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Which is characteristic of low head dams?
Low head dams are usually built to impound water for irrigation, domestic water supply, or hydropower generation. They are typically small in height (usually less than 15 meters), and have a small horizontal cross section compared to their height. Low head dams are usually built of concrete or earth-fill, and may have spillways (chutes or weirs) to dissipate energy and prevent overtopping.
Low head dams are often considered to be "unsafe" because of the potential for dangerous hydraulic jumps to occur at the base of the dam. A hydraulic jump is a sudden change in water surface elevation that can occur when water flows over a constriction, such as a dam. The energy of the flowing water is transferred to the water surface, causing it to "jump" up. This can create a dangerous situation for swimmers and boaters, as the water can become turbulent and even dangerous waves can form.
Despite the potential danger, low head dams serve an important purpose in many parts of the world. They are often the only means of impounding water in a given area, and can provide a vital water source for irrigation, domestic use, and hydropower generation. In areas where low head dams are common, it is important to be aware of the dangers they pose and to take precautions when swimming or boating in the vicinity of a dam.
What is the typical height of a low head dam?
A low head dam is typically between 2 and 4 feet high. Lower dams are usually less than 2 feet high and are used to create small impoundments or ponds. Dams 4 feet high and higher are typically used for storage reservoirs or to impound larger bodies of water.
What is the typical width of a low head dam?
A low head dam is typically between three and six feet wide. The average low head dam is about four feet wide.
What is the typical length of a low head dam?
A low head dam is typically between six and twelve feet tall. The height of a low head dam is usually based on the height of the upstream waterway and the size of the culvert or pipe that drains water from the upstream river. The dam is built with a sloped face on the upstream side and a vertical face on the downstream side. The sloped face is called the spillway. The vertical face is called the abutment.
Low head dams are usually made of concrete or stone. The weight of the material and the size of the spillway help to hold the dam in place. The dam is usually built in the shape of a U with the arms of the U pointing upstream. The arms of the U help to slow the water down as it flows over the spillway.
Low head dams are designed to control the flow of water in a stream or river. They are often used to divert water for irrigation, generate electricity, or prevent flooding. Low head dams can also be used to create ponds or lakes for recreation or water storage.
What is the typical water depth above a low head dam?
A typical water depth above a low head dam is about 10 feet. The depth may vary depending on the dam design and the specific site conditions. Low head dams are usually designed to have a water depth of at least 5 feet above the dam crest.
What is the typical water depth below a low head dam?
A low head dam is defined as a dam with a height of less than 15 feet (4.6 meters) from the crest of the dam to the average natural elevation of the upstream river bed (Law Engineering, 2013). Low head dams are often used for irrigation, hydroelectric power, and water supply (Law Engineering, 2013). The typical water depth below a low head dam varies depending on the purpose of the dam and the size of the dam.
If the low head dam is used for irrigation, the water depth below the dam will be shallow, typically between 1 and 3 feet (0.3 to 0.9 meters) (DamSafety, 2012). This shallow water depth is necessary so that the water can be easily diverted into canals or ditches for irrigation purposes.
If the low head dam is used for hydroelectric power, the water depth below the dam will be deeper, typically between 20 and 40 feet (6 to 12 meters) (DamSafety, 2012). This deeper water depth is necessary to generate the high water pressure required for hydroelectric power.
If the low head dam is used for water supply, the water depth below the dam will depend on the needs of the community that the dam is supplying water to. If the community needs a large volume of water, the water depth below the dam will be shallow, typically between 1 and 3 feet (0.3 to 0.9 meters) (DamSafety, 2012). If the community needs a smaller volume of water, the water depth below the dam will be deeper, typically between 20 and 40 feet (6 to 12 meters) (DamSafety, 2012).
The typical water depth below a low head dam varies depending on the purpose of the dam and the size of the dam. Low head dams are often used for irrigation, hydroelectric power, and water supply.
References:
DamSafety. (2012). Low Head Dams. Retrieved from http://www.damsafety.org/safety-topics/low-head-dams/
Law Engineering. (2013). Low Head Dam. Retrieved from https://www.lawengineering.com/glossary/low-head-dam/
What is the typical water flow rate over a low head dam?
