Check dams bring life back to Asola wildlife sanctuary
NEW DELHI: More than 60 check dams built by the Delhi forest department along the natural rain-fed streams at the Asola wildlife sanctuary, also one of the green lungs of the Capital, over the past year have helped improve the ecology in the area, experts have said.
Besides retaining rain water and preventing soil run-off, these dams help regenerate trees. Seeds in the soil, which would otherwise flow out with the rain water, are now stored in the dams itself. These seeds will then be collected and sowed by a process called dibbling — making shallow holes for the seeds to grow into plants, which experts believe is a more ecologically sound method of growing trees, as it allows natural regeneration unlike mass plantation.
Check dams are built across a water channel or a drainage ditch (depression) to counteract erosion by reducing the velocity of the flow of water. It prevents soil from eroding during rains and allows water to be retained in small pools or water holes which wild animals can use.
Earlier, the top soil layer along with its nutrients was lost every year during monsoon. Though there were two big dams, they did not help retain water along all the seasonal streams. Now, rainwater is being held within the dams.
Sohail Madan, an ecologist and centre manager of the Bombay Natural History Society (BNHS) Conservation Education Centre at the Asola sanctuary, said this is the first monsoon after these small dams were introduced, and its effects are reflected in terms of regeneration of the forest.
“So far the surface run-off during the monsoon would take away all the seeds and nutrients along the top soil. According to our study of the area, now with the dams holding the water and soil, a lot of run-off has stopped. The seeds fall into the holes and grow over time,” said Madan.
Forest officials said the dam sites are being surveyed to assess their impact. “These dams are built along eight seasonal streams ranging from 6km to 11km. With two good spells of rain so far this month, these have been able to retain rain water to a large extent and prevent soil erosion,” said Amit Anand, deputy conservator of forest (DCF), south division.
CR Babu, professor emeritus and head of the Centre for Environmental Management of Degraded Ecosystems (CEMDE) at Delhi University, said check dams play an important role in retaining moisture and seeds for plant growth.
“These dams are a traditional method of rain water harvesting in larger landscapes such as forests which have bigger surface drainage channels,” said Babu.