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Jesse Moore, Chief Executive Officer and Co-Founder, M-KOPA Solar, Kenya at the World Economic Forum on Africa 2017 in Durban, South Africa. Copyright by World Economic Forum / Jakob Polacsek
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Easy Ways To Lose Weight, Best Food To Lose Weight, Ways To Lose Weight In A Week, I Lose Weight
3 TOP Fat Burning Breakfast Foods (add to your diet)
Three of my favorite foods to eat in the morning are…
Fat Burning Breakfast Food #3: Whole Eggs
Eggs contain lean protein, friendly fats, B vitamins like choline for your heart and brain—and naturally occurring antioxidants that benefit your eyes.
One study even found that, compared to those who eat bagels, people who eat two eggs for breakfast lose 65 percent more weight and have higher
energy levels.
TIP: I recommend 2-3 whole eggs over-easy cooked in real olive oil or with fat burning breakfast food #2…
Fat Burning Breakfast Food #2: Coconut Oil
The Journal of Nutrition published a study where they had researchers investigate all studies relative to medium chain fatty acids (MCFAs) that are abundant in coconut fat.
All the studies showed that diets rich in fats, such as those found in coconut oil, prompted a plethora of benefits including:
- Boost in metabolism - Increase in energy
- Decrease in food consumption - Reduced body weight and lower body fat mass
TIP: I add a tablespoon to my coffee at least 5 or 6 days of the week.
Fat Burning Breakfast Food #1: Kefir
Kefir is getting a ton of attention in the nutrition world these days because it’s like a MUCH healthier version of yogurt from the high amounts of probiotics.
A six ounce serving of milk kefir contains 6 grams of protein, along with a healthy dose of calcium, B12, B2 (Riboflavin), phosphorus, magnesium, and even a little bit of vitamin D.
Kefir has also been shown to improve digestion, aid in weight management and mental health, which makes it one of the healthiest breakfast foods you can consume (even though it’s technically a liquid).
TIP: I like using it in my protein shakes as a replacement for milk.
As you’ll notice, I didn’t recommend any higher carb foods for breakfast because, in most cases, they can make you tired and “turn on” your fat storing hormones.
In fact, I would argue that’s it’s not your food choices that are holding you back… it’s WHEN you’re eating certain diet foods that makes all the difference.
This brand new concept of eating at the link below explains how you can avoid this to create enjoyable, consistent fat loss:
New concept of eating anything you have EVER tried before.
Notice - SKAM does not endorse the killing of oneself or others. SKAM endorses an open communication about the damage humans have done to our planet.
The Recycle Yourself Project is meant to invoke an emotion and discussion about such issues as Overpopulation, Pollution, Ecosystem Destruction Humans responsibility to the Environment, Culture Jamming, Art intervention and Anti-Commercialism/over-consumption.
The Recycle Yourself Philosophy
For billions of years the earth has recycled the life that has existed on it. Through a natural cycle. At one time the Human race followed that natural cycle. The humans lived hand and hand with the environment taking and giving back to the land. Even after death humans at one time gave their actual bodies back to the planet to decay in a natural way. Over time mankind has forgotten about our beautiful planet and how it created the life that exists on it. Then comes the age of the industrial revolution and corporations built upon mass consumerism. Marketing companies assault us ever day. By the time you are 5 years old you've already had 200,000 images planted into your brain from television and ad campaigns. This false reality is built and constructed into our minds to appear that if its sold on tv there is an unlimited supply. Buy buy buy this constructed ads tell us that there is nothing wrong with this behavior. The status quo is a false reality.
The real reality
Humans have already started what will be known as the 6th mass extinction on our planet. This has been created by the abuse we've done in the last 300 years to our mother earth. The western mindset has infected the entire planet. Kill, rape and pillage, give nothing back. Even in death humans turn themselves in plastic wrapped corspe's that seep poisons into the ground that in turn effect our drinking water. Cancer, disease, and viruses are a by-product of our planet trying to control this over consumerism culture. Mother earth will win this war in the end but it will be at the expense of all forms of life on our planet. Education is the only thing that will change this behavior. If you want to climb the mountain you don't just jump to the top. This change needs to happen in steps. The first is being aware of such steps. If humans so selfishly ignore these warning signs. Some day there will be no fish in the sea, no birds in the sky, no whales in the ocean, no dogs to follow their masters, no flowers to bloom, no bees to pollinate them. This is a reality.
Now you have to ask yourself?
Do you want to be responsible for a dead planet?
Educate
Reduce
Reuse
Recycle Yourself!
Image Courtesy: Joi Ito (www.flickr.com/photos/joi/1465307343), Licensed under the Creative Commons Attribution 2.0 Generic | Flickr
Dieser Stand schafft es, Bücher noch teurer als im Antiquariat zu verkaufen...den Touristen sei Dank!
This image is excerpted from a U.S. GAO report:
www.gao.gov/products/GAO-16-644
BULK FUEL: Actions Needed to Improve DOD's Fuel Consumption Budget Data
Nothing to do with tuberculosis, consumption means here to consume; in other words this massive field dyke (wall) is composed of stone taken from surrounding parks (fields). Partially done in the 1850s, a moment in what is generally known as agricultural improvement but more exactly was the deepening of the cash economy, capitalism in Aberdeenshire agriculture. The dyke is over 500 yards long and 33 feet wide with a paved way along its length and at breaks dressed stone steps. The manual labour that went into its years of construction was immense giving some idea of the work required to tame much of the agricultural land of Aberdeenshire.
Participants at the World Economic Forum - Annual Meeting of the New Champions in Dalian, People's Republic of China 2015. Copyright by World Economic Forum / Greg Beadle
I was hoping to get a clearer foreground, but the volume of human traffic was such that there was a constant flow into the front of the shot. That I had to take this while standing one-footed on a post which kept the road pedestrianised probably didn't help...
A new study finds girls who drink 1.5 servings or more of sugary drinks each day may start menstruation earlier than those who consume less than two servings a week.
healthnews.juicyworldnews.com/uncategorized/medical-news-...
age, consumption, drinks, girls, menstruation
Mercedes SLS AMG Coupe Electric Drive
With the new Mercedes-Benz SLS AMG Coupé Electric Drive, Mercedes-AMG is entering a new era: the locally emission-free super sports car featuring advanced technology from the world of Formula 1 is the most exclusive and dynamic way in which to drive an electric car. The most powerful AMG high-performance vehicle of all time has four electric motors producing a total output of 552 kW and a maximum torque of 1000 Nm. As a result, the gullwing model has become the world's fastest electrically-powered series production vehicle: the Mercedes-Benz SLS AMG Coupé Electric Drive accelerates from zero to 100 km/h in 3.9 seconds.
