Correct option is D
Total Energy Line (TEL)
The Total Energy Line (TEL) represents the variation of the total head (pressure head + velocity head + elevation head) along the length of a pipe.
It is obtained by joining the energy levels at different cross-sections of the pipe.
In the direction of flow, the TEL continuously slopes downward due to energy losses, unless additional energy is supplied by a pump.
Hydraulic Grade Line (HGL)
The Hydraulic Grade Line (HGL) represents the variation of piezometric head (pressure head + elevation head) along the pipe.
It is drawn by joining the piezometric head values at various cross-sections.
The HGL also falls in the direction of flow because of head losses.
Relationship Between TEL and HGL
For uniform-diameter pipes, the vertical distance between the TEL and HGL at any section equals the velocity head.
The HGL always lies below the TEL by an amount equal to the velocity head.
Velocity Head Relation
Velocity head = TEL − HGL
