TITLE:
Determination of the Pore Water Velocity Using a Salt Tracer Combined with Self-Potential Measurements
AUTHORS:
Huong Huynh Thi Thu, Son Le Van, Hieu Tran Trong, Hai Lai Viet, Quang Nguyen Huu, Luan Phan Thi
KEYWORDS:
Earthen Dams, Tracer Technique, Leakage, Interstitial Velocity
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.11 No.1,
January
16,
2023
ABSTRACT: The
tracer technique is recommended as an effective tool in surveying abnormal
seepage through lakes and dams. By injecting a tracer into a known upstream
location and monitoring the appearance of the tracer in the downstream leak
point, it is possible to determine the direction and the average water velocity
of the preferential flow through the dam. The detailed result achieved depends
on the number of samples and the sampling locations to analyze tracer
concentration over time in the field. This study proposes to use noninvasive
self-potential measurements to determine the location and time the salt tracer
moves through the seepage zone. The connection between the potential signal
according to the propagation of the NaCl salt tracer and the water velocity was
demonstrated through an experiment on a sandbox model. Experimental results
express a good agreement between the time to reach the maximum value of the
potential variation and the salt concentration variation with the time that
water comes to monitoring locations. The result indicates an ability to determine
the pore water velocity of the seepage zone based on the recording of potential
signals produced by a salt tracer movement. The salt tracer test using NaCl
combined with self-potential measurements was then applied to survey a leaking
earth dam in the Dong Nai river basin (Vietnam).