A new dimension of driving performance - a convincing synonym for the AMG brand promise are the outstanding driving dynamics which come courtesy of AMG Torque Dynamics as well as torque distribution to individual wheels, which is made possible by means of wheel-selective all-wheel drive. The most "electrifying" gullwing model ever has been developed in-house by Mercedes-AMG GmbH. The high-voltage battery for the SLS AMG Coupé Electric Drive is the result of cooperation between Mercedes-AMG and Mercedes AMG High Performance Powertrains in Brixworth (GB). This is an area in which the British Formula 1 experts were able to contribute their extensive know-how with KERS hybrid concepts.
"The SLS AMG Coupé Electric Drive is setting new standards for cars with electric drives. As the most powerful gullwing model ever, it is also representative of the enduring innovational strength of Mercedes-AMG. Our vision of the most dynamic electric vehicle has become a reality. With the help of our colleagues at Mercedes AMG High Performance Powertrains in Brixworth, we are bringing exciting advanced technology from the world of Formula 1 to the road", according to Ola Källenius, Chairman of the Board of Management of Mercedes-AMG GmbH.
Mercedes SLS AMG Coupe Electric Drive (2014)
2014 Mercedes-Benz SLS AMG Coupe Electric Drive
Pioneering, visionary, electrifying: the powerful and locally emission-free super sports car with electric drive also embodies the development competence of Mercedes-AMG GmbH. With this innovative and unique drive solution, AMG - as the performance brand of Mercedes-Benz - is demonstrating its technological leadership in this segment. The Mercedes-Benz SLS AMG Coupé Electric Drive is aimed at technology-minded super sports car fans who are open to new ideas and enthusiastic about ambitious high-tech solutions for the future of motoring.
Enormous thrust thanks to 1000 Nm of torque
The pioneering drive package in the SLS AMG Coupé Electric Drive is impressive and guarantees a completely innovative and electrifying driving experience: enormous thrust comes courtesy of four synchronous electric motors providing a combined maximum output of 552 kW and maximum torque of 1000 Nm. The very special gullwing model accelerates from zero to 100 km/h in 3.9 seconds, and can reach a top speed of 250 km/h (electronically limited). The agile response to accelerator pedal input and the linear power output provide pure excitement: unlike with a combustion engine, the build-up of torque is instantaneous with electric motors - maximum torque is effectively available from a standstill. The spontaneous build-up of torque and the forceful power delivery without any interruption of tractive power are combined with completely vibration-free engine running characteristics.
The four compact permanent-magnet synchronous electric motors, each weighing 45 kg, achieve a maximum individual speed of 13,000 rpm and in each case drive the 4 wheels selectively via a axially-arranged transmission design. This enables the unique distribution of torque to individual wheels, which would normally only be possible with wheel hub motors which have the disadvantage of generating considerable unsprung masses.
Powerful, voluminous, dynamic, emotional and authentic: the characteristic sound of the Mercedes-Benz SLS AMG Coupé Electric Drive embodies the sound of the 21st century. After an elaborate series of tests as well as numerous test drives, the AMG experts have created a sound which captures the exceptional dynamism of this unique super sports car with electric drive. Starting with a characteristic start-up sound, which rings out on pressing the "Power" button on the AMG DRIVE UNIT, the occupants can experience a tailor-made driving sound for each driving situation: incredibly dynamic when accelerating, subdued when cruising and as equally characteristic during recuperation. The sound is not only dependent on road speed, engine speed and load conditions, but also reflects the driving situation and the vehicle's operating state with a suitable driving noise. Perfect feedback for the driver is guaranteed thanks to a combination of the composed sound, the use of the vehicle's existing inherent noises and the elimination of background noise - this is referred to by the experts as "sound cleaning". The impressive sound comes courtesy of the standard sound system with eleven loudspeakers.
Advanced Formula 1 technology: high-voltage lithium-ion battery
Battery efficiency, performance and weight: in all three areas Mercedes-AMG is setting new standards. The high-voltage battery in the SLS AMG Coupé Electric Drive boasts an energy content of 60 kWh, an electric load potential of 600 kW and weighs 548 kg - all of which are absolute best values in the automotive sector. The liquid-cooled lithium-ion high-voltage battery features a modular design and a maximum voltage of 400 V.
Advanced technology and know-how from the world of Formula 1 have been called on during both the development and production stages: the battery is the first result of the cooperation between Mercedes-AMG GmbH in Affalterbach and Mercedes AMG High Performance Powertrains Ltd. Headquartered in Brixworth in England, the company has been working closely with Mercedes-AMG for a number of years. F1 engine experts have benefited from its extensive expertise with the KERS hybrid concept, which made its debut in the 2009 Formula 1 season. At the Hungarian Grand Prix in 2009, Lewis Hamilton achieved the first historic victory for a Formula 1 vehicle featuring KERS hybrid technology in the form of the Mercedes-Benz KER System. Mercedes AMG High Performance Powertrains supplies the Formula 1 teams MERCEDES AMG PETRONAS, Vodafone McLaren Mercedes and Sahara Force India with Mercedes V8 engines and the KERS.
The high-voltage battery consists of 12 modules each comprising 72 lithium-ion cells. This optimised arrangement of a total of 864 cells has benefits not only in terms of best use of the installation space, but also in terms of performance. One technical feature is the intelligent parallel circuit of the individual battery modules - this helps to maximise the safety, reliability and service life of the battery. As in Formula 1, the battery is charged by means of targeted recuperation during deceleration whilst the car is being driven.
High-performance control as well as effective cooling of all components
A high-performance electronic control system converts the direct current from the high-voltage battery into the three-phase alternating current which is required for the synchronous motors and regulates the energy flow for all operating conditions. Two low-temperature cooling circuits ensure that the four electric motors and the power electronics are maintained at an even operating temperature. A separate low-temperature circuit is responsible for cooling the high-voltage lithium-ion battery. In low external temperatures, the battery is quickly brought up to optimum operating temperature with the aid of an electric heating element. In extremely high external temperatures, the cooling circuit for the battery can be additionally boosted with the aid of the air conditioning. This also helps to preserve the overall service life of the battery system.
Quick charge function via special wall box
Ideally the Mercedes-Benz SLS AMG Coupé Electric Drive is charged with the aid of a so-called wall box. Installed in a home garage, this technology provides a 22 kW quick-charge function, which is the same as the charging performance available at a public charging station. A high-voltage power cable is used to connect the vehicle to the wall box, and enables charging to take place in around three hours. Without the wall box, charging takes around 20 hours. The wall box is provided as an optional extra from Mercedes-AMG in cooperation with SPX and KEBA, two suppliers of innovative electric charging infrastructures for the automotive industry.
Eight-stage design for maximum safety
To ensure maximum safety, the SLS AMG Coupé Electric Drive makes use of an eight-stage safety design. This comprises the following features:
•all high-voltage cables are colour-coded in orange to prevent confusion
•comprehensive contact protection for the entire high-voltage system
•the lithium-ion battery is liquid-cooled and accommodated in a high-strength aluminium housing within the carbon-fibre zero-intrusion cell
•conductive separation of the high-voltage and low-voltage networks within the vehicle and integration of an interlock switch
•active and passive discharging of the high-voltage system when the ignition is switched to "off"
•in the event of an accident, the high-voltage system is switched off within fractions of a second
•continuous monitoring of the high-voltage system for short circuits with potential compensation and insulation monitors
•redundant monitoring function for the all-wheel drive system with torque control for individual wheels, via several control units using a variety of software
By using this design, Mercedes-AMG ensures maximum safety during production of the vehicle and also during maintenance and repair work. Of course the Mercedes-Benz SLS AMG Coupé Electric Drive also meets all of the statutory and internal Mercedes crash test requirements.
