Friday 2 September 2011

Hamza-Underground River


It is the longest known underground river-running for about a length of 6000km at a depth of nearly 4km.
It flows all the way from the Andean foothills to Atlantic coast like the Amazon river.
The river, named after an Indian born scientist Valiya Mannathal Hamza, along with Amazon is the unusual instant of a twin river system flowing at different levels of the earth’s crust in Brazil.

Difference between Amazon and Hamza
  • Amazon is 1 to 100 km wide where as Hamza is 200 to 400 km in width.
  • Flow speed in the Amazon is around 5 m/s  and less than a millimeter per second in Hamza.

Geological Factors which resulted in formation of Underground Ocean and Hamza

The world’s largest underground ocean, about the size of Arctic Ocean, is located 700 to 1400km below the ground and extends from Indonesia to Russia.
  • It has been formed when the plate carrying the Pacific Ocean bottom gets dragged and ends up under the continental plate. Water at such depths would normally escape upwards but the unusual conditions that exist along the eastern Pacific Rim allow the moisture to remain intact.
  • In the case of the Hamza, the porous and permeable sedimentary rocks behave as conduits for the water to sink to greater depths. East-west trending faults and the karst topography present along the northern border of the Amazon basin may have some role in supplying water to the river. 


Other underground water bodies
  • The 153 km-long underground river in Mexico's Yucatán Peninsula
  • The 8.2 km-long Cabayugan River in the Puerto Princesa Subterranean River National Park in the Philippines.

These rivers are formed due to Karst topography

Karst topography
It  is a landscape shaped by the dissolution of a layer or layers of soluble bedrock, usually carbonate rock such as limestone and dolomite.

Due to subterranean drainage, there may be very limited surface water, even to the absence of all rivers and lakes. Many karst regions display distinctive surface features, with sinkholes or dolines being the most common.
Some karst regions include thousands of caves, even though evidence of caves that are big enough for human exploration is not a required characteristic of karst.  
Water in these places drills its way downward by dissolving the carbonate rock to form an extensive underground river system.


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