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INTERNATIONAL JOURNAL OF GEOMATICS AND GEOSCIENCES

Volume 3, No 1, 2012

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

Review article ISSN 0976 – 4380

Submitted on May 2012 published on July 2012 239

Monitoring of bank line erosion of River Ganga, Malda District, and West

Bengal: Using RS and GIS compiled with statistical techniques Bhaskar Das

1, Milan Mondal

2, Ajoy Das

3

1- Senior Research Fellow, West Bengal State Council of Science and Technology (DST),

Government of West Bengal

2- Senior Research Fellow, The University of Burdwan, Burdwan-713104,

3- M.Tech (GIS) student, NIIT University, Neemrana, Alwar District, Rajasthan- 301705

[email protected]

ABSTRACT

The creation of regional imbalance, inequalities and differentiation in India, starts with the

physiographic element and ends with economic, and socio-cultural parameters of the

inhabitants/population. An attempt has been made to analyze and report the river bank

erosion due to morphometric changes of the river Ganga ,Malda district making thus portion

a high risk zone. For that physical process namely river bank erosion may affect the

economic and socio-cultural aspects and creates drastic change over the period. Continuous

monitoring and maintenance of these flood induced river bank management are necessary for

the beneficial result. The distressed people demand a holistic and positive approach to tackle

the problem.

Keywords: River Migration, banks failure, paradigm shift, mitigation of disasters,

sustainable water resource management, remedial measures.

1. Introduction

Flood hazards can be regarded as uncontrollable extreme events that disrupt social structure

and impair essential functions which are necessary to support human life system. And the

“Management of fluvial systems’ addresses the everyday conflicts between river dynamics

and human investment in the landscape. The proper foundation of protection, and restoration

of rivers is a geomorphic assessment of the physical condition, sensitivity, and the

adjustment process of discreet stream reaches. The primary benefit of effective riverbank (or

stream bank) stabilization planning helps protect the civilization, assets such as open space,

infrastructure and riparian zone on or near the riverbank as well as the purpose to provide a

clearly defined decision process that will identify a strategy to carry out riverbank

stabilization works along sections of the river and major tributaries. In geonomic orientation

the shifting course of river Ganga is causing large scale disaster in terms of flooding and

bank failure in Malda and Murshidabad Districts, West Bengal, India. River bank

erosion/failure and flooding in these two districts have become a chronic phenomenon since

early’60s and the problem manifested itself to formidable magnitude during the last five

decades.

1.1 Objectives

There are several objective of this assessment. One of them is how the potentially dangerous

applied geomorphologic segments like river shifting, bank erosion display the chronic picture

and associated problem regarding human society in terms of loss of property need a pen

assessment. Another important issue of this study is to get the temporal shift measurement,

Monitoring of bank line erosion of River Ganga, Malda District, and West Bengal: Using RS and GIS

compiled with statistical techniques

Bhaskar Das, Milan Mondal, Ajoy Das

International Journal of Geomatics and Geosciences

Volume 3 Issue 1, 2012 240

engulfment of the village by the river or by the river capture of these blocks. Make a general

outline or future prediction in the forthcoming year like 2020, 2030and 2040 through some

statistical techniques can be regard important objective. Finally the main objective is to

analyze how this region and it’s environ will reach its sustainable development that make

emphatic to find this geomorphic hazard and to cover these voices by proper river

management system of stable future regarding this region economy.

1.2 Study area

For fulfilling the objectives, where the above mentioned problem and phenomenon are very

much chronic and serious, the study area has been selected over a part of Malda district of

West Bengal The main flood affected district under the study area is Malda, which consist of

15 blocks and total area is about 3455.66 sq.km. The most affected block of this natural

hazard are Manikchak, Kaliachak-II&III. These three blocks having a total area of about

approx 450sq.kms which has been reduced to about 340 sq.kms. The geographical extent of

the study area is from 24º 51' N to 25º 14' N and 87º 46' E to 88º 06' E (Figure 1).

