Geochemical Ionic Exchange Relate with Sea Water Intrusion ...infokara.com/gallery/98-dec-3383.pdf · Sea Water Intrusion type. The higher and lower concentration was identified based

Geochemical Ionic Exchange Relate with Sea Water Intrusion Study Using Geo

Spatial Technique in the Ramanathapuram Coastal Stretch Tamil Nadu India

M.Vijay Prabhu*1 and S.Venkateswaran2 R.Kannan3 and R.Ayyandurai3 *1UGC, Post Doctorate Fellow, Department of Geology, Periyar University, Salem-11,Tamil Nadu

2 Professor and Head, Department of Geology, Periyar University, Salem-11, Tamil Nadu 3Research Scholars, Department of Geology, Periyar University, Salem-11, Tamil Nadu

Email:[email protected]

ABSTRACT

The geochemical characteristics of groundwater are vital for the support of habitat and for

maintaining the quality of base flow in rivers, while its quality assessment is essential to

ensure sustainable safe use of the resources for drinking in the coastal community. Thirty

nine groundwater sampling sites were selected systematically and samples were taken from a

reference line study to understand the geochemistry of the groundwater and to assess the

overall physicochemical faces pre-monsoon 2017. Generally, coastal regions receive rainfall

during SW-NE monsoon seasons. Ramanathapuram district receives maximum rainfall in

NE monsoon seasons. Rains normally occur in the form of cyclonic storms caused by

depression in the Bay of Bengal. District average annual rainfall is 827 mm. Degradation

groundwater qualities in the coastal region generally due to sea water intrusion, salt pans,

aquaculture activity along the coastal region, wind driven, Sea spray and marine aerosols

deposits on the top soil, evaporation and interaction of groundwater with brines and

sedimentary formation. Sampling was carried out using precleaned polyethylene containers.

The physical and chemical parameters of the analytical results of groundwater were compared

with the standard guideline values recommended by the World Health Organization for

drinking and public health standards. Thematic maps pertaining to TDS, EC, pH, Na, Cl

were generated using the Arc GIS platform. To find out the distribution pattern of the

concentration of different elements to identify Geochemical Ionic Exchange ratio Relate with

Sea Water Intrusion type. The higher and lower concentration was identified based on those

spatial maps for various elements were also generated, discussed, and presented. To mapping

interface of fresh and sea water signatures through high TDS, Na and Cl contents can be

attributed. An alternative graphical approach is to plot Cl vs. electrical conductivity (EC)

(Washington State Department of Ecology, 2005). Three zones on a plot of Cl vs. EC:

normal, mixed and SWI area delineated in the study area.

ISSN NO: 1021-9056

http://infokara.com/989

INFOKARA RESEARCH

Volume 8 Issue 12 2019

Keywords: Geo Spatial Technique, Coastal Stretch, Geochemical Ionic Exchange

Groundwater Quality, Sea Water Intrusion and WHO.

1. Introduction

Ramanthapuram Coast is one of the world’s richest regions of marine bio

diversity perspective and the first Marine Biosphere Reserve in Southeast Asia.

Nearly 3600 species reported in the Gulf of Mannar region. This area is endowed

with a combination of ecosystems including mangroves, seagrass, seaweeds and

coral reefs. The majority of the area is covered by the unconsolidated sediments of

Quaternary age, where isolated patches of Archaen Crystallines and Tertiary

sandstone are exposed. Seawater intrusion is one of the major problems in this area.

It may due to gentle hydraulic gradients, tidal and estuarine activity, sea level rises,

low infiltration, excessive groundwater withdrawal and local hydrogeological

conditions. Rural people mostly trusted on groundwater for domestic purposes. The

following are the reasons why groundwater is attractive for most domestic uses: the

resource is generally sheltered from most surface polluting activities and does not

need bacteriological treatment prior to consumption; aquifers underlie most of the

rural communities and can be tapped at relatively shallow depths; surface water

resources are virtually nonexistent in most of these communities and where surface

water resources exist, they are often so much polluted that the cost of tapping

groundwater is modest compared to the fee of treating surface water resources

before usage. In addition to meeting the domestic water needs of the rural

population, it has been envisaged that groundwater has the potential of being

phased in sufficient quantities to meet irrigation needs to raise the standard of living

of the communities.

Characterization of groundwater in terms of geochemical types is an essential

component of scientific management of groundwater resources in order to monitor

ISSN NO: 1021-9056


INFOKARA RESEARCH


the quality of groundwater in an aquifer, and also for identification of recharge areas

(Schoeller, 1967). Moreover, geochemistry of groundwater is also related to the

nature of host rock as well as the overlying rock types. An understanding of

chemical quality of water is essential in determining its usefulness for domestic,

industrial and agricultural purposes (WHO, 1996).

The total dissolved salts in the water are a direct measure of the quality of

water. Many authors viz., Fetter (1990), Freeze and Cherry (1979) and Davis and De

Wiest (1966) studied the water quality and reported that high values of TDS is

unsuitable for drinking and irrigation purposes. Also, the groundwater chemistry

depends upon various rock-water interactions such as weathering, dissolution and

ion exchange reactions as well as from the anthropogenic activities discussed above.

In order to identify and evaluate the factors and processes that are responsible for

the groundwater chemistry, detailed geochemical studies have to be carried out. The

hydrogeochemical study of groundwater allows us to obtain important information

on chemical weathering of rock/soil, chemical compositions of the aquifers and also

on the impact of the anthropogenic activities.

Groundwater quality comprises the physical, chemical, and biological

qualities of groundwater. Temperature, turbidity, colour, taste, and odour make up

the list of physical water quality parameters. Since most Groundwater is colourless,

odourless, and without specific taste, concern is typically with regard to its chemical

and biological qualities. Natural groundwater contains various ions. These ions

slowly dissolve from soil particles and rocks as the water travels along mineral

surfaces in the pores or fractures of the unsaturated zone and the aquifer. They are

referred to as dissolved solids. Some dissolved solids may have originated in the

precipitation or from seepage from the river water.

