ABSTRACT
The Earth’s temperature at shallow depth is influenced by diurnal and seasonal temperature variations at the ground surface. Fluid can also be driven to flow by a strong temperature gradient or a density gradient that causes gravitational instability. Groundwater is commonly recharged at high elevation and discharged at low topography in a watershed. Along the descending flow path, the groundwater is heated by the ambient rocks but is cooled by the surroundings when it ascends to the discharge area. The temperature-depth curve is concave to the right in the direction of the postive T-axis if temperature increases in the groundwater flow direction; otherwise it is concave to the left. If several profiles are available, the influences by horizontal or vertical flow should be distinguishable. Dashed lines show the approximate locations of equal influence on the temperature-depth profiles by the northwest flowing groundwater.
