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Chapter 1
INTRODUCTION
Water is an irreplaceable resource for us, the human beings. During the last few decades the importance of hydrogeology has been given a new definition. The drastic increase in population, urbanization and modern land use applications (agricultural and industrial), and demands for water supply has limited the globally essential groundwater resources in terms of both its quality and quantity. Quality is a function of the physical, chemical and biological parameters, and can be subjective, since it depends on a specific intended use (Tatawat and Chandel 2008) and is influenced by natural and anthropogenic effects including local climate, geology and irrigation practices. Unlike other mineral deposits, groundwater is replenished by natural process. Of the world’s total water resource nearly 97% is saline, found in oceans and the remaining 3% is non-saline water. 75% of this non-saline water is in solid state locked up in polar regions and on top of mountains and is considered inaccessible for man’s use. In the remaining 25%, 24.6% accounts for groundwater and 0.4% accounts for surface water.
Groundwater utilization is increasing at alarming rates in the fields of agriculture, drinking and industries. In all cases, the return of water from consumption like agriculture, irrigation, power generation, domestic uses and industry, is necessarily polluted with a number of chemicals that are harmful to life supporting systems. . It gets its annual replenishment from the meteoric precipitation.
India is a vast country with varied hydro geological situation resulting from diversified geological climatological and topographic setting, Water-bearing rock formations (aquifers), range in age from Archean to Recent. The natural chemical composition of the groundwater is influenced predominantly by type and depth of soil and subsurface geological formation through which groundwater passes.
Groundwater contains a wide variety of dissolved inorganic chemical constituents in various concentrations, resulting from chemical and biochemical interactions between water and the geological materials. Inorganic contaminants including salinity, chloride, fluoride, nitrite, iron and arsenic are important in determining the suitability of groundwater for drinking purposes. Groundwater quality is also influenced by contribution from the atmosphere and surface water bodies, and the quality of groundwater is also influenced by anthropogenic factors.
Due to the inadequate availability of surface water, to meet the requirement of human activities, groundwater remains the only option to supplement the ever-increasing demand of water (Tyagi et al. 2008). In the present study Hungund halla, in the district of Bagalkot, Karnataka is considered for the investigation of its basin morphometry, groundwater chemistry and Water Quality.
Study area:
Hungund Halla which is a tributary of river Krishna drains over an area of 276 Sq.km and is located between the latitude, 15o 45’ 0” N to 16o 25’ 0” N, and longitude 76o 0’ E to 76o 15’
E. Basin falls under Hungund and Bilgi Taluks and forms the southern part of the Bagalkot District Fig No.1. The basin is under the Survey of India (SOI) toposheet no. 57 A/1 and 56 D/4. The flow of water is from Southwest to North east. The basin is at a distance of 50 km from the nearest Bagalkot railway station, the district head. The Vijaypur-Bengaluru NH and Hungund-Lingsugur are the major roads that pass through the sub basin under study. Most of the villages and townships are connected by motorable roads and are accessible in all seasons. A small southern part of the basin stretches to the Koppal District in the South.
[Location map of the Study Area]
Climate and Vegetation:
The area falls under the Northern Dry region (CGWB Report 2011). In general, rainfall in the district gradually increases from west to east. The seasonal distribution indicates that about 66% of the annual rainfall is received during SW monsoon (June-Sept), 21% during post- monsoon period (Oct-Dec) and the remaining during other seasons. The annual average number of rainy days is. Thunderstorms are common during summer bringing relief from sweltering. The nearest meteorological observatory located at Bijapur and the normals of the observatory may be taken as representative of meteorological conditions in the districts. There are two Hydrometeorological observatories maintained by Water Resources Development Organisation at Mahalingpur and Almatti dam site. Normally, the months of January and February are dry and cool. The month of April is the hottest with mean daily maximum temperature being above 30°C. However, daily temperatures may go above 40°C. With the onset of monsoon there is an appreciable drop in the temperature. Night temperatures are lowest in the cold season; touching 10°C. Humidity is high during monsoon season. During the winter months mist is common leading to foggy conditions occasionally.
