Beginning in May 1965, a 3 yr temperature study was made in a small earth-fill dam in southern California. The objective was to investigate the capability of thermal sensing methods to detect leakage and to monitor changes in leakage.
The dam is 550 ft long, 24 ft high, and impounds a reservoir of 22 acre-ft. Thirty thermistor probes, calibrated to .01° C were set 20 ft apart and 7 ft deep along the axis of the dam. Temperatures were recorded at approximately monthly intervals.
Indicators of fluid flow are the observed temperature, the differential temperature observed over a time interval, and the parameters of the annual cycle. The observed temperature data could be correlated: (1) with visible leakage zones on the downstream face of the dam; (2) with internal zones of recurrent saturation and with structural conditions, as determined by drillholes and piezometers; and (3) with the total amount of flow through the dam as determined by a water budget study. The method shows good promise as an early warning safety system for dams.