SECTION-7 Ground Water and Hydrogeology

GEOLOGICAL CONTROL ON GROUND WATER QUALITY IN YELANDUR TALUK IN KARNATAKA
H.S. Mahadeswara1, D. Nagaraju1 and S.A. Sajid1


ABSTRACT
INTRODUCTION
LOCATION AND MORPHOLOGY
HYDROGEOLOGY
METHODOLOGY
RESULTS AND DISCUSSION:-1. GROUNDWATER TYPES
ELECTRICAL CONDUCTIVITY
TOTAL DISSOLVED SOLIDS (TDS)
GROUNDWATER HARDNESS
GROUNDWATER SALINITY - SODIUM HAZARD
PERMEABILITY INDEX (PI)
NITRATES
SUGGESTIONS
REFERENCES
TABLE 1: CHEMICAL CONSTITUENTS OF GROUNDWATER IN YELANDUR TALUK
TABLE 2: CLASSIFICATION OF WELLS ACCORDING TO ELECTRICAL CONDUCTIVITY
MAP-1: LOCATION OF STUDY AREA
MAP-2: YELANDUR TALUK CHAMARAJ NAGAR DISTRICT
MAP-3: ELECTRICAL CONDUCTIVITY
MAP-4: TOTAL DISSOLVED SOLIDS YELANDUR TALUK CHAMARAJNAGAR DISTRICT
MAP-5: GROUNDWATER HARDNESS YELANDUR TALUK CHAMRAJNAGAR DISTRICT
MAP-6: SALINITY SODIUM HAZARD YELANDUR TALUK CHAMRAJNAGAR DISTRICT
MAP-7: PERMEABILITY INDEX (DONEENS 1948) YELANDUR TALUK CHAMRAJNAGAR DISTRICT


ABSTRACT: first topic previous topic next topic last topic

Groundwater is generally presumed to be good for human consumption and is used as a potential source of drinking water. There is a growing realisation of the importance of protecting groundwater for its beneficial uses such as drinking, irrigation and industrial supply. Agricultural development, urbanisation and industrialization are the major causes for all changes in the quality of water. The chemical quality of groundwater of Yelandur taluk has been studied in detail in order to demonstrate the potable groundwater zones without any deterioration by pollution. The area is mainly composed of metamorphic gneisses. The groundwater occurs in the weathered and fractured zones, under unconfined and semiconfined conditions.

Thirty-one groundwater samples have been collected and analysed to determine the major ions and quality parameters. A simple computer programme HYCH in BASIC language (Balasubramanian et al., 1991) has been used to determine several important quality parameters and ratios. These have been classified into three general categories as 1) desirable, 2) permissible and 3) not permissible, based on ISI (1983) specifications for drinking purpose. The study concludes that in the rapidly growing urban environment, groundwater quality gets completely deteriorated due to human activities and the absence of proper sewage systems. Once the quality of groundwater is modified, it is very difficult and expensive for all urban dwellers to treat the water again before using it.

INTRODUCTION: first topic previous topic next topic last topic

Majority of the urban and rural population in Karnataka State depends mainly on groundwater for drinking and domestic use. Groundwater is expected to be of excellent microbiological quality and generally of adequate chemical quality for drinking and domestic consumption. Groundwater pollution resulting from land disposal of untreated liquid and solid wastes has become a serious problem in India (Bhide, 1990).

In recent years, due to an unpredictable increase in the population and settlements, surface water supply has become very limited and remote. This has resulted in increasing exploitation of groundwater. There are several extension activities that cause concern to the public and will have a detrimental reversible impact, if improperly managed. Complaints to several local bodies regarding the quality of groundwater highlight the necessity for investigation to find its suitability for consumption. In this context, a study was taken up with an objective of examining the chemical quality of groundwater and to determine its suitability for drinking and domestic consumption.

LOCATION AND MORPHOLOGY: first topic previous topic next topic last topic

Yelandur taluk is located between 110 42'-1205' North latitude and 76057'-770 09' East longitude with an area of 264.7 sq. km comprising a population of about 70000. The topography is generally undulating with few steep slopes. Southern and Northern parts have comparatively gentle slopes. The normal annual rainfall is between 620-1140 cm (Map.1).