In general, the topography in the southern part of the district is rugged and undulating while in the northern part it is gently undulating to rolling plains with a number of low lying, flat hills. The southern and south-western parts of the district covering Badami, Bagalkot and western parts of Hungund taluks are traversed by chains of detached hills trending in EW direction.
Soils in Schist and phyllite terrain: These soils are clayey in nature and limited in thickness. They are well drained with moderate permeability. They are less fertile. Soils in Gneissic terrain: These soils are generally sandy-loam in nature with grayish to pinkish in color. Moderate in fertility, good water holding capacity and low in permeability.
Bagalkot district which exists in the semi-arid region experiences hot summer and dry winters and erratic distribution of rainfall. As a result, a very sparse distribution of natural vegetation is noticed in the region. Apart from the odd climatic situations, the vast lands of fertile black soil thickly dotted with human settlements (1040). It has given rise to exhaustive utilization of land for agriculture. The forest covered in the district is only 12.30 %. The concentration of forests in the southern talukas is due to bad lands and hill ranges and it is the least in northern talukas mainly because of the flat surface and fertile black soils most of the vegetation of the districts belong to open thorns. Shrubs and stunted trees, Euphorbias are extensive. Sisyphus and mimosas are also seen widely. The river beds are covered with Tamarind etc. On larger river beds of Krishna, Ghataprabha and Malaprabha, Babul, (Jali) is common. But most of the trees are used for fuel and making agricultural equipment.
Agriculture is the main occupation of the people in the District. Out of the net irrigated area, nearly 60% is through surface water resources and the remaining 40% through groundwater. The area is devoid of large canopy tree vegetation, the region is semi arid. Cotton, Rabi, Jowar, Bajra, Wheat, Sugarcane and tobacco are the crops grown. The dry climate makes the region susceptible to drought and crop failure.
Geology of Karnataka:
Karnataka craton is one of the oldest Precambrian terrains of the world. The geology of Karnataka is mostly confined to the Archaean and Proterozoic eras of earth history.
The Sargur Schist is referred to as the oldest rocks in Karnataka so far (Naqvi, 1981). Major part of central and southern Karnataka is covered by the gneissic complex consisting of an extensive group of gray gneisses known as peninsular gneiss. The controversy as to the relative antiquity of the schist’s over the gneisses has existed since long. The recent view is that peninsular gneiss can be considered only as a complex of gneisses and not as a stratigraphic unit, because it is a complex containing within it several cycles of the schist’s development, granite intrusion and magmatic transformation. Therefore the total peninsular gneiss as a unit cannot be placed either below or above the Dharwar schist’s (Radhakrishnan, 1994). The gneissic complex is to the west and the younger gneissic complex to the east.
In order of age, there is a series of basic igneous rocks of original basaltic composition and association intrusive with few minor sedimentary intercalations. These are auriferous schist belt or Kolar type belt (Swami Nathan and Ramakrishan 1982, Radhakrishna op.cit). These wells developed in the eastern part of the state and these belts are considered older to younger peninsular gneissic complexes (Radhakrishna op.cit). In the western part these are more extensively developed younger schist belts of Dharwar in which there are two main divisions. The older is Bababudan group (Swaminati and Ramakrishan 1990) and is more in character and is composed mainly of Basalts, Orthoquartzites and banded iron formations. The well-known iron ores of Karnataka belong to this group of rocks which are largely sedimentary in character and composed mainly of Polymictic Conglomerates at the base, followed by limestone- manganese-iron formation and Greywackes.
The long linear belt of Potassic Granites, referred to as Clospet granites extends in the north- south direction demarcating the older gneisses and schists to the rest and the younger mobilized and reactivated block to east.
In the southernmost part of Karnataka there are pyroxenes bearing Granulites (i.e. Charnockites) which are considered to be the results of high grade metamorphism and meta-somatic alteration of the older gneisses (Pichamuthu 1960; Radhakrishnan, et al, 1990). At the northern part of Karnataka, between the Deccan traps at the north and schist’s belts/gneisses complex at the south there are rocks of Proterozoic age referred to as Kaladgi and Bhima’s. They mainly comprise Orthoquartzite Argillites and carbonates in the Kaladgi’s (Jayaprakash, et al, 1987) and Sandstones, Shales and Limestones in the Bhima’s (Kale and Phansalkar, 1991). The great Eparchean unconformity separates them from the underlying schistose and granitic rocks of Archaean age. Proterozoic sediments and Deccan traps, consisting of volcanic of Cenozoic era, cover some part in northern Karnataka. Sediments of recent age covering very negligible areas occur along the coastal margin to the west.
