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INTERNATIONAL JOURNAL OF GEOMATICS AND GEOSCIENCES

Volume 4, No 1, 2013

© Copyright by the authors - Licensee IPA- Under Creative Commons license 3.0

Research article ISSN 0976 – 4380

Submitted on June 2013 published on August 2013 149

Application of Remote Sensing and GIS in studying changing river course

in Bankura District, West Bengal Subrata Pan

Assistant Professor and Head, Department of Geography, Bankura Christian College

[email protected]

ABSTRACT

Remote Sensing and Geographical Information System has emerged as the most important tool

of a geographer to handle spatial data. This technique is now widely used around the world to

analyse physical as well as cultural geographical elements. Change in the alignment and course

of streams is one such area where such a sophisticated technique can be applied fruitfully, the

results of which are utilized in several regional planning occasions. Drainage system of an area

is a dynamic system of the earth which always keep on changing in response to the changes in

the earth-atmosphere system. The present study deals with the changes occurred in the drainage

system of Bankura district- its morphology and alignment as well as its adjustment with

underlying structure. Bankura district is the connecting link between the western upland and

eastern alluvial tract of West Bengal. The district is located between 220 38′ N and 230 38′ N

latitude and between 860 36′ E and 870 46′ E longitude, covering an area of about 6882 sq. Km

(DSH, Bankura, 2006). This isosceles triangle look district is geologically a portion of eastern

extension of Chhotanagpur plateau. Thus it has a very long geological history. Consequently,

the evolution of drainage in this area has passed through long period of denudation. Rivers

always undergone through change in its shapes and alignment by continuous changing their

hydrodynamic and morphodynamic processes, depending upon the slope, terrain characteristics,

structural parameters, vegetal cover with due course of time. For the present study,

topographical maps, satellite images (MSS and ETM+) of different dates and the google earth

image of 2011 are analysed using RS-GIS softwares. The results obtained from these analyses

are then overlaid one upon another and the change in alignment of each course is determined

on the basis of various channel morphological parameters such as sinuosity index, cross valley

asymmetry, meander ratio, entrenchment ratio and other morphological characters.

Key Words: Remote Sensing, Geographical Information System, Sinuosity Index, Cross

Valley Asymmetry, Meander Ratio, Entrenchment Ratio

1 Introduction

The natural flow of water supplied either from melting of glacier or rainfall regularly or

intermittently over the crust of the earth following its slope in a definite channel due to gravity

is generally referred to as river. Such natural flow of water has the greatest influence on the

growth and development of human civilization. Nature in the form of rivers helps mankind to

settle and flourish their lifestyle, somewhere it creates great problems of irrigation and

navigation. But since the appearance of the man on earth, rivers have been its cradle of

civilization as it is the main carrier of human cultural traits from place to place. History and

archaeology proved that the major river basins have been the principal hearths of human

civilization. All the ancient towns and cities all over the world are located on the banks of major

or minor rivers. In spite of its helping nature, man has also faced many problems associated

Application of Remote Sensing and GIS in studying changing river course in Bankura District, West Bengal

Subrata Pan

International Journal of Geomatics and Geosciences

Volume 4 Issue 1, 2013 150

with rivers. The problems are multiplied with the increasing controlling attempts of the rivers

by man.

Drainage system is a dynamic system of the earth which always keep on changing in response

to the changes in the earth-atmosphere system. Rivers always undergone through change in its

shapes and alignment by continuous changing their hydrodynamic and morphodynamic

processes, depending upon the slope, terrain characteristics, structural parameters, climatic

variations, vegetal cover etc. with due course of time. According to the models of landscape

evolution, rivers change its course of flow in response to the above factors. The shifting occurs

in almost all the rivers around the world. The Mississippi river of America has shifted its course

of about 100 km like the movement of snake. In India, the greatest channel shift occurred in

Kosi river which shifted about 120 km towards east. The shifting basically depends upon the

lithological character of the area through which the river flows as well as change in seasonal

discharge and bed load. The alluvial areas are more susceptible to channel shifting than the bed

composed of ancient rocks such as granite or gneiss. The time is also an important factor

according to the models of landform development. The minor shifting of the course of major

rivers of the present study area is mainly due to its long history of denudation.