HYDROGEOLOGY: first topic previous topic next topic last topic

The study area comprises metamorphic gneisses, charnockites, pegmatites and dolerite intrusions, overlaid by different soils and aluminum. The area is divided into two equal halves in the NE-SW direction by the contact of the charnockites lying in the eastern part of the area with the gneisses in the western part. The thickness of weathered zone ranges from 3 m to 20 m followed by a deep fracture zone. Groundwater occurs under unconfined and semi-confined conditions. As there are more undulations in the surface topography and severe heterogeneity in aquifer parameters, the groundwater potential zones are very limited (Tamata, 1990).

Rainfall is the main source of replenishment to the groundwater storage. The depth of the groundwater table is from 6 m to 20 m.

METHODOLOGY: first topic previous topic next topic last topic

Thirty one groundwater samples (Map 2) have been collected from the existing borewells located in the area and have been analysed by following the standard methods of water analysis (ISI, 1964).

A basic computer programme - HYCH (Balasubramanian, 1991) developed in the hydrogeology laboratory at Mysore University has been utilised in this study. The computer program can perform the following jobs, once the parts per million concentration data of any groundwater is fed:

  • Conversion of ppm concentration to epm values.
  • Determination of the precision and accuracy of the analysis.
  • Classification of groundwater using Handa's Classification (1964 a).
  • Determination of the indices of base exchange and the groundwater types.
  • Calculation of CaCO3 saturation indices (Handa's, 1964 b).
  • Determination of corrosivity ratio.
  • Determination of the mechanisms that control the chemistry of groundwater.
  • The evaluation of the suitability of groundwater for drinking purpose, based on either individual or gross ionic concentration, has been attempted based on the drinking water specification provided by the Bureau of Indian Standards (1983). Table I gives the ppm concentration of individual constituents, groundwater, hardness, electrical conductance and pH of the groundwater. Map 2 gives sampling locations.

    Increased emphasis on governmental policies in the environmental protection of natural resources has led to many rigorous investigations of the pollutant levels in soil and groundwater. It could be possible to assess the degree of contamination in dry domain of the environment only, when the natural background values are available for comparison with the threshold values (Bhatia et al., 1999).

    It is noticed that in some countries, contamination due to anthropogenic activities has reached such an extent that it is no longer possible to measure the true background concentrations even in hard rock groundwater.

    RESULTS AND DISCUSSION:
    1. GROUNDWATER TYPES:
    first topic previous topic next topic last topic

    The chemical classification of the water as determined by Handa (1964 a) has shown that the majority of water samples were hard (non-carbonate), had medium to high salinity and low sodium percentage. The first and foremost waters are those in which
    r -CO3 > r SO4 - Type I
    As the residence time of the water increases the relation changes to
    r SO4 > r Cl - Type II
    with increase in residence time the chemistry changes to
    r Cl > r SO4 > r CO3 - Type III
    and in the final stages the concentration reaches
    r Cl > r SO4 > r CO3 and
    r Na > r Mg > r Ca - Type IV
    (Where r is the epm content of the different ions)
    The change of water from I to IV is attributed to the relative residence time in the aquifer and extent of rock interactions.

    2. ELECTRICAL CONDUCTIVITY: first topic previous topic next topic last topic

    Ec is an index of the amount of minerals present and it varies with temperature (Map 3). Wilcox (1948) classified the utility of groundwater for irrigation purposes based on Ec. The area could be divided into 3 horizons with stray pockets of high values of conductivity (>200). Horizon with an Ec of 750-2000 mhos/cm at 25°C constitute major pocket and the balance has an Ec with 250-750 micro mhos/cm at 25°C (third horizon).

    Depending on the conductivity, water can be classified as excellent, good, permissible, brackish and saline. A classification on this basis is given in Table-2. There is only one well, which falls in the excellent class, and 12 wells fall in the permissible category. Nine wells have saline water while the remaining wells are brackish.

    3. TOTAL DISSOLVED SOLIDS (TDS): first topic previous topic next topic last topic

    Based on TDS, groundwater has been classified for various uses like general, household, drinking, irrigation and industry using the proposed concentration limits. The area could then be divided into 3 horizons as shown in Map 4 (TDS < 500, 500-1000, and > 1000 ppm). Majority of observed wells has TDS < 500 ppm followed by 500 to 1000. Groundwater during its movement in the subsurface slowly increases in the TDS concentrations. It has been noticed by Freeze and Cherry (1979) that shallow groundwater in the recharge areas has lower TDS than that in discharge areas. Higher concentration of TDS indicates (i) a longer stay of groundwater in the water bearing formation and (ii) the dissolution coefficient of the minerals present in the rock are high and hence gives a higher dissolved solids concentration.

