Lake Sambhar is shrinking

About Sambhar Lake

• The Sambhar Salt Lake, India's largest inland salt lake, is located 80 km southwest of the city of Jaipur and 64 km northeast of Ajmer, Rajasthan. It surrounds the historical Sambhar Lake Town.

• The lake receives water from six rivers: Mantha, Rupangarh, Khari, Khandela, Medtha and Samod.
• The lake is an extensive saline wetland , with water depth fluctuating from as few as 60 centimetres (24 in) during the dry season to about 3 meters (10 ft) at the end of the monsoon season.
• Sambhar has been designated as a Ramsar site (recognized wetland of international importance) because the wetland is a key wintering area for tens of thousands of pink flamingos and other birds that migrate from northern Asia and Siberia.
• The specialized algae and bacteria growing in the lake provide striking water colours and support the lake ecology that, in turn, sustains the migrating waterfowl. There is other wildlife in the nearby forests, where Nilgai moves freely along with deer and foxes.
• The salt (NaCl) concentration in this lake water differs from season to season. The salt concentration in the pans (kyars or Salt pans) varies and, accordingly, the colour of the brine ranges from green, orange, pink, purple, pink and red due to the bloom of haloalkaliphilic microorganisms.
• In November 2019, nearly 20,000 of migratory birds were found dead mysteriously in the lake area.

Avian Botulism in Sambhar Lake

• In late 2019, the lake bed had turned into a mass graveyard for migratory birds. An estimated 25,000 birds dropped dead: Kentish plovers, tufted ducks, northern shovelers, pied avocets, little ringed plovers, stilts and gadwalls, among 36 species.
• The Indian Veterinary Research Institute (IVRI), Bareilly, confirmed avian botulism — a neuro-muscular illness caused by a toxin which is produced by a bacterial strain — as the reason for mass mortality of birds, including migratory species from Northern Asia, at Sambhar Lake in Rajasthan.
• The illness, caused by a bacterium called Clostridium botulinum, affecting the nervous system of birds, leading to flaccid paralysis in their legs and wings and neck touching the ground.

Why is Sambhar Lake Shrinking?

• As Sambhar Lake came under the international spotlight for this mass die-off, another phenomenon drew attention to the lake: rampant illegal salt mining and a shrinking wetland.
• Salt pans were proliferating and illegal borewells dotted the area, causing a massive degradation of the famous lake.

Protection needed

• The 230 sq.km., shallow, elliptical wetland straddles the districts of Jaipur, Nagaur and Ajmer.
• Salt production in Sambhar is nothing new. It has taken place for centuries, but in a traditionally sustainable manner, providing livelihood to the local community. The Mughals, the British, and now Sambhar Salts Ltd (a subsidiary of Hindustan Salts Ltd, a public sector company) have all controlled salt production.
• But today, there is a mushrooming of illegal salt mining and that is grievously threatening the wetland ecosystem.
• Nawa, on the northern side of Sambhar Lake, is controlled by private salt manufacturers. It is notorious for the many illegal borewells that over-extract brine. The salt pans encroach upon the lake, and pipelines transport the brine, with unauthorised electric cables, across several kilometres, connecting the lake bed to villages.
• Following a National Green Tribunal direction, some action against illegal borewells was initiated. Last year, 288 borewells, 32 submersible pumps, and 14 hectares of encroachment were cleared. .
• Sambhar Lake’s future is totally dependent on the seasonal rivers that flow into it during the monsoon. But now this water is being sucked away before it reaches the lake, causing it to dry up.
• Mendham, Rupangarh, Kharain, Khandel and several such streams and rivulets used to recharge the lake. But the farmers in the 7,560 sq. km. catchment area of the lake have built surface embankments across the rivers, obstructing their downstream flow into the lake.
• They have sunk tubewells along the rivers and laid pipelines to transport water to their fields, choking the rivers and ultimately threatening the wetland ecosystem.
• The lake supports flamingos and migratory birds from as far away as Siberia that feed on the algae and micro-organisms found in the saline waters. Members of Wildlife Creature Organization, a local NGO, recall wistfully how the entire lake would turn pink with thousands of flamingos just a decade ago.
• T.K. Roy, a conservationist, counted 1,004 birds belonging to 30 species during the annual Asian waterbird census in 2019. This is a dramatic decline from last year’s 43,510 birds.
• Sambhar, being on revenue land, was never scientifically managed as an ecosystem. “Sustainability will come only when there is optimum use. There is a habitat here for birds. Until the forest department is given an identified area for the habitat, they cannot make it sustainable.”
• To add to the wetland’s woes, a tented heritage resort has come up, and a 117-year-old, 11 km meter gauge train line was re-laid three years ago.

Why in news?

• The world famous Sambhar Salt Lake in Rajasthan, which is constantly shrinking with the degradation of soil and water quality and a decline in the population of migratory birds, needs a faster restoration for conservation of its wetland and salt brine worth $300 million, an expert study on the lake’s ecology has said.
• The study, undertaken by a research team of the Central University of Rajasthan’s School of Earth Sciences, has recommended urgent action to restore the lake’s ecosystem for protecting the birds and biodiversity as well as salt production.
• 30% of Sambhar Lake’s area had been lost to mining and other activities, including the illegal salt pan encroachments.
• It has also threatened the livelihoods of local people who have always lived in harmony with the lake and its ecology.
• The study team conducted geospatial modelling for 96 years, from 1963 to 2059, at a decadal scale with the integration of ground data on birds, soil and water. The satellite images were classified to cover Aravalli hills, barren land, saline soil, salt crust, salt pans, wetland, settlement and vegetation.
• Dr. Sharma said while the past trends showed a reduction of wetland from 30.7% to 3.4% at a constant rate with its conversion into saline soil, which increased by 9.3%, the future predictions had depicted a loss of 40% of wetland and 120% of saline soil and net increase of 30% vegetation, 40% settlement, 10% salt pan and 5% barren land.