Geology and Hydrogeology of Study area:
The Geology is underlain mainly by the crystalline formations of different ages. The oldest rocks in the district consist of schist, phyllites, bonded hematite, quartzites, occurring as distinct bonds mainly to the south-east of the district. The schist’s include hornblende-schist, mica- schist, chlorite schist, talc-schist and hematite-schist. The granites and quartzite gneiss of the Archaean age intrude in to the pre-existing schistose rocks and occur as big, rounded, massive boulders and small isolated hills and knolls The eastern and South eastern part of the district where the study area falls has peninsular gneissic topography. The precambrian formations include granites, gneisses, metasediments of Dharwar SuperGroup. The present study area is underlain by the Schists and Gneiss of Archean to precambrian age.
[Geological map of Karnataka]
Hydrogeology:
Bagalkot district has 29 Observing stations with 11 Piezometers. Groundwater occurs in these hard rock formations in the interconnected interstices of weathered residuum and planar porosities like joints, fractures and shears in unweathered parts. The thickness of the weathered zone varies widely in different formations. GW occurs under water table condition in phreatic zone and semi-confined to confined conditions in the fractures at depth. In shallow or phreatic aquifer, the pre-monsoon depth to water level ranges from 0.41 mbgl to 14.55 mbgl and the general range of water level is 5 to 10 m bgl. During post-monsoon it ranges from 0.36 mbgl to 11.30 mbgl and the general range of water level is 5 to 10 m bgl. Annual water level fluctuation ranges from 0.05 m to 3.25 m and average fluctuation is 1.65 m. The long term water level trend reveals that out of the analyzed 30 dugwells, 27% of the wells show rise in the range of 0.03 m to 4.43 m and the remaining 73% wells show fall in water level ranging from 0.08m to 1.39. The fall in the long term water level mainly observed in non-command areas of the district indicates the effect of high groundwater development where rainfall is the sole source of recharge. Similarly, the rise in water level corresponds to the canal command areas of the district where recharge to groundwater takes place through applied irrigation and canal seepages in addition to rainfall (CGWB Report and Karnataka Ground water Report 2011).
Chapter 2
Geographic Information System
INTRODUCTION
Geographical Information System (GIS) is a technology that provides the means to collect and use geographic data to assist in the development of Agriculture. A digital map is generally of much greater value than the same map printed on a paper as the digital version can be combined with other sources of data for analyzing information with a graphical presentation. The GIS software makes it possible to synthesize large amounts of different data, combining different layers of information to manage and retrieve the data in a more useful manner. GIS provides a powerful means for agricultural scientists to better service to the farmers and farming community in answering their query and helping in a better decision making to implement planning activities for the development of agriculture.
A Geographical Information System (GIS) is a system for capturing, storing, analyzing and managing data and associated attributes, which are spatially referenced to the Earth. The geographical information system is also called a geographic information system or geospatial information system. It is an information system capable of integrating, storing, editing, analyzing, sharing, and displaying geographically referenced information. In a more generic sense, GIS is a software tool that allows users to create interactive queries, analyze the spatial information, edit data, maps, and present the results of all these operations. GIS technology is becoming an essential tool to combine various maps and remote sensing information to generate various models, which are used in a real time environment. Geographical information system is the science utilizing the geographic concepts, applications and systems. The Geographical Information System can be used for scientific investigations, resource management, asset management, environmental impact assessment, urban planning, cartography, criminology, history, sales, marketing, and logistics. For example, agricultural planners might use geographical data to decide on the best locations for a location specific crop planning, by combining data on soils, topography, and rainfall to determine the size and location of biologically suitable areas. The final output could include overlays with land ownership, transport, infrastructure, labor availability, and distance to market centers.
