Paper 7 Pollution alleviation issues: a case study on the River Ganges

I. M. Griffiths
Thames Water International, National Rivers Authority - Thames Region, Reading, Berkshire

Summary: Thames Water International were employed as technical advisors to the Ganga Project Directorate to assist with the implementation of the Ganga Action Plan, an ambitious plan to clean up the River Ganges. A team of water quality and sewerage experts from Thames Water were charged with evaluating the sources and extent of water pollution in the River Ganges and to assist in drawing up a plan for its control or prevention. In addition to the environmental work the consultancy covered a wide range of disciplines including sewage treatment, sewer maintenance and sludge management. This paper will concentrate on the environmental aspects of the work but relates the findings to the management of sewage disposal. Technology transfer was a major element of this project.

Introduction

The work was sponsored by the Overseas Development Administration and consisted of an advisory programme between the governments of India and the UK. Thames Water environmental and sewage treatment specialists worked with counterpart Indian scientists and engineers from the Ganga Project Directorate and the State Pollution Control Boards to effect technology transfer and to facilitate the requirements of the Ganga Action Plan. The work contained a number of key elements including the development of a computer model to assist with strategic water quality planning. This was linked to a project to design and procure an automatic river quality monitoring (ARQM) system and to undertake river quality surveys with which to establish suitable sites for the siting of the monitors and to provide baseline data for input into the model. In addition, advice was given on the selection of appropriate sewage treatment options and associated maintenance requirements. Priorities were set for the rehabilitation of sewers and sewage treatment works. The siting and design parameters for new treatment plants were also considered. This work required a significant amount of time to be spent in India, gathering information and gaining an understanding of the current situation and practices.

When undertaking a programme of water pollution abatement a thorough understanding of the river environment is an essential precursor. The physico-chemical and flow characteristics of the river, seasonal patterns, existing pollution loadings and the use requirements of the river need to be known before the siting and design of sewage treatment works can be undertaken. This information can then be fed into a computer programme which is capable of simulating the impact of varying the concentrations of pollutants upon the river.

This paper will concentrate on the environmental elements of this work, specifically the design, procurement and commissioning of the network of automatic river quality monitoring stations and the water quality surveys undertaken on the River Ganges. The work began with the author making a preliminary visit to India in August 1986 and subsequently writing an ARQM system specification. River surveys were carried out in April and May 1987 and February, March and April 1989. Further visits were made in February 1990 and 1991 to test and commission the equipment.

The Ganga Action Plan

The Ganga Action Plan is best summarised by the following extract from An Action Plan for the Prevention of Pollution of the Ganga, Department of the Environment, Government of India, revised, 1985:

"Based on a comprehensive survey of the Ganga Basin carried out by the Central Board for the Prevention and Control of Water Pollution (CPCB), an Action Plan for the prevention of pollution of the Ganga was prepared by the Department of the Environment (India) in December, 1984. The Central Ganga Authority (CGA) with the Prime Minister (Rajiv Ghandi) as chairman was set up by Government Resolution in February, 1985. This was a high level body for determining policies and programmes, to allocate resources and mobilise public support for accomplishing the Action Plan. In June 1985, the Ganga Project Directorate (GPD) was established as a wing of the Department of the Environment, to appraise and clear the projects prepared by the field level agencies, release funds and co-ordinate the various activities under the Action Plan on a continuing basis.”

The principle aims of the Action Plan are, "the immediate reduction of pollution load on the river and the establishment of self-sustaining treatment plant systems."

General characteristics of the River Ganges

The River Ganges (Ganga) is the largest and most important river in India. It is 2552 kilometres long and carries the drainage of a vast basin of more than 1 060 000 square kilometres, which is bounded by snow-covered peaks of the Himalayas in the north and the peninsular uplands of the Vindya range to the south (figure 1). It extends over four countries, India, Nepal, Bangladesh and China. It drains 814 400 square kilometres within India, covering more than a quarter of the land area. It is a mayor surface and groundwater resource with an annual flow of 468.7 billion cubic metres, equivalent to approximately one-quarter of India's total water resource. The Ganges basin is the home of one third (approximately 200 million) of the Indian population and is one of the most important pilgrim centres of India (CPCB, 1984).

