Spatial analysis of Yamuna River water quality in pre- and post-monsoon periods

Transcription

1 Water Quality: Current Trends and Expected Climate Change Impacts (Proceedings of symposium H0 held during IUGG2011 in Melbourne, Australia, July 2011) (IAHS Publ. 3, 2011). Spatial analysis of Yamuna River water quality in pre- and post-monsoon periods R. B. SINGH & VANEETA CHANDNA Department of Geography, Delhi School of Economics, University of Delhi, Delhi-1007, India Abstract Water quality has interrelationships with anthropogenic activities. The water quality status of the Yamuna River, India, was evaluated spatially in terms of its physical, chemical and biological parameters for both pre- and post-monsoon periods. For the River Yamuna, ph decreased from site 1 to site and then increased from site 5 to 7, showing the alkaline nature of river water. Dissolved oxygen increased slightly at site 2 and then decreased markedly to 0 at site. As the river passes through the Delhi metropolitan city, the pollution load increases from various sources (both point and nonpoint). During the post-monsoon period, there are slight changes in the water quality of the river water due to dilution. With the impending climate change and its impact on the Himalyan river system, the long-term runoff is expected to decrease, whereas short-term flooding will pose more challenges for water quality in terms of increasing concentration of pollutants. Key words seasonal water quality; spatial analysis; Yamuna River; pollution variability; Delhi metropolitan region, India INTRODUCTION In India, the River Yamuna, the main source of water supply to Delhi, suffers from deteriorating water quality. The increasing population has mainly resulted in various anthropogenic activities contributing to water quality deterioration. The major contaminant sources include domestic wastes and industrial effluents. The large demand for water supply and associated sanitation conditions due to the lack of supply in Delhi has resulted in severe water-quality variations of the River Yamuna (Centre for Science and Environment, 12; Trivedy & Goel, 1). The pollution problem of River Yamuna flowing in National Capital Territory (NCT) Delhi was studied with respect to its water quality within a spatial and temporal framework. This paper aims to depict the driving forces, spatial distribution and temporal variations of water quality in different river reaches. Pre- and post-monsoon analysis of the water quality was carried out to show the effect of monsoon. Melting of glaciers in the Himalayan region due to climate change have had a significant impact on the streamflow, as the Yamuna originates from this region. In the short term, climate change-induced flooding will increase pollution loads from agricultural, domestic and industrial sources. In the long term, as water flow decreases, pollution loads will continue to influence the water quality of Yamuna River as millions of people depend on river water for their basic needs, including drinking, bathing and irrigation. The River Yamuna is the largest tributary of the River Ganga and the main source of fresh water in north India. Originating in the Himalayas and flowing through seven states, its total length is 137 km, (22 km in Delhi) with a catchment area of km 2. The River Yamuna occupies a unique position in the cultural ethos of India. As it reaches Delhi, it is flanked by two small dams, viz. Wazirabad and Okhla. The sources of pollution in River Yamuna are the industries located in and around the Delhi Metropolitan Region, sewage disposal and household wastewater from residential areas and chemicals from agriculture fields. It has practically no perennial flow of its own and receives partly treated and untreated wastewater effluents from Delhi. Therefore, this reach is the most polluted of those monitored (Fig. 1(a)). TEMPORAL ANALYSIS OF WATER QUALITY Pollution of the River Yamuna in Delhi has increased markedly with increasing urbanization. The objectives of the study reported herein are to investigate the temporal change in pollution. The tests performed were categorized broadly into three tests corresponding to physical, chemical and Copyright 2011 IAHS Press

