Release of waste water from barrage agitates surfactants present and foam forms, it said
Complete treatment of sewage discharged into the Yamuna from Delhi, Haryana and Uttar Pradesh is needed to prevent froth and foam formation in the river, a parliamentary committee has said.
The presence of phosphates and surfactants in untreated sewage is a major reason behind frothing in the river, the committee said, noting that the foam contained in polluted river can cause skin irritation and infections.
The Standing Committee on Water Resources in its 27th report "Review of Upper Yamuna River Cleaning Projects up to Delhi and River Bed Management in Delhi" highlighted that incidences of foaming in Yamuna have been observed at locations such as at ITO Bridge, Okhla and Kalindi Kunj in Delhi, especially during onset of winter.
It said that froth or foam formation at the downside of Okhla barrage is more due to turbulence caused by fall of water from the barrage, which is being maintained by the UP Irrigation Department.
At the Okhla barrage, all treated and untreated waste water of Delhi is impounded and only excess waste water is released downstream, the panel said in its report.
Release of waste water from the barrage agitates surfactants present and foam forms, which increases with more discharge of waste water from the barrage, the report said.
Besides, large amounts of water hyacinth growth on the pondage of Okhla barrage release surfactants on decomposition, it said.
"The presence of phosphates and surfactants in untreated sewage is a major reason behind frothing in the river," the committee said.
"The committee is of the opinion that a long lasting solution for prevention of froth and foam formation in river Yamuna is complete treatment of sewage by Delhi, Haryana and Uttar Pradesh which is being discharged through various drains into river Yamuna," it said.
The committee reiterated its previous recommendations for enhancing the sewage treatment capacity of STPs by upgrading their technologies and connecting all the industrial clusters to common effluent treatment plants.
Further, the committee flagged that foam formation in Yamuna in Delhi, particularly at the downstream of Okhla barrage near Kalindi Kunj, occurs particularly when the gates of Okhla barrage are opened and water is released through energy dissipating arrangements which creates churning and formation of froth.
Providing a gentle slope at the Okhla barrage for smooth flow may help in avoiding turbulence at the downstream, it said.
The report said opening and closing of gates of the barrage should be regulated such that free fall of discharge is prevented.
The committee also underlined that efforts need to be made to introduce alternatives such as sodium aluminium silicate, sodium citrate and tetrasodium etidronate for phosphates in detergents.
On the issue of encroachment of floodplains or wetland area along Yamuna, the committee said only two states -Delhi and Haryana - have furnished the required information.
Yamuna basin states such as Uttarakhand, Himachal Pradesh, Uttar Pradesh and Rajasthan should also send the relevant information, it recommended.
It also asked to be apprised of the measures taken by them for removing those encroachments within three months of the release of the report.
The committee further observed that the water available in Yamuna at Hathnikund barrage is being utilised for irrigation and supply of water for domestic and industrial use, as a result of which demands at Hathnikund barrage and Wazirabad barrage is invariably more than the availability during non-monsoon seasons causing usually negligible or insignificant flows downstream of Wazirabad.
The panel said pumping of groundwater by borewells in floodplains is one of the reasons due to which rivers get dry during lean season.
Given that the agriculture sector requires a lot of water, the committee recommended that farmers use micro and drip irrigation techniques, suitable pattern of cropping, water budgeting at micro-levels and water-shed management in the command area of Yamuna.
It also underlined the urgent need for storage of monsoon water as well as rain water harvesting to meet the increasing water needs in the Yamuna basin.
The panel said excessive sand mining leads to riverbed alteration, affecting the course of the river and causing bank erosion, and suggested necessary steps to be taken to collate the information regarding sand mining from all the Yamuna basin states and prevent illegal sand mining in the floodplains of river Yamuna.
It also recommended setting up of a portal where all the relevant information like river sand mining, floodplain/wetland encroachment, dumping of waste into the rivers may be furnished by the concerned states in a time-bound manner on a periodic basis.
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