WATER QUALITY IN THREE TYPICAL RIVERS IN U-P.-GANGA, YAMUNA AND KALI

Abstract

The problem of water quality management to maintain an overall environmental quality is a very complex problem. Such management can not be achieved by a mere location of the polluters through effluent monitoring systems, followed by punishment to the defaulters. Very strict standards and punitive methods may on the other hand, adversely affect the process of industrialization, particularly in developing countries like ours. The problem essentially needs a scientific approach in respect of several considerations such as, the beneficial uses of the water, types of pollution likely to occur, levels of relevant pollutional parameters playing significant role, procedure for pollution and water quality monitoring and above all, a scientific analysis of the monitored data to determine the waste assimilation capacity of the streams for indicating the administrative action needed to keep the river water quality at the desired levels. This being an entirely new field in our country needs anumber of pilot studies to develop the necessary understanding to plan such programmes. The thesis presents such a pilot-study. Water Quality Surveys of three rivers of Uttar Pradesh in India, viz., Ganga, Yamuna and Kali, considered to respectively represent very large, medium and small rivers in the Indo-gangetic plain were undertaken. The monitoring of various relevant water quality parameters was carried out at a number of stations along the three streams. Some of the parameters could be directly measured on the field. For others, samples were collected and analysed in the temperory laboratories set up at different stations for the purpose. The analysis of photographs of the water surface at the sampling points, taken at the time of sampling was done at the Institute laboratory, using aDU-2 Beckman Spectrophotometer, to determine whether the photographs could give any indication of stream quality. The data collected was intensively analysed using graphical and mathematical techniques. The following are the broad findings from the studies thus made. Thermal Pollution: The temperatures in the early reaches of rivers Ganga and Yamuna range between 13 to 18 C in winter, while in summers they range between 18 and 28 C. In the later reaches the temperatures are slightly higher ranging from 18 to 20°C in winter and 27 to 31 C in summer. Ganga water is coibler by about 2 C compared to Yamuna water at the corresponding time and stage of the river. At urban centers along Ganga and Yamuna, the temperature rises stieply by 1 C to 3 C in winter and by 1 C to 4 C in summer, the rise being directly due to urban waste discharges. Such temperature rise may help in locating the discharge of significant amounts of wastes, Since continuous recording and remote sensing of temperature is possible through Infra-red photography, this could be of some help in studying pollution over large areas and periods. Between two urban centers radiative and evaporative cooling act to gradually dissipate the thermal pollution added by the upstream community. The cooling rates in Ganga and Yamuna range from 1 C to 3 C per 100 Km. This then would be the capacity of the stream for assimilation of thermal pollution without seriously affecting the overall temperature regime and thence the ecology of the stream. Suspended Matters Near the source of these rivers, the Bepth of Light Penetration (DLP-an indirect measurement of the relative turbidity and suspended solids) is high in winter due to base flows, underflows, springs, seepage etc constituting the major portion of the stream discharge, and low in summer due to runoffs from snowmelts constituting the major portion of the stream discharge. The clarity of all three rivers, Ganga, Yamuna and Kali were almost equal in summer, the DLP being only around 13-16 cms. In winters the water of Ganga and Yamuna was much cleaner, the DLP's being 117 and 102 cms respectively. Kali with a DLP of 37 cms in winter was also much cleaner than in summer though much dirtier than Ganga or Yamuna. The impounding reservoir at Dak Pathar in the upper reaches of Yamuna stabilizes tae turbidity to a near constant value of around 60 cms in both seasons. In the middle reaches, the DLP reduces in winter and rises in summer to attain an almost uniform value of 25-30 cms in both the rivers. In the earlier reaches of Kali and the later reaches of Ganga and Yamuna the DLP and hence the clarity increases in both the seasons probably due to bioflobulation. At urban centers along Ganga and Yamuna, the turbidity caused by organic wastes is also taken care of by bioflucculation within very