VARANASI: Noted river engineer Prof. UK Chowdhary on Thursday wrote a letter to the chairman of the Central Pollution Control Board (CPCB) pointing out some lapses in the existing sewage treatment system for removing pollution from the Ganga and its tributaries Assi and Varuna.
“Since I was included in the virtual meet on the issues related to the management of Assi and Varuna rivers held on June 30 as an expert, it is my duty to raise the factors responsible for the plights of the rivers,” Chowdhary, who is also a former professor of the Indian Institute of Technology, Banaras Hindu University (IIT-BHU), told TOI on Friday.
The virtual meeting was organised by the CPCB after the intervention of the National Green Tribunal (NGT), which has recently set up a high-power independent monitoring committee to look into the issue of pollution in rivers Varuna and Assi in Varanasi by discharge of untreated sewage and unauthorized constructions.
The NGT in its order dated June 17 had mandated that based on the report of the committee, the National Mission for Clean Ganga (NMCG) may give an action taken report in the matter before August 4.
He said, “Without groundwater the dynamics of the river system does not function. The Assi and the Vauna rivers need to be properly dredged to remove the settled garbage in order to explore the groundwater table. The inflowing pollutants should pass through the septic tank/sedimentation tank at the source, and finally the pollutants need to be disposed of in the river in proper quantity at proper location and in proper methodology.”
“The disposal of pollutants from the existing sewage treatment plants (STPs) located on the city side bank, causing soil, air and water pollution spreading along the ghats by dissipating the momentum of flow are hopeless if the outlets of the STPs are not properly linked with the sand bed,” he added.
The outlet of the Assi river joins the Ganga at Nagwa at 90 degree and causes heavy loss of momentum and turbulence of the Ganga. It is causing the spread of pollutants of the Nagwa STP. This is why the Ganga water at Assi ghat is black and smelling. The cause of recent Algal growth in the Ganga was the pollutants of the STPS, he informed TOI.
“Therefore, the STP system is utterly useless,” he said, adding that the Assi river was wrongly shifted, which caused the permanent shifting of the Ganga from the Assi ghat.
The Assi and the Vauna are the river body systems as any river in the world. There is a need to understand their anatomy, morphology and dynamics. The river problems should be solved with the help of experts of the river institutes.
The Varuna confluences with the Ganga in the zone of converging streamlines of the Ganga. It was causing the filling up of the erosion pockets. This has been disturbed due to the construction of a spur on Lalita Ghat. Now the upstream of Lalita Ghat has become the zone of sedimentation and the downstream of Lalita Ghat has become the zone of pollutant logging.
Since they are curved in nature, the water inside them is subjected to centrifugal forces and secondary circulations. Therefore, dilution, diffusion and dispersion of pollutants are functions of location inside the river. For imparting minimum basic knowledge of the river to all officers in water resource departments there must be a sufficient number of river engineering institutes. Further, the river problems should be analyzed with model study.