Double-frequency ground penetrating radar for measurement of ice thickness and water depth in rivers and canals: Development, verification and application

Abstract

In situ measurement of the ice thickness and water depth distributions in a river, canal, or lake is one of the most important means of measuring and responding to an ice flood. In view of the shortcomings of the use of single-frequency ground penetrating radar (GPR) for simultaneous measurement of ice thickness and water depth, a double-frequency GPR with 100 and 1500 MHz antennas was developed in the present study. To avoid interference between the two antennas with different frequencies, there is a 15-ms time-sharing operation. Similarity analysis of neighboring GPR signals was used to obtain the accuracy value of two-way travel time. The proposed GPR system also enables the real-time determination of the longitude and latitude coordinates of the measurement site using a real-time kinematic (RTK) system. The system measured the ice thickness and water depth at 97 and 99 sites, respectively, in the Mohe section of the Heilongjiang River, and the Togtoh, Inner Mongolia section of the Yellow River; both in China. Comparison of the measurements to those obtained by traditional drill-hole methods, yielded a mean value of absolute errors of 0.12 m and 0.04 m for water depth and ice thickness, respectively. The system was further used to measure the distribution of the ice thickness and water depth over a distance of 0.5 km in the Longdao Wharf section of the Heilongjiang River, and over a distance of 67 km in the Mohe section of the river,between the entrance of the Luogu River and Beiji village. The measurement results indicate that the developed double-frequency GPR is suitable for in situ measurement of ice thickness and water depth in rivers during ice periods.