[Schematic representation of the working process of GIS]
GIS software:
Geographic information can be accessed, transferred, transformed, overlaid, processed and displayed using numerous software applications. Within industry commercial offerings from companies such as ESRI and Mapinfo dominate, offering an entire suite of tools. Government and military departments often use custom software, open source products, such as Gram++, GRASS, or more specialized products that meet a well-defined need. Free tools exist to view GIS datasets and public access to geographic information is dominated by online resources such as Google Earth and interactive web mapping. Originally up to the late 1990s, when GIS data was mostly based on large computers and used to maintain internal records, software was a stand-alone product. However with increased access to the Internet and networks and demand for distributed geographic data grew, GIS software gradually changed its entire outlook to the delivery of data over a network. GIS software is now usually marketed as a combination of various interoperable applications and APIs.
Data creation:
GIS processing software is used for the task of preparing data for use within a GIS. This transforms the raw or legacy geographic data into a format usable by GIS products. For example an aerial photograph may need to be stretched using photogrammetry so that its pixels align with longitude and latitude gradations. This can be distinguished from the transformations done within GIS analysis software by the fact that these changes are permanent, more complex and time consuming. Thus, a specialized high-end type of software is generally used by a skilled person in GIS processing aspects of computer science for digitization and analysis. Raw geographic data can be edited in many standard database and spreadsheet applications and in some cases a text editor may be used as long as care is taken to properly format data. A geo-database is a database with extensions for storing, querying, and manipulating geographic information and spatial data.
Geographic Referencing Concepts:
A GIS is to be created from available maps of different thematic layers (soils, land use, temperature, etc). The maps are in two-dimensions whereas the earth’s surface is a 3 dimensional ellipsoid. Every map has a projection and scale. To understand how maps are created by projecting the 3-d earth’s surface into a 2-d plane of an analogue map, we need to understand the georeferencing concepts. Georeferencing involves 2 stages: specifying the 3- dimensional coordinate system that is used for locating points on the earth’s surface that is, the Geographic Coordinate System (GCS) and the Projected Coordinate System that is used for projecting into two dimensions for creating analogue maps. Geographic Coordinate System The traditional way of representing locations on the surface of the earth is in the 3 dimensional coordinate system by its latitude and longitude.
Note that the distance between two points on the 3-d earth’s surface varies with latitude. The 3-d system therefore does not provide a consistent measure of distances and areas at all latitudes. The true surface of the Earth is not the smooth ellipsoid shown in the figure but is quite uneven and rugged. The GCS which is the surface used for specifying the latitude and 5 longitude of a point on the earth’s surface is also an approximation and a 3-d model of the earth. Several standard models of the ellipsoid are available to define the GCS (WGS 84, Everest ellipsoid) etc. The different models vary in their critical parameters ( semi major or equatorial axis and semi minor or polar axis of the ellipsoid and the point of origin). The ellipsoid model that is used to calculate latitude and longitude is called the datum. Changing the datum, therefore, changes the values of the latitude and longitude. Specifying the Geographic Coordinate System therefore requires specifying the Datum. The datum is a fixed 3-d ellipsoid that is approximately the size and shape of the surface of the earth, based on which the geographic coordinates (latitude and longitude) of a point on the Earth’s surface are calculated. In fact describing a place by its lat/long is not complete without specifying its datum. In India the Everest Ellipsoid is used as the Datum for the Survey of India maps. The ideal solution would be a spheroidal model of the Earth that has both the correct equatorial and polar radii, and is centered at the actual center of the Earth. One would then have a spheroid that, when used as a datum, would accurately map the entire Earth. All lat/longs on all maps would agree. That spheroid, derived from satellite measurements of the Earth, is GRS80, and the WGS84. datum matches this spheroid.
Chapter 3
Interpolation Analysis
INTRODUCTION
Interpolation predicts values for cells in a raster from a limited number of sample data points. It can be used to predict unknown values for any geographic point data, such as elevation, rainfall, chemical concentrations, and noise levels.
