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

[87802][参考译文]土壤水分信息在若干科学研究领域中是至关重要的。在水文学和气象学中，近地表土壤水分含量是精确估算地表与大气之间热量和水汽交换通量的必要条件，是全球环流模式的重要组成部分。频繁监测大面积的土壤湿度可以显著提高我们预测土壤侵蚀和物质运动的能力。浅层土壤含水量在决定污染物从地表迁移方面是极其重要的。土壤湿度在空间和时间上都是高度可变的。目前用于测量土壤湿度的仪器，如中子探针或时域反射仪（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，这些方法对于收集大面积的数据实际上是无用的，因为它们只需要钻探和取样少量的土壤。此外，钻探对数据的影响也不容忽视。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含水量测量，这是估算、监测和模拟渗透带水分运动所必需的。该项目的重点是研究探地雷达（GPR）作为大规模监测浅层地下土壤湿度（深度为2-3米）的工具的潜力。该工作包括确定最佳探地雷达数据采集参数的一系列实验，简单的解释方法，土壤质地和湿度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。实验将在受控条件下进行，分别在一个已建成的试验场、露头和加利福尼亚州纳帕谷的一个自然异质场进行。这项工作将用于评估各种土壤类型和饱和度的探地雷达技术和解释方法。对照实验将解决(1)探地雷达对饱和度变化和土壤类型变化（垂直和横向）的敏感性；(2)侵蚀面和土层边界对探地雷达响应的影响；(3)对粘土的敏感性；(4)优化数据采集和解释技术。实地试验将在一年中的不同时间，在一个地质不均匀的地点，在自然条件下测试该方法。来自加州大学伯克利分校和劳伦斯伯克利国家实验室（LBNL）的多学科团队准备在开发方法方面取得重大进展，这些方法将能够更准确、更广泛地估计土壤含水量，用于全球环流模型、干旱管理、渗透带污染物运输和岩土工程问题。

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.