ASSESSMENT OF DYNAMIC MORPHOLOGICAL IMPACT ON BALARI BAR USING GEOINFORMATICS

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A Monthly Double-Blind Peer Reviewed Refereed Open Access International e-Journal - Included in the International Serial Directories.

International Research Journal of Natural and Applied Sciences (IRJNAS) ISSN: (2349-4077)

99 | P a g e International Research Journal of Natural and Applied Sciences Vol. 2, Issue 10, Oct 2015 IF- 2.818 ISSN: (2349-4077)

© Associated Asia Research Foundation (AARF)

Website: www.aarf.asia Email : [email protected] , [email protected]

ASSESSMENT OF DYNAMIC MORPHOLOGICAL IMPACT ON

BALARI BAR USING GEOINFORMATICS

Subhanil Guha1 , Anindita Dey2 1

Department of Geography, Dinabandhu Andrews College, Kolkata, West Bengal 2

Assistant Teacher, Nazrul Balika Vidyalaya, Guma, West Bengal

ABSTRACT

Balari Bar of Hugli estuary, located in the north-east of the Nayachara Island is one

of the important geomorphological features at the northern extent of the Bay of Bengal. It is a

small land, have accreted from the unconsolidated alluvium. Because of the proximity to the

coast, it is vulnerable to the tidal effects. During the last few years it has gained some

landmass due to heavy deposition. The present study has analyzed the erosional as well as

the depositional changes in and around the Balari Bar through a series of multi-temporal

satellite images. IRS 1C 28/11/99, IRS 1C 27/03/2000, IRS 1D 19/02/2001, IRS P6

20/11/2005 and IRS P6 28/02/2008 satellite imageries have been used for the present study.

The final result shows that the land area of the study is gradually increasing which depicts

that heavy deposition has been taken place during the recent years.

KEYWORDS: ALLUVIUM, ESTUARY, MULTI-TEMPORAL, TIDAL, VULNERABLE

INTRODUCTION

The Hugly estuary being a highly dynamic zone requires continuous monitoring and

updated information. Traditional methods are time-consuming and involves lots of manpower

and cost. Satellite image interpretation has the capability to monitor this dynamic

environment and record changes. The gradually increasing study area is located in the West

Bengal state covering parts of Purba Medinipur and South 24 Parganas districts. The

latitudinal extent of the study area is from 22001'00" North to 22005'00" North and

longitudinal extent of the study area is from 88007'00" East to 88011'00" East.

Several works have been done earlier on this context. An assessment was made on

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100 | P a g e An estimation was done on the erosional action of the coast of Sagar Island [2]. A research

was performed on space and time related changes of land surface parameters in the Red river

of the north basin [3]. Apart from these, an evaluation was made on the coastal erosion due to

wave dynamics operative in Sundarban delta [4]. Moreover, Landsat TM data was used in

order to design coastal morphological mapping around the Gulf of Khambhat [5].

GENERAL DESCRIPTION OF THE STUDY AREA

Balari Bar is situated almost in the middle part of the river Hugli, virtually divides the

river into two sub-channels. In the early phase of eighties, the Jellingham-Haldia channel was

navigable up to the Kolkata Dock. But because of the reduced flow, sediments started getting

deposited further up stream instead of compensating erosion in the sea-facing islands. As the

riverbed at Balari became gradually more shallow, the main downward flow of the river

captured the Rangafalla channel on the eastern side of Nayachara, thereby eroding the islands

of Lohachara, Bedford and Ghoramara. The details regarding the depositional growth of

Balari Bar have been minutely analysed through the multi-temporal satellite Image Analysis.

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101 | P a g e OBJECTIVE OF THE STUDY AREA

The main objective of the present study is to monitor the morphological changes

observed in and around the Balari Bar and its extended part using time series satellite images.

Remote Sensing techniques (viz. interpretation of satellite data) are applied to the study area

over the year 1999-2008. The visual interpretation as well as the digital image processing

techniques is applied for understanding the recent morphological changes arising out for

rapid growth of the Balari Bar and presentation of some hydrological parameters adjacent to

the study area are also needed for evaluation.

IMAGE INTERPRETATION

The morphological condition of the estuary is overviewed from the satellite images

covering the Balari Bar between the periods 1999 to 2008. The images considered for

comparison are IRS 1C 28/11/99, IRS 1C 27/03/2000, IRS 1D 19/02/2001, IRS P6

20/11/2005 and IRS P6 28/02/2008. The following results have been derived through the

analysis of the images-

 The overall health of the estuary was good in 1999.

 Balari Bar has been developed gradually since 1999.

 From 2005 image, depositional activity near Balari Bar is clearly visible.

 From 2008 image, it is clear that heavy deposition has been taken place in and

around the Balari Bar.