Figure 1: Location of the Study Area

2. Literature analysis

A report by the Scientist of Dept. of science & Technology, West Bengal is a study based on

the generation the ‘Baseline’ data on sequential changes of the Ganga Padma/ Ganga –

Bhagirathi-Hooghly river system where delineating the nature and pattern of lateral

migration or oscillation of river in the human time scale, identifying the related

Geomorphological and geological features to conclude on morphogenesis of channel

migration. The root cause of bank failure is the presence of sandwiched fine sand layer on the

bank which cannot prevent the high velocity during the high discharge time. A paper by

Goswami, Sharma and Patgiri (1999) present 1) Alteration of the direction of the flow due to

neck cutoff. 2) Widening of a channel in response to bar development, 3) anabranches

development 4) progressive shifting of meander bends. A report by M.Banerjee on “the

impact of Farakka Barrage on the human fabric” emphasis the problem of the rural

impeverisation and marginalization and response to the situation faced by the human beings






of immediate erosional village areas of Malda districts. A report by CWPRS, Puna (2003)

recommended — The topographic feature of Ganga of Rajmahal in the vicinity of

Panchanandapur area are such that the bed level from right to left bank has a transverse slope

towards left bank. Water depth near the left bank of the order of 30mt. to 35mt. during flood

and 25mt to 30m. during non-monsoon period. Therefore construction of any spur or

revetments is not feasible. Recent development central channel was therefore thought useful

for reducing the attack at Panchanandapur area. To active this channels the alignment and

longitudinal profile of the proposed dredging may be adapted. According to the official

report by Irrigation and Waterways Dept.Govt.of West Bengal there could be number of

reason for the culmination of left swing and initiation of the right swing of main channel.

One of the possible reasons could be the progressive diversion of flow from the main channel.

A particular channel might have dominated over the other in course of time due to its more

favorable orientation and ultimately became the carrier of main flow.

3. Methodology

A systematic methodological principle was followed in this project work. This can be

explaining as follows:

i) Pre-field study: this study area as selected earlier, was identified in corresponding

topo sheet 78M/10 the spatial information have been collected from different Govt. office

like-water & Irrigation Dept, Malda, DST-Kolkata, District Welfare Office, D.L.R.O.,

B.L.R.O. and Block Office, Gram Panchayath office of Malda were also taken in to

considerations.

ii) Field study: Primary data were generated by interviewing people upon property desire

questionnaires through intensive field survey. The study of imperial observation can has been

done very carefully through measurement and analysis process to know the temporal shifting

of river Ganga and existing management structure.

iii) Post-field study: Data & other information made available & generating on the field

were compiled using appropriate software & techniques on the computer. The complied

analyzed data were interpreted appropriately to find out the temporal change detection.

3.1 Change of river bank line through extrapolation method

Figure 2: Change of River Bank line of Ganga






The morphological changes indicate an oscillating nature of the main channel in the reach

between Rajmahal and Farakka. In brief 1936 –37 map shows the river Ganga was flowing

along both banks of midstream island Bhutni. 1948-50 survey shows that the river had a

tendency to shift to the left below Rajmahal to Farakka Since 1967-68 the bank line is

moving east ward. The present state of the river falls within the phase of leftward swing.

During this phase, the left bank between Farakka and Khaskol receded further inside the

country than that of the earlier one (Figure 2).

3.2 Change of river embankment line through extrapolation method

3.2.1 For calculation in the year 2009

Method: Simple extrapolation

In h1 calculation X2 & X1 are variables which are changes through the various Cross

sections (Table 1).

Table 1: Calculation using linear extrapolation method

3.2.2 Calculation for the year 2009

3.2.2.1 Linear extrapolation method






h1/h = AD/AE=2009-1977 CQ=CD+DQ=H1+OA

=32/28=8/7 =h1 (932.57) +2297.95=3230.52

h1=(x2-x1)8/7

= (3113.7-2297.5)8/7=932.57

3.2.3 Method: Logarithmic extrapolation

In h1 calculation X2 & X1 are variables which are changes through the various Cross

sections (Table 2).

Table 2: Logarithmic extrapolation (Units in km)

First of all data in respect of cross sectional area were extracted for the year 1977 (from SOI

Toposheet), 2006 & 2009 (from Satellite images). Using linear extrapolation method, data of

2009 were generated synthetically from the data of 1977 & 2005 and compared with that of

image data. It was found that there is gross mismatch in the above mentioned compared data.

