Available at: http://publications.ictp.it IC/2010/103

United Nations Educational, Scientific and Cultural Organization and

International Atomic Energy Agency

THE ABDUS SALAM INTERNATIONAL CENTRE FOR THEORETICAL PHYSICS

OXYGEN AND HYDROGEN ISOTOPIC CHARACTERISTICS OF THE KAVERI RIVER SURFACE WATERS, SOUTHERN PENINSULAR INDIA

Hema Achyuthan1 Department of Geology Anna University, Chennai 600 025, India

and The Abdus Salam International Centre for Theoretical Physics, Trieste, Italy,

Marzia Michelini

Department of Geosciences, University of Trieste, Trieste, Italy,

Somasis D. Sengupta, Vishwas S. Kale Department of Geography, University of Poona, Pune, India,

Barbara Stenni and Onelio Flora

Department of Geosciences, University of Trieste, Trieste, Italy.

Abstract

We present in this paper the spatial distribution of stable isotopic composition (δ18O and δD) of Kaveri River surface waters to understand how the evaporation and precipitation affect the isotopic signature and dynamics of surface river waters. In the southern peninsular India, Kaveri River is one of the longest tropical river. Our stable isotope data indicate that the upper Kaveri region is influenced strongly by the SW monsoon. There is a narrow range between the δ18O values found from the origin of the Kaveri River to its delta, and there is no significant orographic impact of the Western Ghats. A decreasing trend of d values is found along the course of the river. This is attributed to evaporation effects, which nevertheless are not very strong. This difference in deuterium excess due to evaporation is also an indication of the moisture recycling in the lower Kaveri area, which is primarily controlled by evaporation from the wetlands in the delta plain but also from the surface waters and as such from the rivers.

MIRAMARE — TRIESTE

December 2010

1 Regular Associate of ICTP. hachyuthan@yahoo.com

Introduction

A river is the life line of any region and a proper understanding of the hydrodynamics of the

river system and the hydrological processes of the drainage basin helps in the proper management

of the river water resources for irrigation, agriculture, industry and other socio – economic projects.

In the tropics, especially in India, onset of monsoon, its dissemination over the Indian sub continent

and its occasional failure is closely connected to the agroeconomy and industry of the region

(Sengupta and Sarkar 2006). Spatial distribution of stable isotopic composition (δ18O and δD) of

precipitation and surface waters of rivers are powerful tracers for identifying the sources of vapour

generated during the monsoon and its continental mixing. Few studies have been carried out on the

variables that influence stable isotopes values in the tropics (Slati et al., 1979; Longinelli and

Edmond, 1983; Gat and Matsui 1991; Araguas-Araguas et al 1998; Njitchoua et al., 1997 ; Lachinet

and Patterson 2002) and due to this our understanding of stable isotope values of tropical waters is

often inadequate to interpret isotopic records that are preserved by paleoclimate archives such as

sediment, carbonate and ice cores (Lachinet and Patterson, 2002). Compared to Europe (Ogrinc et

al., 2008; Kanduč et al., 2008; Cortecci et al., 2009; Lambs et al., 2009), North America (Lachinet

and Patterson, 2009), China (Hong –jun et al., 2007) and Mongolia (Tsujimura et al., 2007) work on

stable isotopes data on Indian surface river waters and precipitation is scanty (Sengupta and Sarkar,

2006). Barring few studies carried out on Indian rivers - Ganga river and the Himalayan river

waters (Ramesh and Sarin, 1992; Lambs et al., 2005; Gajurel et al., 2006), Gaula river catchment in

the Kumaun Himalaya (Bartarya et al., 1995), no stable isotope analyses have been carried out till

date on the peninsular river surface waters such as the Krishna, Godavari, Mahanadi and Kaveri.

Ramesh and Sarin (1992) suggested that the high-altitude streams (Ganga headwaters) show a δD-

δ18O relationship close to that of the global meteoric water line. Samples from the lowland regions

show a significant effect of evaporation, indicated by a reduced slope (of approximately six) in a

δ18O-δD plot. The easterly flowing peninsular rivers receive the monsoonal rains and debouche the

sediments into the Bay of Bengal. There are very few stable isotopic data collected on river, rain

and lake waters of southern India that reflect the characteristic of the hydrological cycle and the

water of this region (Lambs et al 2005).

