Is the column of the circular reservoir in the middle?

Yes. The design of the circular reservoir column in the middle is for stability considerations. The circular reservoir is a structure with good water storage performance, but its center of gravity is high and it is easily affected by external factors such as wind. If tilt or deformation occurs, if columns are set up around the circular reservoir for support, the columns can be placed at the center of gravity of the circular reservoir, thereby better stabilizing the entire structure.