Theme – Ground Water
IMPACT OF URBAN POLLUTION IN THE ADYAR RIVER AND THE ADJACENT GROUNDWATER IN CHENNAI CITY
G.V. Suresh1, G.J. Chakrapani1 and R. Ramesh2
1 Department of Earth Sciences Indian Institute of Technology, Roorkee- 247667
2 Institute of ocean Management Anna University, Chennai - 600025
Surface water sourses are normally a major source of recharge to the groundwater system and consequently, a possible source of contamination of groundwater, when these water courses are polluted as it often happens in an urban environment. Several ephemeral streams/rivers traverse the Chennai city. The Adyar river flows across the Chennai city and is heavily polluted by means of municipal and industrial waste waters. An attempt has been made here to study the present status of pollution in the river and the possible influence on the groundwater of the adjacent areas. The study revealed high concentrations of Nitrite, Ammonium and Phosphate in the river and groundwater, and in many locations in the city. The study clearly showed the influence of river water on groundwater quality. Correlation analysis between river and groundwater suggest that the contamination of groundwater at many places towards downstream might be due to the pollution of river by a few point sources like outlets from industrial units and untreated sewer drains from human settlements located in the upstream areas. The easterly hydraulic gradient might also have favored the downstream migration of contaminants.
GROUNDWATER QUALITY MAPPING FOR AGRICULTURAL PURPOSES IN A SEMI-ARID RIVER BASIN IN TAMIL NADU
Reader, Department of Geography, School of Earth Sciences,
Bharathidasan University, Tiruchirappalli - 620 024.
All water samples contain various salts in solution but the kind and amounts vary depending upon their sources of origin, places of their movement and the geologic-geomorphic conditions. A generalized statistics of the groundwater quality or quantity does not express which parts of the basin / area are highly favourable for development and where not. Generally, the spatial pattern of a particular salt is associated with other salts present in the parent rocks and soils of the area. Various agents of erosion and deposition like river, wind, groundwater etc., affect the higher / lower salt content of the area appreciably. Vaippar basin, a rain shadow tract in Tamil Nadu, is selected to study the spatial pattern of salinity - alkalinity levels for agricultural purposes.
To assess the groundwater quality, 82 groundwater samples have been collected throughout the basin during July and December months. The major water quality measures like EC, SAR and pH have been estimated for all the samples. Based on the modified Richard’s classification of groundwater for irrigation purposes, developed by Kumaraswamy (1984), has been used in this paper to classify the groundwater samples for agricultural purposes.
The analysis of chemical constituents and their derivatives determine the alkalinity and salinity levels of groundwater samples and the level of contamination by select chemical substances. Usually, the upper limit of EC for water used in irrigation is 5000 micromhos / cm at 250 Celsius. But the same quality waters may not suit for all crops or for all climate conditions. In the Vaippar basin, the EC value varies between 500 and 15000 mmhos/cm. The spatial pattern of the EC is uneven and it is higher in all those areas where higher TDS values occur. While adopting the Wilcox’s (1955) method of classification, of irrigation waters, no sample shows water of excellent quality (less than 250 mmhos/cm). Fifty percent of the wells portray either doubtful to unsuitable quality conditions for irrigation purpose. Only 5 to 8% of the wells oscillate between doubtful condition and good quality during rainy months. Thus, the EC values furnish evidence that the groundwater quality of the basin is not satisfactory for irrigation. The high EC values are found in intensively cultivated and densely populated areas.
Normally, groundwater of good quality (SAR) value of 10-25, unless any one of the elements viz. Chloride, sulphate, carbonate, predominates as the constituents. In Vaippar basin, the high SAR values are found only in the central basin . Moderate SAR values are noted outside the central basin, and in most parts of the basin the sodium concentration is not in itself a quality problem. Sodium saturates with the increase of other chemicals (other than calcium and magnesium) and resulted to alkalinity and salinity problems. The hydrogen ion concentration (pH) pattern shows that the alkalinity is widespread all over the basin. The average pH value for the basin is 7.89 and it varies between 7.2 and 8.4, indicating the dominance of alkalinity. The lower part of the basin is deteriorated with higher alkalinity problems.
Based on modified Richard’s classification (1964), the groundwater samples of Vaippar have been classified (Table 1). About 50% of the samples show medium to very high salinity hazards in the basin. The sodium is high to very high in about 20% of the groundwater samples.
The spatial distribution of the saline-alkaline hazard classes, thus derived, shows small patches of low salinity and low alkalinity zones are found (C2S1) close to the confluence of the river Vaippar. The water quality is a severe handicap to the soils having C5S4 class of ground water with very high salinity-alkalinity levels and when used for irrigation makes the soil condition worse and barren. Fallow lands are not uncommon in these areas. Close to these patches, the groundwater samples are either C4S4 or C4S3 classes (high salinity, very high to high alkalinity).