Here we present a stable isotope study of the Kaveri river from its origin to the delta with

the aim to understand how evaporation and precipitation affects its isotopic signature. This study is

the first data generated on the Kaveri river to understand the water cycle of its basin since this river

is one of the longest draining the tropical southern peninsular India. The data obtained here may

have important implications for understanding the dynamics of surface river waters in the tropics.

2

The Kaveri River

Application of the Shuttle Radar Topographic Mission (SRTM) Digital Elevation Model

(DEM) analysis indicates that the average elevation of the basin is 564 m a.s.l. (Figure 1 and 2).

About 42 percent of the basin area lies between 650 and 1000 m. This upland area in the headwaters

constitutes the Mysore Plateau. Almost an equal percentage of the catchment area occurs below 400

m. Approximately one-tenth of the basin area is above 2000 m.

The Kaveri River basin lies between latitude 10o 07’ N to 13o 28’ N and longitude 75o 28’ E

and 79o52, E and drains a catchment area of nearly 87,900 km2. The river originates on the

Brahmagiri Hills in the Western Ghats (elevation of 1345 m a.s.l.) (Singh and Rajamani 2001), in

Coorg district of Karnataka state, flowing in a south-easterly direction for about 800 km through

Karnataka and Tamil Nadu states, and descending the Eastern Ghats in a series of great falls. Before

reaching the Bay of Bengal south of Cuddalore (Tamil Nadu), it breaks into a large number of

distributaries forming a fan shaped Kaveri delta. Its uppermost course is trellis, tortuous with bed

rock and high banks. The river bifurcates twice, forming the sacred islands of Srirangapatnam and

Sivasamudram, 80.47 km apart. Upon entering Tamil Nadu, the Kaveri continues through a series

of twisted gorges until it reaches Hogenakal Falls and flows through a straight, narrow gorge near

Salem. The Mettur Dam, nearly 1606 m long and 53.3 m high, impounds the Kaveri River water

forming a lake (Stanley Reservoir). Further down the Kaveri River bifurcates forming the

Srirangam Island and the distributaries of the river are the Kollidam, Velar, Vettar and the Coleroon

that form the delta system and the drainage pattern is largely braided.

The important tributaries joining the upper Kaveri are the Kakkabe, the Kadanur and the

Kummahole while the important tributaries joining the middle reaches of the river from the left are

the Harangi, the Hemavathi, the Shimsha and the Arkavathi. The tributaries joining it from the right

are the Lakshmanathirtha, the Kabbani, and the Survanavathi. Further down, the lower Kaveri is

joined by the Bhavani, the Noyil, and the Amravathi.

The Kaveri River drains over several bed rock types of different geological ages. In its upper

and middle reaches the river flows over the peninsular gneiss, charnockites and granitic rocks of

Archaean age (Fig. 1). Intrusions of Closepet granite and the schist belts of the Dharwar craton are

also observed in the upper and middle reaches of the river. Subsequently, the river flows eroding the

exposed Cretaceous deposits comprising conglomeratic sandstone, fossiliferous limestone and shale

north of Tiruchirapalli, where the Kaveri starts forming a delta and incising the Quaternary

alluvium (Pattanaik et al., 2007).

3

The sharp rise of the Sahyadris followed after the narrow western coastal belt (40-140 m)

with step like escarpments are a consequence of the rejuvenated vertical movements along the

North strike slip displacement along the Precambrian basement NNW-SSE faults (Valdiya 2001,

Rajamani et al., 2009) and also the result of the Late Cretaceous plume activity that poured out to

form the Deccan Basalts (Naqvi 2005).

Between the Mysore plateau and the plains, a series of structural blocks formed due to the

collision of the Indian continent and the Asian continent (Radhakrishna 1993; Valdiya 1998)

strongly guiding the river course. The catchment area is also crisscrossed by several N-S and E-W

striking shear zones and fault systems. The uplifted blocks are due to the reactivation of the shear

and fault systems due to the Himalayan orogeny of which the timing and duration of the uplift is

still to be ascertained. Although rocks of the drainage basin are older than 2500 Ma, they must have

been first exposed during the Cenozoic and at places may have been during the late Quaternary

(Singh and Rajamani, 2001; Rajamani 2009).

Thus hypsographically (Fig.2), three geomorphic domains are recognized in the Kaveri

Basin: (i) the high elevation, high relief streams with narrow valleys (ii) middle elevation low relief

Mysore Plateau with broad valleys and low-gradient streams in the west, and (iii) fluvio-deltaic

plains to the east (known as the Tamil Nadu Plains). Between upper and middle domains there are a

series of block mountains, such as the Nilgiris, the Sheveroy, the Biligirirangan, and the

Mahadeswaramalai Hill Ranges.

