Chapter II

Krishna River Basin

23

KRISHNA RIVER BASIN

The river basins in India have been classified into

three groups depending upon their catchment area (Rao 1975).

(i) Major rivers - catchment area> 20,000 sq.km.

(ii) Medium rivers - catchment area 2,000 - 20,000 sq.km.

(iii) Minor rivers - catchment area< 2,000 sq.km.

As per this classification, India has fourteen major,

fortyfour medium and several minor rivers. Krishna flowing

across the Peninsular India is one of the major rivers of

South India. In this chapter, the catchment characteristics,

Geology and Geography of the basin is described in brief.

Location and Catchment characteristics of the River Krishna

The Krishna is an inter-state river wll0se catchment

lies between the latitudes 13 Nand 19 30N and longitudes 73

23 E and 80 30 E. The drainage basin map of Krishna is given

in Fig.1. The basin has the drainage area of 2,58,945

sq.km. of which 26.8% lies in Maharashtra, 43.8% in

Karnataka and 29.4% in Andhra Pradesh (Rao 1975). In terms

of catchment area, this basin is fifth among the Indian

rivers and the largest river after Godavari in Southern

India. The river rises in the western ghats from a slender

spring near ~lahabaleshwar in the Maharashtra State at an

elevation of 1337m, about 64 km from Arabian Sea. It has

been stated by Krishnan (1981) that the major drainage trend

of the rivers of the peninsular India including Krishna is

TRIBUTARIES

1. KOVNA 2. VERLA 3. VARNA

604. PANe HGANGA

1 t. DUDHGAN GA 6. GHAT APRABHA 7 MALAPRABHA 8. SHIMA 9. SINA 10. NIRA 11. TUN GASHADRA 12. TUNGA 13. BHADRA

. 14. VEDAVATI IS. MUSI 16. MUNERU

Fig 1

SCALE IN KM. o 100 200 h-=-a I I

76 o

Drainage basin map of Krishna River Basin

25

towards the East and South-East due to the uplift of the

western ghats and slight tilt of the Peninsular Indian mass

to the East during the Miocene age. After flowing 1400 km

and collecting waters from a number of tributaries Krishna

becomes a mighty river and joins the Bay of Bengal. The 3

annual discharge of the Krishna varies from 3 to 34,000 m -1 3 -1

s ,with 2146 m s as the mean discharge (Rao 1975). Table

3 gives a summary of general hydrological characteristics of

river basins in India. The hydrological and geochemical

data for the Krishna river basin were discussed in detail in

the following chapters, based on the present data.

Tributaries

The river traverses across the peninsular India from

West to East and on its way is met by major tributaries such

as Ghataprabha, Malaprabha, Dhima and Tungabhadra (Fig.I).

In upper reaches, about 137 km from its source it receives a

tributary the Koyna. Lower down the river Yerla falls into

the Krishna from left and then the Varna, the Panchganga and

Dudhganga from the right (Fig.I). Just near its confluence

with Dudhganga and about 306 km from its source, the bed

level of the river is at an altitude of about 533m and the

river has emerged from the heavy rainfall zone. After

flowing for another 201 km the Krishna receives from its

right, the waters of Ghataprabha and 35 km lower down those

of the ~lalaprabha. A short distance downstream of its

26

Table 3 Hydrological Characteristics of river basins in India

-----------------------------------------------------------River Hean annual Drainage ~lean basin TDS TS~l

discharge area elevation (ppm) (ppm) 9 3 3 2

(10 m /yr) (10 km ) (m) -----------------------------------------------------------Ganges 493 970 3000 178 1631

Brahmaputra 510 690 5000 148 1170

Godavari 92 313 400 181 1845

Krishna-;:- 30 251 420 360 1158

l'lahanacl i 67 132 500 155 31

Karmada 41 90 760 322 130

Cauvery 21 87 630 172 30

Tapti 18 62 740 322 333 -----------------------------------------------------------

TDS TS>l

Total dissolved solids Total suspended matter

Data compiled from Rao,1975; Subramanian,1979,1983,lg8S; Abbas and Subramanian, 1984; Biksham,1985.

