Landuse / Landcover change study of Jharkhali Island ... · Jharkhali, an island in the Sundarbans, is situated between two mighty rivers, Matla (on the west) and Bidya (on the east)

INTERNATIONAL JOURNAL OF GEOMATICS AND GEOSCIENCES

Volume 3, No 2, 2012

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

Research article ISSN 0976 – 4380

Submitted on Septmeber 2012 published on November 2012 299

Landuse / Landcover change study of Jharkhali Island Sundarbans, West

Bengal using Remote Sensing and GIS Kaberi Samanta, Sugata Hazra

School of Oceanographic Studies, Jadavpur University, Jadavpur, Raja S.C. Mallick Road,

Kolkata – 700032, West Bengal, India

[email protected]

ABSTRACT

Jharkhali, an island in the Sundarbans, is situated between two mighty rivers, Matla (on the

west) and Bidya (on the east) covering an area of about 161 sq.km (2009). The landuse /

landcover maps of the Jharkhali island have been prepared from the satellite data and field

checking. The time series analysis of land use / land cover changes of this area for the period

1986-2009 reveals a virtual disappearance of the mangroves of Namkhana Reserve Forest. A

forest area of 12.400 km2

has been found to be converted into aquaculture farms or

agricultural fields. Others changes involve conversion of small waterbodies and marginal

erosion of the western blank of the island. A further conversion of 34.152 km2

agricultural

land into settlements is attributed to the growing population pressure in this Biosphere

reserve area, World heritage site, and proposed Ramsar Site.

Key words: Sundarban, Landuse change, Population pressure, Deforestation, Aquaculture.

1. Introduction

Landuse is the human modification of natural environment or wilderness into built

environment such as fields, pastures and settlements. Landcover is the physical material at

the surface of the earth. These two terms are very interrelated as landcover is the type of

features that exist on the earth and landuse is the economic utilization of land (Lillesand and

Keifer, 1994). Knowledge of landuse and landcover change is important for many perspective

planning and natural resource management initiative. Change detection analysis using multi-

temporal satellite data attempts to discriminate areas of landcover change between dates of

imaging. Remote Sensing data have been widely used in change detection analysis. Various

methods are developed for this type of study and the most commonly used technique is image

differencing, principal component analysis and post classification comparison. In this paper

the later technique has been used. In recent years the spectral mixture analysis, artificial

neural networks and integration of geographical information system and remote sensing data

have become important techniques for change detection applications. Research is still going

on to find out the best and effective way of change detection technique (Lu et.al., 2004).

Though landuse categories identified on ground do not undergo significant changes within

short time, dynamic changes are inevitable over a longer time window. These changes may

be due to natural causes, catastrophic disturbances, and also due to human interventions. The

present study area as shown in figure 1 is an island in the Sundarbans (21º59'34.25"N -

22º13'23.98"N latitude and 88º37'23.96"E - 88º48'38.88"E longitude.), the largest mangrove

ecosystem in India, located at the estuary of the Hugli-Matla-Ichamati river system. It is

found that the mangroves of this region has been cut down to utilize it to some economic

activities specially aquaculture farms. The case study area is unique in the sense that it

Landuse / Landcover change study of Jharkhali Island Sundarbans, West Bengal using Remote Sensing and

GIS

Kaberi Samanta, Sugata Hazra

International Journal of Geomatics and Geosciences

Volume 3 Issue 2, 2012 300

comprises the Reserve forest (Namkhana) area under Biosphere Reserve Programme of the

Sundarbans, yet stands as an evidence of the most recent anthropogenic deforestation event.

2. Materials and methods

This paper aims to evaluate the magnitude and direction of landuse change in a partially

protected environment of Sundarbans, and to identify the natural or anthropogenic factors

responsible for such changes. The analysis has been done with the help of Remote Sensing

data with relevant field verifications. The area calculations have been done in the GIS

environment. The first data was Landsat TM digital satellite imagery (date of acquisition –

19th

January, 1986) and the second one was IRS P6 LISS III digital satellite imagery (date of

acquisition – 8th

February, 2009). The study was based on digital as well as vector based

analysis in ERDAS IMAGINE 9.0 and ARCVIEW software.

Multidated (Jan 1986 and Jan 2009) digital satellite data of Landsat TM sensor and Indian

Remote sensing satellite IRS P6 Linear imaging Self Scanning sensor (LISS III) acquired

from NRSC (National Remote Sensing Centre, Hyderabad) were used for this study. The

satellite data were compared with topographical map of Survey of India (SOI).

