What is the name of the thing that flows through the main canal?

Aqueduct. The main canal is an aqueduct, also known as a water bridge, which is a cross building when the canal passes through valleys, rivers, roads and other channels. It consists of an inlet section, a trough, an outlet section and a trough supporting structure. The tank is usually rectangular or U-shaped in cross section and made of masonry or reinforced concrete. The supporting structure of tank can be divided into pier type, bent type and arch type.