Abstract: In this paper, we mainly study water temperature changes at different depth of the Tayuan well, Beijing and the Taihe well, Xichang, Sichuan . It is shown that above the observed aquifer of the well, at sealed section with small temperature gradient, temperature gradient is the main factor of water temperature changes. In positive gradient belt, temperature tidal effects changes directly with water level tide. In negative gradient section, temperature tidal effects changes inversely with water level tide. And in the section at which temperature tidal effects can be observed, the larger the temperature gradient is, the larger the temperature tidal dynamic range. Negative gradient section of the Tayuan well also influences after-seismic temperature changes of geothermometer located under it, making temperature taking more time to come back to the normal level. Water temperature changes are more complicated when probe locates within the observed aquifer range. The result shows that it is necessary to fully understand hydro-geological conditions, well profile and temperature gradient when analyzing temperature changes and installing temperature probe.

Key words: Temperature gradient, Water temperature, Water level, Tide, Tayuan well