Figure 1 General map of the River Ganges

Seasonal and climatic considerations

The subtropical river and climatic conditions are associated with four seasons, characterised as follows (CPCB, 1984):

1. Monsoon season (June to September)

Frequent rainfall, dramatic increase in river level and flow

Air temperature, 25-40°C

High humidity

2. Post - monsoon season (October to November)

River flows decline sharply

Air temperature, 15-35°C

3. Winter season (December to February)

River flows continue to decline

Occasional bursts of winter rainfall

Air temperature, 5-25°C

4. Summer season (March to May)

Flows as for winter

Air temperature, 15-45°C.

This seasonality is reflected in extremes of river depth and flow rate, with the effects being particularly pronounced at Varanasi where the river is constricted by high ground on either side. For example, at Varanasi, during the summer season water depth is approximately 12 metres with a mean flow of 285 cubic metres per second. During the monsoon, depths rise to 20 metres and mean flows increase to 13 454 cubic meters per second.

The subtropical nature of the Indian climate is an important consideration in the design and operation of equipment which must work at high ambient temperatures and variations in air temperature from 5°C during winter nights to 45°C during summer days must be expected.

ARQM system design and specification

The experience gained from the operation and development of the freshwater and tidal ARQM stations in the River Thames catchment provided the basis for the specification of the system for the Ganges. The format of the tidal system was particularly appropriate because of the simplicity of the in-situ (sensors immersed directly in the river) sensor arrangement, designed to operate in harsh conditions which included large fluctuations in water level. Modifications to the format were required to accommodate the subtropical environment and the monitoring needs of the Ganges.

A specification was written for a network of nine monitoring stations to be sited on the Ganges to monitor the effects of water pollution in the vicinity of specified major cities. The stations would be un-manned and would be remote from operational facilities. Mains power would not be available. The project would involve the production of an operational prototype to be tested near Delhi under the supervision of the author. Phased introduction of the nine monitors would follow.

Water quality information provided by the CGA and a review of water quality in the Ganga (CPCB, 1982 and 1984) provided a baseline with which to specify the system. The specification was written in 1986 in the form of an International Tender Document.

Seasonal variations in water level of up to 10 metres had to be taken into account. This factor, combined with unmade banks and the lack of suitable buildings in remote areas excluded the use of fixed stations and meant that a floating platform arrangement anchored to the river-bed or suitable structure offered many advantages. In addition, floating platforms allowed for the possibility of moving outstations at a later date and made them suitable for use on any river in India.

Other factors that had to be taken into account in the design of the floating platforms were as follows:

· provision for anti-fouling measures
· availability and size of craft for positioning and anchoring a platform
· need for specialist advice on anchorage of platforms
· need for the system to be operational during the monsoon, particularly during its 'first flush'. In case this proved impossible, provision had to be made for the removal of the equipment for the duration of the monsoon.

The floating platforms and anchorages were designed in collaboration with marine architects from the Oceanographic Research Centre in Madras. Figure 2 is a schematic drawing of the platform which formed the basis of the detailed design and construction work undertaken by the architects. Figure 3 is a photograph of the equipment in operation on the River Ganges.

Since it was proposed to operate the stations in truly remote locations where mains power would be unobtainable, power consumption had to be kept to a minimum and solar power options were the most suitable choice.

The following factors had to be taken into account in the design of the mounting for the sensors:

· sensors were to be placed directly in the river
· sensors should be mounted on a robust 'lance' assembly to allow for sampling at a depth of 0.5-1.0 m below the surface
· sensors needed to be protected from damaging impacts from floating debris
· sensors needed to be easily removed for servicing and cleaning
· anti-fouling measures
· incorporation of a facility for swinging the probe up and back down in the event of collision with a submerged object.

The ARQM equipment was required to provide the following range of sampling frequencies:

· 24 per day
· 12 per day
· 6 per day
· 4 per day
· 1 per day

The actual frequency of sampling that would be employed in long-term monitoring programmes would depend upon trial results. Dataloggers would be provided in the first instance and options to convert to a telemetry system were specified.

