Question

The chances of silt formation are higher in which of the following water distribution system?

• A. Grid Iron system
• B. Radial system
• C. Ring system
• D. Tree System (Also known as Dead End system)

Hint:

\textbf{Silt formation} in water pipes occurs due to sedimentation of particles at low water velocities.
\textbf{Tree System (Dead End System):} Has many dead ends where water can stagnate. Low flow velocities in these sections promote silt deposition. This system is most prone to siltation and water quality degradation at dead ends.
\textbf{Grid Iron System and Ring System:} Looped systems with better circulation and fewer dead ends, leading to more consistent velocities and less chance of stagnation and siltation compared to dead-end systems.
\textbf{Radial System:} Can have dead ends if not looped at peripheries.

Answer 1

The Correct Option is D

Silt formation (sedimentation) in water distribution pipes occurs when the water velocity is low, allowing suspended particles (silt, sand, debris) to settle out and accumulate. This can reduce pipe capacity, affect water quality, and cause blockages. Let's consider the characteristics of different water distribution systems:
(a) Grid Iron system (Reticulated or Looped system): Pipes are interconnected to form a grid or network. Water can reach a point from multiple directions. This system generally ensures good circulation, fewer dead ends, and more uniform pressure. Stagnation and very low velocities are less likely compared to dead-end systems.
(b) Radial system: The area is divided into zones, and water is supplied from a central distribution reservoir outwards through radially laid pipes. This is suitable for cities with a radial road pattern. It can have dead ends at the periphery of each zone if not looped.
(c) Ring system (Circular system): The main supply pipes are laid in a ring around the distribution area, with branch pipes taken off the ring to supply consumers. This provides two-way supply to many points and improves circulation, similar to a grid system.
(d) Tree System (Dead End system or Branching system): This system resembles a tree, with a main supply pipe (trunk) from which smaller branch pipes extend, and these further subdivide into smaller sub-branches (twigs) that terminate in dead ends. Disadvantage: This system has numerous dead ends. At these dead ends, water can stagnate, leading to low velocities or no flow. This prolonged stagnation and low velocity allow suspended particles (silt) to settle and accumulate. This makes the Tree System (Dead End system) most prone to silt formation and water quality issues (e.g., taste, odor, bacterial growth) at these dead ends. Regular flushing of dead ends is often required. Therefore, the chances of silt formation are higher in the Tree System (Dead End system) due to the presence of numerous dead ends where water stagnates and velocities are low. \[ \boxed{\text{Tree System}} \]