In the presence of forced convection, there exists an energy flux c&rgr;VT, 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 bounderies of aquifers and a semiconfining medium to obtain information about groundwater seepage within the semiconfining layer.