BALARI BAR DURING 1999 -2008

The images are processed to extract maximum information regarding the (i) growth of

the bar, extension of the sand tail both at upslope and downslope of the bar, (ii) adverse

growth of western edge of Nayachara (opposite to Haldi river confluence) and (iii) any other

erosion and/or deposition in the Haldia-Balari compartment.

Between 1999 and 2000 very small deposition has been taken place in west-central

part of Balari bar and small portion of central and southern part is eroded. From 2000 to 2001

a thin sheet of deposition has been seen in the total western part. A small sand bar is also

developed in the north-east side due to accretional activity. Between 2001 and 2005 the

southern portion of Balari bar was completely eroded and heavy accretion was seen along the

north-east part of the bar and two bars were completely joined. Some changes have been

taken place during 2005 and 2008. Erosional activities are seen only along the north-east

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102 | P a g e The formation of a knuckle in the western edge of Nayachara further restricts the flow

through Haldia-Balari region. The region encompassed by lower sand of Balari and

Guidewall not conducive to improve flow phenomena. The bed slope seems to be not

favourable for inducing flow from 2nd Oil Jetty.

Fig.2 Multi-temporal Satellite Imageries of the Study Area

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103 | P a g e RESULTS AND DISCUSSION

Remotely sensed data of different years have examined and interpreted through

logical process of detect, identify, measure and evaluate the significance of environmental

objects, pattern and spatial relationship. In addition to the inherent characteristics of objects

itself the following factors influence the image quality:- (a) Sensor characteristics, (b) Season

of the year and time of the day, (c) Atmospheric effects, (d) Resolution of the imaging system

and scale, (e) Image motion, (f) Stereoscopic parallax, (g) Exposure and processing Besides,

the following image interpretation keys are used for the study –shape, size, tone, shadow,

pattern, texture, site, resolution and association.

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104 | P a g e Table-1

Area of Balari Bar in Different Years

Table-2

Tidal Information synchronous with satellite passes

Fig.4 Overall erosion-accretion scenario of the study area during the full time-period

Year Balari bar-

Area(sq km)

1999 1.19

2000 1.1

2001 1.38

2005 3.9

2008 6.72

Serial Number

Date Name of

the satellite product with details Time of pass Tide in metre At Balari

1.

28-Nov-1999 IRS 1C LISS-III 10.30 AM 1.9

2.

27-Mar-2000 IRS 1C LISS-III 10.30 AM 2.12

3.

19-Feb-2001 IRS 1D LISS-III 10.30 AM 3.65

4.

20-Nov-2005 IRS P6 LISS-III 10.30 AM 3.68

5.

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105 | P a g e Table-3

[image:7.595.67.531.107.273.2]

Erosion-Accretion area of Balari Bar during the different time-periods

Table-1 shows the change of the entire study area from 1999 to 2008. In 1999 the area of the

Balari Bar was almost 1.19 sq km which become 1.38 sq km in 2001. At that time-period the

rate of deposition was comparatively slow than the later years. But, from 2001 to 2008 a huge

deposition has been taken place as the overall area becomes 6.72 sq km. The above

qualitative interpretations and analyses are provided on the basis of Software based satellite

data processing and calculation.

Table-2 reveals the tidal information synchronous with satellite passes throughout the

time-period. In 2001 and 2005 high tides ranges between 3.60 and 3.70 m has been recorded.

Hence, some land area may be invisible due to the submergence by tidal effect.

Table-3 depicts the relative comparison between the common area and also the area

under erosion and accretion during the different successive time-spans It is clear from the

table that the overall area under erosion is just 0.06 sq km in comparison to the 5.59 sq km of

area under accretion.

CONCLUSION

Balari Bar is a newly formed geomorphological feature in Hugli estuary and also a

very significant evidence to determine the complex morphological and tidal nature of the

area. It is a dynamic mixing zone of fresh water and saline water. The Bar is gradually

developed due to the high rate of deposition and hence because of the rapid areal growth of

the Balari Bar the Hugli river channel is deteriorating at very fast rate.

Period Balari Bar (Area in sq. km.)

Common Area Area of Erosion Area of Accretion

1999-2000 0.99 0.19 0.11

2000-2001 0.99 0.12 0.39

2001-2005 0.89 0.49 3.02

2005-2008 3.73 0.17 2.99

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106 | P a g e ACKNOWLEDGEMENT

The authors, thankfully acknowledges the Global Land Cover Facility (GLCF) centre,

National Remote Sensing Centre, Balanagar and Survey of India, Dehradun for providing

quality satellite image and topographical maps. The authors are also grateful to their guide

Prof. S.C. Mukhopadhyay, UGC Emeritus Fellow and Former Head of the Department of

Geography, Calcutta University for his guidance, mental support and valuable suggestions.

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