-> Present Study

27

confluence with the Malaprabha the Krishna drops about 122m.

from the table land of the Deccan plateau to the alluvial

lands of Raichur. Bhima the important tributary of Krishna

originates north of Pune in Maharashtra runs for about 860

km and joins the Krishna from its left near Raichur. The

K~ishna receives its another main tributary Tungabhadra

further dOKnstream near Kurnool from its right at 918 km

from its source. Tungabhadra is formed by the union of twin

rivers Tunga and Bhadra which rise togetller in the Western

ghats at Gangamula at an elevation of about 1196 m. The

united river Tungabhadra flows for about 531 km before it

joins the Krishna. Bhadravathi, known for its steel plant

and Hospet knoKn for its iron ore deposits are located on

the banks of this river only. Musi joins at Wazirabad 40 km

below Nagarjunasagar dam and Muneru joins upstream of

Vijayawada barrage.

On reaching the Eastern ghats, the Krishna turns

sharply South-Eastwards and flows for about 160 km between

the Krishna and Guntur districts and drains into the Bay of

Bengal in two principal months. It is in the lower course

that the Krishna formed its fertile delta and its waters are

largely used for irrigation. In this part of its course,

Krishna is known for its load of silt. During floods, it

carries silt daily to cover an area of about 7 sq.km and to

a thickness of about 30 ems. This enormous load 0f silt and

28

the gentle land slopes have helped the river to build up a

large and fertile delta. Vijayawada is located at the head

of the delta and here the river passes through a gap of 1170

m, wide between low range hills. A barrage, called Prakasam

barrage, was constructed at this gap to take irrigation

canals on both sides of the river.

The gross sown area is 16 million ha forming 80% of the

cultivable area. The percentage of irrigation is 21. Soil

consists of black, red, laterite, alluvium, mixed soil and

saline and alkaline soils.

Geology

The rock types of the drainage basin yielding sediment

debris to the Krishna river and its several tributaries

represent nearly a complete cross section of the geology of

pensinsular India. The geological map of the basin is given

In Fig.2. The following description pertaining to the

Geology of the drainage basin has been compiled from the

published literature. (h'adia 1976, Krishnan 1981 and from

Geological survey of India maps.) The geological formations

of the basin can be grouped under the following heads:-

1. Recent (Alluvium)

2. Cretaceous to Eocene (Basaltic lavas)

3. Upper Precambrians (Sedimentaries)

4. Early to Middle precambrians (Granites and Meta

sediments)

16

D E3 ~

Alluvium

D~ccan Traps (Lava Flows)

Upp~r Pr~cambrians

(Sedim~ntaries )

Early to Middl~

P r eca m br ians (Gr an itu and m~ta s~dim~nts)

Fig 2

SCALE IN a 100 I

Geological map of Krishna river basin

KM. 200

I

30

The major geological formations traversed by the river from

the source area consist of Deccan traps comprising nearly

one third area of the drainage basin and range in age from

upper cretaceous to Eocene. The Deccan traps are formed by

a series of fissure type eruptions. In some places a

complete set of differentiated rock types from mafic to

felsic has been observed. The trap rock is generally fine

grained, non-porphyritic doleritic or basaltic (theoleitic

type) in composition with abundant labradorite and

enstatite-augite (pigeonite). Minerals of late hydrothermal

stage such as Zeolites, Calcite, Chalcedony and its

varieties are commonly observed either as amygdales or as

crystals radiating from the Geodes. Upon weathering, the

trap rock usually gives either laterite or bauxite and the

soil derived from the weathering is called "black cotton

soil".