short distances. The velocity changes in Ganga and Yamuna, significantly affect the DLP in their early reaches where most of the turbidity causing material is high sp.gr. inorganic matter but show insignificant effect in the later reaches where much of the turbidity causing material is low sp.gr. organic matter. The turbidity in streams considered alone does not seem to be a good indicator of pollution and the earlier hill reaches had higher turbidity though devoid of any significant man made pollution. Thus turbidity or clarity based remote sensing or monitoring will not be of much purpose. Bacteriological Quality: The coliform MPN and TPC values are as high and even greater than 2400/100 ml and 7,000/ml respectively in several reaches of the three streams especially reaches close to urban centers. The coliform MPN is found to decrease in the natural environment of these rivers, but TPC survivals are found to high depending on the organic matter and nutrients present in the streams. Fixed Dissolved Solids: Fixed dissolved solids and all ions, including chlorides, hardness, alkalinity etc. in these rivers are found to be greatly affected by the regional ground water characteristics and chemical composition. Underflows, base flows, precipitation or dissolution of CaCO, etc. from bed and sides, and discharge of used ground water are considered to be some of the important phenomena responsible for the increase or decrease in these parameters at urban centers and along the streams. In the early reaches, the chlorides are always low, being less than 8 mg/l in Ganga. In Yamuna also they are even less than 5 mg/l in summer but in winter they are somewhat higher, being upto 30 mg/l. In the later reaches, the chlorides rise significantly to about 35 mg/l in summer and 70 mg/l in winter in Ganga. In Yamuna the rise is even greater, about 120 mg/l in summer and to as high as 300 mg/l in winter by Agra after which it drops to around 35 mg/l in summer and 70 mg/l in winter due to the lesser chloride content of the underflows and Chambal river. There is always a sudden upswing in the chloride content at Delhi by about 30 mg/l due to the discharge of significant amounts of domestic and industrial wastes, and used ground water of higher chloride content. In contrast to this, a sudden drop in the chloride content is observed at Agra by about 50 mg/l in summer and 20 mg/l in winter due to the discharge of significant amounts of used ground water of lower chloride content. The chloride content of Yamuna in winter is rather very high in the Mathura- N is Agra reach. Inspite of the highly polluted character of Kali due to the discharge of industrial wastes, the chloride content in it is always low, ranging from 10 to 50 mg/l. In the earlier reaches of both rivers Ganga and Yamuna, the water is slightly hard, the hardness being between 50 and 100 mg/l. In winters the hardness is larger being upto 120 mg/l in Ganga and 140 mg/l in Yamuna. In the later reaches of Ganga, the hardness varies between 120 to 170 mg/l in both seasons with a drop of about 30 mg/l in the Kanpur- Allahabad reach in winter and Kannauj-Kanpur reach in summer due to precipitation of CaCO^. In the later reaches of Yamuna the hardness rises upto Agra to about 250 mg/l in both seasons after which it decreases to about-;150 mg/l by the time of reaching Allahabad. The Yamuna water will be classified as 'hard* between Delhi and Agra. In Kali, hardness varies between 100 to 200 mg/l and its water would classify as moderately hard to hard. Dissolved Oxygen: On a long term basis, the DO is above 6 mg/l all through in Ganga and Yamuna, and above 5 mg/j, all through in Kali, showing rather high reaeration rates in these streams. At urban centers, just after the sewage disposal points, the DO values droop suddenly sometimes touching near zero, but no where anaerobic conditions were observed. The DO levels are recovered(wit?in) a short reach downstream. The sudden drop in DO may indicate the magnitude of organic pollution, but due to fast recovery it appears that the rivers have significant unutilized capacity for assimilating organic pollution loads. Organic Load and BOD: On a long term basis, the BOD5 varies from 4 to 10 mg/l in summer and 1.4 to 8 mg/l in winter in Ganga; from 2.5 to 12.5 mg/l in summer and 1.5 to 6.5 mg/l in winter in Yamuna; and from 4.4 to 40 mg/l in summer And 2.8 to 30 mg/l in winter in Kali. At urban centers, just after the sewage disposal points, the BOD5 values shottup to even higher than 40 mg/l,in these streams. In Ganga and Yamuna, such high BODrS at urban centers get assimilated£woth~in) short distances from the outfall. Analysis of the data indicates