Rainwater harvesting works wonders for Sukhna Lake

CHANDIGARH - With over 190 water bodies and an equal number of silt detention dams in the Sukhna wildlife sanctuary, Chandigarh has been running one of the biggest soil conservation and rainwater harvesting projects for two decades. And the benefits have been made crystal clear in a new study.

The study conducted by a city-based NGO, Society for Promotion and Conservation of Environment (SPACE), has found a sizeable decline in the flow of silt into the Sukhna lake after the construction of these dams.

“This is an exemplary model not only in India but in the whole Asia continent as nowhere will you find this density of water bodies,” Santosh Kumar, Chandigarh’s chief wildlife warden and conservator of forests, told IANS.

The water bodies are filled by rainwater and they feed the Sukhna lake, a prominent tourist destination here, round the year. The dams retain the silt and prevent it from entering the lake.

Besides, they provide ample water to the animals residing in the sanctuary and attract hundreds of migratory birds every year.

“These dams and water bodies are cleaned once every three to seven years, depending on their size and requirement.”

Sukhna Lake was constructed in 1958 across Sukhna Choe, a seasonal rivulet originating from the Shivalik hills, and formed an integral part of the Chandigarh master plan.

However, it was marred by excessive siltation from the adjoining Shivalik hills that posed a serious threat to its existence.

“The premature siltation of the lake became a cause of serious concern and the severity of soil erosion in its Shivalik catchment was not well realised before the lake was planned. The lake started silting right from the first year of its formation,” Santosh Kumar told IANS.

“Therefore, intensive soil and water conservation measures were taken up in the bordering Sukhna wildlife sanctuary. The measures included effective closure, large-scale plantation and construction of more than 190 water bodies and silt detention earthen dams,” he added.

Kumar said that these measures were systematically taken over a period of almost two decades and they have reduced the siltation rate of the lake from more than 140 tonnes per hectare per year to less than five tonnes per hectare per year.

“The 190 water bodies are very stable and functioning very well. At present, it seems that the Sukhna lake catchment area is floating on water. They preserve the rainwater and significantly support the wildlife.

“Besides, it helped in the reversal of degradation process and resulted in visible improvement in vegetation cover. The overall tree density of the sanctuary increased from 162 per hectare to 450 trees per hectare and bush density from 5,977 per hectare to 8,994 per hectare, during the last few years,” Santosh Kumar said.

Due to the thick vegetation, the leaf litter accumulation on forest floor increased from 2.05 tonnes to 4.4 tonnes per hectare which also resulted in increase of soil organic carbon.

The Sukhna wildlife sanctuary, spread over an area of 25.42 sq km, is fenced from all sides and was declared a protected sanctuary in March 1998.

A variety of butterflies, birds and animals like wild boar, pangolin, mongoose, deer, Indian civet, peacocks, Red Jungle Fowl and snakes like the Indian python and Russell’s viper have made this sanctuary their abode.

Moreover, during the first-ever census at the sanctuary last month, officials found the pug marks of leopards and they have installed a camera here to ascertain the presence of the jungle cat.

Besides conserving soil and water, these water bodies attract a huge number of tourists every year.

In 2009, around 7,500 tourists visited the sanctuary and the number increased to 9,000 last year.

(Alkesh Sharma can be contacted at alkesh.s@ians.in)