All-wheel drive with AMG Torque Dynamics enables new levels of freedom
Four motors, four wheels - the intelligent and permanent all-wheel drive of the SLS AMG Coupé Electric Drive guarantees driving dynamics at the highest level, while at the same time providing the best possible active safety. Optimum traction of the four driven wheels is therefore ensured, whatever the weather conditions. According to the developers, the term "Torque Dynamics" refers to individual control of the electric motors, something which enables completely new levels of freedom to be achieved. The AMG Torque Dynamics feature is permanently active and allows for selective distribution of forces for each individual wheel. The intelligent distribution of drive torque greatly benefits driving dynamics, handling, driving safety and ride comfort. Each individual wheel can be both electrically driven and electrically braked, depending on the driving conditions, thus helping to
•optimise the vehicle's cornering properties,
•reduce the tendency to oversteer/understeer,
•increase the yaw damping of the basic vehicle,
•reduce the steering effort and steering angle required,
•increase traction,
•and minimise ESP® and ASR intervention.
The AMG Torque Dynamics feature boasts a great deal of variability and individuality by offering three different transmission modes:
•Comfort (C): comfortable, forgiving driving characteristics
•Sport (S): sporty, balanced driving characteristics
•Sport plus (S+): sporty, agile driving characteristics
AMG Torque Dynamics enables optimum use of the adhesion potential between the tyres and the road surface in all driving conditions. The technology allows maximum levels of freedom and as such optimum use of the critical limits of the vehicle's driving dynamics. Outstanding handling safety is always assured thanks to the two-stage Electronic Stability Program ESP®.
"AMG Lightweight Performance" design strategy
The trailblazing body shell structure of the Mercedes-Benz SLS AMG Coupé Electric Drive is part of the ambitious "AMG Lightweight Performance" design strategy. The battery is located within a carbon-fibre monocoque which forms an integral part of the gullwing model and acts as its "spine". The monocoque housing is firmly bolted and bonded to the aluminium spaceframe body. The fibre composite materials have their roots in the world of Formula 1, among other areas. The advantages of CFRP (carbon-fibre reinforced plastic) were exploited by the Mercedes-AMG engineers in the design of the monocoque. These include their high strength, which makes it possible to create extremely rigid structures in terms of torsion and bending, excellent crash performance and low weight. Carbon-fibre components are up to 50 percent lighter than comparable steel ones, yet retain the same level of stability. Compared with aluminium, the weight saving is still around 30 percent, while the material is considerably thinner. The weight advantages achieved through the carbon-fibre battery monocoque are reflected in the agility of the SLS AMG Coupé Electric Drive and, in conjunction with the wheel-selective four-wheel drive system, ensure true driving enjoyment. The carbon-fibre battery monocoque is, in addition, conceived as a "zero intrusion cell" in order to meet the very highest expectations in terms of crash safety. It protects the battery modules inside the vehicle from deformation or damage in the event of a crash.
The basis for CFRP construction is provided by fine carbon fibres, ten times thinner than a human hair. A length of this innovative fibre reaching from here to the moon would weigh a mere 25 grams. Between 1000 and 24,000 of these fibres are used to form individual strands. Machines then weave and sew them into fibre mats several layers thick, which can be moulded into three-dimensional shapes. When injected with liquid synthetic resin, this hardens to give the desired structure its final shape and stability.
Optimum weight distribution and low centre of gravity
The purely electric drive system was factored into the equation as early as the concept phase when the super sports car was being developed. It is ideally packaged for the integration of the high-performance, zero-emission technology: by way of example, the four electric motors and the two transmissions can be positioned as close to the four wheels as possible and very low down in the vehicle. The same applies to the modular high-voltage battery. Advantages of this solution include the vehicle's low centre of gravity and balanced weight distribution - ideal conditions for optimum handling, which the electrically-powered gullwing model shares with its petrol-driven sister model.
New front axle design with pushrod damper struts
The additional front-wheel drive called for a newly designed front axle: unlike the series production vehicle with AMG V8 engine, which has a double wishbone axle, the SLS AMG Coupé Electric Drive features an independent multi-link suspension with pushrod damper struts. This is because the vertically-arranged damper struts had to make way for the additional drive shafts. As is usual in a wide variety of racing vehicles, horizontal damper struts are now used, which are operated via separate push rods and transfer levers. Thanks to this sophisticated front-axle design, which has already been tried and tested in the world of motorsport, the agility and driving dynamics of the Mercedes-Benz SLS AMG Coupé Electric Drive attain the same high levels as the V8 variant. Another distinguishing feature is the speed-sensitive power steering with rack-and-pinion steering gear: the power assistance is implemented electrohydraulically rather than just hydraulically.
AMG ceramic composite brakes for perfect deceleration
The SLS AMG Coupé Electric Drive is slowed with the aid of AMG high-performance ceramic composite brakes, which boast direct brake response, a precise actuation point and outstanding fade resistance, even in extreme operating conditions. The over-sized discs - measuring 402 x 39 mm at the front and 360 x 32 mm at the rear - are made of carbon fibre-strengthened ceramic, feature an integral design all round and are connected to an aluminium bowl in a radially floating arrangement.
The ceramic brake discs are 40 percent lighter in weight than the conventional, grey cast iron brake discs. The reduction in unsprung masses not only improves handling dynamics and agility, but also ride comfort and tyre grip. The lower rotating masses at the front axle also ensure a more direct steering response - which is particularly noticeable when taking motorway bends at high speed.
Exclusive, high-quality design and appointments
Visually, the multi-award-winning design of the SLS AMG is combined with a number of specific features which are exclusive to the Electric Drive variant. The front apron has a striking carbon-look CFRP front splitter which generates downforce on the front axle. The radiator grille and adjacent air intakes adorn special areas painted in the vehicle colour and with bionic honeycomb-shaped openings. They are not only a visual highlight but, thanks to their aerodynamically optimised design, also improve air flow over the cooling modules mounted behind them. Darkened headlamps also impart a sense of independence to the front section. Viewed from the side, the "Electric Drive" lettering stands out on the vehicle side, as do the AMG 5-twin-spoke light-alloy wheels with their specific paint design. The SLS AMG Electric Drive comes as standard with 265/35 R 19 tyres on the front and 295/30 R 20 tyres on the rear. The overall look is rounded off to dynamic effect by the new diffuser-look rear apron, and the darkened rear lamps. One feature reserved exclusively for the SLS AMG Coupé Electric Drive is the "AMG electricbeam magno" matt paint finish. A choice of five other colours is available at no extra cost.
