| 摘要 |
A device for creating a local water flow or water jet in a body of water, in such a way that bed material from the bed below said body of water can be displaced, comprises a jet pipe (301), a screw (302) disposed rotatably in the jet pipe (301), and means (303) for supplying a countertorque in the opposite direction to the torque exerted on the device through the rotation of the screw. According to the invention, a second screw (303) is accommodated in the jet pipe (301), which second screw (303) is rotatable in the opposite direction to the direction of rotation of the first screw (302), and the pitch angle of which is opposite to that of the first screw (302).
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