The assumption that makes interpolation a viable option is that spatially distributed objects are spatially correlated; in other words, things that are close together tend to have similar characteristics. For instance, if it is raining on one side of the street, you can predict with a high level of confidence that it is raining on the other side of the street. You would be less certain if it was raining across town and less confident still about the state of the weather in the next county.
Using the above analogy, it is easy to see that the values of points close to sampled points are more likely to be similar than those that are farther apart. This is the basis of interpolation. A typical use for point interpolation is to create an elevation surface from a set of sample measurements. Geostatistical Analyst also provides an extensive collection of interpolation methods. Some typical examples of applications for the interpolation tools follow. The accompanying illustrations will show the distribution and values of sample points and the raster generated from them.
A typical use for point interpolation is to create an elevation surface from a set of sample measurements.
In the following graphic, each symbol in the point layer represents a location where the elevation has been measured. By interpolating, the values for each cell between these input points will be predicted.
In the example below, the interpolation tools were used to study the correlation of the ozone concentration on lung disease in California. The image on the left shows the locations of the ozone monitoring stations. The image on the right displays the interpolated surface, providing predictions for each location in California. The surface was derived using kriging.
Analysis of Study Area:
Groundwater is one of the most commonly occurring substances on the earth. It has the ability to dissolve a great range of substances and slow percolation of precipitated water through ground results in prolonged contact of water with minerals in the soil and bedrock. Depending on the chemical equilibrium condition is established between the minerals in the soil, rock and groundwater. Hence during percolation, the physical-chemical characters of the groundwater changes continuously.
The type and concentration of the ions depend on the environment of the movement of groundwater, the soil and rock through which it has moved and its residence time in the aquifer. Ordinarily, higher concentration of dissolved constituents is found in ground water than in surface water because of great exposure to soluble material in geological strata. Further, the hydro-geochemistry of any area is based on- Determination of concentration of various ions;
Developing a hydro-geochemical model; Identification of the facies of the groundwater systems and Establishing the possible ways of using groundwater.
The study of groundwater quality not only gives the concentration of different cations and anions but also their source, geological history of the rocks, groundwater discharge, movement and storage. Thus complete physico-chemical analysis will determine the groundwater suitability for various uses.
The geochemical study of the groundwater is important with respect to the water use. This study gives better understanding about the quality and development process taking place in the area, which can provide information about the limits of total development or permit planning for appropriate treatment that may be required as the results of future changes in the quality of water supply. Groundwater chemistry changes, as the water flows in the underground environment, by the increase of dissolved solids and major ions (Chebotarev 1955). Longer the duration of the groundwater staying in the ground, the poorer the quality.
The reasons for groundwater deteriorations are:
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Discharge of industrial effluents,
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Discharge of sewage,
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Saline water intrusion along the coastal regions,
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Rock-water interaction in aquifer,
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Microbial activities in biofilms in underground,
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The hydrodynamic and dilution properties of aquifers and
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The intensity of pollution.
As the groundwater moves from the recharge area to the discharge area, the chemistry is affected by a variety of geochemical processes. The dissolved components of water not only undergo changes during transport, but also react and redistribute the mass among various ions. With increase in the demands of groundwater in many coastal areas due to exponential growth of population and other needs, the base flow is decreased or even reversed, causing seawater intrusion. There are several other factors that contaminate groundwater and a few of them are:
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Excess usage of fertilizer in agricultural activities,
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Extensive aquaculture in coastal environments and Salt pan industries
Interpolation Analysis using ArcGIS Pro:
The Hydro-chemical data which was obtained was subjected to interpolation analysis using ArcGIS Pro. The results and the interpretation of different water chemistry parameters are explained in detail in the following paragraphs.
Physical Parameters:
The physical parameters of the groundwater are very important for a better understanding of the geochemistry of groundwater of the study area. Unlike surface water, groundwater is generally clean, colorless and odorless with little or no suspended matter and at relatively constant temperature. It is necessary to assess the physical quality of water in addition to the chemical quality.
