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Dams
A barrier constructed across a waterway to control the flow or raise the level of water.
1,255 Questions
What are the good and bad effects of building dams to run hydroeletric power plants?
Dams in general cutoff the free flow of water and instead store it so it can be allowed to flow as needed. Some fish species navigate and make use of rivers and streams and go there to spawn. A dam either cuts off or impairs the path on the original waterway, so fewer fish can go upstream to spawn.
Would the water from Hoover Dam reach Las Vegas if it went down?
In the event of such a disaster, the water would gush downstream. That would cause widespread loss of life and property, but Las Vegas is not in the path and would not be directly affected.
Where is the Mangla Dam located?
The Mangla Dam, as of 2010 the 6th largest dam in the world, is on the Jhelum River in Azad Kashmir, Pakistan (part of the disputed Kashmir region controlled by Pakistan). It is approximately 100 km (62 mi) SE of Islamabad.
Why are smaller dams better than bigger dams?
The answer there is more pressure on smaller dams which creates MORE electricity.
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Sorry but that makes no sense. The electricity generated depends on rate of flow and head available, not on dam size. In fact the higher the dam the greater the head (depth hence water-pressure at the turbine), though this can be increased still further by piping the water to a power-station situated further down the valley instead of at the dam foot.
A more useful advantage of a smaller dam is its smaller environmental effect.
Why are the walls of a dam thickened near the base?
Dams are built broader at the base for two reasons. The first is because it needs to be stable enough to support the dam, and two, the bottom of the dam needs to be able to deal with the increased pressure of the water, as you get further down.
So basically, they're thicker at the bottom mostly for aesthetic reasons, but luckily this also means they're stronger at the bottom which is where the water pressure is greatest - definitely a bonus.
A:Two reasons:- Particular to dams, the lower part of the structure must hold back the lower levels of water, which are at higher pressure than the upper levels of the water. Higher water pressure on the base of the dam needs greater strength to hold it back.
- The base of the dam must support the weight of all the structure above it. Even if it was not a dam, but just a tower (or a pyramid), the lower sections must be stronger, and higher sections can be weaker because there is less weight above them.
What would happen if Hoover Dam broke?
Let's say the Hoover dam broke. This is difficult to imagine, given its thickness. No conventional bomb would have an effect on a dam like this. It is difficult to imagine even a nuclear bomb having an effect, unless it was an extremely powerful one and it were inside the dam at the time of explosion. But let's say that some sort of tremendous earthquake or an asteroid strike or some other natural disaster were to somehow crack it in halves. The first thing that would happen is that 10 trillion gallons of water would move as quickly as it could out of the lake and down the river in a huge tsunami of water. The Hoover dam is located in a desert area that is not hugely inhabited below the dam, but there are still some sizeable populations. Lake Havasu City, population 40,000, is about the biggest town in the United States along the river. Bullhead city, population 30,000 is also close to the dam. Needles, California and Laughlin, Nevada all have populations of around 10,000 people as well. Damages to the dam Where the water would do immense damage is in the lakes below Hoover dam. It turns out that below Hoover dam is another large lake called Lake Mohave, which is held in place by Davis dam, and below that is Lake Havasu, held in place by Parker dam. These are smaller lakes and smaller dams. For example, Lake Havasu only holds about 200 billion gallons of water. As the water released by the Hoover Dam moved through these two lakes, it would likely destroy them and their dams as well. That's where the real impact would be felt, because these lakes affect a huge number of people. The water in them produces hydroelectric power, irrigates farmland and supplies drinking water to cities like Los Angeles, Las Vegas, Phoenix and San Diego. The Hoover dam produces roughly 2,000 megawatts of power. Davis and Parker dams produce less, but together they might all produce 3,000 megawatts. That represents about one half of one percent of the total electrical power produced in the United States. If you eliminated a sizable amount of generating capacity like that, especially in that area of the country (near Los Angeles and Las Vegas, for example), it would definitely cause problems. The destruction of irrigation water supplies would also have a huge effect on farming in the region. Farmers in the Imperial Valley get most of their water from the Colorado River, and these irrigation systems would collapse. Prior to irrigation, the Imperial Valley was a barren desert. Today it is the home of more than half a million acres of farmland and produces more than a billion dollars in fruits and vegetables every year. There would be large effects as well from the loss of drinking water. For example, Las Vegas gets 85 percent of its drinking water from Lake Mead -- the lake behind Hoover dam. With the loss of water and the loss of power, Las Vegas would become uninhabitable, and that would displace 1.5 million residents and empty more than 120,000 hotels rooms and the casinos, bringing the multi-billion-dollar gambling industry in this city to a halt.