When the exterior colour AMG electricbeam magno is chosen, the high-quality, sporty interior makes use of this body colour for the contrasting stitching - the stitching co-ordinates perfectly with designo black Exclusive leather appointments. AMG sports seats and numerous carbon-fibre trim elements in the interior underscore the exclusive and dynamic character of what is currently the fastest electric car. Behind the new AMG Performance steering wheel there is a newly designed AMG instrument cluster: instead of a rev counter, there is a power display providing information on the power requirements, recuperation status, transmission modes and battery charge.
AMG Performance Media as standard
The AMG DRIVE UNIT comprises the electronic rotary switch for selecting the three transmission modes of "C" (Controlled Efficiency), "S" (Sport) and "S+" (Sport plus), which the driver can use to specify different performance levels from the electric motors, which in turn also changes the top speed and accelerator pedal response. Behind the buttons for "power" and "ESP On/Off", there are also buttons for AMG Torque Dynamics and AMG Setup.
In addition to carbon-fibre exterior mirrors, AMG carbon-fibre engine compartment cover, COMAND APS, Media Interface, Blind Spot Assist and reversing camera, the standard equipment also includes the AMG Performance Media system. Besides full high-speed mobile internet access, the system provides information on engine performance, lateral and longitudinal acceleration, tyre pressure, vehicle setup and lap times, as well displaying a variety of additional information such as:
•vehicle energy flow
•battery charge status
•burrent range
•AMG Torque Dynamics
•temperatures of the battery and motors
•energy consumption kWh/100 km
The Mercedes-Benz SLS AMG Coupé Electric Drive will be celebrating its market launch in 2013. The price in Germany (incl. 19% VAT) will be 416,500 EUR.
A dam is a barrier that impounds water or underground streams. The reservoirs created by dams not only suppress floods but provide water for various needs to include irrigation, human consumption, industrial use, aquaculture and navigability. Hydropower is often used in conjunction with dams to generate electricity. A dam can also be used to collect water or for storage of water which can be evenly distributed between locations. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees (also known as dikes) are used to manage or prevent water flow into specific land regions.
The word dam can be traced back to Middle English, and before that, from Middle Dutch, as seen in the names of many old cities.
ANCIENT DAMS
Early dam building took place in Mesopotamia and the Middle East. Dams were used to control the water level, for Mesopotamia's weather affected the Tigris and Euphrates rivers, and could be quite unpredictable.
The earliest known dam is the Jawa Dam in Jordan, 100 kilometres northeast of the capital Amman. This gravity dam featured an originally 9 m high and 1 m wide stone wall, supported by a 50 m wide earth rampart. The structure is dated to 3000 BC.
The Ancient Egyptian Sadd-el-Kafara Dam at Wadi Al-Garawi, located about 25 km south of Cairo, was 102 m long at its base and 87 m wide. The structure was built around 2800 or 2600 BC. as a diversion dam for flood control, but was destroyed by heavy rain during construction or shortly afterwards. During the XIIth dynasty in the 19th century BC, the Pharaohs Senosert III, Amenemhat III and Amenmehat IV dug a canal 16 km long linking the Fayum Depression to the Nile in Middle Egypt. Two dams called Ha-Uar running east-west were built to retain water during the annual flood and then release it to surrounding lands. The lake called "Mer-wer" or Lake Moeris covered 1700 square kilometers and is known today as Berkat Qaroun.
By the mid-late 3rd century BC, an intricate water-management system within Dholavira in modern day India, was built. The system included 16 reservoirs, dams and various channels for collecting water and storing it.
Eflatun Pinar is a Hittite dam and spring temple near Konya, Turkey. It is thought to be from the time of the Hittite empire between the 15th and 13th century BC.
The Kallanai is constructed of unhewn stone, over 300 m long, 4.5 m high and 20 m wide, across the main stream of the Kaveri river in Tamil Nadu, South India. The basic structure dates to the 2nd century AD and is considered one of the oldest water-diversion or water-regulator structures in the world, which is still in use. The purpose of the dam was to divert the waters of the Kaveri across the fertile Delta region for irrigation via canals.
Du Jiang Yan is the oldest surviving irrigation system in China that included a dam that directed waterflow. It was finished in 251 BC. A large earthen dam, made by the Prime Minister of Chu (state), Sunshu Ao, flooded a valley in modern-day northern Anhui province that created an enormous irrigation reservoir 100 km in circumference), a reservoir that is still present today.
ROMAN ENGINEERING
Roman dam construction was characterized by "the Romans' ability to plan and organize engineering construction on a grand scale". Roman planners introduced the then novel concept of large reservoir dams which could secure a permanent water supply for urban settlements also over the dry season. Their pioneering use of water-proof hydraulic mortar and particularly Roman concrete allowed for much larger dam structures than previously built, such as the Lake Homs Dam, possibly the largest water barrier to that date, and the Harbaqa Dam, both in Roman Syria. The highest Roman dam was the Subiaco Dam near Rome; its record height of 50 m remained unsurpassed until its accidental destruction in 1305.
Roman engineers made routine use of ancient standard designs like embankment dams and masonry gravity dams. Apart from that, they displayed a high degree of inventiveness, introducing most of the other basic dam designs which had been unknown until then. These include arch-gravity dams, arch dams, buttress dams and multiple arch buttress dams, all of which were known and employed by the 2nd century AD (see List of Roman dams). Roman workforces also were the first to build dam bridges, such as the Bridge of Valerian in Iran.
In Iran, bridge dams such as the Band-e Kaisar were used to provide hydropower through water wheels, which often powered water-raising mechanisms. One of the first was the Roman-built dam bridge in Dezful, which could raise water 50 cubits in height for the water supply to all houses in the town. Also diversion dams were known. Milling dams were introduced which the Muslim engineers called the Pul-i-Bulaiti. The first was built at Shustar on the River Karun, Iran, and many of these were later built in other parts of the Islamic world. Water was conducted from the back of the dam through a large pipe to drive a water wheel and watermill. In the 10th century, Al-Muqaddasi described several dams in Persia. He reported that one in Ahwaz was more than 910 m long, and that and it had many water-wheels raising the water into aqueducts through which it flowed into reservoirs of the city. Another one, the Band-i-Amir dam, provided irrigation for 300 villages.
MIDDLE AGES
In the Netherlands, a low-lying country, dams were often applied to block rivers in order to regulate the water level and to prevent the sea from entering the marsh lands. Such dams often marked the beginning of a town or city because it was easy to cross the river at such a place, and often gave rise to the respective place's names in Dutch.
For instance the Dutch capital Amsterdam (old name Amstelredam) started with a dam through the river Amstel in the late 12th century, and Rotterdam started with a dam through the river Rotte, a minor tributary of the Nieuwe Maas. The central square of Amsterdam, covering the original place of the 800 year old dam, still carries the name Dam Square or simply the Dam.
