Dams & The World’s Water The British Dam Society Hoover Dam Tarbella Dam – largest in Pakistan. When built supplied 40% of Hydroelectric Power Tarbella Dam, Pakistan Karun-3 Dam in Iran Only 2.5% of the water in the world is fresh water - in glaciers, groundwater, lakes and rivers
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The British Dam Society
Tarbella Dam, Pakistan 40% of
Karun-3 Dam in Iran 40% of
Only 2.5% of the water in the world is fresh water - in glaciers, groundwater, lakes and rivers
68.9% of the world’s fresh water is in glaciers and permanent snow cover in Artic and Antarctic regionsThe World’s Water
In 2005 the world population was estimated to be 6.45 billion and continues to grow at an annual rate of 1.3% or 77.3 million per year.
The projection for the world population through 2050 is as shown below. A large portion of this growth is in the arid portions of the world - Africa, and Asia.
This growth continues to
place a significant demand
on water, food, energy and
other infrastructure and
Water requirements are classified as domestic, agricultural and industrial.
World-wide standard for water requirement:
A city of 500,000 people requires 25 million litres/day for basic domestic water requirement
Even a small village of 500 requires 25,000 litres/day
In 2000, there were 61 countries with a total population of 2.1 billion who can not get access to the minimum requirement of 50 litres per person per day.
With the anticipated population growth in less developed countries this will double to 4.2 billion people by 2025.Water Requirements
“A dam is defined as a barrier or structure across a stream, river or waterway to confine and then control the flow of water.” ICOLD
Some dams serve one purpose are "single purpose dams". and industrial.
Several purpose dams are called "multipurpose dams".
A multipurpose dam is a very important and cost effective project for developing countries because the population receives several domestic and economic benefits from a single investment.Multipurpose Dams
In the world: and industrial.
Simple earth dams and networks of canals were constructed as far back as 2000 BC
The building of the Marib dam in Yemen began around 750 BC and took 100 years to complete. It consisted of an earth embankment 4 meters in height and stone sluices to regulate discharges for irrigation and domestic use. In 1986, the existing dam was raised to 38 meters that created a reservoir of 398 Mm3History of Dams
In the UK: and industrial.
Oldest dam – Castle Pond, Penbroke, given by King John in 1199 to the Knights Tempar of St. John of Jerusalem
Mill Dams – Ornamental Lakes – CanalsHistory of Dams
Dams are classified by the material used to construct them. Dams built of concrete, stone, or other masonry are called gravity, arch or buttress dams.
Embankment dams represent about 75% of all of the dams in the world. They are constructed of either earth fill or a combination of earth and rock fill.Types of Dams
Gravity dams depend on their own weight to resist the tremendous force of the stored water.
Arch dams are concrete dams that curve upstream toward the flow of water. As the water pushes against the dam, the arch transfers the water's force to the canyon wall. Arch dams require much less concrete than gravity dams of the same length.
Buttress dams use a series of vertical supports called buttresses. The buttresses run along the dam's downstream face.Gravity & Arch Dams
Claerwen Dam tremendous force of the stored water.
Caban Coch tremendous force of the stored water.
Graphs showing when the world’s large dams were placed into operation and their distribution by height
The primary type of dam is the earthfill embankment dam which represents 43.7% of the total.
This is followed by gravity dams (10.6% of the total) and rockfill embankment dams (5.3% of the total).Graph showing the distribution of Large Dams by Geographical Area
◗ 48.6% for irrigation
◗ 17.4 % for hydropower
◗ 12.7% for water supply
◗ 10.0% for flood control
◗ 5.3% for recreation
◗ 0.6% for navigation and fish farming
◗ 5.4% others
These needs range from the direct use in manufacturing to chemical and refining processes and for cooling at conventional and nuclear power plants.
Managed flows from reservoirs can be used to dilute discharged substances by augmenting low river flow to maintain water quality at safe limits.Water Supply for Industrial use
Biggest uses of water on a worldwide scale is irrigation. Since the early 1990s, less than 1/5 of the land suitable for agriculture has been irrigated, and it has contributed about 1/3 of world food production.
Estimated that 80% of additional food production by the year 2025 will need to come from irrigated land. This will add demand on fresh water supply.
Most of the areas in need of irrigation are in arid zones of developing countries.
Construction of more reservoir projects will be required.Meeting agricultural water needs
ULLEY DAM Since the early 1990s, less than 1/5 of the land suitable for agriculture has been irrigated, and it has contributed about 1/3 of world food production.
Inland lock and dam for navigation on the Danube Since the early 1990s, less than 1/5 of the land suitable for agriculture has been irrigated, and it has contributed about 1/3 of world food production.
“Increased awareness of the natural environment and its endangered situation is one
of the most important developments of the late 20th century.”
Resettlement Since the early 1990s, less than 1/5 of the land suitable for agriculture has been irrigated, and it has contributed about 1/3 of world food production.
Loss of habitat
Downstream erosionChallenges of Dams
Teton Dam failure. Hole in the right abutment. 11 killed, 20,000 made homeless.
Shih-Kang weir Dam Earthquake in 1999. Now the broken part of the dam is left in situ and open to public in memory of the devastating 921 Earthquake in Taiwan.
Dam in Iran shown with silt in the bottom outlet and clean water coming out through the spillway.
Three Gorges Dam, China water coming out through the spillway.
One of the Three Gorges along the Yangtze River water coming out through the spillway.
Grand Coulee Dam, USA water coming out through the spillway.
Grand Coulee Spillway water coming out through the spillway.