Nondestructive and noninvasive visualization and quantification of dynamic subsurface hydrologic processes are needed. Using a ground-penetrating-radar (GPR) antenna array, time-lapse common-offset gather and common midpoint (CMP) data can be collected by fixing the antenna at a given location when scanning the subsurface. We have determined wetting front depths continuously during a field infiltration experiment by estimating electromagnetic (EM) wave velocities at given elapsed times using GPR antenna array data. A surface GPR antenna array system, consisting of 10 transmitters (Tx) and 11 receivers (Rx), that can scan each Tx-Rx combination in 10 s at a millisecond scale has been used to acquire all 110 Rx-Tx combinations in approximately 1.5 s. The field infiltration experiment has been conducted at an experimental field near the Tottori Sand Dunes in Japan. Using the estimated EM wave velocity from the CMP data, the depth to the wetting front is computed every minute. The estimated wetting front arrival time agrees with the time at which a sudden increase in the moisture sensor output is observed at a depth from 20 cm and below. We determine that time-lapsed CMP data collected with the GPR antenna array system could be used to estimate EM wave velocities continuously during the infiltration. The GPR antenna array is capable of accurate and quantitative tracking of the wetting front.

中文翻译：

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使用从探地雷达天线阵列获得的延时多偏移道集估计渗透前沿深度

需要对动态地下水文过程进行非破坏性和非侵入性可视化和量化。使用探地雷达 (GPR) 天线阵列，可以通过在扫描地下时将天线固定在给定位置来收集延时共偏移距道集和共中点 (CMP) 数据。我们通过使用 GPR 天线阵列数据在给定的经过时间估计电磁 (EM) 波速度，在场渗透实验期间连续确定了润湿前沿深度。一个由 10 个发射器 (Tx) 和 11 个接收器 (Rx) 组成的表面 GPR 天线阵列系统可以在 10 秒内以毫秒为单位扫描每个 Tx-Rx 组合，已被用于以大约 1.5 s。田间入渗试验是在日本鸟取沙丘附近的试验田进行的。使用从 CMP 数据估计的 EM 波速度，每分钟计算到润湿前沿的深度。估计的润湿前沿到达时间与在 20 厘米及以下深度观察到湿度传感器输出突然增加的时间一致。我们确定使用 GPR 天线阵列系统收集的延时 CMP 数据可用于在渗透期间连续估计 EM 波速度。GPR 天线阵列能够​​准确和定量地跟踪润湿前沿。估计的润湿前沿到达时间与在 20 厘米及以下深度观察到湿度传感器输出突然增加的时间一致。我们确定使用 GPR 天线阵列系统收集的延时 CMP 数据可用于在渗透过程中连续估计 EM 波速度。GPR 天线阵列能够​​准确和定量地跟踪润湿前沿。估计的润湿前沿到达时间与在 20 厘米及以下深度观察到湿度传感器输出突然增加的时间一致。我们确定使用 GPR 天线阵列系统收集的延时 CMP 数据可用于在渗透期间连续估计 EM 波速度。GPR 天线阵列能够​​准确和定量地跟踪润湿前沿。