Surangam
Kasaragod district in the northern Malabar region of Kerala
is an area whose people cannot depend directly on surface water.
The terrain is such that there is high discharge in rivers in
the monsoon and low discharge in the dry months. People here
depend, therefore on groundwater, and on a special water harvesting
structure called surangam.
The word surangam is derived from a Kannada word for
tunnel. It is also known as thurangam, thorapu, mala,
etc, in different parts of Kasaragod. It is a horizontal well
mostly excavated in hard laterite rock formations. The excavation
continues until a good amount of water is struck. Water seeps
out of the hard rock and flows out of the tunnel. This water
is usually collected in an open pit constructed outside the
surangam.
A surangam is about 0.45-0.70 metres (m) wide and about
1.8-2.0 m high. The length varies from 3-300 m. Usually several
subsidiary surangams are excavated inside the main one.
If the surangam is very long, a number of vertical air
shafts are provided to ensure atmospheric pressure inside. The
distance between successive air shafts varies between 50-60
m. The approximate dimensions of the air shafts are 2 m by 2
m, and the depth varies from place to place.
Surangams are similar to qanats which once existed in
Mesopotamia and Babylon around 700 BC.1,2 By 714 BC, this technology
had spread to Egypt, Persia (now Iran) and India. The initial
cost of digging a surangam (Rs 100-150 per 0.72 m dug)
is the only expenditure needed, as it hardly requires any maintenance.
Traditionally, a surangam was excavated at a very slow
pace and was completed over generations. Today, engineers such
as Kunnikannan
Nair are faster and keep the tradition alive. |
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