The typical water flow rate over a low head dam is governed by the height of the dam, the width of the dam, and the type of dam. The height of the dam is the primary factor in determining the water flow rate. The taller the dam, the greater the water flow rate. The width of the dam is also a factor, but it is not as significant as the height of the dam. The type of dam also affects the water flow rate. Gravity dams, for example, have a higher water flow rate than earth dams.
The water flow rate over a low head dam is also affected by the amount of rainfall in the area. If there has been a lot of rainfall, the water flow rate will be higher. If there has been a drought, the water flow rate will be lower.
The water flow rate over a low head dam can be affected by the release of water from the reservoir. If the reservoir is full, the water flow rate will be higher. If the reservoir is empty, the water flow rate will be lower.
The water flow rate over a low head dam can also be affected by the operations of the dam. If the dam is being used to generate electricity, the water flow rate will be higher. If the dam is not being used to generate electricity, the water flow rate will be lower.
What is the typical water flow rate under a low head dam?
A typical water flow rate under a low head dam is typically between 0.5 and 1.0 feet per second. The head is the difference in elevation between the water surface upstream of the dam and the water surface downstream of the dam. Dam operators can control the water flow rate by varying the amount of water released from the upstream reservoir.
Low head dams are used to impound water for a variety of purposes, including irrigation, hydroelectric power generation, flood control, and water supply. Low head dams are typically less than 50 feet tall and have a water surface length of 1,000 feet or less.
The benefits of low head dams include their relatively low cost to construct and operate, and their ability to impound large volumes of water. In addition, low head dams typically have a smaller environmental footprint than taller dams.
The main disadvantages of low head dams are their potential for failure and the resulting downstream flooding, and their potential to trap and drown people and animals. Low head dams have been responsible for a significant number of deaths in the United States. As such, they are often referred to as "drowning machines."
If you are considering swimming near a low head dam, it is important to understand the risks. The water flowing over a low head dam can create a strong undertow that can drag you under the water and hold you there. The best way to stay safe is to stay out of the water within 200 feet of a low head dam.
What is the typical water pressure at the base of a low head dam?
A low head dam is typically defined as a dam between six and fifteen feet in height. The base of the dam is typically where the water pressure is the highest. The water pressure at the base of a low head dam can be determined by the height of the dam, the width of the dam, and the depth of the water. The following formula can be used to determine the water pressure at the base of a low head dam:
P = 0.433 * H * W * D
P is the water pressure in pounds per square inch, H is the height of the dam in feet, W is the width of the dam in feet, and D is the depth of the water in feet.
Using the formula, the water pressure at the base of a low head dam that is six feet tall and fifteen feet wide would be approximately 61.995 pounds per square inch. The water pressure at the base of a low head dam that is fifteen feet tall and thirty feet wide would be approximately 368.925 pounds per square inch.
It is important to note that the water pressure at the base of a low head dam can vary depending on the specific conditions of the dam. The formula is only meant to give a general idea of the water pressure that can be expected at the base of a low head dam.
What is the typical water pressure at the top of a low head dam?
A low head dam is typically a small dam that is used to impound water for a short distance above the dam. The water pressure at the top of the dam is typically very low, because the water is only held back by the weight of the water behind the dam. The typical water pressure at the top of a low head dam is only a few pounds per square inch, which is much lower than the water pressure at the bottom of the dam.
Frequently Asked Questions
Why are low headed dams dangerous Quizlet?
A low head dam is a type of dam that has lower gates than other types of dams. This makes it easier for water to flow over the dam, and it poses less of a danger to people if they are nearby. However, low-headed dams can still be dangerous if the water movement at their base is powerful enough to pull people under.
What is the nickname of low head dam?
'Drowning machines.'
How does a dam affect a boat?
A dam can greatly affect a boat by altering the river's flow and water temperature. The height and width of the dam, as well as its location, all affect these factors. When the flow of the river is changed, so too is the speed and direction of the current running beneath it. Dams also trap cold water within their barriers, resulting in warmer water below the dam. This change can lead to rapid changes in water temperature and may be hazardous to boaters swimming or surfing near a dam.
What is the difference between high head and medium head dams?
High head dams are typically taller than medium head dams, as the water source can be higher up in the mountains. The penstock on a high head dam is also slightly longer due to the greater elevation drop. This type of dam relies both on a significant volume of water flowing and a significant drop in height of the water.
What is the maximum height of a hydropower dam?
The maximum height of a hydropower dam is usually considered to be the crest of the embankment or archway, whichever is higher.
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