Groundwater and surface water are intimately related. During dry periods,

the groundwater contribution may be the total discharge of the stream, whereas

ISSN NO: 1021-9056


INFOKARA RESEARCH


during wet periods, the groundwater contribution may be insignificant. However, in

places where the water table has been lowered, the reverse is true, that is, water

leaks from the streams into the ground, particularly in some undermined areas.

Hence, the geologic framework between groundwater and surface water the

occurrence of water and its movement through the rock are important.

Todd et al., (1984) demonstrated local permeability impairment as a function

of injected particles size and rock properties. They pointed out that initial

permeability or pore size is not simple criteria for explaining the degree of damage

to the cores. As gravity is the dominant driving force in groundwater movement,

water flows from places of higher head to lower head. Under natural conditions,

groundwater flows generally from topographically high places to low places

(Cedergren, 1977).While non-availability of water is one side of the problem, the

deteriorating quality of existing water resources is the other side, causing great

concern. The quality of water is of vital concern for mankind, since it is directly

linked with human welfare. It is generally recognized that the quality of

groundwater in an area is as important as the quantity. Groundwater quality data

provides important clues to the geologic history of rocks and indications of

groundwater recharge, discharge, movement and storage (Walton, 1970).

Quality of water is the function of its physical, chemical, biological and

geological parameters (Bhargava and Killender, 1988), which depend upon the

soluble products of weathering and decomposition and the related changes that

occur with respect to time and space (Raghunath, 1987). The cation and anion

concentration depends upon the solubility of the minerals present in the formation

and the time duration of water in contact with the rocks and the amount of dissolved

CO2 present in the water (Viessman et al., 1989).

Studies on the geochemical processes that control groundwater chemical

composition in and around the river course may lead to improved understanding of

ISSN NO: 1021-9056


INFOKARA RESEARCH


hydrogeochemical systems in such areas. Such studies contribute to effective

management and utilization of the groundwater resources. Exploitation of

groundwater has been increased manifold level particularly for drinking and

agricultural purpose. Poor quality of water adversely affects the plant growth and

human health. Urban rivers have been associated with water quality problems and

the practice of discharging untreated domestic and industrial waste into the water

course has emerged. The problems are associated with the quantity, quality and

temporal distribution of the waste produced effected by different sources and is

aggravated further by routing these directly into the catchment areas of the river.

Various authors studied on the groundwater quality in different parts of the country

with respect to drinking and irrigation purposes (Majumdar and Gupta, 2000;

Sreedevi, 2004; . The chemical alteration of the Groundwater depends on several

factors such as interaction with solid phases, residence time of Groundwater,

seepage of polluted river water, mixing of groundwater with pockets of saline water

and anthropogenic impacts. The water resource and Groundwater reserves have

been contaminated by biological, organic and inorganic wastes . Chennai city

groundwater quality has resulted in saline groundwater nearly 10 km inland of the

sea and similar problems can be found in populated coastal areas around the world

(UNEP, 1996). GIS technology has previously facilitated laborious procedures

(Shamsi, 2005; Assaf et al., 2008;). During the past two decades, various researches

have reported its application in Groundwater modeling and quality assessment.

Balakrishnan et al., (2011) demonstrated spatial variations in Groundwater quality

using GIS and Groundwater quality information maps of the entire polluted area in

India. Assessment of Groundwater quality through spatial distribution mapping for

various pollutants utilizing GIS technology and the resulted information on quality

of water could be useful for policy makers to take remedial measures (Nageswara

Rao et al., 2007; Pradhan et al., 2001; Swarna Latha et al., 2007). In the present work

ISSN NO: 1021-9056


INFOKARA RESEARCH


involves Groundwater quality assessment of saline water intrusion using Geospatial

techniques in the Ramanathapuram district.

The chemical alteration of the rain water depends on several factors such as

soil-water interaction, dissolution of mineral species and anthropogenic activities

(Umar and Ahmed, 2007). The study of relatively large number of groundwater

samples from a given area offers clues to various chemical alterations which the

meteoric groundwater undergoes, before acquiring distinct chemical characteristics.

Knowledge on hydrochemistry is important to assess the quality of groundwater for

understanding its suitability for domestic, irrigation and industrial needs. Various

researchers carried out studies on the hydrogeochemical characteristics of

groundwater and quality of groundwater in different basins as well as in urban

areas (Raju et al. 2007). Further, recent advances in analytical methods have led to

the determination of toxic trace elements which can have an impact on human

health.

2. Study area

The Ramanathapuram District is divided into two municipalities, which is

further subdivided into 7 talks with 429 Panchayats, which includes 400 revenue

villages and 236 hamlet villages. The base map of the study area will be prepared

from Survey of India (SOI) Toposheet maps Nos. 58 N/11 (1971), 13,14 &15 (1970) on

1:50,000 scale. Ramanathapuram is one of the coastal district bounded on the north

by Sivagangai and Pudukottai districts, on the east and south by the Bay of Bengal,

and on the west by Thoothukudi and Virudhunagar districts. The district

headquarters is located at Ramanathapuram. The district lies between 9o 05’ and 9o

50’ North Latitude and 78o 10’ and 79o 27’ East Longitude. The general geographical

information of the district is simple and flat. The Vaigai River and Gundar River are

flowing in the district and they will be dry during the summer season. The coastline

of Tamilnadu has been along the eastern shore of Bay of Bengal. The coast has one

ISSN NO: 1021-9056


INFOKARA RESEARCH


major and ten minor ports in their coastal belt. It is one of the most indented coasts

with numerous river mouths, lagoons, bays, creeks, cliffs, spits sand dunes and long

beaches. Sea erosion, migration of river mouths, siltation of ports and harbours are

the prominent problems along this coast. Eight rivers drain into the Bay of Bengal.

The location map of the Ramanathapuram district shown in Fig.1.