INDUSTRIAL ERA
The Romans were the first to build arch dams, where the reaction forces from the abutment stabilizes the structure from the external hydrostatic pressure, but it was only in the 19th century that the engineering skills and construction materials available were capable of building the first large scale arch dams.
Three pioneering arch dams were built around the British Empire in the early 19th century. Henry Russel of the Royal Engineers oversaw the construction of the Mir Alam dam in 1804 to supply water to the city of Hyderabad (it is still in use today). It had a height of 12 metres and consisted of 21 arches of variable span.
In the 1820s and 30s, Lieutenant-Colonel John By supervised the construction of the Rideau Canal in Canada near modern-day Ottawa and built a series of curved masonry dams as part of the waterway system. In particular, the Jones Falls Dam built by John Redpath, was completed in 1832 as the largest dam in North America and an engineering marvel. In order to keep the water in control during construction, two sluices, artificial channels for conducting water, were kept open in the dam. The first was near the base of the dam on its east side. A second sluice was put in on the west side of the dam, about 6 metres above the base. To make the switch from the lower to upper sluice, the outlet of Sand Lake was blocked off.
Hunts Creek near the City of Parramatta, Australia was dammed in the 1850s, to cater for the demand for water from the growing population of the city. The masonry arch dam wall was designed by Lieutenant Percy Simpson who was influenced by the advances in dam engineering techniques made by the Royal Engineers in India. The dam cost £17,000 and was completed in 1856 as the first engineered dam built in Australia, and the second arch dam in the world built to mathematical specifications.
The first such dam was opened two years earlier in France. It was also the first French arch dam of the industrial era, and it was built by François Zola in the municipality of Aix-en-Provence to improve the supply of water after the 1832 cholera outbreak devastated the area. After royal approval was granted in 1844, the dam was constructed over the following decade. Its construction was carried out on the basis of the mathematical results of scientific stress analysis.
The 75-miles dam near Warwick, Australia was possibly the world's first concrete arch dam. Designed by Henry Charles Stanley in 1880 with an overflow spillway and a special water outlet, it was eventually heightened to 10 meters.
In the latter half of the nineteenth century, significant advances in the scientific theory of masonry dam design were made. This transformed dam design, from an art based on empirical methodology to a profession based on a rigorously applied scientific theoretical framework. This new emphasis was centered around the engineering faculties of universities in France and in the United Kingdom. William John Macquorn Rankine at the University of Glasgow pioneered the theoretical understanding of dam structures in his 1857 paper On the Stability of Loose Earth. Rankine theory provided a good understanding of the principles behind dam design. In France, J. Augustin Tortene de Sazilly explained the mechanics of vertically faced masonry gravity dams and Zola's dam was the first to be built on the basis of these principles.
LARGE DAMS
The era of large dams was initiated with the construction of the Aswan Low Dam in Egypt in 1902, a gravity masonry buttress dam on the Nile River. Following their 1882 invasion and occupation of Egypt, the British began construction in 1898. The project was designed by Sir William Willcocks and involved several eminent engineers of the time, including Sir Benjamin Baker and Sir John Aird, whose firm, John Aird & Co., was the main contractor. Capital and financing were furnished by Ernest Cassel. When initially constructed between 1899 and 1902, nothing of its scale had ever been attempted; on completion, it was the largest masonry dam in the world.
The Hoover Dam was a massive concrete arch-gravity dam, constructed in the Black Canyon of the Colorado River, on the border between the US states of Arizona and Nevada between 1931 and 1936 during the Great Depression. In 1928, Congress authorized the project to build a dam that would control floods, provide irrigation water and produce hydroelectric power. The winning bid to build the dam was submitted by a consortium called Six Companies, Inc.. Such a large concrete structure had never been built before, and some of the techniques were unproven. The torrid summer weather and the lack of facilities near the site also presented difficulties. Nevertheless, Six Companies turned over the dam to the federal government on 1 March 1936, more than two years ahead of schedule.
By 1997, there were an estimated 800,000 dams worldwide, some 40,000 of them over 15 m high.
TYPES OF DAMS
Dams can be formed by human agency, natural causes, or even by the intervention of wildlife such as beavers. Man-made dams are typically classified according to their size (height), intended purpose or structure.
BY STRUCTURE
Based on structure and material used, dams are classified as easily created without materials, arch-gravity dams, embankment dams or masonry dams, with several subtypes.
ARCH DAMS
In the arch dam, stability is obtained by a combination of arch and gravity action. If the upstream face is vertical the entire weight of the dam must be carried to the foundation by gravity, while the distribution of the normal hydrostatic pressure between vertical cantilever and arch action will depend upon the stiffness of the dam in a vertical and horizontal direction. When the upstream face is sloped the distribution is more complicated. The normal component of the weight of the arch ring may be taken by the arch action, while the normal hydrostatic pressure will be distributed as described above. For this type of dam, firm reliable supports at the abutments (either buttress or canyon side wall) are more important. The most desirable place for an arch dam is a narrow canyon with steep side walls composed of sound rock. The safety of an arch dam is dependent on the strength of the side wall abutments, hence not only should the arch be well seated on the side walls but also the character of the rock should be carefully inspected.
Two types of single-arch dams are in use, namely the constant-angle and the constant-radius dam. The constant-radius type employs the same face radius at all elevations of the dam, which means that as the channel grows narrower towards the bottom of the dam the central angle subtended by the face of the dam becomes smaller. Jones Falls Dam, in Canada, is a constant radius dam. In a constant-angle dam, also known as a variable radius dam, this subtended angle is kept a constant and the variation in distance between the abutments at various levels are taken care of by varying the radii. Constant-radius dams are much less common than constant-angle dams. Parker Dam is a constant-angle arch dam.
A similar type is the double-curvature or thin-shell dam. Wildhorse Dam near Mountain City, Nevada in the United States is an example of the type. This method of construction minimizes the amount of concrete necessary for construction but transmits large loads to the foundation and abutments. The appearance is similar to a single-arch dam but with a distinct vertical curvature to it as well lending it the vague appearance of a concave lens as viewed from downstream.
The multiple-arch dam consists of a number of single-arch dams with concrete buttresses as the supporting abutments, as for example the Daniel-Johnson Dam, Québec, Canada. The multiple-arch dam does not require as many buttresses as the hollow gravity type, but requires good rock foundation because the buttress loads are heavy.
GRAVITY DAMS
In a gravity dam, the force that holds the dam in place against the push from the water is Earth's gravity pulling down on the mass of the dam. The water presses laterally (downstream) on the dam, tending to overturn the dam by rotating about its toe (a point at the bottom downstream side of the dam). The dam's weight counteracts that force, tending to rotate the dam the other way about its toe. The designer ensures that the dam is heavy enough that the dam's weight wins that contest. In engineering terms, that is true whenever the resultant of the forces of gravity acting on the dam and water pressure on the dam acts in a line that passes upstream of the toe of the dam.