The study shows that, among various chemical parameters, the salinity and alkalinity influence the agricultural activities to a considerable extent in the basin. By adopting the modified groundwater classification methodology, about 50 % of the water samples are doubtful to unsuitable conditions and about 20 % are with high to very high alkalinity problems for agricultural purposes. The spatial patterns of the combined effects of the salinity-alkalinity problems delineate the areas for reclamation and effective use of groundwater for agricultural purpose.
ASSESSING THE EFFECTS OF SODIC WATER IRRIGATION ON SOIL AND GROUNDWATER QUALITY
M.J. Kaledhonkar1 and Ashok K. Keshari2
1 Division of Irrigation and Drainage Engineering, Central Soil Salinity Research Institute, Karnal 132001
2 Department of Civil Engineering, Indian Institute of Technology, New Delhi-16
In the semi arid regions of the North -Western India, wheat based crop rotations namely rice-wheat, cotton-wheat and millet-wheat are common. The semi arid climate prevailing in this part of the India necessitates the application of supplemental irrigation by means of canal and ground water for optimizing crop production. In case of limited canal supply, farmers are more dependent on groundwater supply for irrigation water. However, in several districts of Punjab, Haryana, Uttar Pradesh and Rajastan groundwater is of poor quality (i.e. either saline or alkali). Sodic groundwater adversely affects the crop production in about 25% and 21% of total cultivated area in states of Punjab and Haryana, respectively. As intensive agriculture is practiced in the region, the indiscriminate use of sodic ground waters for crop production may enhance the rate of sodification of the root zone. It may adversely affect the soil physical and chemical properties of the soil. In order to maintain the productivity level of the agriculture, the farmers are tempted to use the gypsum on large scale. The Ca2+ ions from the applied gypsum may enter into soil exchange complex while dissolved Na+ and SO42- ions may reach to groundwater through unsaturated zone as deep percolation. The use of sodic water in agriculture and application of gypsum to prevent sodification process may deteriorate the soil health and groundwater in the long term, respectively. The present study is aimed to assess the potential effects of such processes. In this paper, the UNSATCHEM model is used to assess how textural classes of the soil influence sodification process. Simulations for different textural classes are carried out while keeping the quality parameters of the sodic water the same. The sodic water quality is mainly defined by the sodium adsorption ratio (SAR) and residual sodium carbonate (RSC). The effect of the individual quality parameter like SAR or RSC on sodification is also judged through simulations. The conjunctive use of sodic and canal water is generally practiced by farmers. Simulations are carried out to investigate the effect of change of irrigation water quality on sodification process. Further two cases of gypsum application to reverse the sodification process are considered and its effects on the movements of Na+ and SO42- ions through deep percolation are investigated.
GROUND WATER CONAMINATION THROUGH LANDFILLS IN NCT DELHI
A.N Bhowmick1, Arijit Dey2 and D. Chakraborty1
1Member Secretary, Central Ground Water Authority, New Delhi
2Scientist, Central Ground Water Authority, New Delhi
The hazard of urban landfills to ground water via leachates if one of the major environmental problems our country is facing in the 21st century. During last decade, solid waste produced in India had been at nearly twice the rate of the population growth. The total municipal waste generated from Indian Cities is estimated around 48,184 tonnes per day, of which 62% is contributed by 23 metrocities alone comprising about 51% of the total population of class I cities. Leachates, an inevitable product from landfills, containing mostly volatile organic compounds, synthetic organic compounds and heavy metals, in absence of protective measures like liners, leachate collection and treatment systems undoubtedly poses serious threat to the ground water system.
The capital city of the country alone generates about 5000 Metric Tonnes a day, which is about 5 times the national average. NCT Delhi has 16 filled up landfills covering an area of 180 hectares and three active landfills, covering an area of 60 acres. As per an estimate (Dinesh Kumar et al, 2001) the landfills of NCT Delhi cumulatively generate a significant quantum of 814800 cum of leachates annually, which is alarming from ground water quality point of view
In the present paper issues related to ground water contamination through Municipal landfills leachates in NCT Delhi have been discussed. An attempt has also been made to evolve abatement measures on ‘Hydrogeologic design principles’ and policy guidelines for mitigating the menace of ground water contamination through landfill sites.