Fig.1.Location map of the Ramanathapuram District

3. Geological Setting

Geological setting comprises mainly of coastal sands of quaternary and recent

ages. Sub-recent marine formations consisting of hard calcareous sandstone and grey

calcareous clay are seen on Rameswaram Island and other islands. The sub-recent

calcareous sandstone forms the basement rock for the present-day coral reefs

growing in the Gulf of Mannar, fringing Rameswaram Island and another group of

islands. A major part of the district is covered with the fluvial, fuvio-marine, Aeolian

ISSN NO: 1021-9056


INFOKARA RESEARCH


and marine sediments of Quaternary age. The fluvial deposits, which are made up

of sand, silt and clay in varying degree of admixture occur along the active channels

of Vaigai, Gundar, Manimuthar and Pambar rivers. They have been categorised into

the levee, flood basin, channel bar/ point bar and paleo-channel deposits. The paleo

channel deposits comprise brown coloured, fine to medium sands with well

preserved cross beddings. The geological map of the study area is shown in Fig.2.

Fig.2. Geology Map of the Ramanathapuram District

4. Geomorphology

Ramanathapuram district has a long coastline of around 260 km. The coastal

areas are flanked by beach ridge complex-sand dunes, swales, swamps and

backwater. The sand flat is another feature of the coast comprising of clays and silts,

often flooded by seawater and encrusted with salt. Other features are the shallow

pediment plain of Kamudhi, parts of Paramakudi and Tiruvadanai taluks with the

thin layer of soil covered over with weathered hornblende gneiss, laterite and the

buried pediments (CGWB 2009). A major part of the district is a gently sloping plain

ISSN NO: 1021-9056


INFOKARA RESEARCH


except for remnant hills in the western area. Recent Quaternary studies have

brought out various erosional and depositional landforms of fluvial and marine

regimes. The fluvial landforms comprise flood plains of Vaigai, Varshalei, Pambar,

Kottakkarai and Gunnar rivers. The marine landforms comprise sand mounds

(Teri’s) and barrier dunes along the present coast. The erosional processes are

manifested in the form of pediments and pedipalain around Kamuthi. Geo-

hydrologically, the district has been divided into three zones with reference to

laterite, flood basin and coastal plain areas respectively. Further, the area is

demarcated into Manimuthar Pambar basin, Vaigai delta and Vaipar-Gundar basin.

The geomorphological map of the study area is shown in Fig.3.

Fig.3. Geomorphology map of the Ramanathapuram District

5. Soils

The soils of Ramanathapuram District can be assorted into the main types

viz., clay, coastal alluvium, sandy loam, alluvium, sandy and red soil clay, black

cotton soil is believed to have been derived from the Archaen gneisses where

calcareous formation are abundant. Calcium carbonate concretions of various sizes

ISSN NO: 1021-9056


INFOKARA RESEARCH


and shapes are present in majority of the black soil area and this affects the fertility

of the soils. Black soil, as a whole constituted about 46 per cent of the total soil. River

alluvium includes alternate layers of sand and clay for a huge thickness. River

alluvium occurs in areas bordering the Vaigai River. Coastal alluvium occurs in

Kadaladi, R.S.Mangalam, Mandapam, Ramanathapuram, Thiruppullani and

Thiruvadanai blocks. There are vast stretches of saline and alkaline soils found in the

coastal blocks. Rameswaram Island contains mainly sandy soil. The fertility status of

soil showed that nitrogen status of soil is low in all blocks and phosphorus status of

soil is also low in all blocks except Thiruppullani, Kamudhi and Kadaladi where it is

medium. The potash content of soil is high in all the blocks. The mineral resources of

the soil include gypsum, limestone and magnesium. While Mudukulathur and

Keelakarai regions account for sizable deposits of gypsum. Rameswaram Island

contains large quantities of limestone deposits. The North western part of the

Ramanathapuram district exposes isolated patches of Archaeans crystallines and

Cuddalore Sandstone is capped by laterite/lateritic soil.

6. Experimental design, materials and methods

6.1 Materials and methods

The coastline of Tamilnadu has been along the eastern shore of Arabian Sea.

The coast has one major and ten minor ports in their coastal belt. It is one of the most

indented coasts with numerous river mouths, lagoons, bays, creeks, cliffs, spits sand

dunes and long beaches. Sea erosion, migration of river mouths, siltation of ports

and harbours are the prominent problems along this coast. Along the

Ramanathapuram district 39 groundwater samples were collected in pre-monsoon

(2017). Samples were collected in polyethylene bottles measured physicolagical

character on the spot. These bottles had been rinsed with distilled water before

sampling. These samples were collected from digging wells farmers used in

agricultural activities. The samples were adequately labeled and preserved in the

refrigerator until they were taken to the laboratory for measurement. Samples were

analyzed in the laboratory for the major ions. As the aquifer salinity ionic exchange

ISSN NO: 1021-9056


INFOKARA RESEARCH


ratio is measured through major cations and anions percentage. Sampling,

preservation and analysis of water samples were carried out following the method

recommended APHA (2005). The pH and EC were measured using pH and EC

meters.

7. Mixing of Fresh and saline water

Groundwater quality monitoring has been carried out by establishing 39

observation wells for pre monsoon of 2017 for providing input to the integrated data

interpretation. The data presented shows that pre monsoon values of most

parameters elevated concentration. Most of groundwater samples indicated a

slightly alkaline nature with pH varying from 7.5 to 8.8. Elevated TDS concentration

levels noticed around Rameswaram, Thondi, Devipattinam, Keelakari, Ervadi,

Upoor, Thiruvettriyur, Vallinokam and Sayalkudi villages. High values of sodium

are also reported in the samples. Further, all the groundwater samples indicated

chloride concentration exceeding permissible limits. High TDS, sodium, and chloride

contents can be attributed to the possible seawater intrusion in the area. High

concentration of TDS, sodium, and chloride have been observed majority of the

coastal locations. The elevated concentration of TDS, sodium, and chloride in

samples mentioned above indicates brackishness of the groundwater.