1.1 Study area

Bankura district occupies the western half of southern West Bengal, consisting of the portions

of western upland, middle rash ground as well as the plains in its eastern and northern fringes.

Figure 1: Location Map


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It can be regarded as a connecting link between the Chhotanagpur plateau on the west and

Bengal basis on the east (O’Malley, 1908). The district is located between 220 38′ N and 230

38′ N latitude and between 860 36′ E and 870 46′ E longitude, covering an area of about 6882

sq. Km (DSH, Bankura, 2006).

1.2 Objectives of the study

The major objectives of the present study are

1. To prepare a drainage map of the district with drainage basin area

2. To detect the changes of the alignment and shifting of the course of major rivers.

3. To identify the nature of changes occurred during the study period

4. Identification of palaeochannels

5. To find out the adjustment of rivers with its underlying structure and to identify the

chance of further shifting.

2. Data Sources and Methodology

The present study explores many sources to suit its research needs. The following are the major

data and satellite images used to meet the objectives of the study

Table 1: Data sources

Satellite Sensors Bands

Used

Date Spatial

Resolution

LANDSAT

LANDSAT

Quickbird

MSS

ETM+

Auto-stitched calibrated

Google Earth Image

1,2,3,4

1,2,3,4

----

07.11.1972

26.10.2001

12.12.2011

23 X 23 metres

30 X 30 metres

0.6 X 0.6 metre

Apart from the satellite images, the district boundary and the drainage map of the district have

been prepared on the basis of NATMO map. A high resolution DEM of the district has also

been procured from NRDMS, Bankura (see figure-2).

3. Drainage System of Bankura District

Rivers have played a formidable role in framing the terrain of the district, nourished its art and

culture having great archaeological importance. Bankura district is bounded by Damodar River

on the north and east traversed by a number of rivers running almost parallel to one another in

north-west to south-east direction. Most of the rivers have their source areas either in the hill

ranges of Jharkhand or Purulia plateau. All of them are rain fed in character, flowing

devastatingly bank full and with rapid speed locally known as ‘hurpaban’ or ‘harqaban’ during

rainy season. During the whole year rivers change their characters seasonally. It becomes

influent during rainy season and effluent in the summers, when ground water contributes river

with its supply.

The entire district is well drained by three major rivers flowing gently from west to east

according to the regional slope of the district. The major drainage systems are


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Figure 2: Methodology flow chart

3.1 Damodar System: The word ‘Damodar’ actually derived from Santhali ‘Da Munda’ or

water of Mundas to ‘Da Munda’ and ultimately corrupted into ‘Damodar’ The length of this

river is about 600 km of which only 98.5 km stretch is flowing through the district. It Owes its

origin in the Khamarpat hills of Chhotanagpur plateau of Palamou district of present Jharkand

state. Major tributaries in the district are: Kalighata Jorh, Sali river and Bodai nadi.

3.2 Dwarakeswar System: Dwarakeswar or Dhalkisor owes its origin in Tilabani Hill (445m)

of Purulia district. Length in the district is about 132 km. Major tributaries are Gandheswari,

Birai, Arkosa and Amodar.Total catchment area is about 4430 sq. km.

3.3 Silabati System: Silai or Silabati is originating from Puncha block of Purulia district. Total

length of the river in the district is 63 km. Major tributaries are: Jaipanda, Purandar and

Champakhali.

3.4 Kangsabati System: Length in the district is 51 km. Major tributaries are: Kumari,

Bhairabanki and Tarafeni.


