In the summer every year, a group of dedicated persons, young and old, assemble at the dry end of the Sukhna Lake and volunteer to save the pride of Chandigarh (City Beautiful), Union Territory, India, from being silted up. This artificial lake created in 1958 as a landmark of the city, has in the past 54 years shrunk by two-thirds of its original size. The volunteers, who at one time came in hundreds, seem to have given up, except a few die-hard "silt addicts" who are still trying to keep the flag of 'self help' flying, but they are now a worried lot. They fondly remember the days when this operation was carried out every year without putting any burden on the administration. Even machines such as drag lines and dumpers etc, were provided by various agencies free of cost. Gradually machines have taken full charge and the voluntary human effort has practically come to a halt.
Mr M. Chhibber, District Forest and Coordinating Officer of this voluntary movement, pointed at the gravity of the situation way back in 1993. Without understanding the spirit behind the movement, he said, no amount of voluntary effort would give any relief unless the underlying causes of siltation were properly understood and attended to. Since 1996 the number of volunteers has vastly reduced. An officer on the spot said even if this voluntary movement had become a regular feature, it had not achieved much.
Siltation is a natural phenomenon. It can be lessened, not stopped. In spite of the enthusiasm behind this noble sentiment, the lake will be silted up again unless the gully-heads that eat up the hills, tablelands and fill up the bed of Sukhna Lake are plugged, the soil is stabilized and a carpet of vegetation is established in the entire catchment area, according to Mr Chhibber.
The Save Sukhna Lake Society still exists, people still feel the urge to participate in this noble work, but the problem is not only that of removal of the silt year after year, but also of slope stability, erosion in the catchment area, eutrophication, water quality disorder and proper protection of the Sukhna wetland as suggested by an environmentalist.
This year mechanized desiltation has been taken up employing poclain, dozer, JCBs and tippers by the BBMB, Punjab and Haryana Governments and several other agencies. Mrs Anuradha Gupta, the then president of the society, had revealed that 150 retention dams were constructed to check the inflow of silt into the lake.
The Sukhna Lake's catchment area is made up of 4,207 hectares. Nearly half the retention dams have been filled up with silt thus preventing 320 hectare meters of silt from flowing into the lake. Another 8, 69,477 cubic feet of silt had been removed from the bed till May 31. The volunteers had from 1988 to 1993 accounted for 310 lakh cubic feet of silt.
The immensity of the problem can be judged from the copious erosion of the Shivalik, hills, the catchment area, by a number of rivulets such as Sukhna, Kansal, Ghareri and Nepli besides Patiali Ki Rao, Jayanti Devi and the losses of vegetation cover. The gradient of the land surface in the area is towards south-southwest and it varies from 37 meters per kilometer near the foothills to 9 meters per kilometers near the city. On the flanks of the Shivalik and in the fore land the annual rainfall ranges from 500-800 mm (in the foothills) to 1000-1250 mm (on the steep slopes). Experts keep pointing at the ad hoc approach to the desiltation operation. The entire work to save the Sukhna needs to be taken with a holistic approach.
The remote sensing application data published by the Punjab Remote Sensing Centre emphasizes the need for checking erosion in the catchment area and undertaking sound conservation measures. The study shows that the vegetation in the Shivalik hills from top to bottom can be classified as (1) mixed forest cover with Khair-a shrunken lot, (2) scrubs with stunted trees-a little more, (3) grass/ herbs with stunted trees-major part of the hill slopes and upper reaches, (4) plantations, herbs/vegetation-very little, mostly on the banks of channels.
The adjoining part of the Sukhna Lake catchment area, with a high gradient, has almost no forest or vegetation cover. The experts observe that the intensity of erosion tends to decrease from the hills to hill slopes, to the catchment slope (Kandi), to the immediate slope of the Sukhna to almost stillness in the coalescing alluvial fans where much water is lost. A vein-like erosion profile by the streamlets has been noticed.
Sukhna deserves some concerted and scientifically planned measures to survive. The problem is not unique. Small or big reservoirs, ponded areas, wetlands etc, do get filled up with sediment accelerated stream erosion and rapid reservoir siltation. A number of corrective measures have been undertaken in such cases the world over. Voluntary effort of people is significant enough to make them participate and create awareness, but the solution lies in checking this natural disaster with state-of-the-art measures. Or the forces that are bent on erasing the smile from the face of the City Beautiful may have the last laugh.
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