2 Spatial analysis of Yamuna River water quality in pre- and post-monsoon periods (a) (b) Fig 1 (a) Location map of study area, and (b) water quality sample sites in various zones. biological characteristics (CPCB, 17). The average ph in the reach of the Yamuna in Delhi for the four stations, Palla, Nizamuddin, Okhla Barrage and Okhla Exit, ranged from 7. to.1 based on monitoring conducted by the Central Pollution Control Board (CPCB). There are no marked variations in ph from 15 to 2005 at the four stations, and this reflects marginal alkalinity. The dissolved oxygen (DO) for each station in general shows a decreasing trend from Palla to Okhla Exit (Fig. 1(b)). From Palla to Nizamuddin, the contribution of average biological oxygen demand (BOD) load increased in comparison to the preceding year. BOD at Okhla Exit during 2005 was three times higher than at Okhla Barrage, i.e. 15 mg L-1 compared to 50 mg L-1. The maximum concentration of chemical oxygen demand (COD) at Palla was observed during 1. Also, COD increased downstream and the maximum COD concentration at Okhla from 2000 to 2005 was 120 mg L-1 (Fig. 2(a) (c)) (CPCB, 200). The average total faecal coliform (TC) concentrations were high, ranging from 3700 counts per 0 ml during 15 at Palla to 1 counts/0 ml at Nizamuddin during Most TC concentrations were extremely high and exceeded water use standards (American Public Health Association, 17) during 2003 at Nizamudin and Okhla Barrage. At Palla, the TC varies from 230 to 00 counts/0 ml (Fig. 2(d)). The average TC decreased from 15 to 1 at Palla, Nizamuddin and Okhla Barrage. The average TC fluctuated as the river enters Delhi at Palla during 15 to 2005, but in general, TC increased markedly both downstream and with time. WATER QUALITY IN THE PRE-MONSOON PERIOD (JUNE 2007) For the primary survey the river reach was grouped into five zones with characteristics varying within each zone, i.e. zone 1 (agricultural flood plain), zone 2 (residential and household industrial wastes), zone 3 (urban agriculture), zone (power plants and sewerage wastes) and zone 5 (industrial wastes). These characteristics have both direct and indirect effects on water quality at the sites which lie between Palla and Okhla Exit. The colour of the river changes from clear to dark grey downstream from site 1 to. The also becomes pungent downstream. Water

3 R. B. Singh & Vaneeta Chandna DO (in mg/l) YEARS (a) YEARS (b) COD in (mg/l) YEARS FC (in million/0 ml) (c) (d) Fig. 2 Temporal trends in select water quality parameters along the River Yamuna in NCT from 15 to 2005: (a) dissolved oxygen (DO); (b) biological oxygen demand (BOD); (c) chemical oxygen demand (COD); and (d) faecal coliform (FC) temperature increases from 30ºC to 32.5ºC and stream velocity decreases from 0.5 to <0.02 m s -1 for sites 1 to, respectively. The ph is 7.7 at site 1 and decreases to 7.2 at site. At site 5 near Gandhi Nagar, ph increases to 7., which may be due to a more alkaline content of water discharged by drains carrying industrial and domestic effluents (Manivasakam, 1). From site to, ph decreases to 7.. In the entire reach of the River Yamuna in NCT, Delhi, DO decreases from 11. to 0.5 mg L -1 at sites 1 and, respectively. The DO decrease is pronounced from site 1 to (11. to 2.1 mg L -1 ), which is followed by a more gradual decrease from 2.0 to 0.5 mg L -1 from site 5 to (Table 1). Table 1 Average values of chemical parameters at water-quality sampling sites along the River Yamuna during the 2007 pre-monsoon period. (Units: mg L -1, except for Coliform count). Sites ph DO Total hardness TDS Calcium Magnesium Nitrate Fluoride Total Coliform Source: Primary survey.

