In order to investigate whether the groundwater moving state is affected after Three Gorges Reservoir impoundment, this study tested the velocity and direction of the groundwater seepage in the monitoring wells around Three Gorges Dam using the method of isotope tracing, and gained good results. Test results showed that the groundwater seepage directions in Gaojiaxi well (W1) and Hanjiawan well (W4) are respectively 25°east by south and 2° south by east, according with the previous

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... cal inference. These indicated that the groundwater seepage directions around the Three Gorges Dam are not affected significantly after reservoir impoundment. The groundwater seepage velocities in W1 and W4 wells are respectively 0.72m/d and 1.29m/d. There is small difference between them and this may be related to the tectonic setting of the two wells.