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| HIGHLIGHTS 1999 |
| TREND
IN POLLUTION LOAD CONTRIBUTION TO RIVER YAMUNA IN DELHI STRETCH The trend in pollution load contribution between 1982 to 1998 in terms of BOD load in Delhi stretch shows a continuous increase in BOD load contributed to the river from 117.3 tonnes/day in 1982 to 211.0 tonnes/day in 1998. There is significant increase in annual average contribution during year 1983, 1986 and 1996 in comparison to its preceding year may be due to contribution of high BOD loads along with run-off water. The BOD load in Delhi stretch is calculated considering the data of seven major drains i.e. Burari Drain, Najafgarh Drain, Civil Mill Drain, Power House Drain, Sen Nursing Home Drain, Barapulla Drain and Shahdara Drain only. The data for flow measurement in drains for the year 1992-94 are not available, since the monitoring was discontinued during the period. No definite trend in water quality has been observed, although pollution load has gradually increased possibly due to following reasons: 1.There is no fresh water flow in many stretches of the river during dry weather, only waste water flows in such stretches. The waste water with almost constant quality over a period of time will not show any trend in the river water quality in such stretches. 2.The abstractive uses of surface and ground water in the catchment area of the river are need based. There is drastic reduction in the water use, if there is rainfall in the command area of the canal used for irrigation, resulting in less abstraction of water and more flow in the river leading to more dilution of pollution and better quality. The rainfall in non-monsoon period are highly unpredictable and irregular, therefore such water quality changes are also irregular. The monitoring has been undertaken on regular basis and such irregular changes are encountered many times leading to irregular water quality trend.
Waste water disposal in River Yamuna from NCT-Delhi A total of 2083 MLD wastewater is generated within sewered areas of Delhi. Even in the sewered areas, all sources of wastewater (including households are not connected to the sewerage system). As a result, a significant volume of wastewater generated, remains untrapped and find its way into the open drains. The five sewerage zones of Delhi are catered by five major sewage treatment plants and two Oxidation Ponds having total capacity of about 1473 MLD (as on June, 1999). While, each of these zones have one major STP each, Okhla & Rithala zones are served by an Oxidation Pond each namely Vasantkunj and Timarpur respectively, but they are also considered as STPs for discussion. The total treatment capacity of treatment plants are inadequate and hence the significant amount of waste water having high BOD Load is bound to flow untrapped. The total amount of BOD, which is released by direct house-connections or through the open drains does not reach to the STPs in the same quantity, but gets exerted due to decomposition of organic matter during course of travel. The extent of exertion can be indicated by the BOD concentration in the sewage at the inlet of each STP. The treatment of STPs provided for the reduction of BOD load upto an extend of 90% depending on the number of stages of treatment but such efficiency are practically difficult to maintain. The treated effluent from STPs other than what is withdrawn for irrigation purposes, joins nearby water bodies. The discharge from Okhla STP goes to Agra canal and from Vasant Kunj Oxidation Pond to Kushak - Barapulla drain. The effluent from Shahdara STP finds it way into the Shahdara drain, whereas all other STPs and Timarpur Oxidation Pond finally discharge into the Najafgarh drain either directly or through various sub drains. The wastewater not trapped for treatment in STPs find its way into various drains and sub-drains from their respective catchment areas and discharged into the river Yamuna. A small fraction of sewage is also discharged into Agra Canal through Kalkaji and Tughlaqabad drains. Estimated wastewater discharge received by drains in Delhi (as on March, 1999)
* Najafgarh drain also receives water from Western Yamuna Canal (WJC). ** Shahdara drain also receives waste water from Ghaziabad and Noida. *** Agra Canal also receives untrapped sewage through Kalkaji and Tughlaqabad drains.
Najafgarh drain receives maximum wastewater discharge followed by Agra Canal and Shahdara drain. Water quality of Yamuna river (Delhi stretch) in respect of selective physico-chemical parameters between April, 1998 to March, 1999
Min. - Minimum Max.- Maximum Av. - Averag
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