger aquifer are typically poorly constrained. To address these problems, we will monitor recharge-induced responses that arise as water flows into the subsurface in a karst aquifer in Florida using geophysical instrumentation to characterize the conduits, subsurface flow, and the larger karst system. The noninvasive remote sensing investigation will generate knowledge for direct societal benefit, including tools to improve the creation of karst hazards maps that highlight areas susceptible to sinkhole formation, the identification of preferential flow paths relevant to contaminant transport, and the development of a methodology to determine subsurface flow for water supply considerations. We will develop a temporary, interactive traveling exhibit in collaboration with the National Cave and Karst Research Institute that will frequent visitor centers near the field site in Florida and in New Mexico to increase public engagement and scientific literacy about karst hydrogeology and environmental seismology. The project will also contribute to the education of the next generation of the scientific workforce through the involvement of two graduate students at New Mexico Tech, an undergraduate student at the University of Florida, two undergraduate student interns through the IRIS undergraduate student intern program, and two early career scientists and a mid-career female scientist in an EPSCoR state. Finally, collected datasets will be incorporated into lecture material and homework sets of undergraduate and graduate courses at New Mexico Tech, which is a Hispanic-serving institution.A previous pilot study demonstrated the generation of seismic signals during artificial recharge experiments and a natural recharge event in a karst aquifer. These and other geophysical signals are caused by processes during flow through karst aquifers and includes pressure pulses generated as recharge enters conduits with full pipe flow, pore pressure changes in fractures and the rock matrix, mass loading induced subsidence due to changes in water mass, and turbulent interaction of flow with the wall rocks. To capitalize on the information content provided by these signals, we will use simultaneous, large-scale observations of recharge events at two co-located geophysical sensor networks to characterize the conduit network, flow processes within this network, and material properties of the larger karst system. Seismometers, tiltmeters, and other instruments will be deployed at the Santa Fe River Sink-Rise system in Florida to observe karst recharge events over a two-year period. This field site has a well-constrained conduit network, and thus it permits verification of the interpreted geophysical signals that arise from hydrologic processes. This transformative project will not only enable delineation of the karst conduit network, but will do so while providing a regionally integrated analysis of the karst aquifer flow system based on deformation observations on the timescales between fractions of a second to months. As recharge activates new flow paths, geophysical monitoring enables extensive 3D characterization of the dynamics and evolution of flow during recharge-induced changes in the aquifer. Furthermore, the signals will help to determine the architecture in the subsurface between the conduits and the surface, advancing knowledge of critical zone environments, for example, by specifically determining soil and regolith thicknesses and depths to the soil-rock interface. The young field of environmental seismology encompasses studies of a range of Earth surface processes, and this project will use and expand the respective methods to transform the understanding of karst aquifers across the full frequency range of deformation and develop techniques in preparation for a future karst critical zone observatory.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.

喀斯特含水层是重要的水资源，为全世界的四分之一人口提供了水。这些含水层是复杂的水理系统，其中流动和运输主要通过优先的流动路径或导管，范围从CM尺度开口到远比人类进入所需的大得多的通道（洞穴）。尽管其水文重要性，但喀斯特管的位置和较大的含水层的特征通常受到限制。为了解决这些问题，我们将使用地球物理仪器使用地球物理仪器来监视当水流入佛罗里达州喀斯特含水层中的地下时产生的充电诱导的响应，以表征导管，地下流量和较大的喀斯特系统。非侵入性遥感调查将为直接社会利益产生知识，包括改善喀斯特危险图的创建工具，这些工具突出了容易受到污水坑形成的区域的区域，确定与污染物相关的优先流动路径的识别以及确定水供应方面的方法的开发。我们将与国家洞穴和喀斯特研究所合作开发一个临时的，互动的旅行展览，该展览将在佛罗里达州和新墨西哥州现场附近的游客中心经常游客中心，以提高公众参与度和有关喀斯特水文地质地理位置和环境安全学的科学素养。该项目还将通过新墨西哥理工学院的两名研究生的参与，佛罗里达大学的一名本科生，两名本科生实习生，通过IRIS本科生实习生计划，两名早期职业生涯和一名中级科学家和一名中级女性科学家。最后，收集的数据集将被纳入新墨西哥理工学院的本科和研究生课程的讲座材料和作业集中，这是一家西班牙裔服务机构。一项先前的试点研究表明，在karst aquifer的人工补给实验中，人工补给实验中产生了一系列的Seissic信号。这些和其他地球物理信号是由流经喀斯特含水层流动过程中的过程引起的，包括充满充足的充分管道，裂缝的孔隙压力变化和岩石基质的孔隙压力，由于水质量的变化以及与壁岩流的湍流相互作用而产生的压力脉冲，裂缝的孔隙压力变化，质量负载诱导的沉降。为了利用这些信号提供的信息内容，我们将在两个共同定位的地球物理传感器网络上同时对充值事件进行大规模观察，以表征导管网络，该网络中的流动过程以及较大的Karst系统的材料属性。地震仪，倾斜度和其他乐器将部署在佛罗里达州的圣达菲河流河流系统中，以观察两年的喀斯特充电事件。该现场位点具有一个受约束的导管网络，因此允许验证由水文过程产生的解释的地球物理信号。这个变革性的项目不仅可以划定喀斯特导管网络，而且还可以根据对喀斯特含水层流量系统进行区域整合的分析，以基于对二个月时间分数之间的时间表的变形观察结果进行区域综合分析。当充电激活新的流动路径时，地球物理监测可以在补给诱导的含水层变化过程中对动力学和流动的演变进行广泛的3D表征。此外，这些信号将有助于确定导管和表面之间地下的体系结构，从而通过专门确定土壤和岩石岩的厚度和深度到土壤摇滚界面来提高关键区域环境的知识。环境地震学的年轻领域涵盖了一系列地面过程的研究，该项目将使用和扩展各自的方法来改变对喀斯特含水层的理解，以在整个变形和开发技术范围内为未来的Karst关键区域观测做准备。 标准。