Water quality surveys of the River Ganges

These investigations represent part of a large programme of surveys carried out in 1987 and 1989 in the vicinity of major cities known to contribute significant pollution loads to the Ganges. All survey sites were potential sites for the introduction of ARQM. These were in the vicinity of Allahabad and Kanpur (surveyed in 1987) and Kannauj, Kanpur, Patna and Barauni. Three sites on the Hoogli Estuary near Calcutta were also surveyed in 1989 and as noted above, surveys were carried out at Varanasi in both 1987 and 1989 (Themes Water International, 1987 and 1989).

Figure 2 Schematic drawing of river quality monitoring station

Topographical, physico-chemical and bacteriological surveys were undertaken across transects at strategic points in the vicinity of the cities studied with effort being concentrated upstream and downstream of the major effluents. A series of depth profiles was recorded at selected transect locations, the number of measurements being dependent upon the variability of the river. The depth profiles showed river bottom features identified by echo sounder. At full transect sites profiles of the flood plain were fixed using the electronic distance measurer.

The results of the river surveys at Varanasi are summarised in Figures 4, 5 and 6 which are examples of a cross-sectional dissolved oxygen profile, bacteriological results and a management summary diagram indicating the distribution of pollution in the river.

Figure 4 Examples of cross-sectional dissolved oxygen profile of the River Ganges at Varanasi, 1987

Figure 5 Bacterial counts: thermo-tolerant coliforms/100 ml, Varanasi, April 1987

Figure 6 Schematic diagram of water depth profiles and pollution streaming: summary of survey findings, Varanasi, 1989

Discussion

Reasons for the use of ARQM on the River Ganges

In order to fulfil the aim of the Ganga Action Plan to improve the water quality status of the River Ganges, it is essential to have comprehensive information on the river's quality on a 2 hour basis. ARQM systems will assist in gathering this information.

ARQM serves to complement the limited laboratory facilities in India and the system specified has an advantage of being based on and adapted from a proven system in operation on the River Thames. The modular design should assist in maintenance and the in-situ configuration will allow the ARQM stations to be easily moved to new sites if required.

The survey work involved in locating suitable monitoring sites improved the basic knowledge of the water quality of the river and the Indian team trained during the surveys has continued to undertake detailed surveys at other sites on the Ganges. The survey equipment used was given to the GPD by the Overseas Development Agency.

Implementation of the ARQM system

The contract to manufacture equipment was awarded to Envirotech (India) Ltd following an international tendering exercise according to World Bank rules. The Indian company tendered a competitive price and some advantage was seen by the Indian government in awarding the contract to an indigenous company. Most of the specialist components were from USA or UK. Considerable delays in manufacture ensued and although the company was competent in electronics and process control it had no experience of constructing equipment to operate in the aquatic environment and considerable redesign of the 'wet end' of the ARQM was required before any acceptable reliability was achieved.

A simple modular approach to equipment design and maintenance was taken with a view to achieving as 'appropriate a technology' as possible for the Indian environment. The use of in-situ probes and the exclusion of ammonia monitoring assisted in this. The commissioning trials of the equipment seem promising but the reliability of the equipment and the ease of servicing cannot be assessed fully until the system is operational. The use of solar power should enable the equipment to operate at truly remote sites and should be well suited to the Indian climate.

The experience of operating ARQM on floating piers on the tidal Thames was particularly relevant and formed the basis for the design which utilises in-situ deployment of the sensors. The harsh environment, including fluctuations in water level, fast current speeds, probability of physical and biological fouling and remote locations meant that the technology developed for the tidal Thames system was applicable. Dissolved oxygen, temperature and conductivity sensors of a similar type to that used on the tideway were supplemented with turbidity and pH, additional factors important to the Indian water quality objective scheme. Measurement ranges were also adjusted to the Indian requirement. Most of the ARQM stations on the tidal Thames are mains powered with the exception of the self-contained floating monitoring station at Crossness. This is solar powered and although considerable scaling down of solar panels and batteries was possible for the subtropical climate, the technology was directly transferable.

Financial and data communications restrictions prevented the immediate installation of telemetered data collection from the Indian stations, although provision was made in the station design to add this at a later date. Dataloggers were installed and earlier experiences in the Thames catchment with their use assisted in the development of working practices, data collection routines and in data storage and presentation.

Finally, assistance in staff training, equipment commissioning and in setting up secure working practices has assisted in the development of ARQM in India.

