Varanasi, July 27 : Professor U.K. Choudhary, a well-known river engineer and former professor at the Indian Institute of Technology, Banaras Hindu University (IIT-BHU), has sent a letter to Prime Minister Narendra Modi, urging him to help in maintaining "the crescent shape of Ganga river in Varanasi". Chaudhary said that the ornamental crescent shape of the Ganga is the unique morphology of the river, and this is the path of least resistance of friction, form and pressure drag forces of the soil in Varanasi. "This is the anatomy which defines the development of centrifugal and centripetal forces in upper and bottom layers of flows, responsible for generation of secondary current and transportation of fine clay and pollutant particles towards the concave bank (city side bank) and that of sand on the convex bank (sand bedside bank), respectively," he explained. He further said that the Ganga water longitudinally runs, circulating and vibrating on the cross section. Thus, the sustainability in the crescent shape of the Ganga at Varanasi is only due to the Assi and Varuna, the tributaries of the Ganga. As the Assi has been shifting course, the Ganga left the Assi Ghat forever. The Varuna (responsible for filling the erosion pockets) and Assi (responsible for keeping the sediment load in suspension) are needed for the protection and conservation of boundary conditions for the crescent shape. This, conceptually, must be realized. "The Assi river needs to be returned to its original position at Assi Ghat in the form of a river not of a nullah," he pointed out. Regarding the construction of the spur at Lalita Ghat and development of the channel in sand bed to facilitate the cargo/ship, he said that the massive work of the spur at Lalita Ghat is with different solid materials arranged in different forms not able to create the resonance with Ganga. As such, the anatomy and morphology of the Ganga has been permanently changed. The dynamics of the region in turbulence, responsible for carrying the sediment will be damped out. This will cause more sedimentation. Thus, the Ganga will leave the Ghat in the upstream and sedimentation and pollutants logging are bound to take place in the downstream of Lalita Ghat, he stated. In this way, the crescent shape of the Ganga will slowly change. And the pollutants logging will be very acute. The wall created along the Ghats will restrict the ground water movement and the water logging problem in the city will increase. Choudhary also questioned the efficiency of the sewage treatment plants (STPs), saying that an STP is capable of removing the organic pollutant load maximum up to 50 per cent only at the cost of several fold enhancement of microbiological load. And it is causing the pollution of all five constituents of nature. "Investment of several crores of rupees under Namami Gange programme is just like a face-washing work of the diseased Ganga. This investment should have been made for the treatment of the base level diseases of the Ganga," said Choudhary in his letter. /IANS