A barrage is a type of dam. Rather than being a tall concrete wall that prevents water from flowing over it, a barrage is a series of gates. When water needs to be diverted rather than stored, a barrage is built. Because of this, a barrage is typically constructed across a river that is flat and moves slowly. A barrage will only raise the level of water by a few feet, as opposed to a dam, which will raise water almost to its height. Since a barrage can make a river deeper by a few feet, this is also helpful for navigation.
Source: Pinterest
Barrage: Difference among dams, weirs and barrages
Source: Pinterest
- A dam is generally categorised as a wall that is built across a water source. Deep water reservoirs that can be used for storing and other purposes are made possible by this method. A weir can function similarly to a dam but serve slightly different purposes.
- The purpose of a weir is to regulate water flow, measure release, prevent flooding, and end up making rivers navigable. Weirs are typically constructed through open channels like rivers. It can also be built from a variety of materials, including timber, concrete, or a combination of boulders, gravel, and rocks.
- The ability to use the water flow in a barrage for various uses, such as irrigation, is a key distinction between a barrage and a dam. Contrarily, the concrete structures that make up dams are typically built to specific heights in order to hold or store water. Usually, one can easily control and manipulate the gates for a barrage.
Given that both are utilised for the following purposes:
- Preventing flooding
- Assisting in the navigation of a river
- Determining discharge
When contrasting these various components, it’s also important to take into account the various types of barrage structures.
Barrage: Types
A barrage is made up of various parts, like shutters or gates, that serve the following purposes:
- Uphold the pond’s level
- Increase water levels when supplies are low
When water overflows, shutters may be lowered. On the other hand, a gated weir can assist construction sites in raising gates during floods.
The various gate types for a barrage serve various purposes.
Fish ladder
Fish can navigate obstacles by swimming and leaping up a series of low steps in a structure known as a fish ladder, also known as a fishway or fish pass. The goal is to manage water flow so that fish are drawn to the ladder but to reduce water flow just enough to prevent washing fish downstream. Additionally, there are various kinds of fish ladders, including:
- Pool and strange
- Confusing fishway
- Lift fish (or elevator)
- Rocky fishway
- V-shaped fish passage
- Fish snorter
- Fishing gun
Different kinds of fish ladders are advantageous to various fish species. Fish migrate from upstream to downstream in search of warmer waters or clearer waters prior to monsoon season, making this barrage component crucial.
Sheet piles
To lower uplift pressure and prevent piping, sheet piles are placed both upstream and downstream of a barrage. While the groundwater sheet pile is better at reducing piping, the upstream sheet pile is better at reducing uplift. Sheet piles serve as protection for the water structure and relief for the barrage.
A weir has water flowing underneath it all the time. When the hydraulic gradient is too high, soil particles start to be moved around and carried away. Unfortunately, if the floor continues to erode, a pipe or funnel will form and the weir may fail.
Inverted filter
Components of the barrage that encompass coarse sand and gravel are called inverted filters. Concrete that is heavy enough to keep this filter in place is layered over it. Water can escape through the space between the frames and the filter. This filter’s job is to inspect the soil fragments that leak into the water during seepage. It also aids in resolving problems brought on by scouring.
Barrage: Various design types
A barrage’s functionality as a whole is determined by the various parts that make it up. There are a number of considerations that should be taken into account when building a barrage, such as:
- Overall river bed flow
- Geology of the region rules
- Conceivable floating debris in floods
- The population of fish and the ecosystem
Barrages are straight constructions positioned perpendicular to the water’s flow or at an angle to reduce the depth of the water passing over the barrage. There are a few different barrage types or groups to take into account:
- Regulated barrages use controlled sluiceways and gates to maintain a constant water level.
- Unregulated barrages do not control the level of the water upstream.
There are various barrage structures and design types within each of these categories. An uncontrolled barrage, for instance, might have components like a main spillway, an environmental flow shutoff valve, an upstream tank, sand and gravel traps, etc.
A barrage is a type of dam that has numerous large gates that regulate the flow of water, though there are a few important distinctions. Every type of barrage contributes to addressing unique aspects of the river where it operates. For dam projects, these robotic structures are crucial because they can establish water profiles and maintain upstream water levels.
FAQs
What variables affect the design of a barrage?
The width of a barrage is governed by three factors: design flood, lacey design width, and looseness factor. It is generally believed that the shoal forming upstream can be removed by restricting the waterway.
How is a barrage built?
Several large entrances that can be shut or opened to limit the amount of water passing through make up a barrage, a type of low-head, diversion dam. As a result, the structure can control and maintain the elevation of the river upstream for use in irrigated agriculture and other systems.
| Got any questions or point of view on our article? We would love to hear from you.
Write to our Editor-in-Chief Jhumur Ghosh at jhumur.ghosh1@housing.com |