Subsequently using Logarithmic extrapolation techniques, data of 2009 were again generated

from the data of 1977 & 2005 and the comparison was made. The logarithmically

extrapolated data of 2009 were found to be very close to that of the satellite image data of

2009. Accordingly Logarithmic extrapolation technique was adopted for future years also

(Table 3 and Figure 3). Up to year 2040 such data were generated synthetically and given in

the following table

Table 3: Future Shifting of River Ganga (Units in meter)






Figure 3: Future Statistical Scenario of Ganga River in 2020, 2030 and 2040

From above statistical calculation and explanation it may be outlined that the channel width

is changing in higher magnitude over time. One cause may be that due to the sedimentation

and high discharge the lateral bank failure become high. The higher channel width

incorporate with the higher island and higher braidedness .So these sample shows very much

correlated along the cross section.

3.3 Spacio-Temporal Change Analysis between the year 1990 and 2006

Table 4: Areas under Land use/Land cover classification map and statistics from 1977, 1990

and 2006 Satellite Imagery

1977 1990 2006 Land use

category Area in

hectare

Area in

hectare

Area in

hectare

Change Area is hectare

Agriculture 14596.46 13146.88 23415.19 Increase 10267

Marshy

Land

1943.56 3687.44 1373.44 Decrease 2315

Barren

Land

8528.30 57253.13 5705.05 Decrease 51547

Sand Bank 4215.58 4642.69 4155.44 Decrease 488

River 14005.14 15599.69 17004.67 Increase 1405

Fallow

Land

17889.32 13488.13 5188.13 Decrease 8298

Plantation 6704.96 7327.19 10397.78 Increase 3070

Schrub 2937.42 4674.25 3282.65 Decrease 1390

Source: District Agriculture Dept, Malda






There are eight land use/land cover training sites have been made on the basis of above

mentioned ground control point and visual signature identification (Table 4). Then maximum

likelihood classifications algorithm has been run. This algorithm reads the signatures set DN

values and give others according to their nearest class values. On the basis of this algorithm

the resultant maps give following data of the land use land cover distribution of an area

covering this region.

3.4 Flood Induced River Bank Management Aspect

Apart from an effective disaster response system, it is important to have a good flood

prevention and mitigation system to achieve objectives of vulnerability reduction. The

erosion has taken an alarming magnitude because of low level of technological adjustment

and ill directed planning (Figure 4). Geomorphologists think that a river is a living reality

that needs space. Deltaic rivers shift constantly, varying from one extreme right bank point to

another on the left bank, may be over centuries, perhaps over decades. The behavior of a

river can be defined in terms of the rhythm of environmental systems. But the absence of

proper attention to the basic delta building geomorphological processes is the cause of

unexpected accelerated rate of bank erosion. The engineer’s view is that the construction of

embankments, spurs etc. are the immediate solution when it is becoming a national disaster.

Plate 1: Picture of River Ganga bank erosion






Figure 4: Standard operating procedure for managing flood hazard.

3.5 Component of Floods Preparedness Plan

A flood preparedness plan (FPP) which is an integral component of the multi-hazard disaster

management plan, is an action oriented document detailing specific actions to be undertaken

prior to floods, which set the ground for effective execution of emergency response and

recovery activities during and after floods. The components of a FPP are

1. Assessment of probable needs.

2. Institutional Mechanism for implementation of FPP.

3. Activating early warning and disaster response systems.

4. Resource mobilization and allocation.

5. Communication within and outside the community.

6. Sectoral components.

4. Suggestive measures

After analyzing lots of committees periodical report, papers and articles about the

examination the river Ganga left bank erosion Problem , some suggested remedial measures

may be

1. By construction of two long spurs on the left bank and dredging of a poll of channel

downstream of Rajmahal on the right Bank.

2. By deflecting the flow away from the left bank by spurs.

3. By construction of two long spurs on the left bank and dredging of Rajmahal channel

which was opening up.

4. Right channel development is a favorable condition and if dredging accelerates, it, the

channel may be develop the 1967 course.