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Figure 3: Drainage basins of Bankura District

4. Changing parameters of major rivers

4. 1 Cross Valley Assymetry: This is a morphometric technique generally helps to identify

the degree of asymmetry present in a river basin. The cross valley asymmetry (CVA) means

how far the fluvial system is adjusted with its neighbourhood. Mathematically it can be

derived by:

CVA= Da/Dd

Where Da= Distance between the channel and the centreline of the basin

Dd= Distance between the basin margin and the centreline of the basin

If the river flows along the midway of the basin the resulting CVA would be 0 meaning thereby

symmetric basin. If the river does not flow midway, the basin becomes asymmetric. It actually

represents pattern of branching system of the master stream. From the study of CVA it is found

that the river basins of the district are little bit asymmetric in shape as CVA of all the basins

does not exceed 0.5. Of the four basins, Kangsabati river has the highest average CVA of 0.52,

followed by Dwarakeswar (0.42), Sali (0.31) and Silabati (0.19) basin. The flow pattern of the

rivers is mostly controlled by its lithology in the district. Thus large scale shifting is not possible

in an area of lithological control. In spite of that, Kangsabati has shown highest asymmetry

because of its structural irregularities. The entire Kangsabati river basin is composed of two

different rocks of different geological period. The western part is composed of relatively older

rock mica-schist of Precambrian period while the eastern part is composed of pliestocene

laterite formation. The Kangsabati river thus shifted its channel towards the relatively soft

laterite rock making the basin asymmetric. Silabati river on the other hand flows entirely


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through the rocks of recent origin and hence the course in the district does not show any large

scale shifting from its centre line.

Figure 4: Cross Valley Assymetry

4.2 Sinuosity Index: It is the measure of deviation of the river from its ideal path of movement

between two points. Mathematically it is calculated by the following formula:

SI = CL/SL Where CL = Actual Channel Length between source and mouth

SL = Straight line length between the same points

SI will be 1.0 if there is no shifting of the channel at all and it will be any value more than

1.0 in case of rivers. For the present study, Rosgen classification (1994) of streams is

considered. In terms of sinuosity index, the major rivers of the district can be classified as

under

Table2: Classification of major rivers

Rivers SI-

Value

Type of

Sinuosity

Nature of Rivers

Damodar 1.09 Weak Almost straight in its entire course within the

district.

Sali 1.15 Weak Straight. SI increases towards its lower reaches.

Dwarakeswar 1.33 Moderate Sinuous in its entire course, higher in the areas

where it leaves the district.

Silabati 1.35 Moderate Most sinuous stream especially in its lower course

where SI-value becomes 1.4

Kangsabati 1.25 Moderate

Less sinuous in its upper course because of high

lithological control as well as the construction of an

earthen dam. SI increases towards the lower

segments of the river.

Note: Based on Sinuosity Index as calculated by the author


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From the study of changes in sinuosity index, the following aspects are found to exist in the

nature of alignment of the major rivers of the district:

1. No river in the district appears to be meandered as the SI-value of all the rivers over the

study period remains below 1.4.

2. Silabati River appears to be most sinuous. Sinuosity value varies from 1.34-1.36. This

stream is moderately sinuous.

a. Damodar river is least affected by natural process of meandering as it maintains

an almost straight flow in the district. SI-value remains 1.06-1.08.

3. Dwarakeswar river also shows a moderate SI. The SI increases downstream.

4. Silabati and Kangsabati rivers show a rising trend in SI during the study period

5. Damodar is the only river in the district shows a declining trend in SI. Thus it

gradually straightens its course during the time period. After the construction of the

dam it lost its original character.

6. Sali and Dwarakeswar river on the other hand show a fluctuation in its flow pattern.

The study further proceeded to analyse the change in sinuosity parameter of each major river

of the district by dividing them in a number of convenient segments (see figure-5). The change

of SI of the major rivers is studied separately as under:

4.2.1 Damodar River: The total length of Damodar river is only about 99 km in the district.

The first 30 km from the west of the district has shown fluctuating SI during the study period

while the last segment of about 42 km has shown a declining trend of SI during the period from

1.11 in 1972 to 1.09 in 2001 and 1.07 in 2011. This is due to the construction of dams in its

upper course and a barrage at Durgapur.

