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You are watching: Which is characteristic of low head dams?

On a flow there have the right to be numerous dangers. Part are much easier to pick out 보다 others. One the many world overlook are low-head dams. In fact, ask the average human being what a low-head dam is and also they will have no idea.

Let’s take a look at what precisely a low-head dam is. Additionally how recirculating currents are developed by them. And finally just how you can see safely navigate a river near them.

What is a Low-Head Dam?

Low-head dams are also called weirs. Like any kind of dam they are meant to change the flow of water in a river. But unlike something favor a huge hydroelectric one, a low-head dam is much smaller. Often they look prefer concrete barriers that expectations a flow from shoreline to shoreline. They space designed to raise the water level upstream in a river.

A low-head dam may exist because that any variety of reasons. They can assist in the generation of hydroelectricity. They can additionally assist navigating for boats. Despite the handy purposes of part low-head dams, over there are additionally dangers.

Why is a Low-Head Dam Dangerous?


There room hundreds if not thousands of low-head dams throughout America. Numerous of this dams date ago over 100 years. Castle were often designed to help power generation in factories. This dams command the flow of water to revolve wheels, for instance. That consequently could allow a mill or other organization to run.

As technology evolved, low-head dams ended up being less necessary. While bigger dams room maintained, low-head dams are frequently ignored. Due to the fact that of their tiny size, lock can conveniently fall right into disrepair. A failing dam is no going to flood a valley or town like a hydropower dam or various other types.

Unfortunately these are safety hazards. They reason what is referred to as a subcritical circulation upstream. That means before the dam the water is slow and also deep follow me the face. After ~ the autumn on the ago side it becomes supercritical. That way it considerably picks up speed.


When the fast present in rivers hits another slow present it can be dangerous. A recirculating existing is formed. Something referred to as a backwash or hydraulic run is present. Water rushes end the top. Yet then other water rushes earlier to fill the depression it creates after the drop. That area is a safety hazard for swimmers or boaters. That is turbulent and also quick moving. That rotates and also can conveniently pull little boats or swimmers under if the current is quick enough. The backwash/hydraulic jump renders unpredictable currents. This is where most victims lose their lives.

Additionally, the upstream side presents a risk. The water passing it is accelerating. Relying on how the dam to be formed, a human being or watercraft could be pinned against the upstream challenge of the waterway. This days, through the variety of damaged and also failing dams, this risk is even much more prevalent.

Low-head dams are often clogged as well. Debris, branches, and other objects deserve to collect top top the structure. If you get trapped close to one, you and also your boat can it is in damaged. Plenty of times stronger, heavier debris will certainly be trapped listed below the surface. This might include steel and also rock.

Just how Dangerous is a Low-Head Dam?


These are major hazard locations as environmental engineer Bruce Tschantz clues out. He defines a low-head dam together a drowning an equipment in rivers and streams. They have actually caused numerous deaths. An ext than any kind of other sort of dam.

Often a these deserve to look innocent when water levels are low. In fact, they often make because that appealing swimming and fishing spots. However when water level rise, backwash existing increases drastically.A low head dam can often be hard to watch from upstream. Downstream they regularly look calm and innocent. The is the reason they have proven to be so dangerous.Because that the rate of the water present, the will generally be really cold. That have the right to increase hazard of hypothermia have to you get trapped.These structures generally span whole river. That eliminates the opportunity for any safe haven choose you can find in organic rapids.

How to stay Safe

Ideally friend will watch signage near one. They should be significant to assist people protect against danger. If you are in a boat, like a kayak, it is finest to portage around the dam. Navigating is as well risky. Make sure you have actually a flotation device.

If the area is not plainly marked the structures might not be in a state of good repair. If it is neglected the risks could be many. And also unpredictable. If you uncover one through no warning indicators or rules, it is in wary. It’s best to stop this area altogether simply to it is in safe.

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The flow conditions near a low-head dam room too unpredictable. What might be trapped listed below the surface ar will be completely unknown. Because that those reasons, any kind of time girlfriend swim, fish or watercraft near one you are at risk. Choose a spot more downstream or upstream to be safe.