This study presents the results from experiment on the groundwater flow in a borehole in porous media. A laser-Doppler velocimeter is employed for measuring the velocity in the hole. The groundwater flow in the porous media around the hole is demonstrated using the observed stream line in the tracer experiment. The measured velocity distributions in the streamwise direction agree well with the theoretical solution presented by Sano (1983). It is experimentally found that (I) the streamwise velocity at the center of the hole is three times larger than the seepage velocity in the porous media before the hole bored, (ii) the streamwise velocity distribution in the hole is a parabolic type, and (iii) the fluid in the vicinity of the upstream side of the hole is sucked into the hole and flows out to the downstream side in a symmetrical stream line. It can be said that these experimental findings will be useful in the in-situ measurement of groundwater velocity using a single borehole.