4.2.2 Sali River: This is the tributary of Damodar river flowing entirely within the district for

about 60 km in a more or less sinuous pattern. The sinuosity of all the segments of the river

during the study period has not shown any large scale change. It is remained within the range

of 1.18 in first 15 km and 1.47 in the last 20 kms of its course. However, it is found to increase

the SI in all its segments during the study period.

Figure 5: Sinuosity Index of Sali River


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4.2.3 Dwarakeswar River: The 132 km stretch of this river also does not show any large scale

bank shifting during the study period. The range of sinuosity between 1.08 and 1.46 states that

there is a pressence of structural control which does not permit the stream to shift its bank. In

the 4th segment of about 40 km where it flows through the alluvial flat lands, the SI value

sharply rises up to above 1.4. Interestingly it is found that there is a declining trend of SI since

1972 in this segment. The pressence of left-over palaeochannel in its bed states that the river is

undergoing through the phase of channel straightening thus leaving the bow-shaped channels

(see figure-6).

4.2.4 Silabati River: This river also shows small scale change in sinuosity over the years. The

entire course of this river is a bit more sinuous than the other rivers ranging from 1.25 to 1.48.

In the last segment of 22 km where it leaves the district has shown a sharp increase of SI from

1.28 to 1.46 (see figure-7).

Figure 6: Change of Sinuosity Index of Dwarakeswar River

4.2.5 Kangsabati River: Kangsabati river flows in almost straight course in its entire flow of

50 km within the district as its SI ranges between 1.04 and 1.24. There is no major change of

SI during the study period. This may be due to the construction of a dam at Mukutmonipur

which restrict the flow of the river as well as strong structural control made by its hard base of

granite and gneiss.

4.3 Lateral Entrenchment Ratio: It is the ratio between lengths of the two banks of a river as

expressed under:

ER= LL/LR

Where LL= Length of the left bank and LR= Length of the right bank


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It helps to identify the amount of bank shifting of a river. If the value remains 1 it means there

is no bank shifting. If it is greater than 1 that means channel has shifted towards its left

bank and ER less than 1 means the channel has shifted towards the right bank at the given

section of the river.

Figure 7: Change of Sinuosity Index of Silabati River

Figure 8: Change of Sinuosity Index of Kangsabati River


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Figure 9: Lateral Entrenchment Ratio of Major Rivers

The lateral entrenchment ratio has been calculated for the four major rivers of the district-

Damodar, Dwarakeswar, Silabati and Kangsabati. Sali river has been exempted from the study

because of the limitation of the satellite data used in the study. The low sesolution of MSS and

ETM+ does not allow to calculate the lengths of the two banks as this river appears to be a

single line stream in the imagery. The same is true for the rivers Dwarakeswar, Silabati and

Kangsabati in case of LANDSAT MSS image. However, during the last 10 years, it is found

that there is no change of lateral entrenchment ration of the three rivers. River Damodar shows

a fluctuating left to right bank shifting over the study period.

4.4. Profile Characteristics: The high resolution Digital Elevation Model (1 m contour

interval) of the district when superimposed on the drainage map gives a clear three dimensional

view of the stream flows of the entire district. From the model, long profiles of the major rivers

have been prepared. From the profiles it is found the nature of flow of the rivers as under

1. Sali river originated at about 120 metres high plateau fringe has a little ups and downs

through its course debouching in the river Damodar. It almost attained grade.

2. River Silabati and Kangsabati flows through eroded peneplain with an average

elevation of 60-80 metres. River Kangsabati has a sharp fall between 25-30 km of its

stretch from about 100 to 80 metres. This stretch lies just east of the Mukutmonipur

dam.

3. River Dwarakeswar has the maximum ups and downs through its upper and middle

course within the district. However, it flows almost regularly with very low gradient in

its last 40 km of the stretch towards the eastern part of the district.