The physical and chemical parameters of the analytical results of

groundwater were compared with the standard recommendation values stated by

the World Health Organization for drinking and public health standards. The table

shows the most samples not coming under suitable limits of drinking purposes.

Several water quality indicators have been proposed in the literature to identify

groundwater that has been impacted Chachadi, A.G. (2005), Chowdhury, A., Madan,

K., and Jha, C.V.M. (2010). Lobo, J.P., Ferreira and Chachadi, A.G. (2005). However,

in some regions the natural chemical evolution of the groundwater system can make

it challenging to apply these indicators, for example, due to cation exchange

processes that raise the relative concentration of sodium compared to calcium Saaty,

T.L. (1987). The drinking water standards are observed below 13 to 18 feet below

ground level in the coastal stretch. The geochemical parameters during pre monsoon

2017 periods for 39 wells were presented in Table.1.

ISSN NO: 1021-9056


INFOKARA RESEARCH


Table.1.Water Sample location in Ramanathapuram district villages in the pre-monsoon 2017

Loc.No Name of the Location Ph EC TDS Ca Mg Cl TH Na K SO4 CO3 HCO3 NO3

1 Ramanathapuram 8.1 1390 907 24 15.795 167 125 248 29 47 6 170.8 4

2 Uthirakosamangai 8.4 8630 4927 140 315.9 2552 1650 1265 164 48 2.6 137.3 4

3 Chitharakottai 8.2 560 307 6 25.515 82 120 71 8 46 2.5 107.3 4

4 Mandapam 8.2 1010 576 26 43.74 163 245 122 10 864 0 408.7 14

5 Idayarvalasai 8 920 517 10 47.385 128 220 106 19 384 0 823.5 22

6 Keelakarai 8.4 5900 3630 80 43.74 1276 380 1196 26 377 6 329.4 7

7 Ragunathapuram 8.2 880 489 26 46.17 96 255 85 15 175 18 689.3 16

8 Valantaravai 8 1650 1151 20 34.02 262 190 239 113 526 30 1024.8 15

9 Ponnalikopttai 7.8 600 327 36 29.16 57 210 39 4 81 12 616.1 6

10 Pondampuli 8.2 520 292 16 15.795 18 105 64 16 144 6 603.9 5

11 Thirupullani 8 5420 3162 80 140.94 1418 780 782 160 686 0 481.9 12

12 Mudukulathur 8 2240 1307 20 31.59 440 180 428 9 516 6 823.5 5

13 Manjur 8.1 1260 720 46 21.87 60 205 207 4 99 18 573.4 14

14 Parthibanur 9 10300 6133 180 60.75 2765 700 2070 14 69 18 256.2 22

15 Kilaramanadhi 8.3 7000 4096 200 376.65 1843 2050 644 176 912 0 298.9 14

16 Kiliyur 7.8 6450 3709 160 145.8 1914 1000 1058 21 302 18 353.8 11

17 Kadambakkudi 8.2 440 221 18 37.665 46 200 7 5 576 18 1043.1 112

18 Thirutheravalai 8 1360 763 18 37.665 291 200 219 14 3816 0 134.2 76

19 Ariyakudi 8.4 19530 11427 1000 194.4 6027 3300 2990 12 40 12 305 7

20 Sadurvedamangalam 8.2 19400 11304 800 243 5672 3000 3220 9 14 5.5 294.4 3

21 Kamutnakudi 8.2 440 221 18 37.665 46 200 7 5 37 2.1 137.9 3

22 Pambur 8.6 4120 2355 84 58.32 950 450 736 19 29 2.9 152 5

23 Veeravanur 8.1 1020 617 18 7.29 117 75 200 6 30 2.1 112.8 6

24 Chittrakkottai 8.2 560 307 6 25.515 82 120 71 8 24 8.4 141.3 4

25 Keelakarai (TP) 8.4 5900 3630 80 43.74 1276 380 1196 26 75 18 555.1 4

26 Panaydiyendal 8.2 6600 4072 64 184.68 1276 920 1035 168 71 3.5 236.4 2

27 Sikkal 8.1 900 491 26 38.88 170 225 99 13 49 0 372.1 4

28 Sayalgudi (TP) 8.5 2610 1495 52 106.92 567 570 322 47 180 6 219.6 3

29 Kamuthi (TP) 8.2 540 286 28 41.31 74 240 13 7 47 5.8 194.1 5

30 Merkkukottagudi 8.1 520 303 16 15.795 53 105 64 18 25 5.5 184.4 4

31 Thimmanathapuram 8.2 540 286 28 41.31 74 240 13 7 576 18 762.5 55

32 S.Tharaikudi 7.3 1180 667 38 147.015 131 700 166 32 26 8.1 216.7 5

33 Narippaiyur 8.2 1480 922 20 88.695 230 415 145 36 35 0 292.8 1

34 Mookkaiyur 8.4 2560 1496 76 51.03 567 400 396 35 324 0 786.9 82

35 Ervadi 8.4 3250 1938 64 174.96 496 880 313 82 141 18 378.2 22

36 Thaliyanendal 8.7 1360 769 12 31.59 184 160 244 3 72 0 292.8 5

37 Vellamarichchukkatti 8 2550 1564 48 68.04 425 400 327 149 312 12 323.3 11

38 Valantaravai 8 1650 1151 20 34.02 262 190 239 113 106 12 597.8 11

39 Pirappanvalasai 8.2 710 396 76 4.86 43 210 64 9 442 12 378.2 8

ISSN NO: 1021-9056


INFOKARA RESEARCH


The geochemical variation in the ionic concentrations in the groundwater can

be easily understood by the plot of scatter diagrams (Fig.4,a,b,c,d,e,f) for the various

ions and their affinities. The scatter plot of Na+ + K+ versus Cl- ions, analyzed in the

ground water samples during 2017. Fig.4.showed that most of the water sample

values were fall above the equiline concentration line indicating additional source of

Na+ and K+ from weathering of silicate minerals. These scatter plot suggested that

the majority of the alkali metal ions were balanced by the chloride ions. Further,

Chloride ions could normally tend to prefer for association with alkali rather than

alkaline earth metal (Ca2+& Mg2+) in the formation of alkali chlorides.

