Inadequate submergence can result in pre-rotation of the water in the wet-well, resulting in the formation of strong free-surface air core vortices and the entrance of air into the pump suction inlet.

This paper presents a method of providing a virtual support for the rotor to assure the meshing stability of a pair of a pre determined spiral bevel gears in rotation.

It is necessery that the total consumptive use of water in the rotation period is equal to the total effective precipitation(pre- cipitation minus runoff depth)in the loess hilly region.