Hydraulic gradient line is basically defined as the line which will give the sum of pressure head and datum head or potential head of a fluid flowing through a pipe with respect to some reference line.
What is a hydraulic gradient line HGL?
A hydraulic grade line (HGL) is: ‘A theoretical line showing the sum of the pressure elevation heads of a flow relative to a datum. The slope of the hydraulic grade line is the hydraulic gradient.
What does hydraulic gradient mean?
The hydraulic gradient (1) is the slope of the water table or potentiometric surface, that is, the change in water level per unit of distance along the direction of maximum head decrease. The hydraulic gradient is the driving force that causes groundwater to move in the direction of maximum decreasing total head.
What is the difference between EGL and HGL?
An HGL above a pipe corresponds to positive pressure while an HGL below the centerline means that the pressure is negative. An energy grade line (EGL) shows the variation of the total head. These effects will be discussed further in conjunction with the energy equation and flow in conduits.)
What is a hydraulic gradient?
The slope of the hydraulic grade line. This is the slope of the water surface in an open channel, the slope of the water surface of the groundwater table, or the slope of the water pressure for pipes under pressure.
What is hydraulic gradient line and total energy line?
Hydraulic gradient Line (H.G.L) – Line representing the sum of pressure head and datum head. Total energy line (T.E.L) – Line representing the sum of pressure head, datum head, and velocity head.
What does a positive hydraulic gradient mean?
A downward flow component is indicated if the gradient is negative, meaning the hydraulic head is less at depth. Conversely, an upward flow component is indicated if the gradient is positive, meaning the hydraulic head is greater at depth. The magnitude of the gradient indicates its significance.
Can hydraulic grade line negative?
An HGL above a pipe corresponds to positive pressure while an HGL below the centerline means that the pressure is negative.