Extra points above the scatter plot inferred that alkalis may also be associated

with carbonate and sulphate ions as alkali bicarbonate and alkali sulphates. Among

the alkalis, Na+ ion was a dominant, K+ ion in groundwater, due to chemical

weathering / dissolution of minerals of local sedimentary rocks. The plots of Ca2+ +

Mg2+ vs total cations and Na+ + K+ vs total cations, in mostly all the sample points,

lie below the theoretical line indicated that alkalis (Na+& K+) were more enriched

two to three times than the amount of Ca2+ and Mg2+ (alkaline) due to leaching from

silicate weathering in the aquifer materials of the study area. Scatter plots suggested

that dissolution of evaporation minerals occurred in source cations via silicate

weathering and /or soil salts were found to be more significant. Furthermore,

silicate weathering can also be understood by estimating the ratio between Na++ K+

and total cations. The relationships between Na+ + K+ and total cations in the study

area indicated that, the majority of the samples were plotted near the Na+ + K+ = TC+

line, indicating the involvement of silicate weathering in the geochemical processes,

which contributes mainly sodium and potassium ions in the groundwater.

ISSN NO: 1021-9056


INFOKARA RESEARCH


a. Na+K vs Cl diagram suggest that silicate weathering

b. Ca+Mg vs TC+diagram shows that carbonate in the study area.

c. Na+K vs TC+ diagram shows that above 50 percent of Na and K come from silicate weathering

d. (HCO3+SO4) vs TA-diagram of the

study area.

e. Cl vs TA-diagram of the study area f. Na vs Cl diagram suggesting that dissolution, it may be derived from silicate weathering.

Fig.4. Plot of scatter diagram shows geochemical variation in the ionic

concentrations in the groundwater

ISSN NO: 1021-9056


INFOKARA RESEARCH


8. Reverse ion exchange study

Generally, Na+ / Cl- ratio indicated that an ion exchange reaction occurs and

typically interpreted as Na+ ions released from a silicate weathering reaction.

Moreover, a high positive correlation between Na+ and Cl- suggested that the

ground water salinity reported which may be due to intermixing of two or more

ground water bodies with the different hydrogeochemical compositions. In the

present study, the molar ratio of Na+ / Cl- for ground water samples confirms that

the ion exchange was found to be the major process along with silicate weathering.

EC versus Na+ / Cl-diagram is shown in Fig.5.g,h,i. In this study area, evaporation

may be the major geochemical process controlling the chemistry of groundwater.

The plot (Ca2+ + Mg2+) vs (HCO3- + SO42-) showed the values to fall scatter to

the equiline, confirm dissolution of cations and anions. Chemical reactions occurred

through ion exchange tend to shift the points to the right of the equiline due to an

excess of HCO3 + SO42) If there is a large excess of Ca2+ + Mg2+over that of HCO3 +

SO42- then the points will be shifted to the left side of the equiline, due to the

occurrence of reverse ion exchange reactions showing that they spread above and

below the linear trend. An ion exchange process is characterized by HCO3 + SO42-

excess over Ca2+ + Mg2+ while the reverse ion exchange is marked by Ca2+ + Mg2+

excess over HCO3 + SO42- For instance, the inequality (Ca2+ + Mg2+) / (HCO3 +

SO42-) > 1, in saline ground water indicates a reverse ion exchange process.

The relationship between (Ca2+ + Mg2+) - (HCO3 + SO42-) vs Na+- Cl- showed

a negative linear trend with a slope of unity, considering the participation of cations

and anions in the ion exchange reaction. The plots of (Ca2+ + Mg2+) - (HCO3 + SO42-)

Vs Na+- Cl- shows a slope value, respectively, which is nearly equal to -1 indicating

that Ca2+, Mg2+ and Na+ ion concentration are interrelated through reverse ion

exchange. Simple linear regression models were constructed to evaluate the

relationship of hydro geochemical constituents to each other. For this analysis, Cl,

TC+, TA- , EC, HCO3 + SO4, andNa-Cl were used as independent variables and

Na+K, Ca+Mg, HCO3+SO4, Na/ Cl, (Ca + Mg) - (HCO3 + SO4), Na, and Cl were

ISSN NO: 1021-9056


INFOKARA RESEARCH


used as dependent variables. The linear regression model’s positive relationship of

cations and anions shown in Table.2.

g.Na / Cl vs EC diagram h. (Ca + Mg) vs (HCO3 + SO4) diagram

i.(Ca + Mg) - (HCO3 + SO4) vs Na - Cl diagram

Fig.5. Plot of the scatter diagram shows that minus sign indicates geochemical variation in reverse ionic concentrations in the groundwater

All regression models revealed positive relationships with correlation

coefficients ranging between 0.9929 and 0.0494 except for one model that showed a

strong negative slope with R2 of -0.9497. The regression analysis revealed that there

was a strong positive relationship between Total Anions (TA-) and Chloride (Cl-)

with the R2 of 0.9929, implying that increasing TA is directly proportional to the

increase in Cl. The next highest positive relationship was seen between TC+ and

Na+K with the R2 of 0.9722 indicating strong contribution of Na+K to total amount

of dissolved solids in water.

ISSN NO: 1021-9056


INFOKARA RESEARCH


Table.2.Positive relationship of cations and anions

S.No X Y R2

1 Cl Na+K 0.9485

2 TC+ Ca+Mg 0.8586

3 TC+ Na+K 0.9722

4 TA- HCO3+SO4 0.822

5 TA- Cl 0.9929

6 Cl Na 0.9464

7 EC Na/ Cl 0.0494

8 HCO3 + SO4 Ca+Mg 0.6087

9 Na-Cl (Ca + Mg) -

(HCO3 + SO4) -0.9497

A model constructed between Na-Cl and (Ca + Mg) - (HCO3 + SO4)

compounds showed the R2 value of -0.9497 as the third highest correlation coefficient

in which the minus sign indicates negative slope meaning that with increasing Na-

Cl, there was a decrease in the (Ca + Mg) - (HCO3 + SO4) compounds. A model using

Cl versus Na+K measured R2 of 0.9485 as the fourth highest correlation coefficient.