Analysis and interpretation of satellite data was done by digital image processing using

ERDAS imaging and ARC GIS software. Accuracy test was also performed by ERDAS

imaging software to confirm the procedure / classification (Manonmani and Mary Divya

Suganya, 2010; Mahdavi et.al., 2010). The satellite data procured were of similar tidal

condition for the scale of the map and this helped in assessing the erosion and accretion of the

Jharkhali island. Distribution of the landuse / landcover features (Dense Forest, Settlement

with vegetation, agricultural land, aquaculture farm, mudflats) were cross checked during the

field survey conducted in 2010. Extent of change in landuse pattern was evaluated by

classification of satellite imagery of 1986 and 2009. Demographic data of the 1981, 1991 and

2001 census were used in this study.

Figure 1: Location map of the study area


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3. Results and discussions

During 1986 – 2009 the area which remained unchanged was about 78.989 km², the erosion

was about 4.193 km² and accretion accounted to be about 2.288 km². A Supervised

Classification by Maximum Likelihood Classifier is operated on each dataset by marking the

training sets.

There is a possible relationship between increasing trend of population with rising settlement

with vegetation area, decline in the forest cover, shifting of economy from agriculture to

aquaculture.

Figure 2: Landuse / Landcover map of Jharkhali Island (1986)

Figure 3: Landuse / Landcover map of Jharkhali Island (2009)


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Figure 4: Variation in area of different Landuse / landcover categories (1986 – 2009)

Table 1: Table showing the Landuse/ Landcover classes and area in sq kms of Jharkhali

Island for the years 1986 and 2009

Sl.No Landuse / Landcover

classes

Area in sq.kms

(1986)

Area in sq kms

(2009)

1 Dense Forest 17.090 5.020

2 Settlement with Vegetation 29.116 63.832

3 Agricultural Land / Other

vegetation 95.938 65.081

4 Aquaculture Farm 5.209 5.040

5 Water Body / Marsh /

Swamp 8.103 6.699

6 Mud Flats 9.018 2.822

7 Deforested Land - 12.400

Total 163.803 160.894

Table 2: Table showing the land transformation matrix between 1986 - 2009


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During 1986 – 2009 the area which has remain unchanged is about 78.989 km², the erosion

was about 4.193 km² and accretion accounted to be about 2.288 km².

Figure 5: Population density map of Jharkhali Island (Basanti Block) – Year - 1991

Figure 6: Population density map of Jharkhali Island (Basanti Block) – Year – 2001


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Figure 7: Year wise Population growth with settlement (1986-2009)

Figure 8: Year wise decline of agricultural land with increasing settlements (1986-2009)

Figure 9: Year wise Population growth with depletion of forest cover (1986-2009)


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3.1 Erosion and accretion

From the above Table no 1 and 2 it is apparent that the erosion is greater than accretion and it

is observed at particular stretches of the island which is otherwise protected by landmasses

from the sea. The erosion is amounting to be about 4.193 km2

and accretion is about 2.288

km2

within the time frame of 23 years. In Table no. 2 the land transformation matrixes

between two existing baseline years have been detailed.

3.2 Forest cover changes

The most significant change that has been noticed in this area is partial deforestation of the

existing forest area at the southern part of the island and this portion is identified as

deforested land. Later this deforested area has been reutilized as settlement area, aquaculture

farm and agricultural land. From Figure. 2 & Table. 1 it is observed that Mangroves were

prevalent at the southeastern edges all along the Jharkhali Island and a considerable patch

existed at the southern part of the island as a remnant of Namkhana Reserve Forest. By the

year 2009 12.400 km2

of Namkhana Reserve Forest of 1986 has been entirely converted to

deforested land as observed from the Figure. 9. The deforested area has increased from 6.555

km² to 11.797 km² during 1986 – 2009, leaving behind 1.638 km² remnant of the previous

reserve forest. This has been done apparently not in conformity with the Forest Conservation

Act (1980/1988) and the Coastal Regulation Act (1991). However there is also an addition of

2.277 kms2

of forest area as some mudflats have been colonized by mangroves There is also

some positive sign that some of the amounting to an addition of to forest area. The amount of

regeneration of mangrove in the Jharkhali island is about 3.922 kms2 from 1986 to 2009.