Furthermore, the designer tries to shape the dam so if one were to consider the part of dam above any particular height to be a whole dam itself, that dam also would be held in place by gravity. i.e. there is no tension in the upstream face of the dam holding the top of the dam down. The designer does this because it is usually more practical to make a dam of material essentially just piled up than to make the material stick together against vertical tension.
Note that the shape that prevents tension in the upstream face also eliminates a balancing compression stress in the downstream face, providing additional economy.
For this type of dam, it is essential to have an impervious foundation with high bearing strength.
When situated on a suitable site, a gravity dam can prove to be a better alternative to other types of dams. When built on a carefully studied foundation, the gravity dam probably represents the best developed example of dam building. Since the fear of flood is a strong motivator in many regions, gravity dams are being built in some instances where an arch dam would have been more economical.
Gravity dams are classified as "solid" or "hollow" and are generally made of either concrete or masonry. The solid form is the more widely used of the two, though the hollow dam is frequently more economical to construct. Grand Coulee Dam is a solid gravity dam and Braddock Locks & Dam is a hollow gravity dam.
ARCH-GRAVITY DAMS
A gravity dam can be combined with an arch dam into an arch-gravity dam for areas with massive amounts of water flow but less material available for a purely gravity dam. The inward compression of the dam by the water reduces the lateral (horizontal) force acting on the dam. Thus, the gravitation force required by the dam is lessened, i.e. the dam does not need to be so massive. This enables thinner dams and saves resources.
BARRAGES
A barrage dam is a special kind of dam which consists of a line of large gates that can be opened or closed to control the amount of water passing the dam. The gates are set between flanking piers which are responsible for supporting the water load, and are often used to control and stabilize water flow for irrigation systems.
Barrages that are built at the mouth of rivers or lagoons to prevent tidal incursions or utilize the tidal flow for tidal power are known as tidal barrages.
EMBARKMENT DAM
Embankment dams are made from compacted earth, and have two main types, rock-fill and earth-fill dams. Embankment dams rely on their weight to hold back the force of water, like gravity dams made from concrete.
ROCK-FILL DAM
Rock-fill dams are embankments of compacted free-draining granular earth with an impervious zone. The earth utilized often contains a high percentage of large particles hence the term rock-fill. The impervious zone may be on the upstream face and made of masonry, concrete, plastic membrane, steel sheet piles, timber or other material. The impervious zone may also be within the embankment in which case it is referred to as a core. In the instances where clay is utilized as the impervious material the dam is referred to as a composite dam. To prevent internal erosion of clay into the rock fill due to seepage forces, the core is separated using a filter. Filters are specifically graded soil designed to prevent the migration of fine grain soil particles. When suitable material is at hand, transportation is minimized leading to cost savings during construction. Rock-fill dams are resistant to damage from earthquakes. However, inadequate quality control during construction can lead to poor compaction and sand in the embankment which can lead to liquefaction of the rock-fill during an earthquake. Liquefaction potential can be reduced by keeping susceptible material from being saturated, and by providing adequate compaction during construction. An example of a rock-fill dam is New Melones Dam in California.
A core that is growing in popularity is asphalt concrete. The majority of such dams are built with rock and/or gravel as the main fill material. Almost 100 dams of this design have now been built worldwide since the first such dam was completed in 1962. All asphalt-concrete core dams built so far have an excellent performance record. The type of asphalt used is a viscoelastic-plasticmaterial that can adjust to the movements and deformations imposed on the embankment as a whole, and to settlements in the foundation. The flexible properties of the asphalt make such dams especially suited in earthquake regions.
CONCRETE-FACE ROCK-FILL DAMS
A concrete-face rock-fill dam (CFRD) is a rock-fill dam with concrete slabs on its upstream face. This design offers the concrete slab as an impervious wall to prevent leakage and also a structure without concern for uplift pressure. In addition, the CFRD design is flexible for topography, faster to construct and less costly than earth-fill dams. The CFRD originated during the California Gold Rush in the 1860s when miners constructed rock-fill timber-face dams for sluice operations. The timber was later replaced by concrete as the design was applied to irrigation and power schemes. As CFRD designs grew in height during the 1960s, the fill was compacted and the slab's horizontal and vertical joints were replaced with improved vertical joints. In the last few decades, the design has become popular.[42] Currently, the tallest CFRD in the world is the 233 m (764 ft) tall Shuibuya Dam in China which was completed in 2008.
EARTH-FILL DAMS
Earth-fill dams, also called earthen dams, rolled-earth dams or simply earth dams, are constructed as a simple embankment of well compacted earth. A homogeneous rolled-earth dam is entirely constructed of one type of material but may contain a drain layer to collect seep water. A zoned-earth dam has distinct parts or zones of dissimilar material, typically a locally plentiful shell with a watertight clay core. Modern zoned-earth embankments employ filter and drain zones to collect and remove seep water and preserve the integrity of the downstream shell zone. An outdated method of zoned earth dam construction utilized a hydraulic fill to produce a watertight core. Rolled-earth dams may also employ a watertight facing or core in the manner of a rock-fill dam. An interesting type of temporary earth dam occasionally used in high latitudes is the frozen-core dam, in which a coolant is circulated through pipes inside the dam to maintain a watertight region of permafrost within it.
Tarbela Dam is a large dam on the Indus River in Pakistan. It is located about 50 km northwest of Islamabad, and a height of 148 m above the river bed and a reservoir size of 250 km2 makes it the largest earth filled dam in the world. The principal element of the project is an embankment 2,700 metres long with a maximum height of 142 metres. The total volume of earth and rock used for the project is approximately 152.8 million cu. Meters which makes it one of the largest man made structure in the world.
Because earthen dams can be constructed from materials found on-site or nearby, they can be very cost-effective in regions where the cost of producing or bringing in concrete would be prohibitive.
BY SIZE
International standards (including International Commission on Large Dams, ICOLD) define large dams as higher than 15 meters and major dams as over 150 metres in height. The Report of the World Commission on Dams also includes in the large category, dams, such as barrages, which are between 5 and 15 metres high with a reservoir capacity of more than 3 million cubic metres.
The tallest dam in the world is the 300-metre high Nurek Dam in Tajikistan.
BY USE
SADDLE DAM
A saddle dam is an auxiliary dam constructed to confine the reservoir created by a primary dam either to permit a higher water elevation and storage or to limit the extent of a reservoir for increased efficiency. An auxiliary dam is constructed in a low spot or saddle through which the reservoir would otherwise escape. On occasion, a reservoir is contained by a similar structure called a dike to prevent inundation of nearby land. Dikes are commonly used for reclamation of arable land from a shallow lake. This is similar to a levee, which is a wall or embankment built along a river or stream to protect adjacent land from flooding.
WEIR
A weir (also sometimes called an overflow dam) is a type of small overflow dam that is often used within a river channel to create an impoundment lake for water abstraction purposes and which can also be used for flow measurement or retardation.
CHECK DAM
A check dam is a small dam designed to reduce flow velocity and control soil erosion. Conversely, a wing dam is a structure that only partly restricts a waterway, creating a faster channel that resists the accumulation of sediment.