The fifth highest positive relationship was encountered between Cl and Na with the

R2 value of 0.9464, probably indicating the association of Na and Cl in the form of

sodium chloride mineral in the water. From R2 value 0.8586 of a model using TC and

Ca+Mg variables, it is obvious that the proportion of total cations is closely related to

the Ca and Mg constituents. A model relating TA- to HCO3+SO4 achieved R2 of

0.822. A model using HCO3 + SO4 against Ca+Mg showed a moderate degree of

positive relationship between the variables with the R2 of 0.6087. of all the simple

regression models, a model using EC against the ratio of Na to Cl measured a very

low R2 of 0.0494 showing a weaker relationship between the two variables.

9. Chloro-Alkaline Indices

It is essential to know the changes in chemical composition of groundwater

during its travel in the subsurface. CAI (1) and CAI (2) indicating the ion exchange

ISSN NO: 1021-9056


INFOKARA RESEARCH


between the groundwater and its host environment shown in Fig.6 and Fig.7. The

chloro-alkaline indexes were used in the evaluation of Base Exchange reactions and

calculated by using the following equations.

CAI (1) = (Cl-) - (Na++K+)/(Cl-)……………………………………..(1)

CAI (2) = (Cl-) - (Na++K+)/(SO42-+HCO32-+CO32-+ NO3-)……….(2)

CAI (1) and CAI (2) can be either positive or negative depending on whether

exchange of Na+ and k+ in water with Mg+ and Ca+ in rock /soil or vice versa. If

Na+ and K+ are exchanged with water with Mg+ and Ca+ , the value of the ratio will

be positive, indicating a base exchange reaction phenomenon. The negative value of

these ratios will be indicating chloro alkaline disequilibrium as a cation-anion

exchange reaction. From equation (1) and (2) is found that 99 % have negative

choloro alkaline index values Saaty, T.L., and Vargas, L.G. (2000).

Fig.6. Trend diagram shows that chloro Alkaline Index value -1 (CAI-1).

ISSN NO: 1021-9056


INFOKARA RESEARCH


Fig.7. Trend diagram shows that chloro Alkaline Index values -2 (CAI-2).

10. Sea Water Intrusion Study

Using the WHO standards for the drinking uses the classes were categorized.

The erratic behavior of groundwater geochemical elements was sorted. It shows that

in the study area, Calcium, Chloride, Magnesium, Total Dissolved Solids (TDS),

Sulphate, Total hardness and EC were observed in not potable limit. To find out the

spatial distribution of these elements in the study area, GIS was employed. The

potability and not potablity sample locations noticed in Table.3.

Table.3.The Result of Water Quality (SWI)

Sr.

No. Potability Nature Well Locations

1 Acceptable 3,5,6,7,8,9,10,17,18,21,24,27,29,30,31,

38 and 39

2 Allowable 1,4,12,20,31,32,33,35 and 36

3 Not potable (SWI) 2,11,13,14,15,16,19,22,23,25,26,28,34

and 37

The geochemical locations were digitized and the corresponding values of its

attributes were given as an input. Using this data, the interpolation raster maps were

ISSN NO: 1021-9056


INFOKARA RESEARCH


generated. Subsequently, these maps were classified with respect to our interest and

converted into vector maps. These maps were clipped with the boundary to arrive

within the boundary of the study area. The result acceptable, allowable and not

potable Sea Water Intrusion (SWI) zones were given through the spatial distribution

map shown in Fig.8.

Fig.8. Final Integration spatial distribution (SWI) map of the

Ramanathapuarm District

Table.4.Groundwater type of the study area

Type of

Samples

Pre-Monsoon 2015

Sample

Numbers

Total No. of

Samples

Percentage

of Samples

Normal

Groundwater

1,32,23,3,24,29,31

,2,6,10,13,14,19,2

0,25,28,34

17 44%

Mixed - Hard

Groundwater 5,7,9,17,21,30,39 7 18%

Sea Water

Intrusion

4,8,11,12,15,16,18

,22,26,27,33,35,36

,37,38

14 36%

ISSN NO: 1021-9056


INFOKARA RESEARCH


11. Chloride vs. Electrical Conductivity Diagram

Plot of chloride vs. electrical conductivity showing normal groundwater

conditions, saltwater intrusion and mixing (Hard groundwater) between the fresh

and salt water intrusion Washington State Department.

Fig.9. Chloride vs. Electrical Conductivity Diagram of the Ramanathapuarm

District

Totally 34% of the coastal area coming under normal groundwater, 14% of the

groundwater samples are coming under mixed type and 28% of the groundwater

samples are coming under sea water intrusion type. The Chloride vs Electrical

Conductivity diagram shown in Fig.9. Groundwater type are shown Table.4.

12. Graphical Projection of Hydrogeochemical Data

12.1 Piper’s Trilinear Diagram

Piper's diagrams, also called trilinear diagrams are drawn by plotting the

proportions (in equivalents) of the major cations ((Ca2+, Mg2+, (Na++K+)) on one

triangular diagram, the proportions of the major anions (Alkalinity (CO3+HCO3), Cl,

SO4) on another, and combining the information from the two triangles on a

quadrilateral. The position of this plotting indicates the relative composition of a

ISSN NO: 1021-9056


INFOKARA RESEARCH


groundwater in terms of the cation anion pairs that correspond to four vertices of the

field. The main drawback that Piper’s trilinear diagrams have in their plotting shows

the chemical character of the groundwater according to the relative concentration of

its constituents, but not according to the absolute concentrations.On the basis of

chemical analysis, groundwater is divided into six facies. The plot shows that the

groundwater samples fall in the field of Na Cl, Mg Cl, Mg HCO3, Na HCO3 and Ca

HCO3 respectively, according to the order of their dominance. From the plot, it is

observed that 51 % of samples fall in Sodium-Chloride type. Groundwater chemical

evolution where the water rock interaction processes are considered important in the

definition of their magnesium-bicarbonate type 31% and (Mg,Na,Ca and Bi-

Carbonate) cumulativly 18% of samples observed in the fields. From the Piper

diagram dispersion of cation and anions could be associated either to lithological

heterogeneities or whichever with human activities in the Ramanathapuram district.