FLUORIDE CONCENTRATION IN GROUND WATER IN INDIA AND ITS EFFECT ON HUMAN HEALTH -AN OVERVIEW
Jawed Raza, M.K.Garg and S.Shekhar
Central Ground Water Board, NH-IV, Faridabad, Haryana
Over the years rapid strides have been made in India to mould the availability of water to match country’s manifold water demand. However, in some part of the country ground water pollution problem has not been addressed properly. Water is frequently referred to as a universal solvent, because it has the ability to dissolve almost all substance; that comes in its contact. Some elements are essential in trace amount for human being while higher concentration of the same can cause toxic effects. Fluoride is one of them. It is a conclusive fact that concentration between 0.6 to1.2 mg/ l is essential to protect teeth decay, while higher concentration (beyond 1.5 mg/l) can cause teeth mottling and still higher concentration of fluoride may lead to different major health hazards .The importance of developing quality drinking water system facilities in any health care programme of the country can hardly be over emphasized.
It is, therefore, imperative that groundwater, free from higher fluoride concentration needs to be explored & where ever the concentration is high, mitigation strategies have to be adopted on urgent basis. Fluorosis was first detected in India among cattle’s by farmers of Nalgonda district (A.P) during early 1930’s .It was during years later; the same disease was detected in human being. However subsequent investigations have established that, the total number of states declared endemic for fluorosis are 15 by the year 1992. In this paper an attempt has been made to synthesize available information on fluoride concentration in ground water of the country, its effect on human health and possible remedial measures have also been looked in to.
IMPACT OF OVER-DEVELOPMENT ON QUALITY ASPECTS OF GROUND WATER REGIME IN NCT, DELHI
S.K. Mohiddin and D. Chakraborty
Scientists, Central Ground Water Board, Jamnagar House,
Mansingh Road, New Delhi – 110 011
Natural replenishment of ground water resources occurs very slowly, therefore, excessive continued exploitation of ground water at a rate greater than the natural replenishment causes decline in ground water levels as well as deterioration of quality. Evidences of decline in quantity are more pronounced and corrective measures can be taken up to arrest the decline in quantity. But quality deterioration is more concealed and may result into complete deterioration of ground water beyond correction, except leaving the aquifer without any ground water development. Systematic analysis of ground water quality in NCT, Delhi with time series shows that the quality deterioration and shallow ground water from more and more areas turning fresh to brackish/ saline. Presently about 45% of NCT, Delhi has brackish to saline water where as the saline area in 1997 was only 25%. Effective ground water management techniques are suggested to arrest the spreading of aerial extent of brackish water zones is suggested.
SUSTAINABILITY OF FRESH GROUND WATER RESOURCES OF NATIONAL CAPITAL TERRITORY OF DELHI
S.B. Singh and S.K. Mohiddin
Scientists, Central Ground Water Board, Jamnagar House,
Mansingh Road, New Delhi-110 011
Chemical quality of ground water in N.C.T., Delhi varies with depth and space. Brackish ground water mainly exists at shallow depths in Northwest, West and Southwest districts with minor patches in North and Central Districts also. In alluvial formations, the quality of ground water deteriorates with depth, which is variable in different areas. The ground water is fresh at all depths in the areas around the ridge in the Central, New Delhi, South and Southwest Districts and also Chattarpur basin. In the areas west of the ridge, in general, the thickness of fresh water aquifers decreases towards north-west, the thickness of fresh water zones being limited in major parts of west and south-west. In the flood plains of Yamuna, in general, fresh water aquifers exist down to 30-45 m. Thus a limited thick fresh ground water resource is present in NCT, Delhi that need to be protected. Static Ground Water Resources have been calculated considering the thickness of alluvium upto 200 m bgl and specific yield as 10%. On the basis of this the, Static Resources of fresh water in alluvium is calculated as 1866 MCM and hard rock quartzite as 28 MCM. Thus the total fresh Static Ground Water Resource is estimate as 1894 MCM. It is estimated these fresh static resources will be exhausted within 10 years period, if about 2650 moderate to high yielding tubewells are constructed. Effective management tools have been recommended for sustainability of ground water resources of NCT, Delhi making the ground water development as the best option for solving the water supply problems of Delhi.
GROUND WATER POLLUTION MANAGEMENT IN COASTAL TRACT
S.K. Sinha and S.K. Swaroop
Central Ground Water Board, Jamnagar House,
Mansingh Road, New Delhi -110 011
The high productivity of the rich coastal Eco-system has attracted development and high population density. The anthropogenic influences on the coastal geomorphology is large, particularly near the development centers. The rivers contributes to coastal pollution by transporting a wide range of pollutants through land drainage. Ground water is one vital component of coastal zone resources, which provides fresh water flow to sustain ecology, agriculture, development and urbanization.
