JPH0619472B

PURPOSE:To measure direction and velocity of flow of ground water at an observation well by providing a heater and three or more temperature sensors non- linearly on the same surface of surrounding water in an observation well. CONSTITUTION:Ground water 17 is standing in an observation well about 50cm in diameter and several tens of meters deep. A detecting section 10 is fixed horizontally by a cable 18 and immersed in ground water 17. A heater 12 is provided at the center of the detecting section 10, and four temperature sensors 13- 16 are arranged at a distance of 90 deg. and at equal distance from the heater 12 in the same surface of surrounding water. Temperature information is frequency converted by an electronic circuit 19 and inputted to a signal processing device on the ground. These are protected by a reticulated sensor protector 11. Temperature of ground water is raised by the heater 12, and temperatur rise at points of specified distance is measured by sensors. Thus, direction and velocity of flow of ground water can be measured.