DRA DAM
A dry dam also known as a flood retarding structure, is a dam designed to control flooding. It normally holds back no water and allows the channel to flow freely, except during periods of intense flow that would otherwise cause flooding downstream.
DIVERSIONARY DAM
A diversionary dam is a structure designed to divert all or a portion of the flow of a river from its natural course. The water may be redirected into a canal or tunnel for irrigation and/or hydroelectric power production.
UNDERGROUND DAM
Underground dams are used to trap groundwater and store all or most of it below the surface for extended use in a localized area. In some cases they are also built to prevent saltwater from intruding into a freshwater aquifer. Underground dams are typically constructed in areas where water resources are minimal and need to be efficiently stored, such as in deserts and on islands like the Fukuzato Dam in Okinawa, Japan. They are most common in northeastern Africa and the arid areas of Brazil while also being used in the southwestern United States, Mexico, India, Germany, Italy, Greece, France and Japan.
There are two types of underground dams: a sub-surface and a sand-storage dam. A sub-surface dam is built across an aquifer or drainage route from an impervious layer (such as solid bedrock) up to just below the surface. They can be constructed of a variety of materials to include bricks, stones, concrete, steel or PVC. Once built, the water stored behind the dam raises the water table and is then extracted with wells. A sand-storage dam is a weir built in stages across a stream or wadi. It must be strong as floods will wash over its crest. Over time sand accumulates in layers behind the dam which helps store water and most importantly, prevent evaporation. The stored water can be extracted with a well, through the dam body, or by means of a drain pipe.
TAILING DAM
A tailings dam is typically an earth-fill embankment dam used to store tailings — which are produced during mining operations after separating the valuable fraction from the uneconomic fraction of an ore. Conventional water retention dams can serve this purpose but due to cost, a tailings dam is more viable. Unlike water retention dams, a tailings dam is raised in succession throughout the life of the particular mine. Typically, a base or starter dam is constructed and as it fills with a mixture of tailings and water, it is raised. Material used to raise the dam can include the tailings (depending on their size) along with dirt.
There are three raised tailings dam designs, the upstream, downstream and centerline, named according to the movement of the crest during raising. The specific design used it dependent upon topography, geology, climate, the type of tailings and cost. An upstream tailings dam consists of trapezoidal embankments being constructed on top but toe to crest of another, moving the crest further upstream. This creates a relatively flat downstream side and a jagged upstream side which is supported by tailings slurry in the impoundment. The downstream design refers to the successive raising of the embankment that positions the fill and crest further downstream. A centerlined dam has sequential embankment dams constructed directly on top of another while fill is placed on the downstream side for support and slurry supports the upstream side.
Because tailings dams often store toxic chemicals from the mining process, they have an impervious liner to prevent seepage. Water/slurry levels in the tailings pond must be managed for stability and environmental purposes as well.
BY MATERIAL
STEEL DAMS
A steel dam is a type of dam briefly experimented with in around the start of the 20th century which uses steel plating (at an angle) and load bearing beams as the structure. Intended as permanent structures, steel dams were an (arguably failed) experiment to determine if a construction technique could be devised that was cheaper than masonry, concrete or earthworks, but sturdier than timber crib dams.
TIMBER DAMS
Timber dams were widely used in the early part of the industrial revolution and in frontier areas due to ease and speed of construction. Rarely built in modern times because of relatively short lifespan and limited height to which they can be built, timber dams must be kept constantly wet in order to maintain their water retention properties and limit deterioration by rot, similar to a barrel. The locations where timber dams are most economical to build are those where timber is plentiful, cement is costly or difficult to transport, and either a low head diversion dam is required or longevity is not an issue. Timber dams were once numerous, especially in the North American west, but most have failed, been hidden under earth embankments, or been replaced with entirely new structures. Two common variations of timber dams were the crib and the plank.
Timber crib dams were erected of heavy timbers or dressed logs in the manner of a log house and the interior filled with earth or rubble. The heavy crib structure supported the dam's face and the weight of the water. Splash dams were timber crib dams used to help float logs downstream in the late 19th and early 20th centuries.
Timber plank dams were more elegant structures that employed a variety of construction methods utilizing heavy timbers to support a water retaining arrangement of planks.
OTHER TYPES
COFFERDAMS
A cofferdam is a barrier, usually temporary, constructed to exclude water from an area that is normally submerged. Made commonly of wood, concrete, or steel sheet piling, cofferdams are used to allow construction on the foundation of permanent dams, bridges, and similar structures. When the project is completed, the cofferdam will usually be demolished or removed unless the area requires continuous maintenance. See also causeway and retaining wall. Common uses for cofferdams include construction and repair of off shore oil platforms. In such cases the cofferdam is fabricated from sheet steel and welded into place under water. Air is pumped into the space, displacing the water and allowing a dry work environment below the surface.
NATURAL DAMS
Dams can also be created by natural geological forces. Volcanic dams are formed when lava flows, often basaltic, intercept the path of a stream or lake outlet, resulting in the creation of a natural impoundment. An example would be the eruptions of the Uinkaret volcanic field about 1.8 million–10,000 years ago, which created lava dams on the Colorado River in northern Arizona in the United States. The largest such lake grew to about 800 kilometres in length before the failure of its dam. Glacial activity can also form natural dams, such as the damming of the Clark Fork in Montana by the Cordilleran Ice Sheet, which formed the 7,780 km2 Glacial Lake Missoula near the end of the last Ice Age. Moraine deposits left behind by glaciers can also dam rivers to form lakes, such as at Flathead Lake, also in Montana (see Moraine-dammed lake).
Natural disasters such as earthquakes and landslides frequently create landslide dams in mountainous regions with unstable local geology. Historical examples include the Usoi Dam in Tajikistan, which blocks the Murghab River to create Sarez Lake. At 560 m high, it is the tallest dam in the world, including both natural and man-made dams. A more recent example would be the creation of Attabad Lake by a landslide on Pakistan's Hunza River.
Natural dams often pose significant hazards to human settlements and infrastructure. The resulting lakes often flood inhabited areas, while a catastrophic failure of the dam could cause even greater damage, such as the failure of western Wyoming's Gros Ventre landslide dam in 1927, which wiped out the town of Kelly and resulted in the deaths of six people.
BEAVER DAMS
Beavers create dams primarily out of mud and sticks to flood a particular habitable area. By flooding a parcel of land, beavers can navigate below or near the surface and remain relatively well hidden or protected from predators. The flooded region also allows beavers access to food, especially during the winter.
CONSTRUCTION ELEMENTS
POWER GENERATION PLANT
As of 2005, hydroelectric power, mostly from dams, supplies some 19% of the world's electricity, and over 63% of renewable energy. Much of this is generated by large dams, although China uses small scale hydro generation on a wide scale and is responsible for about 50% of world use of this type of power.