that the rather high rate of BOD assimilation in the initial stages after sewage disposal points is due to the interaction between the colloidal BOD and the strongly coagulant exocellular polymers already present in the streams, resulting in coagulation followed by settling. This phenomenfis found to remove rapidly, as much as 60 percent of the initial BOD within 30 to 60 minutes time, and such reduction in BOD is found to follow a straight line law rather than the usual exponential curve of BOD excertion. The BOD assimilation in the later stages after the effect of the coagulation-settling is over, follows more or less the expected first order kinetics. However the rate constants for such first order stabilization of BOD are found to be —1 very high, as much as 3.5-5*5 day in Ganga and around 1.5 day in Yamuna against the usual range of 0.2 to 0.5 day"? Presence of large amounts of well adapted microorganisms in these rivers is thought to be the probable cause of such high values. It is also thought, that a relatively lower value in Yamuna may be due to the discharge of significant amounts of heavy metals at Delhi which inhibit the growth of microorganisms. It was also observed that the BOD assimilating capacity is limited in some reaches by a shortage of nutrients. The Kannauj-Kanpur reach of Ganga was found to be low in nitrogen content compared to the other reaches, as a result of which, the BOD assimilation in this reach was very insignifi cant as also the TPC survival was not good. The BOD exertion can be represented by the equation, S - S_ ( 1 - -3-=£— t ) + S„ „ e"Kt 'o-x x ' D u ' ' "o-y 'where, S is the BODp in mg/l at time 't* in days, S and 3 ° O-X s0-y are tile respective colloidal and dissolved B0D5s in mg/l just after the sewage outfall point in the stream, Kis — 1 the rate constant (day ),v Is the settling velocity of flucculated particles in M/day and D is the average depth of the river in meters. Usefulness of Black and White Photographs: The photographic optical density is found to co- relate well with turbidity, increasing with increase in turbidity. It is also found to co-relate with BOD not directly but indirectly because of the colour and turbidity associated with BOD additions. The potential of black and white photographs in water quality monitoring thus seems very limited. Water Quality Index: A "Water Quality Index based on modification of V/alski-Parker index to especially apply to each of the beneficial uses of these streams has been proposed. Values of this index assigning appropriate weightages to the various beneficial uses for different reaches of the three streams have been evaluated. Such overall water quality indices are found to represent the stream water quality at different stations in simple indicative manner. The water quality as indicated by the proposed Q WQI near the source of rivers Ganga and Yamuna is very good in winter but somewhat inferior in -Wtttii I"TuTt of WQI being 95 in winter and 70 in summer at the upstream of Rishikesh on Ganga; and 93 in winter but only 59 in summer at the upstream of Dak Pathar on Yamuna. In both these rivers, the WQI suffers a steep fall as the river traverses through urban center. The overall quality in the middle reaches of Yamuna is all through lower than corresponding values in Ganga, oompared to 69 in winter 38 in summer at the downstream of Kanpur on Ganga, the values of WQI on a corresponding point on Yamuna, viz., downstream of Agra are as as low as 34 in winter and 22 in summer. In the lower reaches of these streams, a significant improvement in the WQI values is observed in both seasons, the numerical values rising to 65 in winter and 75 in summer at the upstream of Varanasi on Ganga; and 74 in winter and 61 in summer at Allahabad on Yamuna. In Kali, the WQI values are generally low all through in both seasons, but at some stations it is found to be rather too low. Like in Ganga and Yamuna in Kali also, the WQI values are higher in winter than in^ummer. Along Kali, the WQI values @Meerut are 73 in winter and 43 in summer, which deteriorate to as low as 26 in winter and only 14 in summer at Bulandshahr. However subsequently the value improves similar- to that in Ganga and Yamuna, to be 62 in winter and 57 in summer at Kannauj. Thus the proposed WQI gives an easily understandable and comparable picture of water quality, indicating the suitability of the water for the various beneficial uses it is 'likely to be put to. It is hoped that the various findings, models and the modified water quality indices would find usefulness in the assessment of the water quality of streams and in implementation of water quality management programmes