The Western Ghats act as a climate barrier since at least the Pliocene period (Gunnell 1998)

making the plateau eastwards arid (Rajamani et al 2009). The Kaveri river basin receives both the

SW and the NE monsoon rains (the upland Kaveri river receives the SW monsoon rains between

June to September (5000 mm) and the southern delta receives the NE rains from October to

December) (Fig.1).

The highest rainfall in the basin is received along the western border of the basin during the

southwest monsoon. The precipitation decreases from west to east (3800 mm to <1000 mm)

because of orographic effects of the monsoon rains along the Western Ghats. The main plateau

remains in the rain shadowed leeward side of the mountains (Fig. 1 and 2) and receives less than

1000 mm of annual rainfall (June to September) by the SW monsoon. The eastern side of the basin

gets most of the rain during the northeast monsoon. Depressions in the Bay of Bengal affect the

basin in the monsoon, causing cyclones and widespread heavy rains. Over 75% of the annual

rainfall and runoff occurs during the southwest monsoon season and about 85% of the annual

sediment load is carried during the wet season (Vaidyanathan et al., 1992). The average annual

runoff for the Kaveri is about 21.4 km3, which is significantly lower than other large rivers of the

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Indian Peninsula, such as the Godavari (111 km3), the Krishna (78 km3), the Mahanadi (67 km3)

and the Narmada (46 km3), implying very low rates of denudation. The mean annual temperature is

25°C although in summer (March to May) the maximum temperature reaches up to 43°C. And the

minimum is 18°C. One observes a marked variation in vegetational canopy along the river course:

evergreen to semi-evergreen forests in the Western Ghats, deciduous forests in the sub-humid zone

on the leeward side of the Western Ghats, dry deciduous vegetation in the semi-arid plateau of

Mysore, and the delta region-highly irrigated and cultivated (Rajamani et al 2009). The delta region

is also called the rice bowl of India. Materials and methods

The Kaveri River waters were collected in 100 ml poly vinyl bottles during the beginning of

SW and NE monsoon seasons in two spells June 2008 and Nov-Dec 2009 avoiding the hot summer

period. The sampling transect ran from the origin of the river Kaveri at TalaKaveri (75o 49’ E; 12o

39”N) to the delta region near Vettar (79o 07.155”E; 10o 50.525”N) including the major tributaries.

The water samples were collected from elevation between approximately 1250 m a.s.l. on the

Western Ghat slope towards the delta 19 m a.s.l. (at or near sea level) with a rainfall gradient about

5000 to less than 1000 mm. Coastal river waters were avoided to prevent saline incursions. The

sample elevation, stream length, and elevation of the stream head were estimated from 1:25,000 and

1: 50,000 topographic maps supported by spot heights using GPS survey instrument (Table 1).

δ18O and δD values were determined using a Wavelength-Scanned Cavity Ring-Down

Spectroscopy (WS-CRDS) isotopic water analyzer (L1102-i) from Picarro, at the Stable Isotope

Laboratory of the Department of Geosciences, University of Trieste (Italy). This new spectroscopy

technology is explained in Brand et al. (2009). The results are expressed in δ notation relative to the

V-SMOW standard (where δ18O or δD = {[(18O /16O)sample/(18O/16O)V-SMOW] -1} x 1000).

Calibrations were carried out using laboratory standards (TS 2010: δ18O -8.19‰ and δD -52.17‰;

BBW δ18O -0.07‰ and δD -11.14‰; NS δ18O -15.52‰ and δD -114.76‰), periodically calibrated

against the IAEA international standards VSMOW2, GISP and SLAP2. Analytical precision for

δ18O and δD is ± 0.08‰ and ±0.5‰, respectively.

A correlation matrix, using several parameters such as, distance from the source, elevation,

distance from Bay of Bengal, distance from Arabian Sea, δD, δ 18O and d was carried out and

presented in Table 2. The correlation factors highlighted in bold are considered significant.

