This article provides a case study of a tropical river Varuna.
Contents
Introduction:
To conduct a detailed investigation we selected river Varuna, a tributary of river Ganga in Varanasi, Uttar Pradesh, India.
Varanasi is among the oldest living cities of the world, where continuity of human habitation and evolution of culture have been uninterrupted since the recorded history available, and its cultural, religious and educational heritage is preserved till date.
It is also considered as the cultural capital of India and a famous seat of learning. Varanasi owes its name from Varuna and Assi, which were the two rivers forming the boundary of the city. At present the river Assi has been reduced to a drainage (nala), i.e. the Assi nala, and the river Varuna has maintained its existence.
River Varuna originates from Varuna Taal near Phoolpur situated at the border line of Allahabad and Pratapgarh districts.
River Varuna at Varanasi is used as a major drainage to carry city sewage. River Varuna, during its flow, receives untreated sewage from twenty-two nalas (Tables 4.1 and 4.2) located in northern and northwestern part of the city. Varuna also pollutes the river Ganga when it meets it at about 1 km downstream of Malviya Bridge.
Sources of Pollution:
Rapidly increasing population has led to expansion in urbanisation and industrialisation at a great pace which has created one of the dreaded threats to life on the earth. The development of modern world has created pollutants in almost all the human endeavors. Once the pollutants are discharged into the different environmental components, it becomes difficult to control them.
Thus, in order to control pollution in any system, it is important to know about the following:
1. Sources of emission of pollutants
2. Nature and intensity of pollutants
3. Physicochemical and biological properties of the receiving aquatic body.
The study of aforesaid information helps in the development of some control devices and Eco management of the aquatic ecosystems.
The main sources of pollution of river Varuna at Varanasi includes:
Crude Agricultural Practices:
Most of the catchment area of river Varuna along its 15 km flow through Varanasi is agricultural land. The topography of the catchment is such that the land is sloping towards the river. Variety of crops are being grown in the catchment area of river Varuna, consisting of wheat, maize, mustard and vegetables like brinjal, cauliflower, cabbage, etc.
In order to get high yield, farmers apply huge quantities of chemical fertilisers, herbicides and pesticides. Major portion of the chemical fertilisers and other chemicals applied remains un-utilised and finds its way into the river as surface run-off during rains and overflow.
Disposal of animal dead bodies, cattle washing and cowshed washing add organic matters into the water. They also increase nitrogenous components and promote the growth of pathogenic microorganisms.
City Sewage:
The city of Varanasi, through which the river Varuna passes, is a densely populated centre. Huge amount of sewage is produced from this city which is mainly as domestic liquid waste. This waste is rich in organic and inorganic components, soap and detergents, dye and paints, phosphates, nitrogenous wastes and miscellaneous products.
It also contains high microbial population, especially the faecal bacteria E. coli. Sewage discharges reach the river Varuna through open drainage system like nalas. During their passage the nalas receive some contaminants from local small scale and cottage industries, in addition.
River Varuna has been extensively used for washing activities. At different places Dhobi Ghats have been established on river Varuna. Soaps and detergents are used in significant quantities, which add to the pollution in Varuna.
Industrial Effluents:
Varanasi is an industrialised city of the country, having about 5,277 large, basic and small scale industries which are situated in and around the city of Varanasi—manufacturing metal products, chemicals and chemical products, electrical and battery industries, food products, spinning, weaving and finishing of textiles, transport equipment’s, motor servicing stations, furniture and fixtures, non-metal mineral products, beverages, rubber products including tyres and leather and numerous other products (Table 4.3).
Untreated effluents from these industries containing toxic heavy metals, oil and grease, chemicals and other hazardous pollutants are discharged into the rivers Varuna and thereby into Ganga directly or indirectly.
In Varanasi, huge quantity of solid-waste is generated. This solid-waste is taken care of by Varanasi Nagar Nigam, which has been entrusted to collect and dispose it off. As very little land is available for the disposal of solid waste, Varanasi Nagar Nigam has selected some solid waste disposal sites.
Most of the disposal sites are located close to the Varuna River. Two major solid waste disposal sites are located near Khajuri Colony and Sampurnand Bridge. Major part of the solid waste generated in Varanasi is of putrescible nature having high percentage of water. Organic wastes along with water find their way into the river, increasing the pollution load.
In view of the increasing number of polluted rivers, various plans have been developed by the Government for their treatment, such as, Ganga Action Plan for river Ganga, Yamuna Action Plan for river Yamuna; similarly Gomati Action Plan, etc. River Varuna has not been included under any such plan, though it is among one of the highest polluted tributaries of Ganga.
No treatment plant has been established to treat the discharges into river Varuna through different drains. It is due to this reason that the sewage discharged into the river Varuna affects the water quality of river Ganga and, consequently, is affecting the results of Ganga Action Plan.
Since no provisions have been laid for the treatment of Varuna water and the treatment facilities being too costly to be employed feasibly, in the case of river Varuna alternative treatment practices are required.
In this regard, a project had been spearheaded under the title Studies on the Chemistry of River Varuna Water in Response to the Discharge of Small Scale Industries:
Specially Automobile Servicing, Battery and Dyeing Industries.