Why is it necessary to hold the water back with a dam in order to produce electricity?
it forces the water to flow in the desired direction
Why dams are made wider at the bottom?
Dams must hold back water of a certain depth, determined by the height of the dam. The pressure exerted by this water on the dam is dependent in part by its depth, since the base of the dam must be able to hold pressures exerted by the weight of all the water above the base. Since the pressure is greater at the base, the dam is broader at the base.
How do dams change the flow of a river?
They stop the natural flow of the water and can also cause a greater flow than previously possible by releasing the stored water.
Dams are typically built to retain water. Some manage or prevent water flow into certain areas (dikes). Dams are also built to be used for hydropower/pumped-storage hydroelectricity to provide energy.
What are the advantages and disadvantages for building large dams?
I believe PROS:
· Dams can store rain water or water directly from the river itself. Then, in case of a Drought, the dam will still have a relatively constant supply of water.
· Producing Power.
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o Controls flooding & PROS:
o Dams can store rain water or water directly from the river itself. Then, in case of a Drought, the dam will still have a relatively constant supply of water.
o Producing Power.
o Controls flooding & provides recreational activities such as boating fishing and swimming, if the lake is not being used for drinking water (Dam Society).
o Simple design makes for inexpensive repairs and maintenance costs (Dam Society).
o Produce inexpensive (after completion) and clean power.
o Renewable energy source, because the water is not destroyed by passing through the dam.
o If needed, dams can be shut down instantly, where thermal plants take hours, and nuclear plants can take days! (Dam Society).
o Very few breakdowns.
o provides recreational activities such as boating fishing and swimming, if the lake is not being used for drinking water (Dam Society).
· Simple design makes for inexpensive repairs and maintenance costs (Dam Society).
· Produce inexpensive (after completion) and clean power.
· Renewable energy source, because the water is not destroyed by passing through the dam.
· If needed, dams can be shut down instantly, where thermal plants take hours, and nuclear plants can take days! (Dam Society).
· Very few breakdowns.
CONS:
· Hydroelectric power production require flooding of entire valleys and scenic areas.
· Disrupts natural seasonal changes in he river, and ecosystems can be destroyed.
· Ends flooding that help to clean out the silt in rivers, causing them to clog (Energy Laboratory).
· The silt that usually flows down to the Beaches and Estuaries is block by the dam.
· Studies show that the plant decay caused downstream of major dams produces as many greenhouse gasses as more conventional methods of producing electricity.
· Dams are expensive to build, and due to drought may become useless, or produce much less power than originally planned.
· A dam being build in Quebec will end up flooding an area as large as Switzerland (Energy Laboratory).
· Dams can break in a massive flash flood.
· Dams can store
rain water or water directly from the river itself. Then, in case of a Drought, the dam will still have a relatively constant supply of water.
· Producing Power.
Controls flooding & pro
What is the second largest dam in the world?
Actually, the world's second largest dam is in Fort McMurray, Alberta, Canada. The dam holds back approximately 50 square kilometers of tailings from oil sands refining. If this dam were to burst it would cause the total destruction of the local ecosystem, as well as making the surrounding groundwater useless due to the presence of toxic heavy metals, and other known carcinogens.
Why are dams built on fast flowing rivers?
A river may be dammed to provide a reservoir for drinking water, or for producing electricity. A dam could also be built to regulate water flow, hold back water during drought, or slowly release water during heavy rain.
Why are dams built near river?
it is bcoz in a hydroelectric power station, fast flowing water spins the turbines. On a wind farm, the wind turbines spin due to fast wind and in the sea, in the sea, waves and the tide can be used to make a turbine spin.
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