Thermonics and Groundwater Exploration
Traditional methods of groundwater exploration only detect properties of the earth through which water flows. Only Thermonic methods actually measure a property of the water as it exists in the subsurface. Thermonics is the name of a geophysical method of groundwater exploration.
It is the only method that actually measures the relative flow velocities of ground water in the subsurface. Those surface locations that overlie zones of high velocity groundwater flow are almost always the best well locations.
Groundwater explorationists over the past 100 years have used seismic, earth resistivity, gravity, and magnetics to explore for groundwater and the best well sites. All of these methods measure properties of the earth medium through which groundwater flows. Thus, seismic methods measure the velocity through which energy moves through rock. The velocity of propagation of energy within rock is directly proportional to the density of the rock. If groundwater occurs in rock of a specific density the seismic method looks for those rocks or for contrast in rock type such as alluvial material within a paleo-channel incised into bedrock granite. Magnetics looks for rocks with a specific magnetic susceptibility. Earth resistivity measures the electrical conductance of rock that may contain groundwater. Gravity measures differences in the density of rock in the subsurface. Several of these traditional methods may be used together. None of the methods measures any property of the water that would lead to the best well locations.
Thermonics is based on three universally true physical principles relating to water: (1) Water has a high heat capacity, (2) Groundwater is almost always in motion; and, (3) Geothermal heat rises from the interior of the Earth to the surface. Consequently, Thermonics analyses subsurface groundwater flow caused by the distribution of rising geothermal heat by moving ground water. The subsurface groundwater flow is analyzed by collecting subsurface temperature in existing wells and boreholes or in shallow observation holes that may be as shallow as three feet. The skill in utilizing Thermonics is to be able to remove thermal noise caused by near surface irregularities in topography or soil moisture content, soil composition, or vegetation all of which are not known with precision.
In Congress Junction, Arizona, Thermonics was used to locate a well site by collecting subsurface temperature date from telephone-pole holes. This reduced cost of shallow data holes because the soils were hard and rich in hard caliches. The resulting well, produced 75 gallons per minute and never went dry as compared with the prior three wells that could only produce 25 gpm for a short period of time.
Thermonics was used to map the flow of groundwater beneath Tarbella Dam on the Indus River in northern Pakistan. Groundwater velocities were very high and it was necessary to locate the zones to prevent piping of the earthen dam foundation. The accuracy of the Termonic analysis was later confirmed by mapping locations of pits in an upstream soils blanket and comparing them with the locations of the high velocity zones determined from Thermonics.
Thermonics was used to map flow of water within the Wolf Creek Dam and its foundation in Kentucky after mud boils developed in the tail race of the dam. The dam had been constructed on karst terrane and flow was highly anisotropic.
Thermonics was used to locate wells in what has become the East Tucson Well Field 20 miles east of Tucson, Arizona. At that location Thermonics identified a zone of extremely high aquifer transmission about 500 feet wide. When the work was done, the largest production well in the Tucson Basin produced 600 gallons per minute. The first well drilled into the Thermonic target produced 600 gpm. Six more wells were drilled into the Thermonic target and the best well did 1,200 gpm. Flush with success and believing that the entire area contained abundant groundwater, an eighth 16-inch diameter well was drilled to a depth of 1,000 feet using cable tool methods and produced only a teacup of water a day. The City of Tucson traded sanitary sewer service to a large subdivision in the area for rights to the water-well field.
ABOUT THE AUTHOR: Dr. William M. Turner
Dr. Turner has degrees in Geology and Hydrology and is an expert in groundwater exploration. His career spans 40+ years throughout the United States, South America, Africa and the Middle East. He is also a licensed reaal estate broker and an expert in the validation, valuation, and brokerage of water rights and water assets. Dr. Turner is also a landman and an expert in land and mineral title work and curage. He is also an oil and gas operator.
Copyright Dr. William M. Turner
Disclaimer: While every effort has been made to ensure the accuracy of this publication, it is not intended to provide legal advice as individual situations will differ and should be discussed with an expert and/or lawyer.For specific technical or legal advice on the information provided and related topics, please contact the author.