    4. GROUNDWATER HARDNESS: first topic previous topic next topic last topic

    Based on this parameter, groundwater in these locations gets classified into two major zones (Map 5): (i) water with temporary hardness (B1, B2 and B3) and (ii) water with permanent hardness (A1 and A2) (Ryzner, 1994). It is found that water belonging to temporary hardness occupies a major part of the taluk and there is a gradual change of hardness from temporary to permanent, depending on the time of residence of groundwater in the subsurface.

    5. GROUNDWATER SALINITY - SODIUM HAZARD: first topic previous topic next topic last topic

    Based on the degree of salinity and sodium hazard (Map 6) the groundwater of this taluk is divided into 6 horizons (C2S1, C3S1, C3S2, C3S3, C4S3 and C5S3) with C3S1 occupying the major areal extent. Among these all the waters up to C3 type could be used to some extent for salt tolerant crops and the extreme salinity class C5 is not suitable for any crop cultivation. Similarly, S2 category water is suitable for permeable coarse-grained soils and S3 type is suitable for soils with good drainage.

    6. PERMEABILITY INDEX (PI): first topic previous topic next topic last topic

    The permeability index (PI) using epm Ionic values

    Map. 7 lists permeability index (PI) at various locations. Based on this, the study region could be divided in to three classes. Water is of good quality if PI falls in class I or II. Higher the PI, lower is the permeability of the soil. Majority of the area has PI belonging to class III indicating very low permeability soils.

    7. NITRATES: first topic previous topic next topic last topic

    The main sources of nitrate are due to either natural or anthropogenic activities - rainfall and dry fall out, soil nitrogen, nitrate deposit, sewage, septic tank and animal waste, manure or compost, green manure and plant residues, atmospheric nitrogen fixation, fertilizer nitrogen from irrigated overflow water outlets and industrial effluent (Ternamche, 1991).

    Nitrate is the end product of oxidation of nitrogen in the environment. Higher level of nitrate concentrations is an indication of pollution from either sewage or agricultural fertilizer waste. It is beyond doubt, an essential plant nutrient, but at the same time a potential threat to human health when present in excess concentrations in the drinking water (Bulusu and Pande, 1990).

    The potential sources of nitrate in groundwater are due to decomposition of soil organic matter, leaching of soluble synthetic or chemical fertilizers particularly N-fertilizers, and human and animal excreta. Apart from these, untreated effluents of nitrogenous industries also contribute significantly to an increase in the nitrate concentrations (Kakkar, 1990).

    Sample analyses indicate that except in two places (Gangawadi and Changachahalli > 72), majority of the area has nitrate < 40 mg/l.

    SUGGESTIONS: first topic previous topic next topic last topic


    1. This study emphasises the need for periodical monitoring of borewell water to assess its suitability for drinking purposes.
    2. Serious health effects are associated with excess nitrate in water and therefore the water supply authority in association with public departments should create awareness among the people about the importance in maintaining the surrounding localities (to maintain the quality of groundwater) from public health point of view.
    3. Periodic maintenance and cleaning of the borewells and the water supply systems should be done to avoid encrustation.
    4. Disposal of solid waste in an environmentally sound way to avoid leaching, etc.
    5. Leakage from underground and open drain system should be stopped.

