Disadvantages
v Cost
Ø Dams are extremely expensive to build and must be built to a very high standard.
Ø Hydro power can impact water quality and flow. Hydro power plants can cause low dissolved oxygen levels in the water, a problem that is harmful to riparian (riverbank) habitats and is addressed using various aeration techniques, which oxygenate the water. Maintaining minimum flows of water downstream of a hydro power installation is also critical for the survival of riparian habitats.
Ø Hydro power plants can be impacted by drought. When water is not available, the hydro power plants can't produce electricity.
Ø Dams are extremely expensive to build and must be built to a very high standard.
Ø Hydro power can impact water quality and flow. Hydro power plants can cause low dissolved oxygen levels in the water, a problem that is harmful to riparian (riverbank) habitats and is addressed using various aeration techniques, which oxygenate the water. Maintaining minimum flows of water downstream of a hydro power installation is also critical for the survival of riparian habitats.
Ø Hydro power plants can be impacted by drought. When water is not available, the hydro power plants can't produce electricity.
v Failure Hazard
Banqiao Dam
Ø Dam failures have been some of the largest man-made disasters in history. Also, good design and construction are not an adequate guarantee of safety.
Ø For example, the Banqiao Dam failure in Southern China resulted in the deaths of 171,000 people and left millions homeless.1975 during Typhoon Nina.
Vajont Dam
Ø Also, the creation of a dam in a geologically inappropriate location may cause disasters like the one of the Vajont Dam in Italy, where almost 2000 people died, in 1963.
v Large Power Outages caused by dam failures
Itaipu Dam
Large dams, can suffer from castrohpic failure to, which can lead to extremely large and sudden loss of output, which can plunge an entire network off line, for hours or even months depending on the damage. Examples are:
Ø The November 2009 Brazil and Paraguay blackout dam failure. The blackout affected an estimated 60 million people.
LOSS OF ELECTRIC POWER =14 GW
Ø The November 2009 Brazil and Paraguay blackout dam failure. The blackout affected an estimated 60 million people.
LOSS OF ELECTRIC POWER =14 GW
Sayano-Shushenskaya Dam
Ø The 2009 Sayano-Shushenskaya hydro accident in Khakassia,Russia:
LOSS OF ELECTRIC POWER = 6.4 GW
LOSS OF ELECTRIC POWER = 6.4 GW
v Environmental damage
Marmot Dam Collapse
Ø Hydroelectric projects can be disruptive to surrounding aquatic ecosystems both upstream and downstream of the plant site.
Ø For instance, studies have shown that dams along the Atlantic and Pacific coasts of North America have reduced salmon populations by preventing access to spawning grounds upstream.
Ø They are also harmed on their migration to sea when they pass through turbines.
In some cases dams have been demolished (for example the Marmot Dam demolished in 2007) because of impact on fish.
Ø For instance, studies have shown that dams along the Atlantic and Pacific coasts of North America have reduced salmon populations by preventing access to spawning grounds upstream.
Ø They are also harmed on their migration to sea when they pass through turbines.
In some cases dams have been demolished (for example the Marmot Dam demolished in 2007) because of impact on fish.
v Population relocation
Ø Another disadvantage of hydroelectric dams is the need to relocate the people living where the reservoirs are planned.
Ø Additionally, historically and culturally important sites can be flooded and lost.
Ø Such problems have arisen at the Three Gorges Dam project in China.
Ø Additionally, historically and culturally important sites can be flooded and lost.
Ø Such problems have arisen at the Three Gorges Dam project in China.
website created on 1st Dec,2009
Author of this web page:- "Aakash" , currently studying in Grade 12.
Author of this web page:- "Aakash" , currently studying in Grade 12.