Most hydroelectric power comes from the potential energy of dammed water driving a water turbine and generator; to boost the power generation capabilities of a dam, the water may be run through a large pipe called a penstock before the turbine. A variant on this simple model uses pumped storage hydroelectricity to produce electricity to match periods of high and low demand, by moving water between reservoirs at different elevations. At times of low electrical demand, excess generation capacity is used to pump water into the higher reservoir. When there is higher demand, water is released back into the lower reservoir through a turbine.
SPILLWAYS
A spillway is a section of a dam designed to pass water from the upstream side of a dam to the downstream side. Many spillways have floodgates designed to control the flow through the spillway. Types of spillway include: A service spillway or primary spillway passes normal flow. An auxiliary spillway releases flow in excess of the capacity of the service spillway. An emergency spillway is designed for extreme conditions, such as a serious malfunction of the service spillway. A fuse plug spillway is a low embankment designed to be over topped and washed away in the event of a large flood. The elements of a fuse plug are independent free-standing blocks, set side by side which work without any remote control. They allow increasing the normal pool of the dam without compromising the security of the dam because they are designed to be gradually evacuated for exceptional events. They work as fixed weir at times by allowing over-flow for common floods.
The spillway can be gradually eroded by water flow, including cavitation or turbulence of the water flowing over the spillway, leading to its failure. It was the inadequate design of the spillway which led to the 1889 over-topping of the South Fork Dam in Johnstown, Pennsylvania, resulting in the infamous Johnstown Flood (the "great flood of 1889").
Erosion rates are often monitored, and the risk is ordinarily minimized, by shaping the downstream face of the spillway into a curve that minimizes turbulent flow, such as an ogee curve.
LOCATION
One of the best places for building a dam is a narrow part of a deep river valley; the valley sides can then act as natural walls. The primary function of the dam's structure is to fill the gap in the natural reservoir line left by the stream channel. The sites are usually those where the gap becomes a minimum for the required storage capacity. The most economical arrangement is often a composite structure such as a masonry dam flanked by earth embankments. The current use of the land to be flooded should be dispensable.
Significant other engineering and engineering geology considerations when building a dam include:
permeability of the surrounding rock or soil
earthquake faults
landslides and slope stability
water table
peak flood flows
reservoir silting
environmental impacts on river fisheries, forests and wildlife (see also fish ladder)
impacts on human habitations
compensation for land being flooded as well as population resettlement
removal of toxic materials and buildings from the proposed reservoir area
IMPACT ASSESSMENT
Impact is assessed in several ways: the benefits to human society arising from the dam (agriculture, water, damage prevention and power), harm or benefit to nature and wildlife, impact on the geology of an area – whether the change to water flow and levels will increase or decrease stability, and the disruption to human lives (relocation, loss of archeological or cultural matters underwater).
ENVIRONMENTAL IMPACT
Reservoirs held behind dams affect many ecological aspects of a river. Rivers topography and dynamics depend on a wide range of flows whilst rivers below dams often experience long periods of very stable flow conditions or saw tooth flow patterns caused by releases followed by no releases. Water releases from a reservoir including that exiting a turbine usually contains very little suspended sediment, and this in turn can lead to scouring of river beds and loss of riverbanks; for example, the daily cyclic flow variation caused by the Glen Canyon Dam was a contributor to sand bar erosion.
Older dams often lack a fish ladder, which keeps many fish from moving up stream to their natural breeding grounds, causing failure of breeding cycles or blocking of migration paths. Even the presence of a fish ladder does not always prevent a reduction in fish reaching the spawning grounds upstream. In some areas, young fish ("smolt") are transported downstream by barge during parts of the year. Turbine and power-plant designs that have a lower impact upon aquatic life are an active area of research.
A large dam can cause the loss of entire ecospheres, including endangered and undiscovered species in the area, and the replacement of the original environment by a new inland lake.
Large reservoirs formed behind dams have been indicated in the contribution of seismic activity, due to changes in water load and/or the height of the water table.
Dams are also found to have a role in the increase of global warming. The changing water levels in dams and in reservoirs are one of the main sources for green house gas like methane. While dams and the water behind them cover only a small portion of earth's surface, they harbour biological activity that can produce large amounts of greenhouse gases.
HUMAN SOCIAL IMPACT
The impact on human society is also significant. Nick Cullather argues in Hungry World: America's Cold War Battle Against Poverty in Asia that dam construction requires the state to displace individual people in the name of the common good, and that it often leads to abuses of the masses by planners. He cites Morarji Desai, Interior Minister of India, in 1960 speaking to villagers upset about the Pong Dam, who threatened to "release the waters" and drown the villagers if they did not cooperate.
For example, the Three Gorges Dam on the Yangtze River in China is more than five times the size of the Hoover Dam (U.S.), and will create a reservoir 600 km long to be used for hydro-power generation. Its construction required the loss of over a million people's homes and their mass relocation, the loss of many valuable archaeological and cultural sites, as well as significant ecological change. It is estimated that to date, 40–80 million people worldwide have been physically displaced from their homes as a result of dam construction.
ECONOMICS
Construction of a hydroelectric plant requires a long lead-time for site studies, hydrological studies, and environmental impact assessments, and are large-scale projects by comparison to traditional power generation based upon fossil fuels. The number of sites that can be economically developed for hydroelectric production is limited; new sites tend to be far from population centers and usually require extensive power transmission lines. Hydroelectric generation can be vulnerable to major changes in the climate, including variations in rainfall, ground and surface water levels, and glacial melt, causing additional expenditure for the extra capacity to ensure sufficient power is available in low-water years.
Once completed, if it is well designed and maintained, a hydroelectric power source is usually comparatively cheap and reliable. It has no fuel and low escape risk, and as an alternative energy source it is cheaper than both nuclear and wind power. It is more easily regulated to store water as needed and generate high power levels on demand compared to wind power.
WIKIPEDIA
Consumption of proteins from fish in % of total consumption of animal protein.
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Salt crystals are poured into measuring spoons on May 17, 2003. Survey data shows that people consume the equivalent of more than 1.5 teaspoons of salt, nearly 3,430 milligrams of sodium, each day. Most U.S. adults consume on average more than twice the maximum daily sodium intake recommended. USDA photo by Peggy Greb.
20x200's Kate Bingaman-Burt is the latest artist to team up with Pinball Publishing for the release of this month's offering in their designer card series. Images come from Kate's series of drawings, What Did You Buy Today? documenting daily purchases from the last three years and are printed on chipboard with rounded corners in Pantone 376 (a lively spring green), black, and opaque white. The designer decks are a collaboration between graphic designers, illustrators, and artists with Pinball's team to show-off exactly what offset printing can do.
Princeton Architectural Press will also publish 650 of Kate's daily drawings in a book forthcoming in March 2010. We can't wait.
Kate's site, Obsessive Consumption.
Kate's editions, I Bought All of These and Plattsmouth, Nebraska, Carts #1 on 20x200.
Kate in the recently released documentary, Handmade Nation: The Rise of DIY, Art, Craft, and Design.
Kate's exhibit at Jen Bekman Gallery.
-Youngna Park