‘Sukhna basin floating on water’

The report was submitted to the department early this month and is slated for a formal release on June 22.

Inflow of water
The original capacity of the lake,created in 1958 in an area of 2.28 square kilometres,was 10.74 million cubic metres and the water inflow was 8,310 acre feet. In the first 20 years,the inflow reduced to 7,370 acre feet.

The Shivaliks are one of the most erodable hills and responsible for the huge silt deposits in the lake. In 1975,silt retention dams were created owing to which inflow of water reduced to 1,870 acre feet between 1978 and 1999. At present,the figure stands at 736 acre feet.

Since then,around 180 silt retention dams have been built in the catchment area,which has significantly reduced silt deposition in the lake. During this period while the water entering the lake has reduced,so has the water holding capacity of the lake due to siltation.

Catchment area
Over the years,Sukhna Lake catchment basin area (spread across 2,540 hectares) has been developed into a wildlife sanctuary with numerous water holes and varied flora and fauna. But in the words of Professor S S Grewal,chairman of SPACE and a former faculty member of the Punjab Agricultural University,Ludhiana,“the basin area is floating on water”. The perched water table here is a good 2 to 4 metres. However,this is not helping in recharging of the underground water.

Professor Grewal says: “The water table outside the catchment area reduces to as low as 100 metre at some places. It seems that there is an impervious layer of soil that is not letting the water seep through. At the south-western periphery of the forest catchment,even surface flowing water disappears from drainage lines. Although there is sufficient water in the catchment area,it does not enter the lake.” “When the lake was built,it seems no one realised that the Shivaliks are one of the most erodable hills. The problem of silt entering the lake has been tackled to an extent but efforts need to be made to increase the inflow of water,” he adds.

Any way out?
* A syphon system should be introduced so that water present in higher dams can be released into the lake
* Soil and water conservation measures need attention and maintenance
* Drainage line between the Sukhna Lake and the forest area needs to be well maintained
* Eucalyptus trees in the catchment area be replaced with grasses that can feed wildlife
* Silt retention dams also need to be desilted at regular intervals
* Water harvesting structures to ensure recharging of the water table