The river water in coastal areas acts as one of the major source for ground water recharge. Sea water is the major pollutant of groundwater in the coastal tract. The influence of sea water reduces with distance from the coast. The natural recharge water contains some major ions like Na, Ca, Mg, HCO3, Cl and SO4. The quality of ground water evolves through interaction with the host sediments and the residence time in the aquifers. The cation exchange process in the clayey sediments, Sulphate reduction by Sulphate reducing bacteria, and sea water contamination are the various factors influencing the quality of ground water. While fresh Na-HCO3 waters are obtained in tubewells close to the coast, Na-Cl waters are obtained in cases far inland. All saline waters in coastal area are of Na-Cl type.
Ground water in the coastal tract varies widely from fresh to saline. In general, the shallow ground water varies from fresh to saline while the deeper aquifers are saline. There is a lot of heterogeneity in distribution of quality both vertically and spatially. Three of the country’s four largest metropolitan cities with burgeoning population are situated along the coast. Besides the nine coastal states; Gujarat, Maharashtra, Goa, Karnataka, Kerala, Tamil Nadu, Andhra Pradesh, Orissa and West Bengal the three union teritories; Pondicherry, Andaman and Nicobar Islands have significant coastal stretches. There are varying degrees of pollutants added to the coastal areas because of the multiple variety of effluents flowing into the sea.
Coastal Ground water quality management comprises the whole set of technical institutional, legal and operational activities. "Groundwater pollution" is the key word in ground water quality management. Assessment and prediction of a ground water pollution situation, ground water protection from pollution and remediation of polluted ground water are the main ground water quality management task. Among various methods used to assess and predict ground water pollution, solute transport modeling and ground water vulnerability assessment can be distinguished as being the most important.
Solute transport models in ground water is largely governed by the parameters, which also shape the flow equation. In addition, it is governed by the factors: (i) advection of the constituent with the water flowing through the aquifer, (ii) dispersion of the constituents, and (iii) sources and sinks of the constituents within the volume. Without solving ground water flow equation, the contaminant transport equation cannot be solved. The most general classification of Vulnerability assessment approaches includes methods employing process- based simulation models, Statistical / Stochastic methods and overlay and index methods. DRASTIC models is one of the system models based on the index methods which is widely used in the vulnerability assessment of the coastal aquifers.
Coastal Ground water problems are by definition hydrogeological problems. Various software tool have been developed to assist in decision making which works in isolation. However, Integration of software tool speeds up processing of quantitative (numerical) information, but complementary qualitative information (Knowledge) is needs to enhance analysis, processing and interpretation. In an ideal case, the user would posses all the knowledge required, but even then knowledge integrated into Decisions Support System (DSS) would be a much useful tool. The type of quality management problem defines substantially the requirement for the analysis, processing and presentation of the information and therefore the various software tools that might be required to be integrated into DSS for quality management.
NEED FOR AWARENESS TO PROTECT GROUND WATER – A CASE STUDY
Uma Kapoor, S.K. Mohiddin and K.J. Anandha kumar
Central Ground Water Board, Jamnagar House,
Mansingh Road, New Delhi - 110 011
A study was carried out in an area of 2 Sq. Km, in parts of Ghaziabad town, on the reported ground water pollution in that area, with a view to demarcate the extent of ground water pollution. The area is predominantly underlain by older alluvium comprising of clay and sand mixed with kankar and gravel. Medium to coarse sand mixed with gravel serve this area as very good aquifer system. Most of the tube wells located in the area are withdrawing the ground water from the coarse sand and gravel bed situated between 40 and 75 metres below ground level.
The detailed study, followed by analysis of data and results of the ground water samples collected indicated that Para-nitrophenol, an intermediate product during the synthesis of paracetamol may be the cause of yellow colour of the water being pumped out by the tube well, which is tapping the aquifer zone between 45 to 55 metres below ground level.
This study has highlighted the need of awareness to use safer disposal methods especially when industrial effluents are to be disposed off. Several other suspected cases of injection of industrial effluents in the ground water were reported earlier also. It is more important to make people or industries aware about this way of ground water contamination because ground water contamination, hidden from the direct view can go undetected for years until the particular aquifer is tapped. Further the reclamation and remediation of the contaminated aquifer or cleaning ground water by pumping out and treating before use or in the worst case abandoning the aquifer and location of alternate aquifer to supply water to the area where the contaminated aquifer was supplying water are all very costly and not at all economical especially considering the economic status of our country.
It is also important that the study for location or relocation of industries should include hydrogeological studies of the area. Heavy amount of withdrawal of ground water in the towns where habitation is more, tend to change the ground water flow towards it. This ground water flow will also result in contamination of ground water being used, by public, if effluents discharged from the industries in and around the town have already polluted the ground water.
There may be need for regulation on development and management of ground water resources in areas prone to ground water contamination. Need of the hour is to study the data and reports of various agencies to locate the areas prone to such ground water pollution, so that the ground water is protected and developed in a sustainable way to serve the coming generation also.