A Field Study on GPR for Non-Invasive Measurement of Soil Moisture and a Preliminary Investigation of GPR-Remote Sensing Imagery Correlations

关于土壤水分的信息在科学研究的几个领域中都是至关重要的。在水文学和气象学中，近地表土壤水分含量是准确估计地表和大气之间的热量和水汽交换通量所必需的，这是全球环流模式的重要组成部分。对大面积土壤水分的频繁监测可以显著提高我们预测土壤侵蚀和质量运动的能力。浅层土壤水分含量在决定污染物从地表迁移的过程中起着极其重要的作用。土壤水分在空间和时间上都是高度可变的。目前用于测量土壤水分的仪器，如中子探头或时间域反射仪(TDR)，在固定位置测量的工作量和精度方面提供了合理的解决方案。然而，这些方法对于在大范围内收集数据几乎毫无用处，因为它们需要钻探和只采集少量土壤样本。此外，人们不能忽视钻探对数据的影响。目前，还没有一种技术可以准确地提供在空间和时间尺度上的土壤水分测量，以估计、监测和模拟包气带的水分运动。该项目的重点是研究探地雷达(GPR)作为一种大规模监测浅层地下土壤水分(深至2-3米)的工具的潜力。这项工作包括一系列实验，以确定最佳的探地雷达数据采集参数、简单的解释方法、土壤质地和水分变化对探地雷达响应的影响，以及评估准确性和可靠性的标准。这些实验将在受控条件下进行，地点包括建造的试验场、露头地点和加利福尼亚州纳帕谷的自然异质田野地点。这项工作将用于评估不同土壤类型和饱和度的探地雷达技术和解释方法。受控实验将涉及(1)探地雷达对饱和度变化和土壤类型(垂直和横向)变化的敏感性；(2)侵蚀面和土层间边界对探地雷达响应的影响；(3)对粘土的敏感性；(4)最佳数据采集和解释技术。来自加州大学伯克利分校和劳伦斯·伯克利国家实验室(LBNL)的多学科团队将在开发方法方面取得重大进展，这些方法将能够更准确和更广泛地估计土壤水分含量，用于全球环流模型、干旱管理、包气带污染物传输和岩土工程问题。

0087802RubinInformation on soil moisture is vital in several areas of scientific research. In hydrology and meteorology, the near-surface soil moisture content is needed for accurately estimating the exchange of heat and vapor fluxes between the surface and the atmosphere, which is a crucial component of global circulation models. Frequent monitoring of soil moisture over large regions could significantly improve our ability to predict soil erosion and mass movement. Shallow soil moisture content is extremely important in determining the migration of contaminants from the ground surface.Soil moisture is highly variable in both space and time. Current instruments for measuring soil moisture, such as neutron probe or time domain reflectometry (TDR), offer reasonable solutions in terms of efforts and accuracy for measurement at a fixed location. These methods, however, become practically useless for collecting data over large areas since they require drilling and sample only small volumes of soil. Additionally, one cannot discount the effects of drilling on the data. Currently, no technique is available to accurately provide soil water content measurements over the spatial and temporal scales necessary for estimating, monitoring and modeling moisture movement in the vadose zone.The focus of the project is to investigate the potential of Ground Penetrating Radar (GPR) as a tool for large-scale monitoring of shallow subsurface soil moisture (down to depths of 2-3 meters). The work includes a series of experiments to determine optimal GPR data acquisition parameters, simple interpretation methods, effects of soil texture and moisture variability on the GPR response, and criteria for assessing accuracy and reliability. The experiments will be conducted both under controlled conditions at a constructed test site, at outcrops, and at a naturally heterogeneous field site in Napa Valley, CA. The work will be used to evaluate GPR technology and interpretation methods for various soil types and saturations. The controlled experiments will address (1) the sensitivity of GPR to variations in saturation and to variations (vertical and lateral) in soil types; (2) the effect of erosional surfaces and boundaries between soil horizons on the GPR response; (3) sensitivity to clay; and (4) optimal data acquisition and interpretation techniques. The field experiments will test the method under natural conditions at a geologically heterogeneous site at different times of year.The multidisciplinary team from U.C. Berkeley and Lawrence Berkeley National Laboratory (LBNL) is well poised to make significant progress in developing methods that would enable more accurate and extensive estimates of soil water content for use in global circulation models, drought management, vadose zone contaminant transport and geotechnical problems.