4. As all the rivers flow through a tectonically ancient peneplain surface all the rivers have

attained grade as exemplified in their long profiles.

5. In terms of average gradient, Silabati river has the highest 1.94 metres per km followed

by Kangsabati 1.76, Sali 1.37 and Dwarakeswar 0.72 metres per km. This states that

Silabati and Kangsabati rivers flow through moderately sloping ground whereas

0.94

0.95

0.96

0.97

0.98

0.99

1

1.01

1.02E

ntr

en

ch

me

nt

Ra

tio

Lateral Entrenchment Ratio

1972 2001 2011


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Dwarakeswar flows through moderately sloping ground in its upper and middle course

in the district and in the eastern part it flows through flat alluvial surface.

Figure 10: Long Profiles of major rivers

Figure 11: Shifting of Dwarakeswar River

4.5. Change of Alignment of Major Rivers: From the study of sinuosity index and

entrenchment ratio, it is found that there is no large scale bank shifting occurred in all the major


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rivers during the study period. But the superimposition of the satellite images of two different

dates 1972 MSS and 2001 ETM+ shows that a small scale shifting occurred during the time

span. Out of four major rivers traversing the district, Silabati is found to be shifted maximum

followed by Dwarakeswar, Kangsabati and Sali river. The shifting of principal channels of the

major rivers is analysed separately as follows:

Figure 12: Shifting of Silabati River

4.5.1 Dwarakeswar River: The figure-12 shows shifting of three main courses –upper, middle

and lower within the district. In the upper course, five reaches have been selected from west to

east. It is found that the shifting gradually increases towards the lower reaches from 97 to 218

metres with an average shifting of about 160 metres. The middle and lower course of the river

is most affected by shifting of about 415 metres.

4.5.2 Sali River: During the last 30 years from 1972 to 2001, Sali river shifted about 218

metres. Among the seven reaches of the river selected, 5 reaches shifted towards the right i.e.

southwards with an average of 200 metres while the two reaches 4 and 5 shifted towards left

i.e. northwards. The average rate of shifting of the river during the study period is 7.5 metres

per year.

4.5.3 Silabati River: Silabati river appears to have shifted most in the district with an average

shifting of about 519 metres. In the middle course the shifting is higher (731 m) than its lower

course (360 m) within the district. The large scale shifting of the river states that the lithological

control is somewhat lesser in case of Silabati river.

4.5.4 Kangsabati River: During the study period thalweg of Kangsabati river has shifted at an

average rate of 8.3 metres per annum. As the lateral entrenchment ratio is unchanged during

the period, the shifting of the thalweg happens to be the major event. Although the study shows


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thalweg shifting of 5-8 metres per year, the channels remain same in appearance during the

entire time span. Every year during rainy season the thalweg of all the rivers shift to a great

extent. But this shifting occurs within the two banks and as the river banks are mostly composed

of hard crystalline rocks these are not vulnerable for bank erosion. A little bit of undercut is

found in the bank towards which the thalweg shifts.

Figure 13: Shifting of Kangsabati River

Thus lithological control is principal cause of almost no change in the alignment of the rivers

of the district under study. To conclude the study the following findings may be summed up

1. Drainage system of the district is well adjusted with its underlying geology.

2. Rivers of the district have a very long geological history

3. Major rivers did not shift at large scale during the study period.

4. Change of lateral entrenchment ratio is almost nil in case of the major rivers

5. Bank shifting of all the major rivers has not occurred during the period.

6. Silabati river is the most sinuous in the district. Sinuosity gradually increased during

the study period.

7. Dwarakeswar and Kangsabati river show fluctuating sinuosity.

8. Silabati river basin is most symmetrical in shape while Kangsabati river basin is most

assymetrical in character. Dwarakeswar basin is moderately assymetric.

9. All the rivers attained grade except Kangsabati.


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10. Maximum shifting of thalweg is found in Silabati river during the study period.

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