5. To make the River flow along a more or less straight course between Rajmahal and

Farakka and river approach was more or less axial to the Farakka Barrage.

6. Diversion by dredging of the central channel to minimize erosion as according to this

study the Right channel was not getting activated by natural process.






7. Dredging the off take reach of Right Channel and did not favour the idea of opening

the central channel by dredging.

8. Proper catchment area treatments.

Plate 2: Some structures suggested

4.1 Effectiveness of control measures in High Risk Zones (HRZ)

The high risk villages of river Ganga in between Manikchak, Kaliachak II & III Blocks and

also the moderate danger villages, the measures adopted to control erosion and flooding were

as follows

1. Construction of Short spurs to divert flow from attacking the bank line.

2. Construction of bed Bars, falling apron and revetment to safeguard the bank under

erosion.

3. Constriction of retired embankment to avert flooding as and when the forward

embankment was danger.

5. Conclusion

This case study demonstrates a proper application of RS and GIS and Statistical technique

corresponding with geographical approach to river bank erosion and management system

with a strong focus on working at the scale of local to focal level. Although covering just a

short section of the river, the project demonstrates the potential for applying similar

approaches at a much wider scale to promote a locally based ‘stewardship’ ethos but this

'base line' data may be considered as a synergetic tool by the decision makers/ planners/

executives for better understanding to put effort in setting up related technical aspects and

social adaptations in monitoring of the recurrence of the natural disasters (flooding, bank

failures etc.) upon the stretch of the Ganga.

Acknowledgement

We would like to express our gratitude and sincere thanks to all the Senior scientists of

Department of Science and Technology, WBSCST, Bikash Bhavan, Salt Lake, Kolkata-






700091. Specially thanks to Dr. Dipankar Das (Senior Scientist, DST) for his kind advice,

suggestions and efforts towards preparation of this paper.

6. References

1. Banerjee M. (2003), A report on The impact of Farakka Barrage on human fabric,

Dams, River and People, South Asia network on rivers, dams and people, New Delhi.

2. Banerjee, S.N. & Chakraborty, P. (1983), Some observations on recent trends of

shifting of the Ganga between Rajmahal and Ahiron, Journal of the Geological

Society of India, 24, pp 318-321.

3. Chakraborty.P and Choudhury.S: Ganga Padma River: Bank Failure and changing

Courses- Down the Ages.

4. CWPRS Pune: Technical Report, Hydraulic Model on River Ganga from 1986 to

2005.

5. Das A. et. Al., (2012), Analysis of drainage morphometry and watershed

prioritization in Bandu Watershed, Purulia, West Bengal through Remote Sensing and

GIS technology - A case study, International Journal of Geomatics and Geosciences,

2(4), pp. 1005-1023

6. Das, Ghanashyam (2000), Hydrology and Soil Conservation Engineering, Prentice

Hall of India, New Delhi

7. Ghani M.U (2007), Participatory strategy for Flood Mitigation in East and North east

India.

8. Mukhopadhyay.S and Mukhopadhyay.S., Bank Erosion of River Ganga, Eastern

India –A Threat to Environmental Systems Management.

9. Nath S.K, Roy D and Singh K.K., (2008), Disaster mitigation and management for

West Bengal, India – An appraisal, Current Science, 94(7), pp 858.

10. National Remote Sensing Centre: Landuse/Landcover-50k (2005-06), Department of

Space, Government of India.

11. Ray. S.C. (2004), A study Report on Control of left Bank Erosion of River Ganga

between Rajmahal and Farakka by Irrigation and water ways Dept. Govt. of West

Bengal.

12. Rudra.K. (1996), Problems of river bank erosion along Ganga in Murshidabad district

of W.B., Indian Journal of Geography and Environment, 1, pp 25-32.

13. Rudra.K. The encroaching Ganga and Social conflicts: the case study of west Bengal,

India, Independent Broadcasting Associates, Littleton, MA, pp 40.

14. Seethapathi P.V, Dutta D, and Siva Kumar R., (2008), Hydrology of Small

Watersheds (eds), New Delhi: TERI (The Energy and Resources Institute).

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