5

Results and Discussion

Data on isotopes in precipitation are available from the Global Network of Isotopes in

Precipitation (GNIP) only for two stations in southern India close to Kaveri basin area (Kozhikode

and Hyderabad stations) (GNIP/ ISOHIS 2001). While the summer monsoon system (June to

September) in the upland part of the Kaveri river is mainly controlled by the vapour derived from

the Arabian Sea, the monsoonal precipitation in the southern Kaveri delta region is linked with the

vapour originated from the Bay of Bengal and the Northeast rains during October to December

(Bhattacharya et al., 1985, Deshpande et al., 2003, Gupta et al., 2005). The NE monsoon enters the

Kaveri delta region and covers a distance of more than 2000 km. Along the Kaveri course no IAEA

station exists and the first entry point of the SW monsoon is Kozhikode and the other Hyderabad.

Both these stations receive the southwest monsoon. The Kozhikode station data show two distinct

isotopic signatures for the SW and NE monsoons (Unnikrishnan et al., 2009) mainly due to

different moisture sources and air mass trajectories.

Having isotopic data only for two stations does not allow us to define a Local Meteoric

Water Line (LMWL). However, LMWL slopes of 7.6 and 7.89 were derived by Unnikrishnan et al.

(2009), using Kozhikode station data, and by Chidabaram et al. (2009) using SW monsoon rain

samples collected in 2006, respectively. Both these values are quite similar to the one reported by

Rozanski et al. (1993) for the Global Meteoric Water Line (GMWL) and hence we are referring to it

in this paper.

Oxygen isotope data

The δ18O values of the Kaveri river range from -3.6 to -1.84‰, with a value of -2.77 at the

source (in the Upper part at TalKaveri - the origin of the Kaveri river) and -2.28‰ (in the Lower

Kaveri at Thiruvaiyar) in the delta plain (Table 1 and Figure 3a). There is a minor difference in the

δ18O data from the upland Kaveri waters towards the delta (a distance of nearly 900 km), and the

δ18O values of the river can be considered quite homogeneous. This minor difference may be due to

the marginal latitudinal difference between the origin and the delta of the Kaveri river. No

correlation between d18O and elevation is discerned nor with distance from the Arabian Sea and the

Bay of Bengal (Table 2).

The isotopic values do not show significant changes before and after the dam (Mettur dam),

although the only δ18O value available for the water reservoir shows a very negative value of -

7.70‰. The tributaries exhibit the same range of δ18O values as the main river, with the exception

of Amravati and Malingi with values of -5.55‰ and -3.61‰, respectively. More depleted δ18O

6

values are observed at the confluence of the main channel of the Kaveri river with Maingi due to the

contribution of more negative values of this tributary. However, no influence is observed at the

confluence of the Amravati with the Kaveri. This different response could be possibly due to a

lower capacity of the Amravati compared to Malingi.

The δ18O values of the Kaveri river are close to the precipitation values of the nearby site

(Kozhikode station) influenced by the SW monsoon (Unnikrishnan et al 2010), suggesting that also

the river is under the influence of the SW monsoon system.

The negative values found in the dam water and in the Amravati river may suggest that these

could be influenced by NE rains. In fact, highly negative values in precipitation are found during

the NE monsoon as shown by Unnikrishnan et al. (2010) at the nearby Kozhikode station, although

the rainfall amount during NE monsoon is lower than during the SW monsoon. This hypothesis

seems difficult and does not explain the values of the lower Kaveri that are not highly depleted as

observed at Amravati and in the reservoir water. On the hand, these more negative values suggests

that deep groundwater may contribute to these highly negative values. In fact the Kaveri basin is

structurally configured by tectonics.

Deuterium excess data Both isotopic ratios, 18O/16O and D/H, were determined in the Kaveri river water samples

allowing us to calculate the deuterium excess. This second order isotopic parameter, first defined by

Dansgaard (1964) as d = δD - 8* δ 18O, mainly depends on the climatic conditions (sea surface

temperarture, relative humidity and wind velocity) in the precipitation source regions (Merlivat and

Jouzel, 1979). The position of a sample with respect to the GMWL (by plotting it in a δ18O/dD

diagram) permits to infer if evaporation effects have affected its initial isotopic value.

The deuterium excess values, hereafter d, are reported in Table 1 and its variability along the

course of the river is shown in figure 3b. d values range from 1.4 to 11.6‰ in the whole data set

with higher values noted in the upland region of the Kaveri river from TalKaveri to Appangala (Fig.

