Introduction:
A regulator provided with an under sluice is a hydraulic structure used in channels to control the flow of water and regulate the water level. It is designed to allow the escape of heavy sand-laden bottom water from the channel. The under sluice is an opening or a system of openings located at the bottom of the regulator structure, which allows the discharge of sediment-laden water.

Explanation:
The regulator provided with an under sluice serves the following purposes:

1. Ejection of sediment:
The under sluice allows the heavy sand-laden bottom water to be ejected from the channel. As the water passes through the under sluice opening, the velocity of flow increases, causing the sediment particles to settle out due to reduced flow velocity. This helps in preventing the deposition of sediments in the channel, which can lead to the reduction of flow capacity and increase the risk of flooding.

2. Dispersal of sediment:
The under sluice helps in dispersing the sediment that settles at the bottom of the channel. When the sediment-laden water is discharged through the under sluice, the sediments get carried away and dispersed in the downstream direction. This prevents the accumulation of sediments at one specific location and promotes the natural movement of sediments along the channel.

3. Washout of sediment:
The under sluice facilitates the washout of sediments from the channel. When the water is discharged through the under sluice, it creates a scouring action that helps in removing the deposited sediments from the channel bed. This scouring action is particularly useful in channels where sediment deposition is a common problem.

4. Removal of sediment:
The under sluice allows for the removal of sediment from the channel by discharging the sediment-laden water. The sediment particles settle out due to reduced flow velocity in the under sluice and are carried away from the channel. This helps in maintaining the desired flow capacity of the channel and ensures the efficient functioning of the hydraulic structure.

Conclusion:
In summary, a regulator provided with an under sluice serves as a means to regulate the water level in a channel and allows for the escape of heavy sand-laden bottom water. The under sluice helps in ejecting, dispersing, washing out, and removing the sediment from the channel, thereby preventing sediment deposition and maintaining the flow capacity of the channel.

Ejection