Since most of the work which are done in parallel direction includes agricultural runoff, domestic sewage or large scale industries etc. where the small scale industries have been totally overlooked here they have been emphasised. Treatment of Varuna water through chemical and biological processes has been explored.
This project was conducted during year 2001-2002 with the following aims and objectives:
Aims and Objectives:
1. To monitor the important small scale industries pouring their effluents in the river Varuna.
2. To monitor the impact of effluents of selected small scale industries on physicochemical properties and heavy metal concentration in the river water and water sediments at the selected sites throughout the year.
3. To evaluate biological properties of the river water at the selected sites.
4. To conduct laboratory experiments for the control of water pollution through chemical and biological methods.
5. Statistical analysis and computation of data; to check the significance of observed data and to establish their relationships.
6. To suggest economic and feasible management practice for the control of water pollution induced by selected small scale industries.
The Study Sites:
The study was conducted in the holy city Varanasi which is situated in the eastern part of Uttar Pradesh, a province of India located in the core of the Indian subcontinent, lying in the middle of Gangetic plain. On the globe Varanasi finds its location at 25°18′ North, 83°1′ East and is situated 76.19 in above the sea level.
River Varuna enters into the domain of Varanasi city near a railway bridge at Varanasi-Lucknow Loop line, which is very close to Imiliya ghat. During 15 km of its flow through Varanasi, the river Varuna receives sewage from twenty two municipal drainage (nalas) located on both the sides (Tables 4.2 and 4.3).
The physicochemical characteristics of river water near all the nala discharge points were analysed, and their sources were studied. On the basis of variety in sources, i.e. some small scale industries and properties of effluents, four sites were selected for detailed investigation.
Detail of the study sites are given in Table 4.4. Five sub-sites were also located at all the sites to collect the true representative of water sample and three sub-sites for sediment sample collection.
Site 2, was located downstream from the Razabazar nala, which drains 1.13 mid of sewage brought from the Nadesar area of the city. The most important additive at this site mainly consisted of discharge from some battery industries in addition to domestic sewage. 586 small scale battery industries were located in this area which poured their effluent directly into the Razabazar nala.
Site 3, was the site near Chaukaghat which poured the discharge from Chaukaghat nala. This site was located very close to G.T. (Grand trunk) road.
The most common profession in this area was heavy and light vehicles servicing, including their washing and painting. Average discharge of Chaukaghat nala was 2.55 mld.
Site 4, located in the area where people are engaged in the processing of Banarsi sarees. This included washing and dying of the sarees. Thus discharge from this site was rich in pigments, dyes, soap and detergents. The site was in the area of Kazzakpura and received discharge from trans-side of the river through Narokhar nala, whose average discharge was 5.45 mid.
In order to compare the results, one control site was also selected upstream at Rameshwar in the Jansa area. This site was free from any kind of pollution source except some agricultural runoff. This control site was coded as Site 1.
Meteorology of Varanasi:
Distribution of macrophytes, zooplanktons and fishes not only depend on quality of water but also on the climatic condition. Accumulation of heavy metals and pollutants by hydrophytes also depend on season and environmental factors.
Climate:
The climate of the region is of tropical monsoon type and is divisible into hot and dry summers (March-June), warm and moist rainy (July-October) and dry cold winter (November-February) with a few sporadic showers.
Temperature:
Monthly mean of minimum and maximum temperature was recorded during the study (April 2001 to March 2002). Lowest minimum temperature (10.03 °C) was recorded during December 2001, but lowest maximum temperature (22.71 °C) was recorded during January 2002, likewise highest minimum temperature (29.65 °C) was recorded during June 2001 and highest maximum temperature (38.16 °C) was found in April 2001.
Seasonally, highest temperature was recorded during summer with lowest in winter and intermediate during rainy season. The maximum average temperature gradually starts falling from May 2001 and reaches to the minimum during December when the winter is coldest, then it starts rising from January 2002 and reaches to maximum during April when the summer reaches its peak.
The rainy season months, i.e., July to October, normally found warm and wet.
Precipitation:
During April 2001 to March 2002 highest monthly rainfall was recorded during July 2001 (380.5 mm) while minimum during November 2001 (0.6 mm). Winter season was dry with slight precipitation during summer; rainy season was wet with heavy rainfall (Fig. 4.2).
Humidity:
Humidity varies widely in different seasons, maximum being in the rainy and minimum in the summer season. The maximum average relative humidity during study period was in December 2001 (92.54%) while the minimum was in April 2001 (41.26%) (Fig. 4.2)
Studies of meteorological variables are essential because they directly or indirectly affect the concentration of pollutants. During summer season the temperature was recorded much higher, precipitation was also recorded to be low, which ultimately causes high rate of evaporation from the surface of water bodies, due to which the water bodies become concentrated.
In the rainy season the average temperature was lower, whereby the amount of precipitation increases manifold, also the rate of evaporation decreases. Rate of evaporation from surface of water bodies is inversely proportional to the relative humidity also.
This results in flow of large amount of water through the rivers, as a result the water body becomes diluted and pollutant concentration lowers. Due to large water content in the river during rainy season the rate of the flow of river increases manifold as compared to other seasons, which lowers the pollutant’s content also by continuous washing.