Water quality of the River Ganges

The programme of surveys provided a considerable amount of information about the water quality status of the Ganges and its tributary the Yamuna (Themes Water International, 1987 and 1989. In general, the water quality of the Ganga and its major tributary, the Yamuna, is able to support a wide diversity of plant and animal species. Its fish and invertebrate communities are exceptional (Jhingran, 1978) and freshwater dolphins, extensive bird populations and reptiles were evident during the survey. High flows and the resultant dilution assist to give great powers of self purification.

Localised areas of gross pollution are associated with major cities where a variety of demands upon the river are made. In these cities the riverside is intensively used for religious bathing, drinking water, disposal of domestic and industrial waste and animal husbandry. It is in the cities and major towns where gross pollution coincides with intensive water use that environmental problems and major public health risks occur.

The major seasonal changes experienced in the subtropical environment must be taken into account when assessing water quality. The surveys were undertaken during the dry season when river flows are at their lowest and temperatures at their highest. The gross pollution from urban areas was expected to have maximum effect at this time. However, the monsoon regime of flow will have a considerable effect upon water quality (Payne, 1986). At the height of the monsoon flows, considerable dilution and river cleansing takes place. This is used by some factory complexes, for example at Barauni where effluents stored in temporary lagoons are flooded away in the monsoon (Mohan, personal communication).

At the onset of the monsoon considerable quantities of silt and other polluting matter are displaced down the river in a short period of time, the 'first flush' effect (Ittekkot et al., 1985). This has been noted on the Yamuna, downstream of Delhi where the river becomes anaerobic during the dry season and sewage sludges settle on the river bed. At the first rains this septic water, sludge and run off from the city sweeps down the river causing gross pollution resulting in major fish kills for tens of kilometres downstream (Trevedi, personal communication). The ARQM may be very important in assessing the effects of this first flush effect. Because the Yamuna has relatively little flow in the dry season the polluting effects on the river downstream are not extensive. Fish populations can recolonise from the unpolluted tributaries once the first flush has passed.

During the post monsoon period, the river flows recede and nutrients are rapidly assimilated by plant and animal activities. During the dry season, the river has the chemical and physical appearance of an oligotrophic environment. However, closer examination of the benthic invertebrate communities shows that high productivity occurs during the post monsoon period (Andrews, personal communication).

The 'oligotrophic' nature of the river in the dry season and the nature of the flora and fauna present make the river very vulnerable to damage from eutrophication. The indigenous fauna and flora are unlikely to withstand a greatly increased pollution load. The river is currently protected by the lack of mains sanitation which, combined with insufficient water resources in the majority of large conurbations, prevents the pollution load from reaching the river. The current pollution loads are a fraction of what might be expected from cities of comparable population in the West. In addition, during the dry season non point source pollution loads to the Ganges are negligible (Payne, 1986).

There are some indications that pollution loads are already increasing. For example at the major industrial city of Kanpur, the Aver is reaching saturation point and water quality is poor, although it never becomes anaerobic (Themes Water International, 1987). At other sites, the river rapidly recovered from the pollution loads generated at each city which, although causing local pollution problems, never extensively threatened the ecosystem to the same extent as at Kanpur.

The immediate problems at Kanpur may be alleviated in the short term by improving the sewage treatment works (the civil engineering is already underway as part of the Ganga Action plan). However, the overall polluting load on the river must be maintained at a low level and the requirements for effluent standards may have to be extremely strict to maintain the vulnerable riverine community.

There is some evidence to suggest that the fish and reptile community has already been damaged by man's influence and migratory fish populations are impoverished. It was likely that large migratory fish runs occurred. Now only meagre catches of small cyprinid fish are taken from the river (Jhingran, 1978). Unlike the River Thames there is no evidence to suggest that water quality forms a complete barrier, either in the estuary or the freshwater Ganges.

This complex climatic and flow regime requires a totally different pollution control strategy from that used in temperate climates, such as the UK, which is so often applied to the Indian environment. It is hoped that ARQM and associated river quality investigations will provide more information on natural, seasonal or man-made water quality changes, which will act as a basis for the management and formulation of practical solutions to public health, pollution control and environmental protection on the River Ganges.