3b), while low d values are found in lower Kaveri area. A slight correlation between d and elevation

is observed as a consequence of its decreasing trend from the source towards the delta (Table 2). An

exception is represented by the high value (11.2‰) exhibited by the dam water sample, similarly to

what was observed in the δ18O value of the dam water.

In order to determine the effect of evaporation we plotted all δ18O values against δD ones

(Figure 4) distinguishing among different water types (Upper, Middle and Lower Kaveri, tributaries

and dam). The upper Kaveri data fall on the GMWL suggesting that these values are not modified

by evaporation and reflect the influence of the SW monsoon. On the contrary, the Middle and

7

Lower Kaveri values, as well as the tributaries, lie below the GMWL indicating that these samples

have suffered some evaporation effects. Again, an exception is observed in the case of the dam

water, which falls very close to the GMWL. We calculated the regression lines for middle and

lower Kaveri data, as well as for the tributaries, in order to assess the magnitude of the evaporation

slopes. The tributaries are lying on a line with a slope of 7.34, not so far from the values of LMWL

found by other authors in nearby areas (7.6 and 7.89, Unnikrishnan et al. 2009 and Chidabaram et

al. 2009, respectively) while slightly lower values are found along the course of the Kaveri river.

This fact suggests that evaporation effects are increasing along the river, in agreement with the

vegetation change observed. However, the slope values of Middle (6.69) and Lower (6.23) Kaveri

do not indicate intense evaporation effects.

Conclusions

We analysed the surface river water of the Kaveri river from its origin to the delta using

stable isotopes of oxygen and hydrogen. The stable isotope data shows that the upper Kaveri region

is influenced strongly by the SW monsoon, being its isotopic values similar to that of the

precipitation during SW monsoon as derived from nearby Kozhikode site. There is a narrow range

between the δ18O values found at the origin of the river to its delta, and significant orographic

impact of the Western Ghats is not discerned. However, a decreasing trend of d values is found

along the course of the river. This has been attributed to evaporation effects, which is not very

strong. This difference in deuterium excess due to evaporation is also an indication of the moisture

recycling in the lower Kaveri area, which is primarily controlled by evaporation from the wetlands

in the delta plain but also from the surface waters and as such from the rivers.

The data reported in this study are preliminary but the only ones available presently for the

entire length of the Kaveri River. No enough data is available at present to understand the impact of

NE monsoon and its complexities involved with the evapotranspiration. Therefore more data need

to be collected not only from the river surface waters but also, a network of rain gauge and

pluviometer needs to be installed along the river course spatially and the data needs to be collected

continuously for at least two-three years.

Acknowledgements

This paper was possible due to the funding on Kaveri river by the ISRO CELL, University

of Poona, Pune to V.S. Kale. V.S.K, Somasis D and HA thank the ISRO Cell, University of Poona,

8

Pune, for facilities provided. This work was done within the framework of the Associateship

Scheme of the Abdus Salam International Centre for Theoretical Physics, Trieste, Italy. The authors

thank the editor and the reviewers for their constructive comments that helped in the presentation of

the manuscript.

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11

P. Vaithyanathan, A.L.Ramanathan and V. Subramanaian, Sediment transport in the Kaveri River basin: sediment characteristics and controlling factors, J. Hydr. 139, 1-4 (1992), 197-210.

K.S. Valdiya, Late Quaternary movements and landscape rejuvenation in southeastern Karnataka and adjoining Tamil Nadu in southern Indian shield, J.Geol. Soc. India, 51 (1998),139-166.

K.S.Valdiya, River response to continuing movements and the scarp development in central

Sahyadri and adjoining coastal belt, J.Geol. Soc. India, 57 (2001), 13-30.

U.C. Warrier, M. Praveen Babu, P. Manjula, K.T.Velayudhan, A. Shahul Hameed and K. Vasu

2010. Isotopic characterization of dual monsoon precipitation – evidence from Kerala, India, Curr.

Sci. 98(11) (2010), 1487-1495.

12

Figure1. The panel A is showing the location of the Kaveri Basin with respect to the Peninsular India. The panel B is the Digital Elevation Map of the Kaveri Basin showing the main course of the river.

13

y = -1.3176x + 955.23R2 = 0.9227

0

400

800

1200

1600

0 100 200 300 400 500 600 700 800 900 1000Distance(km)

Ele

vatio

n (m

)

Figure 2. Elevation versus distance of the sites along the Kaveri River basin and sampled sites.

