In the context of drainage system design, comprehending the concepts of the Hydraulic Grade Line (HGL) and the Energy Grade Line (EGL) is pivotal. These lines are integral tools for analyzing and visualizing the behavior of fluid within a drainage network. InfoDrainage incorporates these concepts to enhance the efficiency and accuracy of drainage system designs.
Hydraulic Grade Line
The Hydraulic Grade Line (HGL) represents the maximum water level within each node of the drainage system. It is a crucial indicator of the static pressure in the system.
Calculation: The HGL is determined as a line that connects the highest water level in each node. It is important to note that we are not capping the HGL at the ground level.
Significance: Understanding the HGL is essential for ensuring that the drainage system operates within its capacity. By monitoring the HGL, you can identify potential overflow and bottle-necks points and areas where the system might be under stress.
Energy Grade Line
The Energy Grade Line (EGL) is a graphical representation that embodies the total energy present within the drainage system at various points.
Calculation: The EGL is defined as:
where:
V = represents the velocity of the flowing water, derived from the weighted average according to the flow of all incoming and outgoing pipes.
g = acceleration due to gravity.
At each node within the drainage system, the EGL is calculated, creating a continuous line that connects all EGL values across nodes. These values are then assigned to the upstream and downstream ends of each pipe.
In order to avoid having HGL and EGL crossing the pipe in systems with backdrops, HGL will always stop at the downstream water level within the pipe then will be dropped to follow the water level in the system downstream following the backdrop.
Significance: The EGL provides a comprehensive view of the energy dynamics within the drainage system. By analyzing the EGL, you can understand how energy is distributed throughout the system and identify areas where energy losses may occur. This understanding is crucial for optimizing the design for energy efficiency and ensuring the long-term sustainability of the drainage system.