Conclusions

River surveys yielded considerable information on the quality of the River Ganges. In general the water quality of the river is good and it is able to support a wide variety of plant and animal species. Localised areas of gross pollution are associated with major cities where a variety of demands on the river are made. Here gross pollution coincides with intensive water use and public health and environmental risks occur.

The river appears vulnerable to extensive damage if pollution loads increase significantly. The river is currently protected by the lack of mains sanitation which, combined with insufficient water resources in the majority of large conurbations, prevents the pollution load from reaching the river. The current pollution loads are a fraction of what might be expected from cities of comparable population in the west. In addition, during the dry season non point source pollution loads to the Ganges are negligible (Payne, 1986). Some evidence of the deleterious effect of increasing pollution loads were noted at Kanpur.

The research and development work undertaken in the River Thames catchment was invaluable for the transfer of the technology to the River Ganges. It enabled a structured approach to be taken to the specification of the system so as to ensure that a reliable and serviceable monitoring system was developed.

The integrated nature of the project enabled a full overview of the pollution control issues to be taken. The water quality data from the survey were fed back into predictive mathematical models enabling the design criteria for the sewage treatment plants to be calculated. Remedial work could be prioritised and short-term solutions have been progressed. These include the reciting of outfalls away from potable abstractions and bathing areas in Varanasi and Allahabad.

Water quality monitoring programmes are now underway on the River Ganges. Three prototype monitors are currently undergoing extended trials. A data archive to collect, interpret and store the data from the ARQM stations and the complementary manual sampling programmes has been developed and is being commissioned. In addition, biological monitoring methods have been developed and are in use.

Acknowledgements

The author is grateful to Thames Water International, the Ganga Project Directorate, the State Pollution Control Boards and those people involved in the project from the UK and India. The views expressed in this paper are those of the author and are not necessarily those of Thames Water International, the ODA or the National Rivers Authority.

References

CENTRAL BOARD FOR THE PREVENTION AND CONTROL OF WATER POLLUTION (CPCB) (1982) Basin Sub-Basin Inventory of Water Pollution; The Yamuna Sub-Basin, Part I. Department of the Environment, India, New Delhi.

CENTRAL BOARD FOR THE PREVENTION AND CONTROL OF WATER POLLUTION (CPCB) (1984) Basin Sub-Basin Inventory of Water Pollution; The Ganga Basin, Part II. Department of the Environment, India, New Delhi.

GOVERNMENT OF INDIA (1985) An Action Plan for the Prevention of Pollution of the Ganga, (Reviled duly 1985). Central Ganga Authority, Department of the Environment, India, New Delhi.

ITTEKKCOT, V., SAFIULLAH, S., MYCKE, B. and SIEFERT, R. (1985) Seasonality and geochemical significance of organic matter in the River Ganges, Bangladesh. Nature, 317, 800-803.

JHINGRAN, V. G. (1978) Fish and Fisheries of India. Hindustan Publishing Corporation (India), Delhi, India.

PAYNE, A. L. (1986) The Ecology of Tropical Lakes and Rivers, John Wiley & Sons, Chichester, UK.

THAMES WATER INTERNATIONAL (1987) River Quality Surveys to Establish the Location of Automatic Monitoring Stations at Varanasi Allahabad and Kanpur, June 1987. Report No. 2, for the Central Ganga Authority. Thames Water International, Reading, UK.

THAMES WATER INTERNATIONAL (1989) River Ganga and Hoogli Estuary surveys, February to April 1989. Report No. 3, for the Central Ganga Authority. Thames Water International, Reading UK.

Discussion

The criteria used for improving river water quality was discussed. Criteria were related to intended uses including drinking, sustaining fish and particular to India, for bathing. It was said that there is a tendency for pesticides and other potential effluents to accumulate on the land during the dry season but it is flushed into the river during the first rains of the monsoon. Some industries used lagoons for storage of their effluent and relied on these being flushed out during the monsoon. This was probably an acceptable procedure at present, provided that the waste did not contain a toxic component. It was asked whether the changes in flora and fauna in the Varanasi indicated that the river was more seriously polluted than the paper suggested. Fish stocks were smaller than expected but it was said that this was due primarily to river barrages which have disrupted migration patterns. Lack of data and difficulties of access to that which existed was recognised as a serious problem.