Application of surface geophysical techniques in a study of the geomorphology of the lower Copper River, Alaska

As part of a geomorphology study of the lower Copper River, three surface geophysical techniques were tested for their ability to detect infilled scour holes at bridge piers, old river channels, and subbottom deposits in a glacier-formed lake. The methods were (1) ground-penetrating radar, (2) continuous seismic reflection using a color fathometer, and (3) continuous seismic reflection using a tuned transducer. In water depths less than 20 feet, ground-penetrating radar detected infilled scour holes at bridge piers and old river channels on land. Continuous seismic reflection using a tuned transducer was effective in water and detected infilled scour holes at bridge piers and subbottom deposits in a glacier lake. The color fathometer was useful in determining depths of water but was not able to penetrate the subbottom.