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pH
pH is one of the important parameters of water whose determination facilities a quick evolution of acidic and alkaline nature of water. The pH is affected by organic and inorganic solutes present in water. Any alteration in water pH is accompanied by the changes defined as the negative logarithm of hydrogen ion concentration of the solution . Natural ground water generally has a pH range from 5-8 for drinking water, a pH range of 6.5-8.5 units is acceptable. A wide range pH can be occurring due to the influence of rock composition and vegetation. This is the measurement of the hydrogen ion concentration in the water. A pH below seven is acidic (the lower number, the more acidic the water) and a pH above seven (to a maximum of 14) is basic (the higher the number, the more basic the water. The samples collected from the study area show the variation of pH 7.03 - 8.12, and hence the water is acceptable.
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Total dissolved salts
The TDS includes all dissociated and undissociated substances, except suspended sediments, colloids or dissolved gasses. TDS is valued by the factor 0.64 (HEM, 1950). The bulk of TDS includes bicarbonates, sulfates and chlorides of calcium, magnesium, sodium and silica. Chlorides and nitrates of potassium and boron form a minor part of the dissolved solids in groundwater. Heavy metals and radioactive constituents occur in trace amounts. The area where the water has low TDS may be considered as a possible area of recharge. TDS in the study area varies from 260 to 4450 mg/l with an average of 1892.3 mg/l
[Map Showing the Interpolation Data of pH Values of the Study Area]
[Map Showing the Interpolation Data of TDS Values of the Study Area]
Hardness:
Water hardness is the capacity of water to react with soap to produce lather, hardness of water is not a specific element but a variable accounted by a complex mixture of cations and anions, calcium, magnesium, strontium, ferrous iron and manganese ions are the chief hardness causing divalent cations. Hard water leads to formation of heaters, boilers and other units in which water temperature is increased materially and hence are unfit. For industrial purposes water is classified from soft to very hard depending on the amount of hardness quantified as CaCO3 in milligrams/liters. It ranges from 246 to 2800 mg/l.
[Map Showing the Interpolation Data of Hardness Values of the Study Area]
Chemical Parameters:
Calcium:
Carbonate rocks are the chief source of calcium in natural water and on a global scale they contribute 80% or more of the calcium in streams. Silicate mineral groups like plagioclase, pyroxene and amphibole among igneous and metamorphic rocks and limestone, dolomite and gypsum among sedimentary rocks are the main source of calcium in groundwater. Silicate minerals are not soluble in water, but weathering breaks them down into soluble calcium products and clay minerals. The carbonates and sulfates of calcium however, are soluble in water. Due to its abundance in most of the rocks and its solubility, calcium is present almost everywhere in groundwater. In the presence of water containing carbon dioxide in dissolved form calcium carbonate is quite soluble, the reaction being broadly as given in equation
CaCO3 +H2O+CO2→Ca (HCO3)2
In the present area the Ca might have leached from feldspars, amphibole or pyroxene minerals. Calcium content of ground water samples varies from 20.04 to 280.56 ppm and the average value is 81.29 ppm
Magnesium:
In groundwater the magnesium is derived part from silicates and part from magnesium calcite or dolomite. Mica from intensive weathering of mafic rocks and from pyroxene and amphiboles give rise to silicates. The Weathering of igneous and metamorphic rocks gives rise to soluble carbonates, clay and silica. In the presence of carbonic acid in water magnesium carbonate is converted into more soluble. Under ordinary atmospheric conditions the solubility of magnesium carbonate in water in the presence of carbon dioxide is nearly ten times that of calcium carbonate. In groundwater the calcium content generally exceeds the magnesium content in accordance with its relative abundance in rocks but contrary to the relative solubilities of its salts. In the present area the Mg might have been derived in groundwater by leaching of olivine, biotite, hornblende and augite minerals from basalts.