    REFERENCES: first topic previous topic next topic last topic

  • Balasubramanian, A., Subramanian, S.N and Sastri, J.C.V., 1991. HYCH BASIC Complex Program for Hydro geological Studies, Groundwater Management and Development in irrigation and other water sector, 7-8 March 1991, Trivandrum.
  • Bhatia, K.K.S., Sharma M.K. and Jain C.K., 1999., "Statistical Analysis of Groundwater Quality Data of Doon Valley, Dehra Dun", Journal of Applied Hydrology Vol. XII No 283, April and July 1999, pp: 27-33.
  • Bhide, A.D., 1990. Groundwater pollution due to solid wastes. Bhu-Jal News. Vol. 5. No, 2, pp: 13-15.
  • Bulusu, K.R. and Pande, S.P., 1990. Nitrates-A serious threat to groundwater pollution. Bhu-Jal, News. Vol. 5.No.2, pp: 39-43.
  • Freeze, R.A. and Cherry, J.A. 1979. Groundwater, Prentice Hall. Inc., New Jersey, pp: 604.
  • Handa, B.K., 1964. A) Modified classification procedure for rating irrigation water. Soil Sci., 98, pp: 264.
  • Handa, B.K., 1964. B) Calcium Carbonate saturation of aquifers in India. Rep 22nd Int. Nat. Geol. Cong. 1964, Part 12, Geohydrology, pp: 88-101.
  • I.S.I., 1964. Indian Standard methods of sampling and test (physical and chemical) for water used in Industry. pp: 122.
  • I.S.I., 1983. Indian Standard Specification for drinking water. I.S.I. New Delhi.IS. 10500.
  • Kakkar, Y.P. 1990., Groundwater pollution due to Industrial Effluents, Bhu-Jal News. Vol.5.No.2, pp: 1-12.
  • Ryzner, J.W., 1944. A new index for determining amount of calcium carbonate scale formed by water, Jour Amer. W. W. Assn., 36, pp: 472-486.
  • Tamata, S.R., 1990. Mineral-CaCO3 saturation and stability of groundwater in Karnataka State - A preliminary study. Bhu-Jal News. Vol.8No.3&4 pp: 14-24.
  • Ternamche, A.P.S., 1991. Health Hazards of Nitrate in drinking water, Water, Vol. 17, pp: 77-82.
  • United States Environmental Protection Agency, 1990. Hand book of Groundwater. Vol.1. Groundwater contamination EPA 625/6-90/016 ach5, pp: 94-113.
  • Wilcox, L.V., 1948. The quality of water for irrigation uses U.S. Dept. Agri. Bull. 962, Washington DC, pp: 40.

    TABLE 1: CHEMICAL CONSTITUENTS OF GROUNDWATER IN YELANDUR TALUK first topic previous topic next topic last topic

