Monitoring the thermal state of permafrost by automated time-lapse capacitive resistivity imaging

通过自动延时电容电阻率成像监测永久冻土的热状态

• 批准号: NE/I000984/1
• 负责人: Julian Murton
• 金额: $ 2.06万
• 依托单位: University of Sussex
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FI000984%2F1
• 关键词: Monitoring; thermal; state; permafrost; automated

Long-term monitoring of subsurface processes increasingly relies on intelligent, systematic data collection by innovative field sensors. The aim of the proposed project is to develop a new technology concept for the non-invasive volumetric imaging and routine temporal monitoring of the thermal state of permafrost. Permafrost has been identified as one of six cryospheric indicators of global climate change within the monitoring framework of the World Meteorological Organization (WMO) Global Climate Observing System (GCOS). Changes in permafrost temperature, associated with the freezing or thawing of pore water, result in significant changes in electrical resistivity. Non-invasive assessment and volumetric monitoring of resistivity changes are facilitated by 4D Electrical Resistivity Tomography (ERT). Tomographic reconstruction with appropriate spatial and temporal resolution enables intuitive visualisation and opens up the important opportunity for quantitative analysis of freeze-thaw processes, including the calibration to permafrost temperature. However, despite the broad appeal of conventional ERT methodology, electrical sensors require galvanic coupling with the ground. This requires that metal electrodes are physically implanted into the active layer (which is subject to seasonal freezing and thawing) or into the underlying permafrost. As a result, this can lead to significant practical limitations on field measurements due to high levels of and large variations in contact resistances between sensors and the host bedrock, soil or building material as it freezes and thaws. Using a novel capacitively-coupled ERT approach, we propose to demonstrate the technical feasibility of undertaking time-lapse tomographic measurements using permanent, in-situ capacitive sensors to remotely monitor the thermal state of permafrost. This will lead to significant improvements in monitoring capability, both for permafrost simulation experiments in the laboratory and for practical applications in the field. The work will include numerical simulation to determine optimal distributed capacitive sensor networks required for volumetric imaging and long-term monitoring of permafrost temperature, both at the field and laboratory scale. Based on the results, a measurement system for multi-sensor automated time-lapse data acquisition will be designed and a viable architecture for a laboratory prototype system will be established. Subsequently, a functional benchtop prototype will be developed and technical feasibility of multi-sensor data acquisition and automated operation will be demonstrated. Finally, we will validate the concept of making automated time-lapse temperature-calibrated CRI measurements in controlled laboratory experiments that simulate permafrost growth, persistence and thaw in bedrock.

地下过程的长期监测越来越依赖于创新的现场传感器进行智能、系统的数据收集。拟议项目的目的是开发一种新的技术概念，用于永久冻土热状态的非侵入性体积成像和常规时间监测。在世界气象组织（气象组织）全球气候观测系统（气候观测系统）的监测框架内，多年冻土被确定为全球气候变化的六个冰冻圈指标之一。多年冻土温度的变化，与孔隙水的冻结或融化，导致电阻率的显着变化。电阻率变化的非侵入性评估和体积监测由4D电阻率断层扫描（ERT）促进。具有适当的空间和时间分辨率的层析重建能够实现直观的可视化，并为冻融过程的定量分析（包括冻土温度的校准）提供了重要的机会。然而，尽管传统的ERT方法具有广泛的吸引力，但电传感器需要与地面的电流耦合。这需要将金属电极物理植入活性层（其受到季节性冻结和解冻的影响）或下方的永久冻土中。因此，由于传感器与宿主基岩、土壤或建筑材料之间的接触电阻在冻结和解冻时的高水平和大变化，这可能导致对现场测量的显著实际限制。使用一种新的电容耦合ERT方法，我们建议证明进行延时层析成像测量的技术可行性，使用永久性的，原位电容传感器远程监测冻土的热状态。这将导致监测能力的显着改善，无论是在实验室中的永久冻土模拟实验，并在现场的实际应用。这项工作将包括数值模拟，以确定体积成像和长期监测冻土温度所需的最佳分布式电容传感器网络，无论是在现场和实验室规模。基于这些结果，将设计一个多传感器自动延时数据采集的测量系统，并将建立一个可行的实验室原型系统架构。随后，将开发一个功能台式原型，并展示多传感器数据采集和自动化操作的技术可行性。最后，我们将验证的概念，使自动延时温度校准CRI测量在受控的实验室实验，模拟永久冻土生长，持久性和基岩解冻。

项目成果

Monitoring rock freezing and thawing by novel geoelectrical and acoustic techniques

• DOI: 10.1002/2016jf003948
• 发表时间: 2016-12
• 期刊: Journal of Geophysical Research: Earth Surface
• 作者: J. Murton;O. Kuras;M. Krautblatter;T. Cane;D. Tschofen;S. Uhlemann;Sandra Schober;P. Watson