The Piper's diagrams trilinear plot and its output are given in the Table.5. and Fig.10.

Fig.10.Piper’s Trilinear Diagram of the Ramanathapuarm District

ISSN NO: 1021-9056


INFOKARA RESEARCH


Table.5. Hydrogeochemical facies of groundwater

Facies

Pre-Monsoon 2017

Sample Numbers Total No. of

Samples

Percentage of

Samples

Na Cl

1,2,6,8,11,12,14,16,

18,19,20,22,23,25,2

6,30,34,36,37,38

20 51%

Mg Cl 3,4,5,7,15,24,27,28,

29,31,33,35 12 30%

Mg HCO3 9,17,21,32 4 10%

Na HCO3 10,13 2 5%

Ca HCO3 39 1 3%

Traditional Piper plots (Steinich et al., 1998; Appelo and Postma, 2005) can be

used to plot the relative concentrations of the major ions on ternary diagrams.

Finally, site-specific approaches can be used. For example, an approach specific to

the situation where cation exchange (Ca to Na) dominates the chemical evolution

involves plotting depth relative to sea level verses TDS, classified according to water

type (represented as zones) (Allen and Liteanu, 2006). Zone 1 is characterized by

waters that have a high TDS concentration due to direct salinization (mixing

between fresh groundwater Ca-HCO3 and sea water Na-Cl). Zone 2 is characterized

by waters with TDS values that do not increase with depth, or that just slightly

increase. These waters reflect a cation exchange process (Ca to Na) whereby no

increase in salinity is observed. The water types in Zone 2 vary from Ca-HCO3 to

Na-HCO3, with Na a rich waters generally found at greater depths. Finally, Zone 3

represents waters that are mixed (between Zone 2 waters and a saline end member).

These waters show variable cation composition (Ca or Na), but with increasing Cl

concentration .

ISSN NO: 1021-9056


INFOKARA RESEARCH


12.2. Gibb’s Plot

Various workers have discussed the mechanisms controlling the chemical

compositions of water. It’s well established that there is a close relationship between

water composition and aquifer lithology. Gibbs plot distinguishes the interactions of

groundwater due to precipitation or rock or evaporation, which helps to understand

the factors that controlling the chemistry of groundwater, from a ratio of 1.

Na+K/Na+Ca+K and TDS and 2. Cl/Cl+HCO3 and TDS. It is found that the

majority of the samples suggests interactions between rock and evaporation

dominance. Gibb's plot and its output are given in the Fig.11. and Table.6.

Fig.11.Gibb’s diagram of the Ramanathapuarm District

ISSN NO: 1021-9056


INFOKARA RESEARCH


Table.6. Results of Gibbs Diagram Interpretation

Field

Cations ((Na + K) / (Na + K +

Ca))

Percentage of Cations

Anions Cl / (Cl +

HCO3)

Percentage of Anions

Pre-monsoon 2017

Pre-monsoon

2017

Pre-monsoon 2017

Pre-monsoon

2017

Evaporation crystallization dominance

1,2,6,8,12,14,15, 16,18,

21,22,25,26,28, 33,34,35,36,37,38

49

2,6,8,11,14,15,16,19,20,

22,25,26,28,34,35,38

42

Rock dominance

3,4,5,7,9,10,11,13,17,19,20,23,24,27,29

,30,31,32,39 51

1,3,4,5,7,9,10,12,13,17,18,21,23,24,27,29,30,31,32,33,36,37,3

9

58

Precipitation dominance

-

-

13. Conclusion

The groundwater samples of the Ramanathapuram district have been found

with more salinity, TDS, calcium hardness, total alkalinity and chloride in majority

of the samples beyond the drinking level standards of WHO. Chloride contends

greater input in coastal track compare to mainland samples. Saltwater intrusion into

the mainland and coastal aquifers causing injurious and high contamination samples

was noticed 3km perpendicular and away from the coast. As the aquifers salinity

ionic exchange is mainly cations dominated over anions. From the sea water

intrusion plot clearly represent fresh, mixed and sea water intruded areas, treatment

techniques such as water softening, desalination may solve the existing water quality

parametric complications. The hydrogeochemical analysis has been proved majority

of the villages can serve as an indicate for salt water intrusion. The

hydrogeochemical analysis reveals that the groundwater of the study area is sodium

type and Chloride type. The hydrogeochemical facies infer pre monsoon 2017

majority of the samples fall Na, Cl type remaining samples mixed Cl+SO4+HCO3,

Cl+SO4 and Na+K type. Spatial analysis of various quality parameters using in

Geospatial techniques was found to be efficient. Thematic maps generated in the

ISSN NO: 1021-9056


INFOKARA RESEARCH


study will be helpful to planners and policy makers, especially on public health and

irrigation departments, for sustainable water management in a holistic way.

Hydrogeochemical mixing of water and ionic exchange relationship along the coast

of Ramanathapuram district 34% of the samples coming under normal groundwater,

14% of the groundwater samples are coming under mixed (Hard groundwater) type

and 28% of the groundwater samples very near the coast are coming under sea water

intrusion type. The analytical results have been utilizing the resources for planning

groundwater development the coastal areas and predict further contamination in

fresh water zone.

Acknowledgment

The authors are thankful to the University Grants Commission (UGC)

Division, Government of India, New Delhi for providing financial support for

sanction the UGC Post Doctoral Fellow award vide letter

Reference.F.No./PDFSS/2014-15-SC-TAM-9825 dated on 05.02.2015. The author

thankful to Professor and Head, Department of Geology, Periyar University, Salem

for their kind support during the field work and laboratory analysis.

