Evaluation of the Magnetic Induction Conductivity Method for Detecting Frazil Ice Deposits

• Main Authors: Arcone, Steven A, Brockett, Bruce E, Lawson, Daniel E, Chacho, Edward F , Jr
• Other Authors: COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH
• Format: Text
• Language: English
• Published: 1987
• Subjects: Magnetic & Electric Fld Detection & Detectors; Snow; Ice and Permafrost; *MAGNETIC INDUCTION; *CHANNEL FLOW; *ICE FORMATION; ADVERSE CONDITIONS; ALASKA; ANTENNAS; CALIBRATION; CHANNELS; COLD WEATHER; CONDUCTIVITY; CROSS SECTIONS; FAIRBANKS(ALASKA); FREQUENCY; GRAVEL; INSTRUMENTATION; MODELS; PHYSICAL PROPERTIES; POSITION(LOCATION); PROFILES; RESISTANCE; RIVERS; SURVEYS; THEORY; WATER; MAGNETIC INDUCTION; WATER FLOW; UNDERICE; REMOTE DETECTORS; ERROR ANALYSIS; *Frazil ice; AST24; PE61102A; LPN-CWIS-31722; WU014; Fairbanks; Ice; permafrost; Alaska
• Online Access: http://www.dtic.mil/docs/citations/ADA186940; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA186940

The ability to map frazil ice deposits and water channels beneath an ice-covered river in central Alaska using the magnetic induction conductivity (MI) technique has been assessed. The study was performed during the first week of March of 1986 on the Tanana River near Fairbanks and employed a commercially available instrument operating at a fixed frequency with a fixed antenna (coil) spacing and orientation. Comparisons of the MI data with theoretical models based upon physical data measured along three cross sections of the river demonstrate the sensitivity of the MI technique to frazil ice deposits. The conductivity generally derived for the frazil ice deposits encountered is very low (approx. .00063 s/m) when compared with the measured value for water (approx. 0.011 S/m), and is similar to the calculated values for gravel and sandy gravel bed sediments. In all three cross sections, maxima in the apparent conductivity profiles correlated with frazil ice deposits. Difficulties, possibly due to adverse effects of cold weather upon instrument calibration, affected the quantitative performance of the instrument on one cross section, although the interpretation of the data (locations of open channels vs frazil deposits) was qualitatively unaffected. Keywords: Resistivity surveying.