A vertical groundwater movement correction for heat flow

Abstract

In the presence of forced convection, there exists an energy flux cρVT, because of mass‐transported heat energy. By plotting temperature gradient versus temperature the significance of convective heat transfer can be determined. Such a plot is useful even when the flow system is not one‐dimensional or vertical. As an example of convective heat transfer, a temperature log from the Rio Puerco area of New Mexico shows that downward groundwater movement of 4.7×10−7 cm/s over a 77‐m interval can reduce the observed geothermal gradient and heat flow by a factor of 2 from 4.1 to 2.0 HFU (1 HFU = 1 μcal cm−2 s−1). Such strong perturbations of heat flow by groundwater indicate the need for deep heat flow measurements to obtain a geothermal heat flux undisturbed by near‐surface groundwater. By considering the convective flux one can use the total energy balance at the boundaries of aquifers and a semiconfining medium to obtain information about groundwater seepage within the semiconfining layer.