References

Assaf, H. and Saadeh, M. Assessing Water Quality Management Options in the Upper Litani Basin, Lebanon, using an Integrated GIS-Based Decision Support System. Environmental Modeling and Software. 2008. 23 (10-11) 1327-1337.

Bahrgava, D.S. and Killender, D.J., (1988) The technology of water resources in

Industries. A rational approach. Jr. Ind. Wat. Works Assn., v.20(1), pp.107-112 Balakrishnan, P., Saleem, A. and Mallikarjun, N.D. Groundwater Quality Mapping

Using Geographic Information System (GIS): A Case Study of Gulbarga City, Karnataka, India. African Journal of Environmental Science and Technology. 2011. 5 (12) 1069-1084.

Cedergren, H.R., (1977) “Seepage, Drainage and Flow Nets”, John Wiley and Sons,

New York, 534p Chachadi, A.G. (2005). Seawater intrusion mapping using modified GALDIT

indicator model- case study in Goa. JalvigyanSameek 20:29–45

ISSN NO: 1021-9056


INFOKARA RESEARCH


Chowdhury, A., Madan, K., and Jha, C.V.M. (2010). Delineation of Groundwater

recharge zones and identification of artificial recharge sites in West Medinipur district using RS, GIS and MCDM techniques. Environ Earth Sci 59:1209–1222.

Davis S N and Dewiest R J M (1966) Hydrogeology. Wiley, New York. Eutech Instruments (1997) Conductivity to TDS conversion factors.

http://www.eutechinst.com/techtips/tech-tips40.htm Accessed: February 19, 2014.

Fetter C W (1990) Applied Hydrogeology. 2nd edn. Prentice Hall, Englewood Cliffs,

New Jersey Freeze, R.A & Cherry, J.A., (1979) Groundwater, Prentice – Hall, inc. Englewood

Cliffs, New Jersey,604P. Lobo, J.P., Ferreira and Chachadi, A.G. (2005). Assessing aquifer vulnerability to

saltwater intrusion using GALDIT method: Part 1 – Application to the portuguese aquifer to Monte Gordo, Proceedings of this 4thInterselticColloquim on Hydrol. Mangt. Water Resor., Portugal.1-12.

Majumdar, D. and Gupta, N. (2000) Nitrate Pollution of Groundwater and

Associated Human Health Disorders. Indian Journal of Environmental Health, 42, 28-39.

Mondal NC, Singh VP, Singh VS, Saxena VK (2010) Determining the interaction

between groundwater and saline water through groundwater major ions chemistry. J Hydro 25:100–111

Nageswara, Rao K., Narendra, K. and Venkateswarlu, P. Assessment of

Groundwater Quality in Mehadrigedda Watershed, Visakhapatnam District, Andhra Pradesh, India: GIS Approach. Pollution Research. 2007. 26 (3); 1526.

Pradhan, S.K., Dipika, P. and Rout, S.P. Water Quality Index for the Groundwater in

and Around a Phosphatic Fertilizer Plant. Indian Journal of Environmental Protection. 2001. 21; 355-358.

Raghunath, H.M., (1987) Groundwater, Wiley Eastern Ltd.New Delhi, India, pp.563. Raju N J, Ram P and Dey S (2007) Hydrogeochemical parameters for assessment of

groundwater quality in the upper Gunjanaeru River basin, Cuddapah district, Andhra Pradesh, south India. Environ Geol 52 1067-1074

Saaty, T.L. (1987). The Analytic Hierarchy Process: McGraw Hill.1-287.

ISSN NO: 1021-9056


INFOKARA RESEARCH


Saaty, T.L., and Vargas, L.G. (2000). Models, Methods, Concepts and Applications of the Analytic Hierarchy Process, Boston: Kluwer Academic Publishers.

Schoeller,H, (1967) Qualitative evaluation of Groundwater Resources (in methods

and techniques of Groundwater investigations and Development), water Resources Series,33, UNESCO,pp44-52

Shamsi, U.M., (2005) GIS Applications for Water, Wastewater, and Storm water

Systems. United States of America: Taylor & Francis. Sreedevi, P.D. (2004) Groundwater Quality of Pageru River Basin, Cuddapah

District, Andhra Pradesh. Journal of Geological Society of India, 64, 619-636. Swarna Latha, P., Nageswara Rao K., Ramesh Kumar, P.V. and Hari Krishna, M.

Water Quality Assessment at Village Level a Case Study. Indian Jour. Environ. Prot. 2007. 27 (11) 996-1000.

Todd, A.C., Somerville, J.E. and Graham, S. (1984) The Application of Depth of

Formation Damage Measurement in Predicting Water Injectivity Decline. Formation Damage Control Symposium, Bakersfield, California, February, SPE 12498.

Umar R and Ahmed I (2007) Hydrogeochemical characteristics of groundwater in

parts of Krishni-Yamuna Basin, Muzaffarnagar district, UP. Jour Geol Soc India 69 989- 995

United Nations Environment Programme (UNEP). Groundwater: a Threatened

Resource. 1996. UNEP Environment Library No.15, UNEP, Nairobi, Kenya. Viessman W, Knapp JW, Lewis GL (1989). Introduction to Hydrology, Harper and

Row Publishers, New York Walton, W. (1970) Groundwater Resource Evaluation. McGraw-Hill Series, 664 p. Washington State Department of Ecology (2005).Water Resource Inventory Area 06

Islands. Seawater Intrusion Topic Paper. Retieved From:https:// fortress. wa. gov

/ecy/publications /Summary Pages/1203271. WHO (1996) Guideline for drinking water quality, V.l, Recommendation. Geneva:

WHO, pp.1 - 4

ISSN NO: 1021-9056


INFOKARA RESEARCH


Documents

Geochemical Ionic Exchange Relate with Sea Water Intrusion ...infokara.com/gallery/98-dec-3383.pdf · Sea Water Intrusion type. The higher and lower concentration was identified based