Magnesium content of groundwater samples from the study area varies from 29.23 to 526.27 ppm and the average value is 131.11 ppm
[Map Showing the Interpolation Data of Calcium Values of the Study Area]
[Map Showing the Interpolation Data of Magnesium Values of the Study Area]
Sodium:
Most of the sodium salts are soluble in water, but take no active part in chemical reactions, as do the salts of alkaline earths. Sodium salts tend to remain in solution unless extracted during evaporation. In saline water, the Sodium content may be several hundred times the total amount of the calcium and magnesium contents. Certain clay minerals and zeolites can increase the sodium content in ground water by base Sodium exchange reaction. Sodium bearing minerals like albite and other members of plagioclase feldspars, nepheline, sodalite, glaucophane, aegirine etc. are not as widespread or abundant as the calcium and magnesium bearing minerals. Weathering of these rocks gives rise to soluble sodium. The most important source of sodium in groundwater particularly in arid and semi-arid regions is the precipitation of this salt impregnating the soil in the shallow water tracts. Sodium content in ground water ranges from about 1 ppm in humid and snow-fed regions to over 10,000 ppm in brines. In general, when the total dissolved solids increase the concentration of sodium and chloride increases. An increase in sodium with concomitant reduction of calcium and magnesium, preponderance of sodium over chloride ions, or alternation of calcium carbonate to sodium carbonate may be indicative of Base Exchange enrichment of sodium if such changes are not accomplished by an increase in the total mineralization of groundwater. Groundwater in well-drained areas with good amounts of rainfall usually has less than 10 to 15 ppm of sodium. In the present area the presence of Na may be due to weathering minerals of feldspars. Sodium content of ground water samples in the study area varies 42 to 184 mg/l and the average is 121 mg/l.
Potassium:
It is nearly as abundant as sodium in igneous rocks and metamorphic rocks but its concentration in groundwater is one-tenth or even one hundredth of sodium. The potassium is derived from silicate minerals like orthoclase, microcline, nepheline, leucite and biotite. Parity in concentrations of sodium and potassium is found only in water with less mineral contents. Potassium concentration in the groundwater sample of the study area varies between 0 mg/l to 15.12 mg/l.
[Map Showing the Interpolation Data of Sodium Values of the Study Area]
[Map Showing the Interpolation Data of Potassium Values of the Study Area]
Sulphate:
Groundwater present in igneous or metamorphic rocks contains less than 100 ppm sulfate (Davis and Dewiest 1966). The sulfate content of atmospheric precipitation is only about 2 ppm, but a wide range in sulfate content in groundwater is made possible through oxidation, precipitation, solution and concentration, as the water traverses through rocks. In sulfide mineralization zones, solution of other sulfide minerals like chalcopyrite, sphalerite, etc. The range of sulfate values of ground water samples is 68 to 720 ppm and the average value is 412.83 ppm.
Chloride:
The chloride content of ocean water, an important entity in the hydrological cycle, is of the order of 13,000 ppm, the chloride content of rainwater may be high in coastal areas and in desert tracts. Chloride salts, being highly soluble and free from chemical reactions with minerals of reservoir rocks, remain stable once they enter in solution. Most chloride in groundwater is present in sodium chloride, but the chloride content may exceed the sodium due to base-exchange phenomena. In the present area the high concentration of Cl may be due to sewage water .Chloride content in the groundwater samples varies from 29 to 770 ppm and the average value is 185.39 ppm.
Fluoride:
Higher fluoride concentrations are observed in dug wells at places and are comparatively more in deeper aquifers as evidenced in bore well samples. The fluoride is geogenic and its concentration is likely to increase with over-development of groundwater. The limit for Fluoride is from 1-1.5 mg/l (BIS). Fluorine is the lightest member of halides. In the study area the content of fluoride ranges from 0.03 to 1.42 ppm with an average of 0.7 ppm.
[Map Showing the Interpolation Data of Sulphate Values of the Study Area]
[Map Showing the Interpolation Data of ChlorideValues of the Study Area]
[Map Showing the Interpolation Data of Fluoride Values of the Study Area]
References:
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10-Eaton, E. M. (1950). Significance of carbonate in irrigation water. Soil Science, 69, 12– 133.
11-Federation, W. E., & American Public Health Association. (2005). Standard methods for the examination of water and wastewater. American Public Health Association (APHA): Washington, DC, USA.
12-Gibbs RJ (1970) Mechanism controlling world water chemistry. Science 170:1088 1090
13-Gibbs. R. J (1970). Mechanisms controlling world water chemistry, Science,Vol.170, pp.1088-1090.
14-Golterman, H. L. (1969). Methods for chemical analysis of fresh waters.