In irrigation systems, various structures are used to manage, direct, and control the flow of water through canals to ensure that crops receive the right amount of water. These canal structure can be grouped into categories based on their purpose: controlling water, preventing erosion, and allowing passage over or under canals. Key structure include check gates, turnouts, siphons, division boxes, open drop structure, pipe drop structure, aqueducts, inverted siphons, and culverts. Let’s break down what each of these structure does and why they are important.
Table of Contents
Structure And Functions of Canal Structures
1. Water Control Structure
Water control structures are designed to regulate and direct water flow in canals, ensuring proper water distribution across the irrigation system.
Check Gates
A check gate is a simple device used to control the water level in a canal. It acts like a small dam, raising or lowering the water flow as needed. Check gates are typically placed along the canal to help manage water levels and direct water to specific areas. They are useful when there is a need to adjust the flow or temporarily stop the water from moving through a section.
Turnouts
A turnout is a structure that allows water to be diverted from the main canal into smaller canals or directly to agricultural fields. These structure help farmers control the amount of water they get from the main system. Turnouts are adjustable, meaning the flow of water can be increased or decreased based on the needs of the field.
Siphons
A siphon is a type of water flow system that lets water pass under an obstacle, such as a road or another canal. It works by using the pressure difference between the water levels on either side of the obstacle. Siphons are useful when you need to carry water under a structure without disturbing the flow in the canal.
Division Boxes
A division box is a structure that splits the flow of water into multiple smaller channels. It ensures that water is evenly distributed across the system. Division boxes are important in irrigation networks with many users or fields, allowing farmers to get the exact amount of water needed for each section.
2. Erosion Control Structures
Erosion control structures are built to protect canal banks and surrounding land from the damaging effects of water flow. They help prevent soil erosion, which can weaken the banks and cause water loss.
Open Drop Structures
An open drop structure is used to slow down the flow of water and prevent it from eroding the canal banks. It works by letting water flow down a series of steps or terraces, which gradually reduces its speed. These structures are typically installed at places where water might flow too fast and start washing away soil from the canal edges.
Pipe Drop Structures
A pipe drop structure functions in a similar way to an open drop structure but uses pipes to control the flow. Water enters a pipe and is carried down a drop, which helps slow it down and prevent erosion. These are typically used when there isn’t enough space for an open drop structure, or when a smoother flow is needed.
3. Channel Crossing Structures
Channel crossing structures allow roads, other canals, or infrastructure to pass over or under a canal without interrupting the water flow. They help ensure that the irrigation system remains functional while accommodating other activities, such as transportation.
Aqueducts
An aqueduct is a bridge-like structure that carries water over roads, valleys, or other canals. When a canal needs to cross a low area, an aqueduct allows the water to flow over the gap while other vehicles or infrastructure pass underneath. Aqueducts are important for larger irrigation systems where the canal needs to cross over obstacles without disrupting the water flow.
Inverted Siphons
An inverted siphon is a structure that lets water flow under a barrier, such as a road or another canal, using the siphon effect. Water flows through a pipe that is designed to carry the water downward and then back up on the other side. This is useful when a canal needs to pass under an obstacle, and an aqueduct isn’t practical. It is a more cost-effective solution in some cases.
Culverts
A culvert is a tunnel-like structure, usually a pipe, that allows water to flow through a canal under a road or other infrastructure. Culverts are commonly used when a canal needs to cross under a road or railway. They are smaller than aqueducts and inverted siphons and are designed to maintain the water flow while allowing other activities to continue without disruption.
Conclusion
Canal structures are vital components of any irrigation system, helping manage water flow, prevent erosion, and allow the canal to cross other infrastructure. Water control structures like check gates, turnouts, siphons, and division boxes ensure that water is properly distributed to where it’s needed. Erosion control structures, such as open drop and pipe drop structures, protect canal banks from damage caused by fast-moving water. Channel crossing structures, including aqueducts, inverted siphons, and culverts, ensure that roads and other infrastructure can coexist with irrigation systems without disrupting the water flow.
Each of these canal structures serves a specific purpose, making sure that water is efficiently managed, safely carried, and used where it’s needed most. By combining these structures, irrigation systems can function smoothly, benefiting both farmers and the surrounding environment.
Frequently Asked Questions (FAQ)
How do check gates work?
Check gates are used to control the flow of water in a canal by raising or lowering the water level. They can temporarily block or divert water, helping to manage the water supply and maintain consistent flow in different parts of the irrigation system.
What are open drop structures used for?
An open drop structure is used to reduce the speed of water flowing in a canal and prevent it from eroding the banks. Water flows down a series of steps or terraces, which gradually slow it down, helping to dissipate the energy of the flow and protect the canal’s integrity.
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