Abstract
A new probe for groundwater flow measurement using a single borehole has been developed, which provides a simple and economical way to estimate the flowing velocity and its direction simultaneously. The principle of the measurement is based on mixed convection temperature field around the vertical heated cylinder subject to a uniform lateral flow. It is found by numerical analysis that the magnitude of temperature deviation from the concentric field is proportional to the strength of lateral velocity. A simple probe consisting of an electric heater in the center and thermistors around it has been built and its performance is examined by a calibration system, which is a two-meter long water tank filled with sands. According to the calibration, a good correlation has been obtained between the temperature deviation and the lateral water velocity (Darcy velocity). In order to simulate more practical situation, we also examine a case, where the rectification material fills the space between the flow meter and the perforated casing pipe, and an equally good correlation has been confirmed. A few field tests have proven promising results and future commercial use.
