Types of Spillway Gates

20 Mar Types Of Spillway Gates

Posted at 02:36h in Dam, Gates, Resources by Matt Hannah

A spillway gate is also referred to as a stop gate. These are adjustable gates which can control the water flow of rivers, streams and reservoirs. Therefore, they act as a type of barrier as well for storage of additional water too. They help to pass water safely and in a controlled way around, over and through a dam when there is an excess of water. Let review different types of spillway gates and uses.

There are several types of spillway gates, each serving a specific purpose for dams. In this article, we will see what a spillway gate is and how they work.

How Do Spillway Gates Work?

Spillway gates are used to control the amount of water that enters into the reservoir or river. This is done by controlling the size of the opening between the gate and the reservoir. The smaller the opening, the more water will enter the reservoir. When the gate is closed, it creates a wall between the reservoir and the river. The larger the opening, the less water will enter the reservoir from the river.

With different types of spillway gates, each have its own function. There are three main ways that spillway gates work: gravity, hydraulics, and mechanical. Gravity-based spillway gates rely on the force of gravity to move them. Hydraulic-based spillway gates use hydraulic power to move them. Mechanical-based spillway gates are powered by motors.

Gravity-Based Spillway Gates

These types of gates are based on the principle of gravity. Gravity dams have a particular function. The weight of the gate causes it to fall. When the gate falls, it opens the gap between the upstream part and the downstream part. Once the gap is opened, water can flow freely between the upstream part and downstream part.

Hydraulic-Based Spillway Gate

These types of gates use hydraulic power to open and close them. The hydraulic system consists of two chambers separated by a diaphragm. One chamber contains air while the other contains water. When the valve is closed, the air fills the water chamber. This creates an air bubble which pushes down on the diaphragm. This forces the diaphragm to rise up and open the valve. When the valve is opened, the air bubbles escape out of the water chamber. This causes the diaphragm’s downward push to stop. This closes the valve again.

Mechanical-Based Spillway Gateway

These types of gates operate with motors. The motor moves the gate back and forth. When the gate is fully closed, the motor stops moving. When the gate is completely open, the motor starts moving again.

Different Types Of Spillway Gates

There are a range of different spillway gates that you may come across. Here at Gracon’s, we have vast experience with working with all of these different types of gates.

Sluice Gate

The most common type of spillway gate is a sluice gate. It consists of two parts: an upstream part and a downstream part. Both parts are connected with each other via a hinge. The upstream part has a small hole on its top edge. Water flows through the hole and down into the downstream part. The downstream part has a large hole at the bottom edge. Water then flows out of the downstream part and into the reservoir. If you want to open the gate, you need to lift the upstream part so that it releases the water. Then you can lower the downstream part so that it closes the gap between the upstream and downstream part.

Slide Gate

Another kind of spillway gate is called a slide gate. It works similar to a sluice gate, but instead of having a hole on the top edge of the upstream part, it has a slot. You can see the difference below:

The advantage of a slide gate is that it does not require any lifting mechanism. All you need to do is slide the upstream part along the downstream part until it reaches the desired position.

Crest Gate

With a crest gate, they use a bottom hinge flap, which is used to control the water levels. This is a much more compact design, with the gate being built on a fixed axis.

These are typically hydraulically operated, which makes the gates open when there are power issues or flooding. This type of gate will open and close with the hinges of this gate rotating. Making this gate the ideal option when you also need bees to pass other materials such as ice downstream.

Radial Gate

This type of gate is positioned at the top of a dam, which increases the overall water and reservoir captivity of the dam. With this gate, the aim is to maintain the right water levels. The gate can be opened or closed with very little effort. As the pressure transfers from the curved face of the gate through to the support beams and into the curved arms, which provides much better resistance.

Miter Gate

The miter gate is also referred to as the canal lock or lock gates. As they are made with two leaves that offer closure at the one end of the lock which then forms an angle that is pointing up the stream. These are used to block the entrance and exit of the lock, which allows water to flow through.

These gates help the water levels go up or down in the lock. They are still commonly used in waterways or canals today.

Drum Gate

A drum gate is a hollow structure which is seen floating on the water. It can rotate up or down and is hinged to the top of a dam in a horizontal cylinder. This cylinder can then be raised to allow more water to enter.

These gates are perfect when you want to precisely control the water levels of your reservoir.

What Are Spillway Gates Used For?

With different types of spillway gates, what are they used for? Spillway Gates are used for many purposes. Some examples include:

To prevent flooding in reservoirs – flooding occurs when the level of water rises above the height of the dam. Dam operators use spillway gates to prevent this.
Regulating water levels – when dams are built near cities, it is important to keep the water levels low enough so that people don’t get hurt if the dam breaks.
Protect against erosion – Erosion happens when the soil erodes away because of excessive water pressure. Dams are often built close to rivers and streams. As such, they may cause erosion. An example of this is the Grand Coulee Dam, located in Washington State.
Store excess water – when dams are built, they usually create reservoirs. Reservoirs collect rainwater, snowmelt, and runoff from rivers and streams. However, sometimes these reservoirs regulate the amount of water coming into the city.
Releasing water – when a dam is being repaired or rebuilt, the operator may decide to release some water stored behind the dam.
Protects against erosion – sometimes dams are located in areas where there is a lot of soil movement. If the dam were to break, the soil would erode away. By using a spill gate, the operator can reduce the amount of soil movement.
Control the flow of water – there might be times when the dam operator wants to change the direction of the water flow. He/She can do this by using a spillway gate. The gate allows him/her to direct the water towards it. In order to release some water, spillway gates are used.

Additionally, when dams are built near lakes, it’s important to make sure that the lake doesn’t overflow. This could damage the surrounding land. With spillway gates, the operator can regulate how much water goes where.

Why Is Maintenance Key For Spillway Operations?

Spillways play an important role in maintaining safe drinking water. They help prevent flooding and protect property. However, if spillways are not maintained properly, they could become ineffective. This would result in serious consequences. Below are some examples of how poorly maintained spillways can harm society. Different types of spillways gates can protect against these issues if maintained properly:

Flooding

Flooding occurs when the spillway doesn’t work correctly. If the spillway becomes blocked, then the water cannot drain away. This results in flooding. Flooding can damage houses and other structures. It can also kill animals and plants.

Property Damage

Damaging property is another problem caused by floodwaters. Damaged property can mean higher repair costs. It can also mean that insurance companies won’t cover your losses.

If you own a business, then you know how much money you spend every year on repairs. Damaging property can cost you more than just money. It can also hurt your reputation. Your customers will think less of you if you let them down.

Environmental Impact

Damaging property can lead to environmental problems. For example, if the spillway is leaking into rivers, this can pollute those areas. It can also contaminate soil and groundwater.

Health Issues

When the spillway leaks, it can release dangerous chemicals. These chemicals can enter our bodies through our skin or lungs. Some of these chemicals can cause cancer. Others can affect our nervous systems.

Safety Issues

Damaging property can make the spillway unsafe. A damaged spillway may fail at any time. This can put people in danger.