    Sampling Site

    Ca

    Mg

    Na/K

    HCO3

    CO3

    Cl

    NO3

    SO4

    TDS

    Ec

    Malligahally

    44.0

    52.0

    471.0

    544.0

    186.0

    389.0

    19.0

    88.0

    1375

    2325.0

    Yeriyur

    63.0

    50.0

    150.0

    400.0

    60.0

    150.0

    20.0

    60.0

    780

    1390.0

    Agara

    40.0

    21.0

    144.0

    392.0

    24.0

    56.0

    0.0

    32.0

    570

    860.0

    Mambally

    60.0

    20.0

    60.0

    350.0

    0.0

    30.0

    5.0

    10.0

    400

    550.0

    Dasanahally

    20.0

    24.0

    118.0

    420.0

    0.0

    32.0

    12.0

    38.0

    450

    703.0

    Kesturu

    29.0

    25.0

    119.0

    421.0

    0.0

    30.0

    11.0

    36.0

    480

    740.0

    B.R.Hills

    46.0

    43.0

    48.0

    372.0

    10.0

    20.0

    8.0

    14.0

    389

    296.0

    Agrahara

    93.0

    84.0

    187.0

    490.0

    43.0

    280.0

    13.0

    100.0

    1075

    1850.0

    Basavapura

    34.0

    44.0

    424.0

    735.0

    38.0

    269.0

    9.0

    120.0

    1375

    2150.0

    Kalanahundi

    0.0

    61.0

    600.0

    784.0

    43.0

    440.0

    9.0

    215.0

    8090

    3000.0

    Duggahatti

    39.0

    26.0

    151.0

    350.0

    50.0

    70.0

    20.0

    21.0

    578

    850.0

    Mayarapalya

    39.0

    72.0

    220.0

    600.0

    70.0

    160.0

    23.0

    35.0

    956

    1400.0

    Devanahally

    40.0

    29.0

    161.0

    382.0

    58.0

    73.0

    22.0

    24.0

    590

    900.0

    Hosur

    26.0

    18.0

    125.0

    279.0

    86.0

    17.0

    5.0

    10.0

    390

    550.0

    Buditittu

    48.0

    43.0

    203.0

    603.0

    53.0

    87.0

    9.0

    26.0

    800

    1100.0

    Gowdahally

    38.0

    75.0

    227.0

    608.0

    72.0

    162.0

    20.0

    36.0

    956

    1500.0

    Chamalapura

    69.0

    66.0

    123.0

    461.0

    38.0

    151.0

    9.0

    52.0

    775

    1150.0

    Avalakandalli

    50.0

    52.0

    321.0

    794.0

    14.0

    134.0

    18.0

    150.0

    1.220

    1625.0

    Maddur

    48.0

    32.0

    223.0

    583.0

    38.0

    81.0

    11.0

    70.0

    865

    1100.0

    Ambale

    117.0

    27.0

    180.0

    603.0

    19.0

    95.0

    0.0

    120.0

    930

    1250.0

    Bannisarge

    18.0

    19.0

    143.0

    270.0

    53.0

    31.0

    19.0

    50.0

    500

    590.0

    Vaddegere

    35.0

    34.0

    160.0

    524.0

    0.0

    42.0

    25.0

    50.0

    675

    870.0

    Yeragamballi

    98.0

    102.0

    157.0

    647.0

    0.0

    235.0

    44.0

    98.0

    1150

    1800.0

    Gangavadi

    715.0

    152.0

    325.0

    676.0

    0.0

    1425.0

    72.0

    400.0

    3540

    6000.0

    Changachahalli

    713.0

    150.0

    320.0

    670.0

    0.0

    1420.0

    70.0

    390.0

    3560

    5090.0

    Yelandur

    120.0

    76.0

    196.0

    559

    24.0

    294.0

    0.0

    120.0

    1170

    1750.0

    Mellahalli

    48.0

    68.0

    162.0

    480.0

    39.0

    137.0

    26.0

    100.0

    840

    1500.0

    Ganiganur

    96.0

    100.0

    150.0

    640.0

    0.0

    230.0

    40.0

    96.0

    1140

    1798.0

    Komaranapura

    65.0

    20.0

    68.0

    360.0

    0.0

    30.0

    6.0

    18.0

    400

    550.0

    Krishnapura

    66.0

    59.0

    157.0

    412.0

    62.0

    154.0

    26.0

    65.0

    800

    1350.0

    Gumballi

    32.0

    58.0

    101.0

    429.0

    34.0

    67.0

    13.0

    25.0

    575

    840.0

    TABLE 2: CLASSIFICATION OF WELLS ACCORDING TO ELECTRICAL CONDUCTIVITY first topic previous topic next topic last topic

    Range of electrical conductivity in micro mhos/cm at 250C

    Quality

    Well Numbers

    Total Number of Wells

    0-333

    Excellent

    7

    01

    333-500

    Good

    -

    -

    500-1000

    Permissible

    3, 4, 5, 6, 11, 13, 14, 21, 22, 23, 29, 31.

    12

    1000-1500

    Brackish

    2, 12, 15, 17, 19, 20, 26, 27, 30.

    09

    1500-10,000

    Saline

    1, 8, 9, 10, 16, 18, 24, 25, 28.

    09

    MAP-1: LOCATION OF STUDY AREA first topic previous topic next topic last topic


    MAP-2: YELANDUR TALUK CHAMARAJ NAGAR DISTRICT first topic previous topic next topic last topic


    MAP-3: ELECTRICAL CONDUCTIVITY first topic previous topic next topic last topic


    MAP-4: TOTAL DISSOLVED SOLIDS YELANDUR TALUK CHAMARAJNAGAR DISTRICT first topic previous topic next topic last topic


    MAP-5: GROUNDWATER HARDNESS YELANDUR TALUK CHAMRAJNAGAR DISTRICT first topic previous topic next topic last topic


    MAP-6: SALINITY SODIUM HAZARD YELANDUR TALUK CHAMRAJNAGAR DISTRICT first topic previous topic next topic last topic


    MAP-7: PERMEABILITY INDEX (DONEENS 1948) YELANDUR TALUK CHAMRAJNAGAR DISTRICT first topic previous topic next topic last topic


    ADDRESS: first topic previous topic

    1.) Hydrogeology Laboratory,
    Department of Geology,
    Manasagangothri,
    Mysore-570 006. Karnataka,
    India.