14

Figure 3a. δ18O values versus the distance from the source showing no significant variations of the upper Kaveri and the lower streams. Distinct values are observed for the Mettur dam water and the Amravati river.

Figure 3b. Deuterium excess values versus the distance from the source showing a decreasing trend along the river course and distincy values for the Mettur dam water.

15

Figure 4. δ18O/δD plot for all water samples discussed in this study. The black line refers to the Global Meteoric Water Line(GMWL); the orange, green and blue lines refer to the regression lines calculated for the tributaries, the middle and lower Kaveri river samples, respectively. The regression line equations are also shown: the slopes are 7.3, 6.7 and 6.2, respectively. The graph suggests that the Middle and Lower Kaver water samples have undergone evaporation. On the contrary, the Upper Kaveri samples are generally falling close to the GMWL. This may indicate absence of significant evaporative modification in the Upper Kaveri.

16

Tabl

e 1

Geo

grap

hica

l coo

rdin

ates

of t

he si

tes a

long

the

Kav

eri R

iver

and

isot

opic

dat

a.

S. N

o.

Site

Lo

ngitu

de

Latit

ude

Dis

tanc

e fr

om th

e so

urce

(k

m)

Elev

atio

n (m

)

Dis

tanc

e fr

om

BO

B

(km

)

Dis

tanc

e fr

om A

S (k

m)

δD  ‰

                                     

(V-­‐SMOW)  

δ18 O

 ‰                                      

(V-­‐

SMOW)  

d ‰

(V

-SM

OW

)

Upp

er K

aver

i

 

 

1 Ta

laka

veri

75.4

9 12

.39

0 12

81

502

49

-11.

8 -2

.77

10.4

2

Bag

aman

dala

75

.53

12.3

8 5

882

491

58

-10.

9 -2

.68

10.5

3

Nea

r Med

iker

i 75

.56

12.3

8 24

89

9 47

5 77

-9

.7

-2.6

2 11

.3

4 B

akka

75

.69

12.3

6 27

89

5 47

1 80

-9

.7

-2.4

8 10

.1

5 A

ppan

gala

75

.71

12.3

8 31

93

7 46

9 84

-9

.4

-2.6

2 11

.6

6 N

ellia

hudi

keri

75.8

7 12

.31

65

851

461

86

-9.7

-2

.05

6.7

7 D

ubar

e 75

.90

12.3

7 74

84

5 45

1 95

-1

1.7

-2.5

1 8.

4 8

Dod

dabe

ttigi

ri 75

.92

12.4

3 77

84

3 45

4 10

4 -9

.7

-1.8

4 5.

0 M

iddl

e K

aver

i

9 K

usha

l Nag

ar

75.9

7 12

.45

86

800

450

107

-11.

1 -2

.73

10.8

10

H

aran

gi R

iver

75

.95

12.4

9 89

81

8 45

1 11

4 -1

0.3

-2.3

2 8.

2 11

K

aniv

egra

ma

75.9

6 12

.51

115

817

450

116

12

G

adde

hosa

halli

76

.03

81

80

7 45

4 11

9 -1

0.9

-2.2

7 7.

3 13

R

aman

atha

pura

76

.09

12.6

1 11

9 79

1 44

9 12

1 -9

.8

-2.2

6 8.

3 14

B

asav

apat

tana

76

.12

12.6

1 14

9 79

8 44

3 13

1 -1

1.5

-2.3

8 7.

6 15

C

hunc

huna

katte

76

.30

12.5

1 15

8 76

8 42

3 13

5 -1

2.4

-2.3

6 6.

5 16

H

ampa

pura

76

.39

12.4

7 17

2 74

7 42

3 13

8 -2

0.6

-2.7

5 1.

4 17

K

rishn

araj

asag

ar

76.5

8 12

.43

210

725

396

161

-9.6

-1

.61

3.3

18

Srir

anga

patn

a 76

.68

12.4

3 21

5 67

4 36

4 18

1 -1

2.1

-2.1

9 5.

4 19

B

annu

r 76

.84

12.3

2 24

9 65

6 34

0 19

7 -1

0.4

-1.8

2 4.

2 20

T.

Nar

sipu

r 76

.91

12.2

2 25

4 63

5 33

0 19

8 -1

7.3

-2.9

7 6.

5

21

Tala

kad,

Out

ter

Ben

d 77

.03

12.1

7 27

4 63

0 32

1 21

3 -1

2.3

-2.1

9 5.

