Tuesday, January 3, 2012

Krishna delta front is increasing in area, according to Geological Survey of India

Syed Akbar
Hyderabad:  The Krishna delta is constantly growing at a “rapid
pace” gaining as much as 28 sq km of area in the last five decades.

A detailed analysis of the research data on the Krishna delta by the
Geological Survey of India reveals that the delta is regularly gaining
land at the “front” region. Delta front is the area that protrudes
into the sea. This in other words means that the Krishna delta has
projected further into the Bay of Bengal since the early 1960s.

The Krishna River divides into two main branches, a few kilometres
downstream of the Prakasam Barrage in Vijayawada. One branch joins the
Bay of Bengal at Hamsaladivi, while the other branch further divides
into three distributaries, which later join the sea downstream of

According to GSI, the Krishna delta front is “constantly growing at a
rapid pace on both sides of all the three distributaries, particularly
the western most, through sand deposits (spits and bars). Over the
past half century, the Krishna delta has gained about 28 sq km of
area”. Since the growth is more in the western most distributary that
borders Repalle, the Krishna delta front is adding new area from the
Guntur district side.

The growth of the Krishna delta further into the sea (progradation)
has been noticed at Kaikaluru- Bapatla strandline, Gudur strandline,
Machilipatnam strandline and the Koduru strandline. The delta front is
sandy or marshy in nature with a vast stretches of wild grasses or
protected mangrove forests. The mangrove forests have gained some of
this newly added area.

The Krishna delta is “lobate” (lobe like) and unique in having the
greatest protuberance of 37 km from the adjoining coast, points out
“GSI Memoirs”, containing the summerised data of the research work
done by GSI scientists at its Hyderabad centre. As new land is added
to the delta front, the protuberance into the sea increases. The
deltaic shore is about 90 km long.

A delta is highly sensitive to any change, natural or manmade. Changes
in the Krishna delta started after the construction of dams in the
upstream. This has reduced the sediment carrying capacity of the
river. With the outflow into the sea coming down drastically in the
last few decades, the sea is depositing sands, increasing the area of
the delta front.

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