The bottom flow mode was used for the flood discharge energy dissipation of Xihe hydropower station,combining with adjective energy dissipation structures to meet the need of the features of the project,concerning lower water head,low Froude number,high discharge per unit width,large variation of tail water table,weak ability of anti scouring of the bed rock and so on.

Unloading and water head difference between the inside and outside of a foundation pit would induce seepage in high water table ground,which had significant influence on excavation engineering.

To optimize water head allocation of main canal is important for saving investment and reasonably designing Structures.

Based on the characteristics of distribution of settlement in the cross section of embankment and large-area loading zone,equations of hydraulic head in sand mats and equations of requirements of thickness of sand mats with different cross sections were derived according to the principle that the permeability of sand mats was equal to the velocity of draining of ground.

There have been a lot of achievements on hydraulic head distribution in aquifer, but the research work on hydraulic head distribution in relative water resisting layer is not sufficient.

Based on the hydraulics theory a research has been made on change of hydraulic head and discharge through orifice in filter underdrain system,and some mistakes have been illustrated in reference.

The absorbing height of pump will be used in conquering the losses of speed head and distance head and the relative installed height of the pump,as well as the both sides pressure difference of drill stem produced to carry the .

Meanwhile,the best applicable range of water head for it is considered to be ranging from 20 to 300 meters.

Meanwhile,the best applicable range of water head for it is con- sidered to be 20 to 300 meters.