It has been observed by many workers (Goldberg and

Griffin 1970; Subramanian 1980; Bikshamiah 1985) that

~'lontmorillonite is the predominant clay mineral ]_n the

altered products of the Deccan traps.

Descending from the Deccan plateau, the Krishna river

traverses through unclassified crystalline rocks comprising

essentially of Dharwars,various gneisses and granites

including charnockites. More than half of the drainaae basin ""

is covered by the unclassified crystalline rocks. The

31

Dharwars are regionally metamorphosed igneous and

sedimentary (pelitic) rocks composed of phyllites, schists,

quartizites, amphibolites and granites. Tungabhadra, the

most important tributary of the Krishna river originates in

Dharwar formations and flows 531 km before joining the

river. The usual mineral in Dharwarian rock types are

hornblende, epidote, diopside, garnet and zircon. The

cuddapah formations are meta sediments predominantly

consisting of quartzites, limestones and shales. The

contribution of heavy minerals from cuddapahs is less

significant and even if these rocks have contributed to some

extent, the heavy minerals would have been presumably

reworked assemblages from Dharwars.

The Krishna river In its last phases of journey

traverses through Khondalities, which upon intensive

weathering has given rlse to brick red soil. The clay

mineral in the brick red soil is chiefly of kaolinite

composition. The mouth of the basin is constituted by

Alluvium deposits which is composed of clays and silts.

Broad strips of Tertiary and post-tertiary

constitutes all along the eastern coast of India,

Ganges delta to the extremity of the peninsula.

alluvium

from the

32

Geography

Spatial distribution of rainfall in the South Indian

region is strongly influenced by the interaction between the

monsoonal circulation and Orography (Subramanyam and Sarma

1978). The western ghats having an average elevation of

about 900 TIl and runf1,ing in an unbroken range of hills from

north to south down to Kerala play a prominent role in

determining the rainfall climate of South India. During the

South-west monsoon season they are mainly responsible for

heavy rainfalls on their windward side and scanty rainfall

on the leeward side, resulting in the formation of humid

climates onthe west coast and dry climates in tile Peninsular

interior. It is for this reason that all the Peninsular

river systems of the region originate on the western ghats

and flow both eastward and westward (Subramanyam et.al.

The map of climatic types moisture region of the

Krishna river basin 1S represented in Fig. 3. "lost of the

basin is semi arid with an arid zone in the centre. Humid

zones are found only in the west on the hills. Rainfall 1n

this basin is mainly due to South-west monsoon current and

its distribution is influenced by physical features. Except

for a narrow strip along the western ghats and a small

portion at the lower end, the Krishna basin has an average

annual rainfall of less than 500 mms of which 75% occurs

during the South-west monsoon.

• PERHUMID

~ HUMID

BJ SUBHUMID

0 ... SEMI - ARID

Ef ARID

Fig 3

... · .. · . .. . . · .... · .... · .. · . · .

o 76

. .

a I

. .. . .. . ., .. ' . . . " " .

HYDE RA BAD' . . . . . . . .... . . . . . . . .. . ' . . . . . . . . .. . . .. ... , . " . ., . . . . . . . ... . . . . .

Climate (After

basin 1984)

Krishna river types of Subrahmanyam et.al

SCALE IN 100

KM. 200

I

o 16

w w

34

Various Pro:jects in Krishna

Irrigation has been practised in the basin long since

by tanks and 6iversions. The rivEr plays a key role in

agricultural economy and the devel Jpment of hydro electric

power. The present total intalled capacity of hydroelectric

projects in this basin is 1892.8 m\" of which 40% comes from

the Koyna Proj (~ct. Srisailam project is another major one

located ln tht; lower stretch of the river. Number of

projects have been constructed in the basin namely

Rajolibanda, lDga bhadra, Musi, Nagar junasagar, Radhanagr i,

Ghod, Koyna, Vir, l1alaprabha,

Ghataprabha, l jer Krishna etc. These structures will

defini tely havE ln impact on geochemistry f the basin.