3

22

Mal

ingi

Riv

er

77.0

4 12

.17

276

628

320

213

-22.

6 -3

.61

6.2

23

Ham

papu

ra2

77.0

7 12

.17

279

632

315

210

-20.

0 -3

.07

4.6

24

Kol

lega

l Lak

e 77

.13

12.2

0 28

2 63

5 30

3 21

5 -2

2.3

-3.6

0 6.

5 25

S

hiva

sam

udra

m

77.1

5 12

.29

309

650

320

225

-14.

1 -2

.33

4.6

26

Ark

avat

hi R

iver

77

.43

12.2

9 34

1 37

4 26

7 26

0 -1

4.4

-2.2

5 3.

6

17

27

Con

fluen

ce o

f A

rkav

athi

& K

aver

i 77

.43

12.2

9 34

1 37

4 26

7 26

0 -1

3.6

-2.2

3 4.

2

28

Mek

edat

tu

77.4

4 12

.27

343

366

265

261

-15.

0 -2

.05

1.5

29

Chi

nar R

iver

77

o 46.

913"

12

o 7.2

56"

386

271

256

266

-15.

3 -2

.08

1.4

Dam

30

Met

tur n

ear t

he

dam

77

o 48.

566"

11

o 47

.769

" 44

1 20

3 22

8 24

3 -5

0.3

-7.7

0 11

.2

Low

er K

aver

i

32

Am

rava

ti riv

er

78o 0

3.35

8"

10o

56.5

37"

568

119

192

241

-38.

3 -5

.55

6.0

33

Lala

pet K

aver

i riv

er

78o 2

0.36

6"

10o

57.3

53"

607

92

154

277

-15.

3 -2

.54

5.0

34

Srir

anga

m

Kol

lidam

78

o 41.

486"

10

o 52

.328

" 64

1 67

11

3 32

2 -1

4.3

-2.3

7 4.

7

35

Kal

anna

i Ani

cut

78o 4

9.01

1"

10o

50.0

89"

645

61

113

317

-14.

5 -2

.65

6.7

36

Chi

ntam

ani

78o 7

1.1"

10

o 50

.084

" 65

1 48

35

1 38

0 -2

3.8

-3.5

6 4.

7

37

Thiru

vaiy

aru

79o 0

6.57

3"

10o 5

2.77

" 65

4 47

35

0 38

2 -1

2.4

-2.2

8 5.

8

38

Kud

amur

utti

79o 06

.498

" 10

o 51.

82"

657

49

353

380

-16.

7 -2

.47

3.1

39

Vet

tar

79o 0

7.15

5"

10o

50.5

25"

667

42

10

431

-15.

4 -2

.54

4.9

40

Ven

nar

79o 0

7.95

9"

10o

49.1

50"

672

41

10

432

-17.

0 -2

.47

2.7

41

Pad

ithur

ai

78o 4

2.10

5"

10o

50.1

71"

706

67

10

431

-21.

2 -3

.29

5.1

42

Utta

mac

heri

78o 4

6.48

7"

10o

50.0

04"

712

64

117

317

-15.

3 -2

.55

5.1

43

Muk

hom

bu

78o 3

4.96

0"

10o

53.6

25"

713

76

140

293

-17.

1 -2

.67

4.3

44

Mus

iri

78o 2

5.67

8"

10o

51.2

81"

715

85

161

276

-10.

7 -1

.60

2.1

BO

B=

Bay

of B

enga

l, A

S= A

rabi

an S

ea, d

=δD

-8δ18

O

18

Tabl

e 2.

Cor

rela

tion

mat

rix o

f the

var

ious

par

amet

ers.

D

ista

nce

from

the

sour

ce

(km

) E

leva

tion(

m)

Dis

tanc

e fro

m B

OB

(km

) D

ista

nce

from

AS

(km

) δD

 δ1

8O  

d(*)

D

ista

nce

from

the

sour

ce (k

m)

1

E

leva

tion(

m)

-0.9

7 1

D

ista

nce

from

BO

B(k

m)

-0.9

1 0.

89

1

D

ista

nce

from

AS

(km

) 0.

78

-0.7

8 -0

.96

1

δD  

-0.3

4 0.

38

0.40

-0

.35

1

δ1

8O  

-0.1

7 0.

20

0.24

-0

.18

0.96

1

d(

*)

-0.4

8 0.

50

0.43

-0

.47

-0.1

7 -0

.45

1

19