The Forest Department will conduct an impact study on the efforts being taken to rejuvenate river Noyyal under the ongoing Noyyal Rejuvenation Programme, a Nabard funded-initiative.
The study will assess the volume of water percolating into the ground through the trenches dug up alongside 32 streams that are connected to the Noyyal and the amount of silt the streams carry into the river.
The study will be done simultaneously in four forest ranges — Madukkarai, Pooluvampatti, Periyanaickenpalayam and Coimbatore — through which the river flows.
“The impact study will assess the volume of water recharged by the 5,000 trenches and the percolation ponds. Similarly, the amount of silt prevented with the help of the gabion structures that are put in place along the streams will be assessed. The District Forest Officers have been directed to submit reports,” said Deepak Srivastava, Chief Conservator of Forests, Coimbatore Circle.
He said that 5,000 trenches had been made in 250 hectares for the rejuvenation programme.
The gabion structures are made of loose boulders stacked using wire mesh. These structures, also known as gully plugs, arrest the silt that is carried by the streams to the river. Apart from these, 10 check dams are also constructed to recharge the groundwater.
Major threat
“Silt accumulation is a major threat to the river. The gabion structures work as natural filters,” said Mr. Srivastava.
For improving the local biodiversity, seeds of stylo grass were sown near the trenches. The grass also becomes fodder for animals like deer and elephant.
While ₹2.42 crore was allotted for the rejuvenation programme for the year 2017-18, the allocation for 2018-19 is ₹2.74 crore.
A similar rejuvenation programme for the Vaigai river is being carried out in Madurai and Theni districts.