4 Spatial analysis of Yamuna River water quality in pre- and post-monsoon periods 11 Hardness increased gradually from site 1 to. Total dissolved solids (TDS) increased for all the water samples from site 1 to. Calcium (Ca) concentrations increased from site 1 to 3, decreased at site, increased markedly at site 7 and then decreased to site. The Ca concentration is much higher than the permissible limit of 75 mg L-1 (Golterman, 1) at all sites. Magnesium (Mg) concentrations increased from site 1 to, i.e. from 0 to 0 mg L-1, respectively. Nitrate (NO3) concentrations increased from site 1 to, and the increase is attributed to fertilizer use in the agricultural fields along the river (Singh & Pandey, 1) (Fig. 3(a) and (b)). Fluoride (F) concentrations increased from site 1 to, i.e. from 0.5 to 1.5 mg L-1, respectively. The water quality of the Yamuna River with respect to total coliforms (TC) deteriorates from site 1 to site. TC ranged from 000 counts 0 ml-1 at site 1 to 2 counts 0 ml-1 at site, which is extremely high for any beneficial use. Fig. 3 (a) Spraying of insecticides in the fields along the River Yamuna; (b) pollutants entering from a drain. WATER QUALITY IN THE POST-MONSOON PERIOD (OCTOBER 2007) Analyses of the same physical and chemical parameters of water quality along the River Yamuna were done at the same selected sample sites during the post-monsoon period in October 2007 (Table 2). The ph fluctuated from site 1 to, but is generally circum neutral to alkaline. It is only for site 1 that the ph is <7, while for all the other sites it is >7. Pollutants draining the neighbouring Panipat industrial area likely caused the low ph at site 1. For the post-monsoon period, DO is a maximum for site 1, i.e..0 mg L-1, and decreased gradually from site 1 to (Table 3). For the post-monsoon period, total hardness increased from 220 to 500 mg L-1 at site 1 and sites and, which is hypothesized to be associated with an increased contribution of alkaline waters from site 1 to site derived from the dissolution of carbonate minerals. TDS is the lowest at site 1 (70 mg L-1). There is not much variation in TDS until site 3, where TDS increased to 0 mg L-1. Thereafter, there is a progressive increase in TDS with the maximum of 0 mg L-1 at site. This could be due to the addition of wastes from both point and nonpoint sources (Sykes & Skinner, 11). Table 2 Average values of physical parameters at water-quality sampling sites along the River Yamuna during the 2007 pre-monsoon period. (Units: mg L-1, except for Coliform count). Sites Colour 1 Clear No Temp. (ºC) 27 Stream velocity 11 (m/ s) Source: Primary survey. Odour 2 Light brown No blue No 2 blue Slight 2 5 Unpleasant 2.5 Stinking Stinking 2 Rotten egg 30 5 Pungent 30.5 Pungent 30.5

5 12 R. B. Singh & Vaneeta Chandna Table 3 Average values of chemical parameters at water-quality sampling sites along the River Yamuna during the 2007 monsoon period. (Units: mg L -1, except for Coliform count) ph DO T Hardness TDS Calcium Magnesium Nitrate Fluoride Total Coliform Source: Primary survey. Ca concentrations increased gradually from site 1 (75 mg L -1 ) to site (20 mg L -1 ). After this, there is only a slight change in the values for site and. Mg concentrations increased gradually from site 1 (30 mg L -1 ) to site (5 mg L -1 ) due to power plants and auxiliary iron industries. Subsequently, the Mg concentrations decrease slightly at site to 0 mg L -1. NO 3 concentrations increased gradually from site 1 (0 mg L -1 ) to site (120 mg L -1 ); at site it decreased to 1 mg L -1 and thereafter at site it again increased to 120 mg L -1 ; The increase from sites to might be due to an increase in fertilizer use and mobilization from adjacent fields to the river. Fluoride concentrations increased from site 2 (0.50 mg L -1 ) to 3 (1.0 mg L -1 ), increased again at site and 5 (1.25 mg L -1 ), remained the same through to site (1.25 mg L -1 ) and then increased at sites and (1.50 mg L -1 ). TC concentrations increased from site 1 ( MPN L -1 ) to site ( MNP L -1 ). WATER QUALITY ANALYSIS IN THE CONTEXT OF CLIMATE CHANGE The major water-quality differences between the pre- and post-monsoon periods are: (1) The ph was slightly lower for samples collected during the post-monsoon period compared to the premonsoon period. (2) DO and TDS concentrations were higher during the post-monsoon period than during the pre-monsoon period for all the sites. The lowest DO was 0.3 mg L -1, which is much lower than the average DO of mg L -1 during the post-monsoon period. (3) Total hardness fluctuated markedly at all sites during the post-monsoon period, indicating that dilution associated with the monsoon did not have much of an effect on the water quality. () Ca concentrations were similar for both periods at site 1 (75 mg L -1 ). Ca concentrations at the other sites were less during the post-monsoon period compared with those of the pre-monsoon period. (5) Mg concentration patterns were similar to those of Ca. () NO 3 concentrations were lower at each site during the post-monsoon period than during the pre-monsoon period. (7) TC concentrations were markedly lower at each site during the post-monsoon period. The lower concentrations for many of the constituents during the post-monsoon period is attributed to dilution by the rainfall during the monsoon. Rainfall occurs for only 3 months each year from July to September, and the amount fluctuates within the period and from year-to-year. The fluctuations and amounts are likely to increase with the changing climate. The surface water during the pre-monsoon period is used for irrigation and domestic purposes. Water scarcity is increasing due to abstraction and increasing water demand by an increasing population. The abstraction degrades water quality. Water scarcity is expected to increase due to changes in rainfall due to climate change, as will the deleterious effects on water quality. Unpredictable and irregular rainfall leads to intermittent dam releases at Wazirabad and Okhla into the downstream of the river leading to dilution of the pollution load and significant change in water quality. Delhi has recently experienced an increase in the western disturbances. Specifically, winter rains occurring in northwestern India, which originate from the Mediterranean Sea and are brought by the jet stream, have resulted in more water availability

