Saturday, March 10, 2012

Mansar and Surinsar Lake

It is high time that this published scientific data be given wide publicity by the concerned quarters such as Departments of Tourism and Information etc. through revised/updated brochures. The abstract version of this data is published in Records Of Geological Survey Of India, Vol.131 Part-8 : Extended Abstracts Of Progress Reports Of Northern Region : Field Season 1996-97, P.16 - 24. Full report on Geoenvironmental Appraisal Of Mansar & Surinsar Lakes, issued in 2001, is also available with Geological Survey Of India.

Historical Myths :
Mansar lake is considered to be abode of a Hindu serpent god, Shesh Nag by the locals and populace of surrounding areas and some religious rites such as mundan ceremonies are performed here for their sons by many families at the Shesh Nag temple. Even to this day, local folk and many others believe that the lake doesn't have any bottom. In other words they mean that the depth of the lake is so great that it cannot be fathomed.

Well, when oceans can be fathomed, why not a small lake? Science has made all that possible.
* Regarding the formation or origin of the lakes also, there are mythological stories such as - the great Arjuna of Mahabharata times shot an arrow to carve out twin lakes of Mansar and Surinsar. But such magical things are very hard to digest by the modern educated generation, especially. These lakes have been formed by a well defined geological process, though a rare one.
* Have you ever noticed that for reaching Mansar lake, you have to climb a hill from southern Samba side? From northern Battal side (on Dhar - Udhampur road) also there is a gentle upward gradient towards the lake. Isn't this peculiar? Normally lakes are found in depressions and you have to go down to access them. Generally, only glacial lakes such as Kaplas Kund also called as Vaskund at 13500 feet height in the Kaplas Range in Bhadarwah area, are formed at great heights due to scooping action of moving ice (glaciers) on the rocks over a long period of times.
* So, Mansar lake is formed on a structural high called as an Anticline in geological parlance. Anticline means an arch of rocks with its high turned upwards. Same is true for its sister lake called as Surinsar, situated at 11.7 Km Northwest(N55W) of Mansar lake. The core of this anticline has a number of fractures or faults, including cross-faults. It is these fractures or faults which have resulted in spring activity in the lake basins (Mansar and Surinsar) yielding perennial source of lake waters. Most of the lake waters are coming from below, welling up as copious springs along the fracture planes, in what is called as artesian conditions.
* Next time you visit Mansar or Surinsar, please note that no stream or nala is feeding the lakes for water source and the catchment area is also very limited, the rainfall being about 1400 mm annually. In other words both the lakes are closed drainage type.
These TDS values are well within permissible limit for A-class potable water which is 500 milligrams per litre as per Indian Standard IS-2296 (1982).

Safeguards :
So we are lucky to have such beauties in the form of two very deep fresh water lakes in Jammu which still enjoy pristine glory of environment. Any future surveys of this nature would reveal the current status of the lakes at that time. This is the first ever baseline data generated which will be useful in the future studies for comparative assessment.
In the year 1977, Surinsar lake was surveyed by Department of Geology & Mining, J&K Government by Plane Table mapping on 1 : 2000 scale. That report was also consulted in the studies by GSI. On comparison of 2 maps on same scale of 1:2000, one prepared by DGM in 1977 and the other by GSI in 1997 , it was found that there is no change in depth or area of Surinsar lake in 20 years time. No early data on accurate surveys existed for Mansar lake.

This, however, doesn't mean that we should not take due care about the ecology and pollution of the lakes. We must preserve them in all purity and beauty. Mansar and Surinsar lakes are amongst the deepest fresh water lakes in India. We have much deeper lakes in Ladakh, but they are not fresh water, they are brackish waters, remnants of great seas of the past with enchanting geological history. Kashmir lakes which also are fresh water lakes are of much lesser depths, Mansbal being the deepest one amongst them at around 10 metres depth. Nainital lake at the noted hill station Nainital is considered to be very deep. It, however, is 18 metres only at its deepest point.

Facts & Figures :
So let us have the facts about the twin lakes, as revealed by authentic ground surveys:
Mansar Lake Surinsar Lake
1 Area 0.522 Sq.Km (52.2 ha) 0.29 Sq.Km.(29 ha)
2. Circumference 3020 metres 2420 m.
3. Catchment area 0.778 Sq.Km 0.46 Sq.Km
(lake areas inclusive)
4. Deepest point 35 metres 23.20 m.
5. Height 666 metres above msl.
6. Long Axis(Max.length) 1038 m (N32W-S32E) 862 m (N33W-S33E)
7. Max.Width 644 m (N62E-S62W) 510 m (N57E-S57W)
8. Lake Island - 1 (NNW-NNE : 90m x 18m)
9. Water Quality…Very High Geochemically for both lakes.
Average Total Dissolved
Solids(TDS) ..151 mg/litre (surface water)
175 mg/litre (sub-surface water).

By J.K.Vaid

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