TY - JOUR
T1 - Frequency domain electromagnetic and ground penetrating radar investigation of ephemeral streams
T2 - Case study near the Southern High Plains, Texas
AU - Burrell, Jeffrey
AU - Gurrola, Harold
AU - Mickus, Kevin
N1 - Funding Information:
Acknowledgments The EM34 equipment was purchased with a grant from the National Science Foundation (#9252267) awarded to KM.
PY - 2008/9
Y1 - 2008/9
N2 - A frequency domain electromagnetic (FDEM) and ground penetrating radar (GPR) study was conducted on an ephemeral stream in north-central Texas to determine if FDEM and GPR measurements can be combined to determine the electrical characteristics of current and ancient stream channels. GPR data were collected at several frequencies to image sedimentary structures of different scale lengths, and to determine the formation porosity and water content of stream sediments. FDEM measurements were collected using Geonics EM31 and EM34 loop-loop instruments on a profile along the current stream channel and five profiles perpendicular to the channel. The results indicate that the greater spatial resolution of the EM31 mapped the current and possible ancient channels better than the EM34, however, the EM34 provided depth information on the formations underlying the channel sediments that the EM31 could not image. GPR measurements taken along a point bar deposit with 200, 100 and 25 MHz antennae indicated that the higher frequency antenna better resolved channel structures including laminar bedding, trough scours and cross-bedding, however, lower frequency antenna (25 MHz) imaged sedimentary structures within the underlying channel sediments. Common midpoint GPR measurements collected along the point bar deposit were used to estimate the sediment formation porosity (26%) and the water content, during a dry period, of the unsaturated (12%) and saturated (26 or 100% of the pore space) sediments. The combined results indicated that the FDEM data should be collected first because of the speed and ease of measurements. The FDEM data (especially the EM31) pointed to the locations of possible sedimentary structures, which can then be resolved by using different frequency GPR measurements.
AB - A frequency domain electromagnetic (FDEM) and ground penetrating radar (GPR) study was conducted on an ephemeral stream in north-central Texas to determine if FDEM and GPR measurements can be combined to determine the electrical characteristics of current and ancient stream channels. GPR data were collected at several frequencies to image sedimentary structures of different scale lengths, and to determine the formation porosity and water content of stream sediments. FDEM measurements were collected using Geonics EM31 and EM34 loop-loop instruments on a profile along the current stream channel and five profiles perpendicular to the channel. The results indicate that the greater spatial resolution of the EM31 mapped the current and possible ancient channels better than the EM34, however, the EM34 provided depth information on the formations underlying the channel sediments that the EM31 could not image. GPR measurements taken along a point bar deposit with 200, 100 and 25 MHz antennae indicated that the higher frequency antenna better resolved channel structures including laminar bedding, trough scours and cross-bedding, however, lower frequency antenna (25 MHz) imaged sedimentary structures within the underlying channel sediments. Common midpoint GPR measurements collected along the point bar deposit were used to estimate the sediment formation porosity (26%) and the water content, during a dry period, of the unsaturated (12%) and saturated (26 or 100% of the pore space) sediments. The combined results indicated that the FDEM data should be collected first because of the speed and ease of measurements. The FDEM data (especially the EM31) pointed to the locations of possible sedimentary structures, which can then be resolved by using different frequency GPR measurements.
KW - Electromagnetics
KW - Ephemeral Streams
KW - Formation Porosity
KW - Ground Penetrating Radar
UR - http://www.scopus.com/inward/record.url?scp=50849126805&partnerID=8YFLogxK
U2 - 10.1007/s00254-007-1063-5
DO - 10.1007/s00254-007-1063-5
M3 - Article
AN - SCOPUS:50849126805
SN - 0943-0105
VL - 55
SP - 1169
EP - 1179
JO - Environmental Geology
JF - Environmental Geology
IS - 6
ER -