6 Spatial analysis of Yamuna River water quality in pre- and post-monsoon periods 13 during the winter. The knock-on effect is that farmers are using more fertilizers to produce winter crops in comparison to summer crops, thus the western disturbances induced rainfall has caused higher fertilizer use, resulting in higher pollutant loads reaching the River Yamuna. POLLUTION MITIGATION MEASURES FOR ENHANCING WATER QUALITY There have been various water related plans and projects to improve the water quality of the River Yamuna, i.e. to keep it from becoming a dead river. Following the recommendations of the Ganga Action Plan (GAP), the Yamuna Action Plan (YAP) was implemented in 13 (Central Pollution Control Board, 200)). Treatment capacity has increased almost -fold during the last 0 years, but wastewater generation has grown faster, i.e. 12-fold, during the same period. Various actions to control the deteriorating water quality of the River Yamuna have been suggested. The actions include: (1) construction and use of sewage treatment plants at the mouth of major drains, eliminating the problems of sewage supply and discharge. Special care should be taken during the winter when water flow is the lowest. Alternatively, the city s wastewater could be diverted away from Delhi by a master drain built along the banks of the river to a master water treatment plant at a distance from the river; (2) construction of low cost toilets and crematoriums; (3) the minimum flow required by the river should be maintained; () encouragement of proper application of fertilizers and use of alternative organic fertilizers; (5) relocation of factories still operating on the banks of the River Yamuna; () use of treated effluent, both domestic and industrial, for irrigation; (7) idols immersed in the river during cultural festivals should be made of traditional clay rather than baked clay; and () discourage the alteration of the river bed. CONCLUSION The temporal and spatial analysis of the reach of the River Yamuna in Delhi indicates that the river maintains a reasonably good quality upstream of Delhi. The river degrades rapidly as it enters the Delhi metropolitan area where it receives pollution loads from various sources such as wastewater and industrial effluents. Wastewater input to the river causes a progressive and negative suite of chemical and biological events downstream. River water quality is seriously degraded in the Delhi region, with values of most parameters exceeding prescribed water quality standards. Postmonsoon water quality generally shows the effect of dilution by the monsoon rainfall. Consequently, and despite the degradation caused by increasing water abstraction and wastewater contamination, the monsoon is a key factor for improving water quality. The availability of water in the River Yamuna varies temporally and spatially, and this is already affected by climatic variability. A combination of a changing climate and increasing demand on water resources, coupled with the seasonal wet and dry cycles, water quality will likely continue to be adversely affected. Acknowledgement The authors would like to thank A. K. Gurjar for providing assistance. REFERENCES American Public Health Association (17) Standard Methods for the Examination of Water and Wastewater. APHA, New York, USA. Central Pollution Control Board (17) Manual for Water Testing Kit. Ministry of Environment and Forests, New Delhi, India. Central Pollution Control Board (200) Water Quality Status of Yamuna River (1 2005). Assessment and Development of River Basin Series. Ministry of Environment and Forests, New Delhi, India. Centre for Science and Environment (12) The State of India s Environment. New Delhi, India. Golterman, H. L. (1) Methods for Chemical Analysis of Freshwater, Handbook no.. Blackwell Scientific, Oxford, UK. Manivasakam, N. (1) Physico-Chemical Examination of Water, Sewage and Industrial Effluents. Pragati Prakashan, Meerut. Singh, R. B. & Pandey, B. W. (1) Environmental monitoring of particulate matter and pollution in major rivers of India. Adv. Limnology 7, Sykes, G. & Skinner, E. A. (11) Microbial Aspects of Pollution. Academic Press, New York. Trivedy, R. K. & Goel, P. K. (1) Chemical and Biological Methods for Water Pollution Studies. Environmental Publications, Karad, India.