3.3. Changing settlement with vegetation and agricultural land with population pressure

The population pressure is increasing at a faster rate than the increase in the settlement area

which is quite prominent from the Figure. 7. The maximum change in the island is noticed in

the agricultural sector which involves conversion of 34.152 kms2 of

agricultural land into

settlement with vegetation. The history behind this conversion of forest area into agricultural

land and settlements can be traced back to the refugee rehabilitation program during 1952 –

60. The swampy areas of 5.655 kms2

have been well utilized by settlement in due course of

time. The census report portrays that in 1991 the population was about 92276 while it

increased to 113639 during 2001 (Census of India 1991 and 2001). Population has played a

significant role in reduction in the agricultural area (Figure 8) from 95.938 km² to 65.081 km²

(1986 – 2009) while the settlement has increased to 63.832 km² from 29.116 km² (1986 –

2009). The decrease in the agricultural sector leads to the reduction in the per capita

availability of agricultural land. The percentage share of agricultural land and settlement with

vegetation was about 76.71 and 23.29 respectively in the year 1986 while it became nearly 50

– 50 in the recent years. From the HDI report prepared by Govt. of West Bengal, it is

understood that the area under total foodgrains was about 437.8 (’000 hect) in the year 2000-

01 while it came down to 410.0 (’000 hect) in the year 2004-05 for South 24 Pgs (Human

Development Report 2007), where Jharkhali has a significant contribution.

3.4 Aquaculture farms

Aquaculture Farm areas have been found to be increasing and it is presently about 5.04 km²

(2009). The matrix ( Table 2) shows Aquaculture Farms have grown at the expense of the


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Namkhana Reserve Forest. There are numerous small aquaculture farms all over the island.

Aquaculture farms which were left as dry are made economically viable in recent years. From

field observations it has been found that brick kilns which have become more profitable in

the recent years have started coming up along the fringes of the aquaculture farms. There is a

notable decrease of Water Body / Marsh areas from 8.103 km² to 6.699 km².

4. Conclusions

The landuse change dynamics of Jharkhali island indicate prolonged anthropogenic pressure

on a fragile ecological niche of the World Heritage Site (UNESCO, 1989) of the Sundarbans.

There are other areas in Gosaba and Hingalganj where similar changes have taken place in

recent times. Of late, serious conservation efforts have resulted in partial regeneration of

mangroves in mudflats, as evidenced from recent satellite images. However among the

erstwhile 9600 km2

forested area of Sundarbans, only 4225 km2

forest area remains, which

have restricted access to mankind.

5. References

1. Lillesand, T.M., and Keifer, R.W., (1994), Remote Sensing and Image Interpretation

(5th Edition), John Wiley and Sons Inc.

2. Lu, D., Mausel, P., Brondizio, E., and Moran., E., (2004), Change Detection techniques,

International Journal of Remote Sensing, 25(12), pp 2365-3401.

3. Manonmani, R., and Mary Divya Suganya G., (2010), Remote Sensing and GIS

Application in Change Detection Study In Urban Zone Using Multi Temporal Satellite.,

International Journal of Geomatics and Geosciences, 1(1), pp 60-65.

4. Mahdavi, A., (2010), IRS-1C image data applications for landuse / landcover mapping in

Zagros region, Case Study: Ilam Watershed, West of Iran., Caspian Journal of

Environmental Sciences, 8(1), pp 35-41.

5. Forest Conservation Act (1980), with Amendments Made in 1988, Ministry of

Environment and Forest, available at http://envfor.nic.in/legis/forest/forest2.html,

accessed during June 2012.

6. Notification under Section 3(1) and Section 3(2)(v) of the Environment (Protection) Act,

1986 and Rule 5(3) (d) of the Environment (Protection) Rules, 1986 Declaring Coastal

stretches as Coastal Regulation Zone (CRZ) and Regulating Activities in the CRZ, New

Delhi, 1991 (as amended up to 3rd October 2001), available at

http://www.moef.nic.in/legis/crz/crznew.html, accessed during June 2012.

7. Census of India, Ministry of Home Affairs, Government of India, available at

http://censusindia.gov.in/, accessed during June 2012.

8. Human Security and Vulnerability, Human Development Report, Chapter 7, (2007)

available at http://wbplan.gov.in/HumanDev/DHDR/24%20 pgsSouth/ Chapter%

2007.pdf , accessed during June 2012.

Documents

Landuse / Landcover change study of Jharkhali Island ... · Jharkhali, an island in the Sundarbans, is situated between two mighty rivers, Matla (on the west) and Bidya (on the east)