TOPICTOPIC

DAMS AND BARRAGES AND THEIR ENVIRONMENTAL

IMPACTS

DAMS

• A dam is a barrier that impounds water or underground streams.

• worldwide in development.

• generate electric power.

• manage or prevent water flow into specific land regions.

• evenly distributed between locations.

• The earliest known dam is the Jawa Dam in Jordan, 100 kilometres (62 mi)

northeast of the capital Amman.

BENEFITS OF DAMS OF DAMS

• Power generation

• Water supply

• Stabilize water flow / irrigation

• Flood prevention

• Land reclamation

• Recreation and aquatic beauty

• Navigation

DAMS IN PAKISTAN

LIST OF DAMS IN PAKISTAN

DISADVANTAGES OF DAMS

• Seepage and evaporation

• Groundwater table effects

• Sedimentation behind dams

• Erosion downstream by sediment-starved waters

• Clogging of rivers by side-canyon floods

ENVIRONMENTAL IMPACTS OF DAMS

• Biological, chemical and physical properties of rivers

• blocks fish migrations

• traps sediments

• Changes in temperature, chemical composition, dissolved oxygen levels and the physical properties of a reservoir are often not suitable to the aquatic plants and animals.

• reservoirs often host non-native and invasive species (e.g. snails, algae, predatory fish)

• species in the area

• water qualitywater quality

• fertility of the landfertility of the land

• problems of pollutionproblems of pollution

• Social impactsSocial impacts

• Soil ErosionSoil Erosion

• Species ExtinctionSpecies Extinction

• Spread of Disease

CHANGES TO EARTH'S ROTATIONCHANGES TO EARTH'S ROTATION

• Nasa geophysicist Dr. Benjamin Fong Chao found evidence that

large dams cause changes to the earth's rotation, because of the shift

of water weight from oceans to reservoirs. Because of the number of

dams which have been built, the Earth's daily rotation has apparently

sped up by eight-millionths of a second since the 1950s. Chao said it

is the first time human activity has been shown to have a measurable

effect on the Earth's motion.

BARRAGES

• special kind of dam

• a line of large gates that can be opened or closed.

• control the amount of water passing the dam

• control and stabilize water flow for irrigation systems.

• Raising of water level for diversion in to a canal

LIST OF BARRAGES IN PAKISTAN:

• Chashma BarrageChashma Barrage

• Guddu BarrageGuddu Barrage

• Jinnah BarrageJinnah Barrage

• Kotri BarrageKotri Barrage

• Littel BarrageLittel Barrage

• Sukkur BarrageSukkur Barrage

• Taunsa BarrageTaunsa Barrage

ENVIRONMENTAL IMPACT

• Turbidity

• Sediment movements

• Fish

• Salinity

• mosquitoes to breed

• trees disappeared.

• disposal of sewerage into the lake. Waste of more than 2,50.000

humans is dumped directly into the lake

Thank YOU