It is used to control the water level in the system. In water retention structures, the water level is controlled by having a movable pipe within a fixed vertical pipe and moving it up and down. Telescopic valves work according to the siphon system to transport water. Since the water transport process occurs from the water surface, it does not interfere with the sediments at the bottom. For this reason, it is also used in mud collection structures. In addition, since they allow precise adjustments in determining the water level, they are used in sedimentation tanks to determine the exit level of water from the system.